• TITLE

    Big Idea

    Thesis Statement: Is grass fed beef intrinsically healthier for human consumption than grain fed beef? If so, what characteristics make it that way? Is it more of a quality of the feed, or a quality of their lifestyle? Should humans be recommended to consume grass fed over grain fed beef?

    Thesis Statement: A growing consumer preference trend for grass-fed beef has [ ] called for change word a closer examination in the difference between feeding regimes. Older research focused on general carcass characteristics like color, palatability, and shear force, while newer studies are examining detailed information about fatty acid composition profiles, ratios, and biochemical pathways that feed takes from mouth to meat. While many studies present conflicting evidence, a general trend can be seen that grass-fed beef has a lower total fat content and higher beneficial fatty acid concentration than concentrate-fed beef, although concentrate-fed beef generally has higher palatability, color, and marbling scores. Extrapolation to the implications for human health is difficult since diet recommendations are not universal and differences in forage quality and concentrate composition make lipid profiles change from producer to producer. In general, a consumer wishing to purchase red meat that will supplement a low-saturated-fat diet should look for grass-fed beef. Further research is necessary to conclusively indicate that grass-fed beef has a healthier nutritive value than conventionally-fed beef, and that research will better assist consumers in making informed dietary choices for their meat consumption.

  • Abstract

  • Introduction

  • Discussion

  • Conclusion

  • Literature Cited

  • Thesis Statement: A growing consumer preference trend for grass-fed beef has [ ] called for change word a closer examination in the difference between feeding regimes. Older research focused on general carcass characteristics like color, palatability, and shear force, while newer studies are examining detailed information about fatty acid composition profiles, ratios, and biochemical pathways that feed takes from mouth to meat. While many studies present conflicting evidence, a general trend can be seen that grass-fed beef has a lower total fat content and higher beneficial fatty acid concentration than concentrate-fed beef, although concentrate-fed beef generally has higher palatability, color, and marbling scores. Extrapolation to the implications for human health is difficult since diet recommendations are not universal and differences in forage quality and concentrate composition make lipid profiles change from producer to producer. In general, a consumer wishing to purchase red meat that will supplement a low-saturated-fat diet should look for grass-fed beef. Further research is necessary to conclusively indicate that grass-fed beef has a healthier nutritive value than conventionally-fed beef, and that research will better assist consumers in making informed dietary choices for their meat consumption.

  • Definition of Grass Fed and USDA Marketing Claims

    • Consumer preference changes
    • Marketing numbers for grass-fed and the difference in prices— has this been caused by a change in consumer preference? Is there really a need for the higher price if consumers are buying it for health reasons?
    • Overview of how FA and PUFA affect human health
    • 3 factors in determining health from FA- n-6:n-3, P:S, etc.
    • Trans FA and the role they play
  • Early Data

    • Yellow color in fat
    • Palatability findings
    • How did forage and grass ideas change since the 70s?
  • Recent Findings

    • Fatty acid comparisons- different between studies, might have to dig
    • Overall carcass quality and carcass weight differences
    • P:S ratio and n-6:n-3 ratio differences
  • Human Health Diet Implications

    • Conclusion of what the differences in n-6:n-3, P:S, total FA concentrations mean to human health
    • Red meats can be substituted for fish for a source of n-3
    • trans fatty acid levels in grass fed beef
  • #BIG HEADING

    Smaller Heading

    Smallest Heading

    Bold Italicize

    Later- look up different source

    #ABBRIEVATION = DEFINITION

    SOC

    #SOC

    #SOC

  • Future Research: What Needs to Be Done?

    • RNA Sequencing study (Yaokun et al., 2015) could help prove that diet changes the biochemistry of the animal, which could open doors for further manipulation of efficiency could help reduce environmental impact of grass-fed if compare different forages that give overall beneficial impact on microbial populations?
    • Further manipulating grass-fed diets to give the best overall composition of fatty acids to human health
    • Further studies on mineral differences (iron)
    • For human health purposes: amount of minerals in the meat, which will be largely affected by the minerals in the soil maybe quote Dr Jones quivira presentation?
    • ROOM FOR ERROR: How it’s difficult to compare and contrast these studies without really digging into the differences between geographic location, genetic variations, microbial populations, feedstuff differences, etc. Going to have to take a very general overview of all statistics given and go with general trends, and even those are changing over time
  • Overall, data has been mixed and inconclusive regarding the levels and health benefits of omega-3 fatty acids present in grass-fed beef. Until such time as the role of fatty acids in human health is more fully understood and the Food and Nutrition Board of the Institute of Medicine can recommend a dietary intake, grass-fed beef cannot be regarded as beneficial in that regard (Clancy, 2006). However, there is sufficient evidence to conclude that grass-fed beef can be labeled as lean and lower in total fat than conventionally fed cattle (Clancy, 2006).

  • Bringing it all together

    • Grass fed beef is not necessarily more healthy
    • What matters is what the animal is fed TMR: a forage component to the diet (or mostly forage with some concentrate supplements) can have a beneficial effect on the total fatty acid profiles
    • If consumers want to tailor their meat choices to a healthy diet, should go generally with grass-fed (only low-fat healthy diet)
    • Overall, need a lot more research to justify the huge premiums and switch from feedlot to pasture
  • Yoakun, et al. 2015

  • Kurve, et al. 2015

  • Enser, et al. 1998

  • Ponnampalam, et al. 2006

  • Capper, J.L. 2012

  • Harrison, et al. 1978

  • Daley, et al. 2010

  • Leheska, et al. 2014

  • French, et al. 2001

  • USDA. 2016

  • USDA. n.d.

  • Biensen, 2016

  • National Agricultural Statistics Service, 2016.

  • Agricultural Marketing Service, 2016.

  • Pasiakos, et al., 2015

  • McNeill, 2014.

  • USDA & US Dept of Health & Human Services, 2015

  • White, 2014.

  • Clancy, 2006

  • “By definition, grass-fed means an animal has spent its entire life on grass or other green plants, from birth to death” (White, 2014).

  • As of January 1, 2016, the total of all cattle and calves in the United States was 92.0 million head. This total is up 3% from January 1, 2015 (National Agricultural Statistics Service, 2016).

  • The USDA certification of grass-fed beef allowed producers to market their meat with a lucrative premium. In January 2016, the last month that the USDA condoned the certification, the USDA Market News reported the average price of a wholesale grass-fed ribeye steak at $14.50-22.80/lb (Biensen, 2016). A direct-sale grass-fed beef ribeye steaks sold for an average of $19.50/lb (Biensen, 2016). In contrast, the National Retail Report for the week of February 19-25, 2016 reported the weighted average price of a boneless ribeye steak at $9.83 (Agricultural Marketing Service, 2016). These prices limit the sales of grass-fed beef to customers who can afford the premium, and has probably contributed to the controversy surrounding its health claims. Is grass-fed beef worth the pricey premium for better health benefits?

  • Before 2016, “grass-fed beef” was defined by the Agricultural Marketing Service of the United States Department of Agriculture as a small-scale production system. The producer could market under forty-nine cattle per year or lambs from ninety-nine ewes per year. The animals had to be entirely fed by grass and forage, and could not be fed grain or “grain by-products”. The two-year certification period also guaranteed that they were raised with continuous access to pasture during appropriate seasons. Meeting those requirements would allow the producer to market their products as USDA Certified Grass-Fed (UDSA, n.d.)

  • In 2012, grass-fed beef operations certified by USDA’s Grass Fed Small & Very Small Producer Program contributed 11.5% of all cattle and cow-calf operations in the United States, or 640,000 head. Sheep producers made up 29.5% of all ewe flock operations and 32.4% of total inventory of ewes and lambs, with 59,127 producers certified by the USDA (USDA, n.d.).

  • The USDA certification of grass-fed beef allowed producers to market their meat with a lucrative premium. In January 2016, the last month that the USDA condoned the certification, the USDA Market News reported the average price of a wholesale grass-fed ribeye steak at $14.50-22.80/lb (Biensen, 2016). A direct-sale grass-fed beef ribeye steaks sold for an average of $19.50/lb (Biensen, 2016). In contrast, the National Retail Report for the week of February 19-25, 2016 reported the weighted average price of a boneless ribeye steak at $9.83 (Agricultural Marketing Service, 2016). These prices limit the sales of grass-fed beef to customers who can afford the premium, and has probably contributed to the controversy surrounding its health claims. Is grass-fed beef worth the pricey premium for better health benefits?

  • Consumer preferences have changed over time to favor leaner cuts of red meat, driven by newer dietary guidelines that recommend increased consumption of lean proteins and lower fat. Meat production has changed in response and currently approximately two-thirds of the beef sold in the United States meets government guidelines for lean (McNeill, 2014). Nevertheless, misconceptions are still present, especially given the common American dietary pattern of “high intakes of refined grains, sugar and red meat… associated with increased risks for certain types of cancer, coronary heart disease, diabetes, and obesity” (McNeill, 2014).

    The recommended dietary patterns for Americans has changed drastically over the last few decades. In 2011, the World Cancer Research Fund/American Institute for Cancer Research Project released a statement condemning red meat as a correlation factor for colorectal cancer (McNeill, 2014). The statement has since been retracted after more research lead to inconsistent results, but the process of looking for “healthier” and lower-fat red meat had been jumpstarted. As beef is the predominate red meat consumed in most developed nations, beef production systems were examined for meat characteristics that could be manipulated.

  • Most of the beef produced until the 1940’s was from cattle finished on grass. During the Green Revolution of the ‘50s, the feedlot generation was begun and high energy grains decreased the time cattle spent on feed and improved marbling (intramuscular fat). US consumers have “grown accustomed” to the taste of grain-fed feed, but changes in consumer demand coupled with new research on the effect of feed on nutrient content, “have a number of producers returning to the pastoral approach to beef production despite the inherent inefficiencies” (Daley et al., 2010).

  • Research conducted at the Kansas Agricultural Experiment Station in 1978 was an early example of exploring the growing trend of grass-fed beef. Thirty-eight steers were divided into four separate dietary regimes: grass-fed only (winter forage ration, summer grazing); short-fed (grass-fed and finished for 49 days in a feedlot); long-fed (grass-fed and finished for 98 days in a feedlot) and forage-fed (finished for 98 days in a feedlot on a high forage ration). The study found that increased feeding gave higher marbling scores and quality grades, carcass weight, fat thickness, and overall higher taste panel scores. They concluded, “carcasses from cattle fed the longest time and the highest plane of nutrition had the most desirable quality and palatability characteristics” (Harrison et al., 1978).
    Other carcass characteristics that were assessed showed differences due to feeding as well. Meat from the grass-fed group had the yellowest fat, the least marbling, and “barely graded low Good” for quality scores (Harrison et al., 1978). They found that carcass weight increased with length of feeding, and that grass-fed cattle had the overall lightest carcass weight (Harrison et al., 1978). The study gave overwhelming evidence against the quality of grass-fed beef. All of the carcass qualities tested showed that the long-term feedlot group had highest quality and palatability, and while short-term feeding and forage-feeding had some middle ground, the grass=fed group inevitably ended up with the lowest scores.

    The beef strip steaks from grass-fed group had more yellow fat and less marbling than grain-fed control beef (Leheska et al., 2014). Fat color can be altered as a result of the greater level of vitamins like beta-carotene, or because of the changes in the fatty acid profile (Leheska et al., 2014).

  • Fatty Acid Comparisons

    Areas that allow for error (Enser et al., 1998)

    Several factors that will change the ratio of fatty acid composition are the level of fatness, castrated males versus intact, and geographical location of management. An increased level of fatness increases the fatty acid ratio of the total lipid composition. Steers are intrinsically fatter than bulls and therefore have different lipid fatty acid compositions. Grass-fed production systems almost always graze steers because grazing bulls presents management problems and are unable to gain enough fat to reach market weigh on a low-energy diet. However, bulls are most often used in a concentrate management system because of their “innate leanness and efficiency”. Cattle in the United States are usually raised to a higher fatness content than cattle in Europe, which would also change the lipid composition (Enser et al., 1998). Research that present differences in fatty acid composition ratios must take into account these factors which would skew results.

    Trans fatty acids
    CLA and trans-vaccenic acid are shown to have health benefits (Leheska et al., 2014). Not to be confused with normal trans fatty acids?? —— “Naturally occurring and manufactured trans-fatty acids do not function equally because manufactured trans-fatty acids have been associated with a greater risk of coronary heart disease, whereas naturally occuring trans fats have been found to be beneficial to human health” (Leheska et al., 2014).

  • Increasing the functional lipid components in meat products while decreasing the levels of saturated and trans fatty acids and cholesterol is important because according to the World Review of Nutrition and Dietetics, foods of animal origin are a major source of lipids for human nutrition (Ponnampalam et al., 2006). There are also “potential benefits for human health” linked to intake of conjugated linoleic acid (CLA) from ruminant products, although the research has not shown conclusive evidence yet (Ponnampalam et al., 2006).
    #Implications
    Long chain omega-3 fatty acids are reportedly linked to improved immune, nervous, and cardiovascular functions in humans, and higher reproductive abilities and meat qualities in ruminant animals (Ponnampalam et al., 2006).

  • Comparing P:S ratio to n-3:n-6 ratio

    Nutritional values of fatty foods depend on three factors: P:S ratio (polyunsaturated fatty acids: saturated fatty acids), n-6:n-3 ratio, and the total fat content (Enser et al., 1998). Generally, beef and lamb have low values (unfavorable) for P:S ratio, and grass-fed beef reduced the ratio where concentrate fed cattle increased it (Enser et al., 1998). However, concentrate-fed beef has a higher n-6:n-3 PUFA ratio, which was shown to be significantly lower in grass-fed (Enser et al., 1998). The controversy lies in deciding which factor is more weighted for overall nutritional health. Ruminant meas and oily fish are the only sources of preformed C20 and C22 PUFA in the diet, so the lower n-3:n-6 ratio could potentially off-set the higher P:S ratio found in grass-fed beef (Enser et al., 1998).

    Trans fatty acids

    Higher levels of dietary trans fatty acids increase serum LDL-cholesterol which decreasing serum HDL-cholesterol levels (Ponnampalam et al., 2006). They also increase other lipids that are considered risk factors for heart disease (Ponnampalam et al., 2006).

    Previous Recommended Dietary Patterns
    The recommended dietary patterns for Americans has changed drastically over the last few decades. In 2011, the World Cancer Research Fund/American Institute for Cancer Research Project released a statement condemning red meat as a correlation factor for colorectal cancer (McNeill, 2014). The statement has since been retracted after more research lead to inconsistent results, but the process of looking for “healthier” and lower-fat red meat had been jumpstarted. As beef is the predominate red meat consumed in most developed nations, beef production systems were examined for meat characteristics that could be manipulated. Consumer preferences have changed over time to favor leaner cuts of red meat, driven by newer dietary guidelines that recommend increased consumption of lean proteins and lower fat. Meat production has changed in response and currently approximately two-thirds of the beef sold in the United States meets government guidelines for lean (McNeill, 2014). Nevertheless, misconceptions are still present, especially given the common American dietary pattern of “high intakes of refined grains, sugar and red meat… associated with increased risks for certain types of cancer, coronary heart disease, diabetes, and obesity” (McNeill, 2014). Most Americans are now looking for a lean protein that meets recommendations from the Dietary Guidelines for Americans, published by the USDA & United States Department of Health and Human SErvices.

  • The human body cannot synthesize essential fatty acids, yet they are critical to human health, so they must be obtained from food (Daley et al., 2010).
    A healthy diet should reflect a ratio of 4:1 omega-6:omega-3 fatty acids. The typical American diet tends to range from 11-30:1, which has been hypothesized as a factor in the rising rate of inflammatory disorders in the US (Daley et al., 2010).

  • Where does change in fatty acid profile come from
    Evidence from many recent studies has shown that ruminant meat characteristics can be more or less easily manipulated by making drastic change in diets. Taking a closer look at the composition of feedstuffs could give valuable insight into what it making the change in meat qualities, and how we can further manipulate grass-fed diets to give the best [ ] replace word panel of nutritive value. Grasses and legumes are predominantly glycolipids, and the fatty acid content of grass is low and mainly composed of esterified fatty acids (Ponnampalam et al., 2006). Commonly utilized concentrates in cattle feed are less than 5% lipids with the exception of oilseeds which are significantly higher. The lipids that are present in concentrates are almost all storage triglycerides. Cereal grains and cottonseed have high concentrations of n-6 and little n-3 fatty acids. Extrapolating from those numbers, it can be assumed that grass-fed cattle would have a higher proportion of n-3 PUFA than grain-fed, which would show a higher proportion of n-6 in the diets (Ponnampalam et al., 2006).

  • A study conducted in 2015 tested the ruminal environments of four different steers taken from a homogenous genetic line. Two steers were raised on forage feed and two were fed on grain rations. All four steers were raised in a feed lot setting. RNA was extracted from rumen wall samples and read for gene expression level (Yoakun 2015). The researchers were looking to prove that cattle would produce different compositions and flavors of beef when fed under different regimes. They found that 342 genes displayed “significant” differential expression levels. Of those, seventy-eight percent displayed a higher expression level in the grass-fed group. Two of the differentially expressed genes (DEGs) functioned in the vitamin-C transport pathway, which can alter beef color and fatty acid composition, among other carcass characteristics. Three of the DEGs found functioned in glutathione pathways. While details are not yet known, this could potentially explain why other studies have found that grass-fed beef contains higher amounts of glutathione than grain-fed (Yaokun et al., 2015).
    This particular study was limited by the number of cattle tested, differentially expressed genes analyzed, and by relying on computational strategy that “has not been experimentally validated” (Yaokun et al., 2015). However, further studies of this type could further project the biochemical differences between grass-fed and grain-fed beef. There has been clear evidence that the two meat types share many differences, mainly due to the composition of the feed they are taking in, but little is known about the specific molecular pathways. Understanding the pathways from feed to rumen to meat qualities would be the key to deciphering reliable differences between grass- and grain-fed beef, and techniques like RNA sequencing of ruminal wall samples would be a piece [ ] (replace for better word) of the puzzle.

  • “Development of animal genetic improvement and breeding methodology can bring about leaner beef products” (Yaokun et al., 2015).

  • Several factors that will change the ratio of fatty acid composition are the level of fatness, castrated males versus intact, and geographical location of management. An increased level of fatness increases the fatty acid ratio of the total lipid composition. Steers are intrinsically fatter than bulls and therefore have different lipid fatty acid compositions. Grass-fed production systems almost always graze steers because grazing bulls presents management problems and are unable to gain enough fat to reach market weigh on a low-energy diet. However, bulls are most often used in a concentrate management system because of their “innate leanness and efficiency”. Cattle in the United States are usually raised to a higher fatness content than cattle in Europe, which would also change the lipid composition (Enser et al., 1998). Research that present differences in fatty acid composition ratios must take into account these factors which would skew results.

  • “The World Review of Nutrition and Dietetics recommend producers to improve the lipid profile of foods of animal origin through ‘optimal’ feeding systems, since animal foods are a major source of lipids for humans” (Ponnampalam et al., 2006).

    #Implications
    Increasing the functional lipid components in meat products while decreasing the levels of saturated and trans fatty acids and cholesterol is important because according to the World Review of Nutrition and Dietetics, foods of animal origin are a major source of lipids for human nutrition (Ponnampalam et al., 2006). There are also “potential benefits for human health” linked to intake of conjugated linoleic acid (CLA) from ruminant products, although the research has not shown conclusive evidence yet (Ponnampalam et al., 2006).

    #Implications
    Long chain omega-3 fatty acids are reportedly linked to improved immune, nervous, and cardiovascular functions in humans, and higher reproductive abilities and meat qualities in ruminant animals (Ponnampalam et al., 2006). If grass-fed beef really does produce a higher quantity and quality of lipid profiles, producers could see an incentive to make the switch to gain higher reproductive production and better premiums for higher meat qualities.

    #Introduction
    Agricultural technologies have changed the way we feed our ruminants, especially in the United States and United Kingdom. The increasing use of feedlot production systems coupled with the ability of grain rations to make the ruminant more energy efficient have resulted in a shift in the beef industry to concentrate-based diets. The total of cattle and calves on feedlots in January 2016 was 13.2 million head, which was up 1% from the 2015 total (National Agricultural Statistics Service, 2016). However, Ponnampalam et al., concludes that changing feeding systems have resulted in changing levels of functional lipids, saturated and trans fatty acid content in our modern meat animals, which can affect carcass characteristics and the nutritive value of the meat (Ponnamplam et al., 2006).

    “The type of feeding regimens used in beef cattle production can influence the level of essential fats in red meat, due to the variations in the fatty acid composition of diet” (Ponnampalam et al., 2006).

    A goal for health professionals in recent studies has been to “reduce and replace” saturated fatty acids in red meats with beneficial fatty acids, with the hopes that it might change consumer outlook on the health value of red meat (Ponnampalam et al., 2006). The significance of the Ponnampalam study was a “diet-induced change in functional FA such as n-3 FA, CLA, trans fatty acids and ratio of n-6:n-3 FA”. Basically, lipid components of beef meat can be altered by the feeding system.

    “Grass-fed lean beef can be accredited as ‘a source’ of n-3 PUFA for those who do not consume fish, because the n-3 FA content is similar to that provided by some white fish” (Ponnampalam et al., 2006).

  • Grass-fed beef production in the US is “highly variable because of the variety of genetics, forages, and management practices used, which affect the fatty acid composition of beef” (Leheska, 2014). In addition, feedstuff nutritive value is highly variable across geographic locations, genetic strains, crop variety, season, year, and more factors, which can all change the end nutritive value of the meat (Leheska, 2014).

  • In 2005, the recommended average daily consumption of protein foods was around 150 g/day or 5.5 oz/day (depending on age and gender), while in 2010 the average intake in the United States was 1.7 oz/day (McNeill, 2014). Recent data from the Dietary Guidelines for Americans states that overall average intakes of protein foods are close to recommended amounts (USDA & US Dept. of Health & Human Services, 2015). The Dietary Guidelines for Americans also recommends an overall to more nutrient-dense proteins, including more seafood, to reduce overall caloric intake (USDA & Us Depth of Health & Human Services, 2015).

  • In January 2016, the USDA Agricultural Marketing System (AMS) hosted a conference call to announce the ending of their condonement of the grass-fed certification. The AMS announced that the USDA would no longer recognize a standard definition for grass-fed beef and all marketing claims would have to be verified through third-party organizations or marketed without the backing of a USDA claim (USDA, 2016).

  • “The type of feeding regimens used in beef cattle production can influence the level of essential fats in red meat, due to the variations in the fatty acid composition of diet” (Ponnampalam et al., 2006).
    A goal for health professionals in recent studies has been to “reduce and replace” saturated fatty acids in red meats with beneficial fatty acids, with the hopes that it might change consumer outlook on the health value of red meat (Ponnampalam et al., 2006). The significance of the Ponnampalam study was a “diet-induced change in functional FA such as n-3 FA, CLA, trans fatty acids and ratio of n-6:n-3 FA”. Basically, lipid components of beef meat can be altered by the feeding system.
    “Grass-fed lean beef can be accredited as ‘a source’ of n-3 PUFA for those who do not consume fish, because the n-3 FA content is similar to that provided by some white fish” (Ponnampalam et al., 2006).

  • Research performed since the 1980s indicates that grass-fed beef has a consistently higher total CLA, omega-3 fatty acid, and trans-vaccenic acid on a g/g fat basis, as well as an overall lower fat content (Daley et al., 2010). There is some variability within age, gender, and genetic differences within animals but the effect of nutrition remains a significant factor (Daley et al., 2010). However, it should be noted that due to the higher overall fat content of grain-fed beef, consumers can achieve a similar intake of desirable CLA, omega-3 FA, trans- vaccenic acid by consuming the higher-fat portions of grain-fed beef (Daley et al., 2010). Therefore, grass-fed beef is most suitable to consumers looking for an overall low-fat diet while maximizing the lipid profiles in their protein sources.

  • Ruminal transcriptomic analysis of grass-fed and grain-fed angus beef cattle.

    Rumen functions differently in grass and grain fed environments which results in different compositions and flavors of beef

    “The RNA sequencing method was used to identify differentially expressed genes in the ruminal wall…. then based on the DEGs list, we performed a computational function analysis and found potential mechanisms contributing to the difference between the two groups”

    “Two DEGs were involved in teh canonical pathway vitamin-C transport, which may alter beef color, lipid stability, and fatty acid composition between grass-fed and grain-fed cattle.”

    Three DEGs functioned in glutathione pathways, which could explain why previous studies have found that grass-fed beef contains higher amounts of glutathione (Yaokun et al, 2015).

    DEG= differentially expressed genes = what the RNA sequencing was trying to identify

    sdfl;kjsdf

  • The effect of feeding native warm-season grasses during the stocker phase on meat composition, quality characteristics, and sensory properties of loin steaks from forage-finished cattle.

    Test carcass qualities on cattle fed native warm-season grass and forage finished, compares different forage techniques without grain comparison

  • Fatty acid content and composition of UK beef and lamb muscle in relation to production system and implications for human nutrition

    Content and composition of fatty acids from grazed steers vs cereal concentrates and also grass fed lambs

    #PUFA = polyunsaturated fatty acid
    #P:S = PUFA: saturated fatty acid ratio

  • Effect of feeding systems on omega-3 fatty acids, conjugated linoleic acid and trans fatty acids in Australian beef cuts: potential impact on human health

    Compare grass and grain fed cattle for fatty acid analysis, specifically if grass fed contains more functional lipids

    Beef cattle in Australia

    #Functional fatty acids = long-chain omega-3 and conjugated linoleic acids (biological role in cells)

    #CLA = conjugated linoleic acids
    #STGF = short term grain-fed
    #LTFL = long term grain-fed

  • Don’t really want to use: not well written and not good research

  • Nutritional regime effects on quality and yield characteristics of beef

    Roughages are more cost effective given feed grain prices, so comparing carcass characteristics of beef from pasture-finished cattle

  • A review of fatty acid profiles and antioxidant content in grass-fed and grain-fed beef

    Grass fed have overall lower fat content, but higher favorable fatty acids- tradeoff is distinct grass flavor and unique cooking qualities

  • Effects of conventional and grass-feeding systems on the nutrient composition of beef

    Study that encompasses setting standards for grass-fed beef for inclusion in USDA National Nutrient Database for Standard Reference, compared FAs as well as minerals, vitamin B12 and thiamine along with carcass characteristics

  • The eating quality of meat of steers fed grass and/or concentrates

    Measure quality of carcass from cattle finished on grass, or ratio of grass to concentrates, or just concentrates

  • USDA. 2016. Grass Fed Marketing Claim Standard. Available: www.ams.usda.gov/grades-standards/beef/grassfed. Accessed 19 February 2016.

    As of January 12, 2016 the Agricultural Marketing Service no longer stands by the Grass (Forage) Fed Claim for Ruminant Livestock and the Meat Products Derived from Such Livestock.

    Basically: The USDA no longer recognizes a standard definition for grass-fed beef. All marketing claims must be verified through third-party organizations (much like the way organic products are certified) or marketed without the backing of a USDA claim.

    This article does not mention WHY it has decided that.

  • USDA. n.d. Grass Fed Small & Very Small Producer Program. Available: www.ams.usda.gov/services/auditing/grass-fed-SVS. Accessed 19 February 2016.

    Program for “small-scale livestock producers” for under 49 cattle/year or lambs produced from 99 ewes/year. Animals must be fed only grass and forage (can be milk fed before weaning). Cannot have grain or grain by-products and have continuous access to pasture during the growing season. 2 year period of certification. Can market cattle/sheep as USDA Certified grass-fed.

    2012: small operations had 640,000 or 11.5% of all cattle/calf ops in US and 59,127 sheep producers or 29.5% of all ewe flock ops in US- 32.4% total inventory of ewes and lambs.

  • Agricultural Marketing Service. USDA Market News: National Monthly Grass Fed Beef Report (For the month of January). Available: www.ams.usda.gov/mnreports/nw_ls110.txt. Accessed 19 February 2016.

    Alternate citing: Biensen, Nina. 2016. National monthly grass fed beef report for the month of January. Available: www.ams.usda.gov/mnreports/nw_ls110.txt. Accessed 19 February 2016.

    Wholesale grass fed beef:

    • Ribeye, bonelss, whole: 11.99-16.18/lb
    • Tenderloin, Whole: 19.29-21.95
    • Ribeye steak: 14.50-22.80/lb

    direct (FOB?) grass fed beef:

    • Ribeye Steak: avg 19.50/lb
    • Tenderloin: avg 28.16/lb
    • Stew meat: avg 10.06/lb
    • Ground beef 90/10, bulk: avg 9.17/lb
  • National Agricultural Statistics Service, USDA. Cattle (January 2016). Available: usda.mannlib.cornell.edu/usda/current/Catt/Catt-01-29-2016.pdf. Accessed 21 February 2016.

    Total: all cattle & calves in US as of Jan 1, 2016 = 92.0 million head

    • up 3% from Jan 1, 2015

    Calf crop up from 2% from 2015.

    Cattle and calves on feed (feedlots) = 13.2 million head on Jan 1, 2016- up 1% from 2015

  • Agricultural Marketing Service, USDA. National Retail Report- Beef. February 19-25, 2016. Available: www.ams.usda.gov/mnreports.lswbfrtl.pdf. Accessed 21 February 2016.

    Weighted average for boneless ribeye steak is $9.83.

    Ground beef 90% or more: 4.84

    Prices in dollars per pound

  • Inclusion of red meat in healthful dietary patterns

    http://www.sciencedirect.com/science/article/pii/S030917401400196X

    Fluffy Stuff

    “The Western [dietary] pattern is most commonly defined as a diet characterized by high intakes of refined grains, sugar and red meat, and has been shown to be associated with increased risks for certain types of cancer, coronary heart disease, diabetes, and obesity” (McNeill, 2014).

    “Increased dietary protein has been shown to promote healthy body weight and composition, in part by increasing satiety, and to improve vitality and stamina” (McNeill, 2014).

    In 2011, the World Cancer Research Fund/American Institute for Cancer Research Project concluded that consumption of red meat and processed meat could correlate with risk factors for colorectal cancer. However, that conclusion has been controversial eventually the research was re-done, leading to inconsistent results (McNeill, 2014). Regardless, the statement was a blow to the beef industry and started consumers on a path to looking for the healthiest red meat possible. (McNeill, 2014).

    Generally, red meat is classified as either beef, pork, mutton, or veal (McNeill, 2014).

    Beef is the predominate red meat consumed in several developed nations and on the rise worldwide (McNeill, 2014).

    “Consumer preferences for leaner cuts of red meat, driven by dietary guidance in recent decades instructing the increased consumption of lean meats and trimming excess fat from meats, have results in changes in meat production and merchandising that produce meats with 80% less external fat. Currently, appx. 2/3 of the beef sold retail in the US meets the government guidelines for lean” (McNeill, 2014).

    “The relationship between SFA intake and risk for heart disease is complex, and recent evidence challenges earlier conclusions” (McNeill, 2014).

    “A broader understanding of the fatty acid profile of lean red meat is important to understand its relationship with cardiovascular heatlh” (McNeill, 2014).

    Lean red meat can act equal to lean white meat for lowering total cholesterol and total LCL-cholesterol, when incorporated into an overall low-fat diet (McNeill, 2014).

    The average consumption of beef in 2010 in the United States was 1.7 oz per day (McNeill, 2014).

    “Research regarding red meat as a source of high quality protein and highly bioavailable iron and other nutrients for improving vitality and stamina is emerging” (McNeill, 2014).

    Recommended amounts of daily intake of meat and “meat alternatives- things like legumes, nuts, seed” range from 65-250 g/day. 2010 US Dietary Guidelines recommend 150 g/day depending on age and gender (5.5 oz/d) of protein foods (McNeill, 2014).

  • Dietary Guidelines for Americans 2015-2015 8th Edition

    http://health.gov/dietaryguidelines/2015/guidelines/

    Overall average intakes of protein foods are close to recommended amounts for all age-sex groups (USDA & US Depth of Health & Human Services, 2015).

    Recommends an overall shift to more nutrient-dense proteins, including more seafood, to reduce overall caloric intake.

  • White, Courtney. 2014. Grass, soil, hope: a journey through carbon country. Chelsea Green Publishing, White River Junction, VT. p. 82.

    original inspiration- needs to be referenced to in Intro

    “By definition, grass-fed means an animal has spent its entire life on grass or other green plants, from birth to death” (White, 2014).

    “health benefits of grass-fed over feedlot meat have become widely know. They include the following: more omega-3 fatty acids (“good” fats) and fewer omega-6 (“bad” fats), fewer saturated fats linked with heart disease, much more conjugated linoleic acid (CLA), a cancer fighter, much more vitamin A, much more vitamin E, higher levels of beta-carotene, higher levels of the B vitamins thiamin and riboflavin, positive effect on enhancing immunity, increasing bone density, and suppressing cancer cells, does not contain traces of added hormones, antibiotics, or other drugs”

  • Clancy, Kate. Greener pastures; how grass-fed beef and milk contribute to healthy eating. 2006. Union of Concerned Scientists Publications, Cambridge, MA.

    An extensive literature review conducted by the Union of Concerned Scientists found that overall, grass-fed ground beef and steak are “almost always” lower in total fat, and have higher levels of CLA. They also reported “sometimes” higher levels of omega-3 fatty acids (Clancy, 2006).

    Overall, data has been mixed and inconclusive regarding the levels and health benefits of omega-3 fatty acids present in grass-fed beef. Until such time as the role of fatty acids in human health is more fully understood and the Food and Nutrition Board of the Institute of Medicine can recommend a dietary intake, grass-fed beef cannot be regarded as beneficial in that regard (Clancy, 2006). However, there is sufficient evidence to conclude that grass-fed beef can be labeled as lean and lower in total fat than conventionally fed cattle (Clancy, 2006).

    The Union for Concerned Scientists recommends to the USDA to “support more research to identify pasture management strategies that will produce an optimal fat composition in meat and milk from different regions of the United States” (Clancy, 2006). It also recommends funding more research to specifically look at different types of US pasture systems and their effects on nutrient levels (Clancy, 2006).

    #definition
    #LDL #HDL
    LDL: “bad” cholesterol because high levels increase risk of heart disease
    HDL: “good” cholesterol, transports water-soluble fats in the blood, high levels protect against heart attack

  • Introduction

    #introduction

    As of January 1, 2016, the total of all cattle and calves in the United States was 92 million head. (National Agricultural Statistics Service, 2016). Beef is the predominantly consumed red meat for most developed nations (McNeill, 2014). The number of beef cattle in the United States is growing (Agricultural Marketing Statistics, 2016) as are nationwide health concerns regarding the traditional American diet high in risk factors for cancers, coronary heart disease, diabetes, and obesity (McNeill, 2014). Beef has come under close scrutiny regarding its nutritive value and implications for human health when consumed with the intent of creating a low-fat diet. Research has been conducted for decades to manipulate meat products that are higher in beneficial fats and low in total fat. At the same time, debates over which fatty acid complexes are considered desirable for human health have been controversial and conceded mixed evidence (Clancey, 2006). A production method utilizing grasses and forages to produce grass-fed beef has shown promising evidence that it could create meat high in omega-3 fatty acids and conjugated linoleic acids while still being lower in total fat content (White, 2014). However, decades of research have conflicted and while a few major generalizations can be made, more research is called for to conclusively determine if grass-fed beef can be considered an overall healthier alternative to conventionally-fed beef.

    Historically, grass-fed beef was the only production method utilized until the 1950s, when new agricultural technology created the feedlot industry. The discovery that high energy grains could simultaneously reduce time cattle spend on feed while pushing a rapid weight gain led to cheaper beef products with more intramuscular fat, or marbling. However, changes in consumer demand and new focuses on nutritive effects of feed regime have incentivized some producers to return to the “pastoral approach to beef production” (Daley et al., 2010).
    Grass-fed beef is somewhat self-defining. At the most basic, it is defined as a ruminant fed entirely by grass and forage since weaning (USDA, n.d.). It is considered a life-long production system where the animal spends its entire life eating forages, as opposed to being raised on forages and finished on cereal concentrates or raised entirely on a feedlot system (White, 2014). Before 2016, the USDA certified grass-fed producers who marketed under 49 cattle per year or lambs from 99 ewes per year, and the producer had to guarantee the animals were not fed grain or grain by-products (USDA, n.d.). In 2012, grass-fed beef operations certified by USDA’s Grass Fed Small & Very Small Producer Program contributed 11.5% of all cattle and cow-calf operations in the United States. Grass-fed sheep producers contributed 29.5% of all ewe flock operations and 32.4% of total inventory of ewes and lambs, with 59,127 producers certified by the USDA (USDA, n.d.). Defining grass-fed beef is necessary to compare the differing production systems, feeding regimes, and geographic areas that the beef is produced in the United States.

    If conclusive data could be produced affirming the hypothesis that grass-fed beef is a healthier alternative to conventional, it would further shift consumer preference and therefore incentive for producers to switch production styles. Therefore, it is imperative to fully understand the breadth of variability in studies as well the generalities that can be drawn before making an overall conclusion. The research being performed on grass-fed beef versus concentrate-fed beef could very well have a lasting impact on the types of production systems and therefore the market economics of beef production in the United States.

  • Discussion

    #Discussion

    Early Data

    Early research comparing grass-fed beef to conventionally-fed beef focused on traditional carcass quality testing that measured gross differences. A Kansas Agricultural Experimental Station study conducted in 1978 divided steers into four separate dietary regimes:grass-fed only (winter forage ration, summer grazing); short-fed (grass-fed and finished for 49 days in a feedlot); long-fed (grass-fed and finished for 98 days in a feedlot); and forage-fed (finished for 98 days in a feedlot on a high forage ration). The study found that increased grain feeding gave higher marbling scores and quality grades, carcass weight, fat thickness, and overall higher taste panel scores. In addition, grass-fed group had the yellowest fat, considered undesirable by consumers, the lowest marbling scores, and the lowest quality grades of the other 3 groups. Overall, the evidence presented was overwhelmingly in favor of long-term grain feeding, and the researchers concluded those carcasses “had the most desirable quality and palatability characterstics” (Harrison et al., 1978).
    Newer research has corroborated early findings that grass-fed beef usually has a yellow fat color and generally less marbling than grain-fed. The most desirable color of fat is white, and the yellow color is altered from the ideal as a result of a greater level of beta-carotene, or can be because of changes in the fatty acid profile (Leheska et al., 2014). While yellow fat is typically considered an undesirable trait for consumers, it could potentially be overlooked in exchange for a more nutritive profile.
    A contrast between earlier research and today’s studies is the emphasis placed on marbling. The research described prior graded the grass-fed beef group on the lowest amount of marbling which was then seen as undesirable. Today, a lower amount of marbling would contribute to an overall lower fat content which modern consumers are more concerned with (McNeill, 2014).
    The lower palatability scores found in the prior study have since been correlated with a characteristic “grassy” taste of grass-fed beef. This was an early indicator of later studies that focused in on fatty acids, as a 2006 article found that increased omega-3 fatty acids contribute to an “intense” flavor that is characteristics of grass-fed beef (Ponnampalam et al., 2006)

  • Discussion

    #Discussion
    Fatty acid comparisons

    A relatively recent area of focus has been the effort to profile the lipid amount and composition of grass-fed beef. A standard which is comparable between grass-fed meat carcasses across the United States could give valuable insight to which production methods produce a healthier product. Functional lipid components in meat products have a promising relation to improving human health, although research is still pending conclusive evidence. Long-chain omega-3 fatty acids are reportedly linked to improved immune, nervous, and cardiovascular functions in humans, and higher reproductive abilities and meat qualities in ruminant animals (Ponnampalam et al., 2006). A comprehensive literature review determined that while there is promising evidence that shows correlation between different lipid compounds and health benefits, the research is not yet conclusive and requires further work to draw convincing conclusions (Clancey, 2006).
    In general, three factors of fatty foods determine the nutritional value. The polyunsaturated fatty acids:saturated fatty acids (PUFA:SFA or P:S) ratio should be low. The omega-6:omega-3 fatty acid (n-6:n-3 FA) ratio should also be low. The third factor is total fat content. There is much debate over which factor should be more weighted for overall nutritional health (Enser et al., 1998). However, most research directed at comparing lipid profiles of grass-fed beef has compiled data that fits one of the above factors in order to compare and contrast.
    Trans fatty acids have been studied in detail as well. Higher levels of dietary trans fatty acids increase serum LDL-cholesterol while decreasing serum HDL-cholesterol levels (Ponnampalam et al., 2006). LDL (low density lipoprotein)-cholesterol is considered the “bad” cholesterol as it transports water insoluble lipids in the blood, while HDL (high density lipoprotein)-cholesterol is considered beneficial to cardiovascular health (Clancey, 2006). Generally, manufactured trans fatty acids are associated with cardiovascular risk factors, whereas naturally occurring trans fatty acids like conjugated linoleic acid (CLA) and trans-vaccenic acid have had health benefits (Leheska et al., 2014). Overall, a food considered high in beneficial fats should adhere to the P:S ratio and n-6:n-3 ratio described above, as well as have an adequate amount of CLA and trans-vaccenic acid.

  • Discussion

    #discussion
    future research

    An emerging trend of research to develop more nutrient-dense products has been pushed largely by dietary recommendations from governmental institutes. The World Review of Nutrition and Dietetics officially recommended producers to improve the lipid profile of animal meats through “optimal” feeding systems, since most humans source the majority of their lipids through animal foods. Recommendations like this and convincing evidence that feeding systems have a great impact on meat characteristics has led to published research within the last decade that focuses in on nutritive value of grass-fed beef (Ponnampalam et al., 2006). In order to make a broad statement to release to consumers regarding dietary recommendations, it is imperative to critically examine the variabilities of the past research performed and any further research that should be conducted.

    Studies that compare the feedstuff of cattle to the meat characteristics should be very specific about the type of feed and other factors. Nutritive value in feedstuffs can be highly variable across geographic locations, genetic strains, crop variety, season, year, and more, which can all affect the characteristics of the meat (Leheska et al., 2014). Comparing a grass-fed group of cattle to a grain-fed group is difficult without further examining the feed. In grass-fed beef, variability arises because of the genetics, forages, and management practices used, which can all affect the composition of the beef (Leheska et al., 2014). For example, the study conducted in Mississippi examining native warm-season grasses might find the lipid fatty acid profiles were different than the Australian beef cattle raised on native Australian pasture forages (Kurve et al., 2015 and Ponnampalam et al., 2006). There is also variability within age, gender, and genetic strains between animals (Daley et al., 2010). Perhaps the most obvious of this is comparisons made between countries. Beef cattle raised in the US are typically fatter than cattle in Europe, for example, and reflect an overall difference in production systems and consumer preferences (Enser et al., 1998). To conclusively demonstrate that grass-fed beef contains a significantly different meat characteristic profile, more specific research needs to be conducted over wide geographic areas to ensure that within variabilities, the overall trend stays constant. For example, a nation-wide study conducted in 2014 aimed to include grass-fed beef in the USDA National Nutrient Database for Standard Reference. It compared the fatty-acid composition of grass-fed and conventionally-fed beef (used as a control) that represented 13 states of grass-fed beef production. While the study found that fatty acid amounts were relatively consistent with other studies, the researchers also found that there was no difference in concentrations of PUFA, trans-fatty acids, omega-6 fatty acids, and cholesterol between the grass-fed and control groups (Leheska et al., 2014). This study is an example of further research that should be conducted on a larger scale to eliminate the variabilities that will be found due to feed grown in specific geographical origins, and regional genetic strains of beef cattle.

    Another topic of research that could assist in manipulating carcass qualities for dietary value is ruminal biochemistry. A preliminary study compared RNA extractions taken from the rumen wall of forage-fed versus grain-fed cattle from a homogenous genetic line. They found that 342 genes displayed significant differential expression levels. Of those, 78% had a higher expression level in the grass-fed group. Two of the differentially expressed genes (DEGs) functioned in the vitamin-C transport pathway, which can alter beef color and fatty acid composition, among other carcass characteristics (Yaokun et al., 2015). While this particular study was limited by the number of cattle tested and number of differentially expressed genes analyzed, it called for further research that could project the biochemical differences between grass-fed and grain-fed beef. Understanding the biochemical pathways from feed to rumen to meat qualities would be the next step to developing genetic improvements that could make grass-fed cattle more environmentally efficient (Capper, 2012) and create a leaner product (Yaokun et al., 2015).

  • Conclusion

    #conclusion

    The 2015-2020 Dietary Guildelines for Americans recommends that Americans make an overall shift in their diet towards more nutrient-dense proteins in order to reduce overall caloric intake (USDA & US Dept of Health & Human Services, 2015). Scientific findings that are strongly correlating dietary intake to risk factors for obesity, cardiovascular disease, and more diseases (McNeill, 2014), are pushing producers towards genetic manipulations and changing feeding regimes to create healthier animal products for human consumption. Substantial research conducted since the 1980s indicates that grass-fed beef has a consistently higher total CLA, omega-3 fatty acids, and trans-vaccenic acid on a g/g fat basis, as well as an overall lower fat total (Daley et al., 2010). There are many variabilities within feedstuffs, production management, and animals that create difficulty in comparing different studies to each other (Ponnampalam et al., 2006). The overall trend shows that grass-fed beef can be labeled as lean and lower in total fat than conventionally fed cattle (Clancey, 2006). However, it should be noted that due to the higher overall fat content of grain-fed beef, consumers can achieve a similar intake of desirable CLA, omega-3 FA, trans- vaccenic acid by consuming the higher-fat portions of grain-fed beef (Daley et al., 2010). Therefore, grass-fed beef is most suitable to consumers looking for an overall low-fat diet while maximizing the lipid profiles in their protein sources. In addition, data has been mixed and inconclusive regarding the levels and health benefits of omega-3 fatty acids present in grass-fed beef. Until such time as the role of fatty acids in human health is more fully understood and the Food and Nutrition Board of the Institute of Medicine can recommend a dietary intake, grass-fed beef cannot be regarded as beneficial in that regard (Clancy, 2006).
    In 2005, the recommended average daily consumption of protein foods was around 150 g/day or 5.5 oz/day (depending on age and gender), while in 2010 the average intake in the United States was 1.7 oz/day (McNeill, 2014). Recent data from the Dietary Guidelines for Americans states that overall average intakes of protein foods are close to recommended amounts (USDA & US Dept. of Health & Human Services, 2015). The best conclusive recommendation for American consumers looking to improve their dietary choices is for them to select different types of lean meat that fit their palatability preferences and combine them to create a healthy diet. Grass-fed beef will provide a lower total fat content while still providing a beneficial ratio of “good” fatty acids, at the cost of a sometimes intense grassy flavor, while grain-fed beef can provide the same ratio of fatty acids at the cost of a higher total fat content (Daley et al., 2010). More research is called for to further narrow variabilities, explore opportunities in biochemical manipulation of forages in the ruminant digestive system, and make better recommendations to producers on how to maximize their production output while producing animal products with a desirable panel of carcass characteristics.

  • Summary

    A study conducted in 2015 tested the ruminal environments of four different steers taken from a homogenous genetic line. Two steers were raised on forage feed and two were fed on grain rations. All four steers were raised in a feed lot setting. RNA was extracted from rumen wall samples and read for gene expression level (Yoakun 2015). The researchers were looking to prove that cattle would produce different compositions and flavors of beef when fed under different regimes. They found that 342 genes displayed “significant” differential expression levels. Of those, seventy-eight percent displayed a higher expression level in the grass-fed group. Two of the differentially expressed genes (DEGs) functioned in the vitamin-C transport pathway, which can alter beef color and fatty acid composition, among other carcass characteristics. Three of the DEGs found functioned in glutathione pathways. While details are not yet known, this could potentially explain why other studies have found that grass-fed beef contains higher amounts of glutathione than grain-fed (Yaokun et al., 2015).
    This particular study was limited by the number of cattle tested, differentially expressed genes analyzed, and by relying on computational strategy that “has not been experimentally validated” (Yaokun et al., 2015). However, further studies of this type could further project the biochemical differences between grass-fed and grain-fed beef. There has been clear evidence that the two meat types share many differences, mainly due to the composition of the feed they are taking in, but little is known about the specific molecular pathways. Understanding the pathways from feed to rumen to meat qualities would be the key to deciphering reliable differences between grass- and grain-fed beef, and techniques like RNA sequencing of ruminal wall samples would be a piece [ ] (replace for better word) of the puzzle.

    Fluffy Stuff

    “Flavor, as the combination of taste and aroma, is one of the most important factors affecting consumer preference” (Yaokun et al., 2015).

    “Development of animal genetic improvement and breeding methodology can bring about leaner beef products” (Yaokun et al., 2015).

  • Mississippi State University

    72 British crossbred steers to 9 pasture plots with 3 different forage treatments that included bermuda grass, Indian grass monoculture, and big blustem, little bluestem,a nd Indian grass and forage finished on tall fescue. Fed native warm-season grass in stocker phase and forage finished on tall fescue. The carcasses did not differ in sensory attributes, average sensory acceptability, color, tenderness, pH, or bacteria counts. There were some differences in aroma, flavor, and texture. Overall, researchers concluded that high-quality forage-fed beef can be produced when cattle are fed mixed native warm season grasses, Indian grass, or Bermuda grass during the stocker phase and then finished on tall fescue.
    The goal of the study was to compare carcass qualities including fatty acid profile, tenderness, lipid oxidation, cooking loss, sensory testing, yield grade, and quality grade between groups of grass-fed steers on different types of pasture.
    Results: There were mixed results in the comparison of fat percentage, meat pH, and color, however the results were minimal. Interestingly, there were no differences reported in the fatty acid composition among the carcasses from all treatments. The averages of the lipid fatty acid profiles fell within accepted averages for grass-fed beef. Consumers rated the carcasses similarly. Perhaps the most important finding was that the cattle from the Indian treatment had a higher percentage of Select grade carcasses, which was likely related to the higher fat percentage even though no statistical difference existed. The overall result was that forage-finished beef was deemed acceptable by consumers and the research urged farmers to make better use of their pastures to feed cattle during the stocker phase (Kurve et al, 2015).

    No concentrate control groups.

    Fluffy Stuff

    Although higher omega-3:omega-6 ratios have been reported in grass-fed beef, the actual amounts may not be greater since concentrate-fed beef has a higher total fat percentage (Kurve et al., 2015).

    In 2007, forage systems in the United States totaled at least 24 million hectares of perennial forages and 8 million hectares of annual forage (Kurve et al., 2015).

  • Summary

    In 1998, a study conducted by researchers in Bristol, UK, looked at the fatty acid content and compositions of beef cattle raised on different production systems. Thirty steers were finished on grass pasture for a shorter period of time and measured against ten steers finished for a longer period of time. These groups were measured against a control group of concentrate-fed bulls fed concentrate pellets and given barley straw ad libitum. The study also looked at lambs grazed on pasture, which is a less common area of research but valuable nonetheless. Samples were measured from several areas in the carcass and analyzed for lipid content and composition. The study found that the grazed steers took longer to finish (18 months) versus the control bulls which finished by 12.5 months with both groups retaining a similar amount of visual fatness. The total fatty acid weight was greater in grass-finished steers than control bull group. The grain-fed bulls showed higher levels of omega-6 PUFA than grass-fed. The P:S ratio was 2-3 times higher in grain-fed group. The study also confirmed that lamb muscle has higher concentrations of omega-3 PUFA than beef muscle taken from comparative locations in the carcass. The differences in fatty acid percentages were negligent between muscles but the effects of feeding regime remained constant. Grain-fed muscles held 2-3 times the amount of omega-6 PUFA than grass-fed, and grass-fed held a 2-4 times amount of omega-3 PUFA (Enser et al., 1998). This study strongly correlated with the notion that grass-fed beef has overall beneficial profiles for omega-6:omega-3 ratios.

    Nutritional implications:
    Nutritional values of fatty foods depend on three factors: P:S ratio (polyunsaturated fatty acids: saturated fatty acids), n-6:n-3 ratio, and the total fat content (Enser et al., 1998). The UK Food Advisory Committee states that foods below 5g of total fat per 100g are considered “low-fat” (Enser et al., 1998). Generally, beef and lamb have low values (unfavorable) for P:S ratio, and grass-fed beef reduced the ratio where concentrate fed cattle increased it (Enser et al., 1998). However, concentrate-fed beef has a higher n-6:n-3 PUFA ratio, which was shown to be significantly lower in grass-fed (Enser et al., 1998). The controversy lies in deciding which factor is more weighted for overall nutritional health. Ruminant meas and oily fish are the only sources of preformed C20 and C22 PUFA in the diet, so the lower n-3:n-6 ratio could potentially off-set the higher P:S ratio found in grass-fed beef (Enser et al., 1998).

    Fluffy Stuff

    “Several studies have shown that the fatty acid composition of ruminant meats is different from that of non-ruminants. The ratio of polyunsaturated to saturated fatty acids is lower because the rumen hydrogenates unsaturated fat from the diet” (Enser et al., 1998). Nonruminants abosrb and deposit dietary unsaturated fats unchanged.

    Ratio of n-6:n-3 PUFA is lower in ruminant meats, which is favorable and more closely matches recommended value by British Department of Health of 4:0 or less (Enser et al., 1998).

    Grass is higher in n-3 series precursor fatty acid 18:3 (alpha-linolenic) and grains are higher in the n-6 series precursor fatty acid 18:2 (linoleic) (Enser et al., 1998).

    Several factors that will change the ratio of fatty acid composition are the level of fatness, castrated males versus intact, and geographical location of management. An increased level of fatness increases the fatty acid ratio of the total lipid composition. Steers are intrinsically fatter than bulls and therefore have different lipid fatty acid compositions. Grass-fed production systems almost always graze steers because grazing bulls presents management problems and are unable to gain enough fat to reach market weigh on a low-energy diet. However, bulls are most often used in a concentrate management system because of their “innate leanness and efficiency”. Cattle in the United States are usually raised to a higher fatness content than cattle in Europe, which would also change the lipid composition (Enser et al., 1998). Research that present differences in fatty acid composition ratios must take into account these factors which would skew results.

  • Summary

    Australian beef makes an interesting comparison to domestic production systems because only 35-40% of cattle in 2006 were in a feedlot production regime (Ponnampalam et al., 2006) A study conducted by Ponnampalam et al. compared the difference between raising cattle entirely on grass diets, raising them under forage conditions and then finishing for 80 days on grain diets (short term grain-fed or STGF), and feeding long-term grain for 150-200 days before slaughter (LTFL) (Ponnampalam et al., 2006). The study focused primarily on long-chain fatty acids of C14 and above, as they are the “predominant” FA present in beef.

    The grass-only group showed a two-fold increase in concentration of omega-3 fatty acids compared to both STGF and LTL. The grass-fed beef group had significantly higher concentrations of long chain omega-3 and total omega-3 fatty acids in all primal meat cut areas than the grain-fed group. Long-term grain feeding significantly increased the total saturated, omega-6 and trans fatty acid contents. The muscle showed increase in trans fatty acids in the short term grain feeding group and was further increased in the long term grain group, which suggests that length of grain feeding is probably a factor for increased trans fatty acids in the meat (Ponnampalam et al., 2006). In effect, changing the diet regimen had a drastic effect on the amount and composition of different fatty acids (Ponampalam et al., 2006). This holds exciting implications for health professionals, which have shifted focus to trying to remove saturated fatty acids from red meat and replace them with beneficial fatty acids.

    Finding that a change in diet could induces changes in functional FA such as n-3 FA, CLA, trans fatty acids and the ratio of n-6:n-3 FA holds promise that a change in feeding system could benefit human health (Ponnampalam et al., 2006). The n-6:n-3 ratio was significantly reduced in the grass-fed beef group compared to grain-fed.
    SHORT VERSION OF RESULTS: The grass-fed beef group had significantly higher concentrations of long chain omega-3 and total omega-3 fatty acids in all primal meat cut areas than the grain-fed group. Long-term grain feeding significantly increased the total saturated, omega-6 and trans fatty acid contents. The muscle showed increase in trans fatty acids in the short term grain feeding group and was further increased in the long term grain group, which suggests that length of grain feeding is probably a factor for increased trans fatty acids in the meat (Ponnampalam et al., 2006). The broad conclusion states that from a human nutritional stance, the “shift from pasture fed to grain feeding should be discouraged” (Ponnampalam et al., 2006).

    Where does change in fatty acid profile come from

    Evidence from many recent studies has shown that ruminant meat characteristics can be more or less easily manipulated by making drastic change in diets. Taking a closer look at the composition of feedstuffs could give valuable insight into what it making the change in meat qualities, and how we can further manipulate grass-fed diets to give the best [ ] replace word panel of nutritive value. Grasses and legumes are predominantly glycolipids, and the fatty acid content of grass is low and mainly composed of esterified fatty acids (Ponnampalam et al., 2006). Commonly utilized concentrates in cattle feed are less than 5% lipids with the exception of oilseeds which are significantly higher. The lipids that are present in concentrates are almost all storage triglycerides. Cereal grains and cottonseed have high concentrations of n-6 and little n-3 fatty acids. Extrapolating from those numbers, it can be assumed that grass-fed cattle would have a higher proportion of n-3 PUFA than grain-fed, which would show a higher proportion of n-6 in the diets (Ponnampalam et al., 2006).

    Trans fatty acids

    Higher levels of dietary trans fatty acids increase serum LDL-cholesterol which decreasing serum HDL-cholesterol levels (Ponnampalam et al., 2006). They also increase other lipids that are considered risk factors for heart disease (Ponnampalam et al., 2006).

    Fluffy Stuff

    “The World Review of Nutrition and Dietetics recommend producers to improve the lipid profile of foods of animal origin through ‘optimal’ feeding systems, since animal foods are a major source of lipids for humans” (Ponnampalam et al., 2006).

    #Implications
    Increasing the functional lipid components in meat products while decreasing the levels of saturated and trans fatty acids and cholesterol is important because according to the World Review of Nutrition and Dietetics, foods of animal origin are a major source of lipids for human nutrition (Ponnampalam et al., 2006). There are also “potential benefits for human health” linked to intake of conjugated linoleic acid (CLA) from ruminant products, although the research has not shown conclusive evidence yet (Ponnampalam et al., 2006).

    #Implications
    Long chain omega-3 fatty acids are reportedly linked to improved immune, nervous, and cardiovascular functions in humans, and higher reproductive abilities and meat qualities in ruminant animals (Ponnampalam et al., 2006). If grass-fed beef really does produce a higher quantity and quality of lipid profiles, producers could see an incentive to make the switch to gain higher reproductive production and better premiums for higher meat qualities.

    #Introduction
    Agricultural technologies have changed the way we feed our ruminants, especially in the United States and United Kingdom. The increasing use of feedlot production systems coupled with the ability of grain rations to make the ruminant more energy efficient have resulted in a shift in the beef industry to concentrate-based diets. The total of cattle and calves on feedlots in January 2016 was 13.2 million head, which was up 1% from the 2015 total (National Agricultural Statistics Service, 2016). However, Ponnampalam et al., concludes that changing feeding systems have resulted in changing levels of functional lipids, saturated and trans fatty acid content in our modern meat animals, which can affect carcass characteristics and the nutritive value of the meat (Ponnamplam et al., 2006).

    “The type of feeding regimens used in beef cattle production can influence the level of essential fats in red meat, due to the variations in the fatty acid composition of diet” (Ponnampalam et al., 2006).

    A goal for health professionals in recent studies has been to “reduce and replace” saturated fatty acids in red meats with beneficial fatty acids, with the hopes that it might change consumer outlook on the health value of red meat (Ponnampalam et al., 2006). The significance of the Ponnampalam study was a “diet-induced change in functional FA such as n-3 FA, CLA, trans fatty acids and ratio of n-6:n-3 FA”. Basically, lipid components of beef meat can be altered by the feeding system.

    “Grass-fed lean beef can be accredited as ‘a source’ of n-3 PUFA for those who do not consume fish, because the n-3 FA content is similar to that provided by some white fish” (Ponnampalam et al., 2006).

    The “intensity of flavor” increases with increased levels of n-3 in lamb and beef (Ponnampalam et al., 2006). This could explain the flavor described as “grassy” by ?? Enser??

  • Research conducted at the Kansas Agricultural Experiment Station in 1978 was an early example of exploring the growing trend of grass-fed beef. Thirty-eight steers were divided into four separate dietary regimes: grass-fed only (winter forage ration, summer grazing); short-fed (grass-fed and finished for 49 days in a feedlot); long-fed (grass-fed and finished for 98 days in a feedlot) and forage-fed (finished for 98 days in a feedlot on a high forage ration). The study found that increased feeding gave higher marbling scores and quality grades, carcass weight, fat thickness, and overall higher taste panel scores. They concluded, “carcasses from cattle fed the longest time and the highest plane of nutrition had the most desirable quality and palatability characteristics” (Harrison et al., 1978).
    Other carcass characteristics that were assessed showed differences due to feeding as well. Meat from the grass-fed group had the yellowest fat, the least marbling, and “barely graded low Good” for quality scores (Harrison et al., 1978). They found that carcass weight increased with length of feeding, and that grass-fed cattle had the overall lightest carcass weight (Harrison et al., 1978). The study gave overwhelming evidence against the quality of grass-fed beef. All of the carcass qualities tested showed that the long-term feedlot group had highest quality and palatability, and while short-term feeding and forage-feeding had some middle ground, the grass=fed group inevitably ended up with the lowest scores.

  • Summary

    Fluffy Stuff

    “Research spanning 3 decades suggests that grass-based diets can significantly improve the fatty acid composition and antioxidant content of beef, albeit with variable impacts on overall palatability” (Daley et al., 2010). Specifically, grass-fed diets increase total conjugated linoleic acid (CLA), omega-3 fatty acids, and trans-vaccenic acid on a g/g fat basis, as well as an overall lower total fat.

    Consumers may achieve similar intakes of both omega-3 and CLA through the consumption of higher fat grain-fed portions (Daley et al., 2010).

    Most of the beef produced until the 1940’s was from cattle finished on grass. During the Green Revolution of the ‘50s, the feedlot generation was begun and high energy grains decreased the time cattle spent on feed and improved marbling (intramuscular fat). US consumers have “grown accustomed” to the taste of grain-fed feed, but changes in consumer demand coupled with new research on the effect of feed on nutrient content, “have a number of producers returning to the pastoral approach to beef production despite the inherent inefficiencies” (Daley et al., 2010).

    There is genetic, age related and gender differences among meat animals with respect to lipid profiles and ratios, but the effect of animal nutrition is “quite significant” (Daley t al., 2010).

    The human body cannot synthesize essential fatty acids, yet they are critical to human health, so they must be obtained from food (Daley et al., 2010).

    A healthy diet should reflect a ratio of 4:1 omega-6:omega-3 fatty acids. The typical American diet tends to range from 11-30:1, which has been hypothesized as a factor in the rising rate of inflammatory disorders in the US (Daley et al., 2010).

    Grass-fed ruminant species produce 2 to 3 times more CLA than grain-fed ruminants, largely due to a “more favorable rumen pH” (Daley et al., 2010).

    Grass finishing alters the biochemistry of the beef, so aroma and flavor will be affected (Daley et al., 2010).

    “To maximize the favorable lipid profile and to guarantee the elevated antioxidant content, animals should be finished on 100% grass or pasture-based diets” (Daley et al, 2010).

    HOWEVER: Grain-fed beef consumers can achieve similar intakes of n-3 and CLA with higher fat portions with higher overall palatability scores. (Daley et al., 2010).

  • A nation-wide study conducted to include grass-fed beef in the USDA National Nutrient Database for Standard Reference compared the fatty-acid composition of grass-fed and conventionally-fed beef (used as a control). 13 states were represented in the grass-fed sections, and control beef samples were taken from 3 regions. The findings of the fatty acid comparisons were relatively consistent with other studies, showing that grass-fed samples had significantly less content of monounsaturated fatty acids and a greater content of n-3 and trans-vaccenic acids than the conventional control samples. However, the research found that there was no difference in concentrations of PUFA, trans-fatty acids, n-6 fatty acids, and cholesterol between the grass-fed and control groups (Leheska et al., 2014).

    The beef strip steaks from grass-fed group had more yellow fat and less marbling than grain-fed control beef (Leheska et al., 2014). Fat color can be altered as a result of the greater level of vitamins like beta-carotene, or because of the changes in the fatty acid profile (Leheska et al., 2014). #olderdata

    Total PUFA between grass-fed and grain-fed control did not differ, but grass-fed samples had greater concentration of n-3 fatty acids than did control, and the control group had a higher ratio of n-6:n-3 fatty acids (Leheska et al., 2014).

    #minerals/vitamins An older study from 1983 found that grass-fed steers had greater concentrations of Zn, Fe, P, Na, and K. However, the level of many trace minerals in feed is largely determined by the level in the soil where feed is grown or other environmental factors (Leheska et al., 2014).

    Trans fatty acids

    CLA and trans-vaccenic acid are shown to have health benefits (Leheska et al., 2014). Not to be confused with normal trans fatty acids?? —— “Naturally occurring and manufactured trans-fatty acids do not function equally because manufactured trans-fatty acids have been associated with a greater risk of coronary heart disease, whereas naturally occuring trans fats have been found to be beneficial to human health” (Leheska et al., 2014).

    Fluffy Stuff

    Grass-fed beef production in the US is “highly variable because of the variety of genetics, forages, and management practices used, which affect the fatty acid composition of beef” (Leheska, 2014). In addition, feedstuff nutritive value is highly variable across geographic locations, genetic strains, crop variety, season, year, and more factors, which can all change the end nutritive value of the meat (Leheska, 2014).

    “There has been an increase in demand for natural meat products, such as grass-fed beef, partially as a result of consumer interest in the fat content of foods” (Leheska, 2014). [ ] Food Marketing Institute, 2005 need to look up

  • A frequent finding in studies contrasting grass-fed and concentrate-fed cattle is that grass-fed steers either have a lighter carcass weight or take longer to achieve the equivalent carcass weight than concentrate-fed steers. A study conducted in 2001 found that “high carcass growth can be achieved on a grass-based diet without a deleterious effect on meat quality” (French et al., 2001). The study compared steers raised on six diets of differing ratios. One diet was completely grass, and then the kg DM of grass decreased and the kg concentrate increased gradually in four diets until the sixth diet was completely concentrate-based. The steers were harvested after 95 days following their diet regimes. Carcass weight gain for the grass-fed group was 360 g/day while the concentrate group averaged 809 g/day. However, the study found no difference in color or shear force and noted a negligent variation in meat quality (French et al., 2001). This study noted an important variability in accuracy: the maturity stage and season at which the grass forage was harvested. The grass used in the study was harvested in autumn and hence had “low digestibility and high crude protein relative to that reported for grass earlier in the grazing season” (French et al., 2001). They concluded that “only a small proportion of the large variation in both sensory and instrumental assessments of tenderness could be attributed to diet pre-slaughter, carcass growth rate pre-slaughter and carcass fatness” (French et al., 2001).

    Fluffy Stuff

    “Meat flavour is influenced by a number of factors including animal age and genetics, pre-slaughter dietary regimen, environment, length of post-slaughter aging and the particular primal cut examined” (French et al., 2001).

  • In January 2016, the USDA Agricultural Marketing System (AMS) hosted a conference call to announce the ending of their condonement of the grass-fed certification. The AMS announced that the USDA would no longer recognize a standard definition for grass-fed beef and all marketing claims would have to be verified through third-party organizations or marketed without the backing of a USDA claim (USDA, 2016).

    Why did USDA make such a statement? What was the reason for shutting down the certifications system? WEbsite does not state.

  • Before 2016, “grass-fed beef” was defined by the Agricultural Marketing Service of the United States Department of Agriculture as a small-scale production system. The producer could market under forty-nine cattle per year or lambs from ninety-nine ewes per year. The animals had to be entirely fed by grass and forage, and could not be fed grain or “grain by-products”. The two-year certification period also guaranteed that they were raised with continuous access to pasture during appropriate seasons. Meeting those requirements would allow the producer to market their products as USDA Certified Grass-Fed (UDSA, n.d.)

    In 2012, grass-fed beef operations certified by USDA’s Grass Fed Small & Very Small Producer Program contributed 11.5% of all cattle and cow-calf operations in the United States, or 640,000 head. Sheep producers made up 29.5% of all ewe flock operations and 32.4% of total inventory of ewes and lambs, with 59,127 producers certified by the USDA (USDA, n.d.).

  • The USDA certification of grass-fed beef allowed producers to market their meat with a lucrative premium. In January 2016, the last month that the USDA condoned the certification, the USDA Market News reported the average price of a wholesale grass-fed ribeye steak at $14.50-22.80/lb (Biensen, 2016). A direct-sale grass-fed beef ribeye steaks sold for an average of $19.50/lb (Biensen, 2016). In contrast, the National Retail Report for the week of February 19-25, 2016 reported the weighted average price of a boneless ribeye steak at $9.83 (Agricultural Marketing Service, 2016). These prices limit the sales of grass-fed beef to customers who can afford the premium, and has probably contributed to the controversy surrounding its health claims. Is grass-fed beef worth the pricey premium for better health benefits?

  • As of January 1, 2016, the total of all cattle and calves in the United States was 92.0 million head. This total is up 3% from January 1, 2015 (National Agricultural Statistics Service, 2016).

    According to the National Agricultural Statistics Service, cattle and calves on feedlots in the United States totaled 13.2 million head as of January 1, 2016- a number that is 1% up from 2015 (2016). The recent and growing trend of grass-fed beef has not seemed to make a major economic dent in the beef industry.

  • The recommended dietary patterns for Americans has changed drastically over the last few decades. In 2011, the World Cancer Research Fund/American Institute for Cancer Research Project released a statement condemning red meat as a correlation factor for colorectal cancer (McNeill, 2014). The statement has since been retracted after more research lead to inconsistent results, but the process of looking for “healthier” and lower-fat red meat had been jumpstarted. As beef is the predominate red meat consumed in most developed nations, beef production systems were examined for meat characteristics that could be manipulated. Consumer preferences have changed over time to favor leaner cuts of red meat, driven by newer dietary guidelines that recommend increased consumption of lean proteins and lower fat. Meat production has changed in response and currently approximately two-thirds of the beef sold in the United States meets government guidelines for lean (McNeill, 2014). Nevertheless, misconceptions are still present, especially given the common American dietary pattern of “high intakes of refined grains, sugar and red meat… associated with increased risks for certain types of cancer, coronary heart disease, diabetes, and obesity” (McNeill, 2014). Most Americans are now looking for a lean protein that meets recommendations from the Dietary Guidelines for Americans, published by the USDA & United States Department of Health and Human SErvices. In 2005, the recommended average daily consumption of protein foods was around 150 g/day or 5.5 oz/day (depending on age and gender), while in 2010 the average intake in the United States was 1.7 oz/day (McNeill, 2014). Recent data from the Dietary Guidelines for Americans states that overall average intakes of protein foods are close to recommended amounts (USDA & US Dept. of Health & Human Services, 2015). The Dietary Guidelines for Americans also recommends an overall to more nutrient-dense proteins, including more seafood, to reduce overall caloric intake (USDA & Us Depth of Health & Human Services, 2015).

  • Discussion

    #discussion

    Comparing different studies

    In 1998, a study conducted by researchers in Bristol, UK, examined the fatty acid content and compositions of beef cattle raised on different production systems. Thirty steers were finished on grass pasture for a shorter period of time and measured against ten steers finished for a longer period of time. These groups were measured against a control group of concentrate-fed bulls fed concentrate pellets and given barley straw ad libitum. The study also examined lambs grazed on pasture, which is a less common area of research but valuable nonetheless. Samples were measured from several areas in the carcass and analyzed for lipid content and composition. The study found that the grazed steers took longer to finish (harvested at 18 months) than the control bulls which finished by 12.5 months with the same amount of visual fat. The total fatty acid weight was greater in grass-finished steers than control bull group. The grain-fed bulls showed higher levels of omega-6 FA than grass-fed. The P:S ratio was 2-3 times higher in grain-fed group. The study also confirmed that lamb muscle has higher concentrations of omega-3 FA than beef muscle taken from comparative locations in the carcass. The differences in fatty acid percentages were negligent between muscles but the effects of feeding regime remained constant. Grain-fed muscles held 2-3 times the amount of omega-6 FA than grass-fed, and grass-fed held a 2-4 times amount of omega-3 FA (Enser et al., 1998). This study strongly correlated with the notion that grass-fed beef has overall beneficial profiles for omega-6:omega-3 ratios. Although this study is valuable for its comparison of fatty acid profiles, it has problems that make it difficult to compare to other systems. The beef was not considered “grass-fed” since the steers in the grass-fed group were only finished on grass pasture, not fed their entire lives (or not explicitly specified). Comparing steers to bulls is problematic since steers are developmentally fatter than bulls and will intrinsically have altering lipid fatty acid composition (Enser et al., 1998). The difficulty in comparing pasture-raised to feedlot-raised cattle is intact versus castrated males. While bulls are usually preferred in a feedlot setting because of their rapid weight gain abilities, they present management problems in pasture and cannot gain enough weight to reach market weight on low-energy diets (Enser et al., 1998). This study has more variability from comparing steers to bulls, but can still draw some generalizations regarding lipid profiles.

  • #discussion
    Comparing different studies
    Australian beef makes an interesting comparison to domestic production systems because only 35-40% of Australian cattle in 2006 were raised in a feedlot production system (Ponnampalam et al., 2006) A study conducted compared the difference between raising cattle entirely on grass diets, raising them under forage conditions and then finishing for 80 days on grain diets (short term grain-fed or STGF), and feeding long-term grain for 150-200 days before slaughter (LTFL). The grass-only group showed a two-fold increase in concentration of omega-3 FA compared to both STGF and LTFL in all primal meat cut areas. Long-term grain feeding significantly increased the total saturated, omega-6 and trans fatty acid contents. The muscle showed increase in trans fatty acids in the short term grain feeding group and was further increased in the long term grain group, which suggests that length of grain feeding is probably a factor for increased trans fatty acids. In effect, changing the diet regimen had a drastic effect on the amount and composition of different fatty acids (Ponampalam et al., 2006). This holds promising implications for health professionals, who have shifted focus to trying to remove saturated fatty acids from red meat and replace them with beneficial fatty acids.
    Like the Enser et al., study, this research has limitations on its comparison to domestic production. The Australian breeds used in this study have genetic strains bred for ability to produce on low-quality ranges, since the majority of cattle are raised on pasture in Australia. A similar study conducted in the United States could given valuable insight to correlating the results with feeding regime and negating the variability of genetic strain and the nutritional value of different forages.

  • #discussion

    comparing different studies
    Feedstuffs for ruminant animals ranges due to their innate ability to be able to glean energy from sources that nonruminants cannot. However, the majority of cattle feed is grown, meaning it absorbs some amount of nutrients from the soil it grows it. In the United States alone, forage systems total at least 30 million hectares, with 24 million being perennial forages and 8 million of annual forages (Kurve et al., 2015). The types of grass grown and fed to grass-fed beef will create some amount of variability in the meat characteristics. However, a 2015 study contrasted that conclusion and found that when comparing cattle raised on different grasses in the stocker phase and finished on tall fescue, little to no variability in carcass traits occurred. The study compared 3 different forage treatments from native warm-season grasses in Mississippi, US: Bermuda grass monoculture (BER), Indian grass monoculture (IND), and and Indian grass mix (MIX). They compared fatty acid profiles, tenderness, lipid oxidation, cooking loss, sensory testing, yield grade, and quality grade. There were little to no statistically significant differences between treatments. Interestingly, there were no differences reported in the fatty acid composition between treatments. The averages of the fatty acid composition fell within accepted averages for grass-fed beef. Consumers also rated the meats similarly, with variability due to personal preference and cooking style, but the overall result was that forage-finished beef is deemed acceptable by consumers and the researchers urged farmers to make better use of their pastures to feed cattle during the stocker phase (Kurve et al., 2015). This data could indicate that grasses grown in the same geographic region under the same season and from similar genetic strains (native warm-season grasses) result in overall similar carcass characteristics. However, further research is indicated to compare grasses from from different geographic origins.

  • #discussion
    comparing different studies
    A detriment to the production of grass-fed beef is traditionally the longer time it takes for cattle to reach the equivalent carcass weight of concentrate-fed cattle, or the less desirable option of marketing them with a lighter carcass weight. A 2001 study hypothesized that a high carcass growth could be achieved on a grass-based diet without deleterious effect on meat quality. The study compared steers raised on six diets of differing ratios. One diet was completely grass, and then the kg DM of grass decreased and the kg concentrate increased gradually in four diets until the sixth diet was completely concentrate-based. The steers were harvested after 95 days following their diet regimes. Carcass weight gain for the grass-fed group was 360 g/day while the concentrate group averaged 809 g/day. This confirmed previous studies that looked at carcass weight gain rates, but also confirmed that meat quality did not suffer due to the slower weight gain. This study noted an important variability in accuracy: the maturity stage and season at which the grass forage was harvested. The grass utilized was harvested in fall and had lower digestibility and higher crude protein relative to grass grown earlier in the grazing season (French et al., 2001). Higher rate of digestibility could lead to an increase in weight gain rate which could potentially close the gap between grass-fed and grain-fed carcass weights.

  • Feedstuffs for ruminant animals ranges due to their innate ability to be able to glean energy from sources that nonruminants cannot. However, the majority of cattle feed is grown, meaning it absorbs some amount of nutrients from the soil it grows it. Thus begins the list of variabilities that falls between feedstuffs grown in different geographical origins, seasons, crop varieties, years, under different management, et cetera. In the United States alone, forage systems total at least 30 million hectares, with 24 million being perennial forages and 8 million of annual forages (Kurve et al., 2015). The types of grass grown and fed to grass-fed beef will create some amount of variability in the meat characteristics. However, a 2015 study contrasted that conclusion and found that between cattle raised on grass in the stocker system and finished on tall fescue, little to no variability in carcass traits occurred. The study compared 3 different forage treatments from native warm-season grasses in Mississippi, US: Bermuda grass monoculture (BER), Indian grass monoculture (IND), and and Indian grass mix (MIX). They compared fatty acid profile, tenderness, lipid oxidation, cooking loss, sensory testing, yield grade, and quality grade. There were little to no statistically significant differences between treatments. Interestingly, there were no differences reported in the fatty acid composition between treatments. The averages of the fatty acid composition fell within accepted averages for grass-fed beef. Consumers also rated the meats similarly, with variability due to personal preference and cooking style, but the overall result was that forage-finished beef is deemed acceptable by consumers and the researchers urged farmers to make better use of their pastures to feed cattle during the stocker phase (Kurve et al., 2015). This data could indicate that grasses grown in the same geographic region under the same season and from similar genetic strains (native warm-season grasses) result in overall similar carcass characteristics. However, further research is indicated to compare grasses from from different geographic origins.

  • Research performed since the 1980s indicates that grass-fed beef has a consistently higher total CLA, omega-3 fatty acid, and trans-vaccenic acid on a g/g fat basis, as well as an overall lower fat content (Daley et al., 2010). There is some variability within age, gender, and genetic differences within animals but the effect of nutrition remains a significant factor (Daley et al., 2010). However, it should be noted that due to the higher overall fat content of grain-fed beef, consumers can achieve a similar intake of desirable CLA, omega-3 FA, trans- vaccenic acid by consuming the higher-fat portions of grain-fed beef (Daley et al., 2010). Therefore, grass-fed beef is most suitable to consumers looking for an overall low-fat diet while maximizing the lipid profiles in their protein sources.

  • For example, a nation-wide study conducted in 2014 aimed to include grass-fed beef in the USDA National Nutrient Database for Standard Reference. It compared the fatty-acid composition of grass-fed and conventionally-fed beef (used as a control) that represented 13 states of grass-fed beef production. While the study found that fatty acid amounts were relatively consistent with other studies, the researchers also found that there was no difference in concentrations of PUFA, trans-fatty acids, omega-6 fatty acids, and cholesterol between the grass-fed and control groups (Leheska et al., 2014). This study is an example of further research that should be conducted on a larger scale to eliminate the variabilities that will be found due to feed grown in specific geographical origins, and regional genetic strains of beef cattle.

  • A detriment to the production of grass-fed beef is traditionally the longer time it takes for cattle to reach the equivalent carcass weight of concentrate-fed cattle, or the less desirable option of marketing them with a lighter carcass weight. A 2001 study hypothesized that a high carcass growth could be achieved on a grass-based diet without deleterious effect on meat quality. The study compared steers raised on six diets of differing ratios. One diet was completely grass, and then the kg DM of grass decreased and the kg concentrate increased gradually in four diets until the sixth diet was completely concentrate-based. The steers were harvested after 95 days following their diet regimes. Carcass weight gain for the grass-fed group was 360 g/day while the concentrate group averaged 809 g/day. This confirmed previous studies that looked at carcass weight gain rates, but also confirmed that meat quality did not suffer due to the slower weight gain. This study noted an important variability in accuracy: the maturity stage and season at which the grass forage was harvested. The grass utilized was harvested in fall and had lower digestibility and higher crude protein relative to grass grown earlier in the grazing season (French et al., 2001). Higher rate of digestibility could lead to an increase in weight gain rate which could potentially close the gap between grass-fed and grain-fed carcass weights.

    • Introduction- final draft version

      As of January 1, 2016, the total of all cattle and calves in the United States was 92 million head. (National Agricultural Statistics Service, 2016). Beef is the predominantly consumed red meat for most developed nations (McNeill, 2014). The number of beef cattle in the United States is growing (Agricultural Marketing Statistics, 2016) as are nationwide health concerns regarding the traditional American diet high in risk factors for cancers, coronary heart disease, diabetes, and obesity (McNeill, 2014). Beef has come under close scrutiny regarding its nutritive value and implications for human health when consumed with the intent of creating a low-fat diet. Research has been conducted for decades to manipulate meat products that are higher in beneficial fats and low in total fat. At the same time, debates over which fatty acid complexes are considered desirable for human health have been controversial and conceded mixed evidence (Clancey, 2006). A production method utilizing grasses and forages to produce grass-fed beef has shown promising evidence that it could create meat high in omega-3 fatty acids and conjugated linoleic acids while still being lower in total fat content (White, 2014). However, decades of research have conflicted and while a few major generalizations can be made, more research is called for to conclusively determine if grass-fed beef can be considered an overall healthier alternative to conventionally-fed beef.
      Historically, grass-fed beef was the only production method utilized until the 1950s, when new agricultural technology created the feedlot industry. The discovery that high energy grains could simultaneously reduce time cattle spend on feed while pushing a rapid weight gain led to cheaper beef products with more intramuscular fat, or marbling. However, changes in consumer demand and new focuses on nutritive effects of feed regime have incentivized some producers to return to the “pastoral approach to beef production” (Daley et al., 2010).
      Grass-fed beef is somewhat self-defining. At the most basic, it is defined as a ruminant fed entirely by grass and forage since weaning (USDA, n.d.). It is considered a life-long production system where the animal spends its entire life eating forages, as opposed to being raised on forages and finished on cereal concentrates or raised entirely on a feedlot system (White, 2014). Before 2016, the USDA certified grass-fed producers who marketed under 49 cattle per year or lambs from 99 ewes per year, and the producer had to guarantee the animals were not fed grain or grain by-products (USDA, n.d.). In 2012, grass-fed beef operations certified by USDA’s Grass Fed Small & Very Small Producer Program contributed 11.5% of all cattle and cow-calf operations in the United States. Grass-fed sheep producers contributed 29.5% of all ewe flock operations and 32.4% of total inventory of ewes and lambs, with 59,127 producers certified by the USDA (USDA, n.d.). Defining grass-fed beef is necessary to compare the differing production systems, feeding regimes, and geographic areas that the beef is produced in the United States.
      If conclusive data could be produced affirming the hypothesis that grass-fed beef is a healthier alternative to conventional, it would further shift consumer preference and therefore incentive for producers to switch production styles. Therefore, it is imperative to fully understand the breadth of variability in studies as well the generalities that can be drawn before making an overall conclusion. The research being performed on grass-fed beef versus concentrate-fed beef could very well have a lasting impact on the types of production systems and therefore the market economics of beef production in the United States.

    • Discussion- final draft version

      Early research comparing grass-fed beef to conventionally-fed beef focused on traditional carcass quality testing that measured gross differences. A Kansas Agricultural Experimental Station study conducted in 1978 divided steers into four separate dietary regimes:grass-fed only (winter forage ration, summer grazing); short-fed (grass-fed and finished for 49 days in a feedlot); long-fed (grass-fed and finished for 98 days in a feedlot); and forage-fed (finished for 98 days in a feedlot on a high forage ration). The study found that increased grain feeding gave higher marbling scores and quality grades, carcass weight, fat thickness, and overall higher taste panel scores. In addition, grass-fed group had the yellowest fat, considered undesirable by consumers, the lowest marbling scores, and the lowest quality grades of the other 3 groups. Overall, the evidence presented was overwhelmingly in favor of long-term grain feeding, and the researchers concluded those carcasses “had the most desirable quality and palatability characterstics” (Harrison et al., 1978).
      Newer research has corroborated early findings that grass-fed beef usually has a yellow fat color and generally less marbling than grain-fed. The most desirable color of fat is white, and the yellow color is altered from the ideal as a result of a greater level of beta-carotene, or can be because of changes in the fatty acid profile (Leheska et al., 2014). While yellow fat is typically considered an undesirable trait for consumers, it could potentially be overlooked in exchange for a more nutritive profile.
      A contrast between earlier research and today’s studies is the emphasis placed on marbling. The research described prior graded the grass-fed beef group on the lowest amount of marbling which was then seen as undesirable. Today, a lower amount of marbling would contribute to an overall lower fat content which modern consumers are more concerned with (McNeill, 2014).
      The lower palatability scores found in the prior study have since been correlated with a characteristic “grassy” taste of grass-fed beef. This was an early indicator of later studies that focused in on fatty acids, as a 2006 article found that increased omega-3 fatty acids contribute to an “intense” flavor that is characteristics of grass-fed beef (Ponnampalam et al., 2006) A relatively recent area of focus has been the effort to profile the lipid amount and composition of grass-fed beef. A standard which is comparable between grass-fed meat carcasses across the United States could give valuable insight to which production methods produce a healthier product. Functional lipid components in meat products have a promising relation to improving human health, although research is still pending conclusive evidence. Long-chain omega-3 fatty acids are reportedly linked to improved immune, nervous, and cardiovascular functions in humans, and higher reproductive abilities and meat qualities in ruminant animals (Ponnampalam et al., 2006). A comprehensive literature review determined that while there is promising evidence that shows correlation between different lipid compounds and health benefits, the research is not yet conclusive and requires further work to draw convincing conclusions (Clancey, 2006).

      In general, three factors of fatty foods determine the nutritional value. The polyunsaturated fatty acids:saturated fatty acids (PUFA:SFA or P:S) ratio should be low. The omega-6:omega-3 fatty acid (n-6:n-3 FA) ratio should also be low. The third factor is total fat content. There is much debate over which factor should be more weighted for overall nutritional health (Enser et al., 1998). However, most research directed at comparing lipid profiles of grass-fed beef has compiled data that fits one of the above factors in order to compare and contrast.
      Trans fatty acids have been studied in detail as well. Higher levels of dietary trans fatty acids increase serum LDL-cholesterol while decreasing serum HDL-cholesterol levels (Ponnampalam et al., 2006). LDL (low density lipoprotein)-cholesterol is considered the “bad” cholesterol as it transports water insoluble lipids in the blood, while HDL (high density lipoprotein)-cholesterol is considered beneficial to cardiovascular health (Clancey, 2006). Generally, manufactured trans fatty acids are associated with cardiovascular risk factors, whereas naturally occurring trans fatty acids like conjugated linoleic acid (CLA) and trans-vaccenic acid have had health benefits (Leheska et al., 2014). Overall, a food considered high in beneficial fats should adhere to the P:S ratio and n-6:n-3 ratio described above, as well as have an adequate amount of CLA and trans-vaccenic acid.

      In 1998, a study conducted by researchers in Bristol, UK, examined the fatty acid content and compositions of beef cattle raised on different production systems. Thirty steers were finished on grass pasture for a shorter period of time and measured against ten steers finished for a longer period of time. These groups were measured against a control group of concentrate-fed bulls fed concentrate pellets and given barley straw ad libitum. The study also examined lambs grazed on pasture, which is a less common area of research but valuable nonetheless. Samples were measured from several areas in the carcass and analyzed for lipid content and composition. The study found that the grazed steers took longer to finish (harvested at 18 months) than the control bulls which finished by 12.5 months with the same amount of visual fat. The total fatty acid weight was greater in grass-finished steers than control bull group. The grain-fed bulls showed higher levels of omega-6 FA than grass-fed. The P:S ratio was 2-3 times higher in grain-fed group. The study also confirmed that lamb muscle has higher concentrations of omega-3 FA than beef muscle taken from comparative locations in the carcass. The differences in fatty acid percentages were negligent between muscles but the effects of feeding regime remained constant. Grain-fed muscles held 2-3 times the amount of omega-6 FA than grass-fed, and grass-fed held a 2-4 times amount of omega-3 FA (Enser et al., 1998). This study strongly correlated with the notion that grass-fed beef has overall beneficial profiles for omega-6:omega-3 ratios. Although this study is valuable for its comparison of fatty acid profiles, it has problems that make it difficult to compare to other systems. The beef was not considered “grass-fed” since the steers in the grass-fed group were only finished on grass pasture, not fed their entire lives (or not explicitly specified). Comparing steers to bulls is problematic since steers are developmentally fatter than bulls and will intrinsically have altering lipid fatty acid composition (Enser et al., 1998). The difficulty in comparing pasture-raised to feedlot-raised cattle is intact versus castrated males. While bulls are usually preferred in a feedlot setting because of their rapid weight gain abilities, they present management problems in pasture and cannot gain enough weight to reach market weight on low-energy diets (Enser et al., 1998). This study has more variability from comparing steers to bulls, but can still draw some generalizations regarding lipid profiles.

      Australian beef makes an interesting comparison to domestic production systems because only 35-40% of Australian cattle in 2006 were raised in a feedlot production system (Ponnampalam et al., 2006) A study conducted compared the difference between raising cattle entirely on grass diets, raising them under forage conditions and then finishing for 80 days on grain diets (short term grain-fed or STGF), and feeding long-term grain for 150-200 days before slaughter (LTFL). The grass-only group showed a two-fold increase in concentration of omega-3 FA compared to both STGF and LTFL in all primal meat cut areas. Long-term grain feeding significantly increased the total saturated, omega-6 and trans fatty acid contents. The muscle showed increase in trans fatty acids in the short term grain feeding group and was further increased in the long term grain group, which suggests that length of grain feeding is probably a factor for increased trans fatty acids. In effect, changing the diet regimen had a drastic effect on the amount and composition of different fatty acids (Ponampalam et al., 2006). This holds promising implications for health professionals, who have shifted focus to trying to remove saturated fatty acids from red meat and replace them with beneficial fatty acids.
      Like the Enser et al., study, this research has limitations on its comparison to domestic production. The Australian breeds used in this study have genetic strains bred for ability to produce on low-quality ranges, since the majority of cattle are raised on pasture in Australia. A similar study conducted in the United States could given valuable insight to correlating the results with feeding regime and negating the variability of genetic strain and the nutritional value of different forages.

      Feedstuffs for ruminant animals ranges due to their innate ability to be able to glean energy from sources that nonruminants cannot. However, the majority of cattle feed is grown, meaning it absorbs some amount of nutrients from the soil it grows it. In the United States alone, forage systems total at least 30 million hectares, with 24 million being perennial forages and 8 million of annual forages (Kurve et al., 2015). The types of grass grown and fed to grass-fed beef will create some amount of variability in the meat characteristics. However, a 2015 study contrasted that conclusion and found that when comparing cattle raised on different grasses in the stocker phase and finished on tall fescue, little to no variability in carcass traits occurred. The study compared 3 different forage treatments from native warm-season grasses in Mississippi, US: Bermuda grass monoculture (BER), Indian grass monoculture (IND), and and Indian grass mix (MIX). They compared fatty acid profiles, tenderness, lipid oxidation, cooking loss, sensory testing, yield grade, and quality grade. There were little to no statistically significant differences between treatments. Interestingly, there were no differences reported in the fatty acid composition between treatments. The averages of the fatty acid composition fell within accepted averages for grass-fed beef. Consumers also rated the meats similarly, with variability due to personal preference and cooking style, but the overall result was that forage-finished beef is deemed acceptable by consumers and the researchers urged farmers to make better use of their pastures to feed cattle during the stocker phase (Kurve et al., 2015). This data could indicate that grasses grown in the same geographic region under the same season and from similar genetic strains (native warm-season grasses) result in overall similar carcass characteristics. However, further research is indicated to compare grasses from from different geographic origins.

      A detriment to the production of grass-fed beef is traditionally the longer time it takes for cattle to reach the equivalent carcass weight of concentrate-fed cattle, or the less desirable option of marketing them with a lighter carcass weight. A 2001 study hypothesized that a high carcass growth could be achieved on a grass-based diet without deleterious effect on meat quality. The study compared steers raised on six diets of differing ratios. One diet was completely grass, and then the kg DM of grass decreased and the kg concentrate increased gradually in four diets until the sixth diet was completely concentrate-based. The steers were harvested after 95 days following their diet regimes. Carcass weight gain for the grass-fed group was 360 g/day while the concentrate group averaged 809 g/day. This confirmed previous studies that looked at carcass weight gain rates, but also confirmed that meat quality did not suffer due to the slower weight gain. This study noted an important variability in accuracy: the maturity stage and season at which the grass forage was harvested. The grass utilized was harvested in fall and had lower digestibility and higher crude protein relative to grass grown earlier in the grazing season (French et al., 2001). Higher rate of digestibility could lead to an increase in weight gain rate which could potentially close the gap between grass-fed and grain-fed carcass weights.

      An emerging trend of research to develop more nutrient-dense products has been pushed largely by dietary recommendations from governmental institutes. The World Review of Nutrition and Dietetics officially recommended producers to improve the lipid profile of animal meats through “optimal” feeding systems, since most humans source the majority of their lipids through animal foods. Recommendations like this and convincing evidence that feeding systems have a great impact on meat characteristics has led to published research within the last decade that focuses in on nutritive value of grass-fed beef (Ponnampalam et al., 2006). In order to make a broad statement to release to consumers regarding dietary recommendations, it is imperative to critically examine the variabilities of the past research performed and any further research that should be conducted.
      Studies that compare the feedstuff of cattle to the meat characteristics should be very specific about the type of feed and other factors. Nutritive value in feedstuffs can be highly variable across geographic locations, genetic strains, crop variety, season, year, and more, which can all affect the characteristics of the meat (Leheska et al., 2014). Comparing a grass-fed group of cattle to a grain-fed group is difficult without further examining the feed. In grass-fed beef, variability arises because of the genetics, forages, and management practices used, which can all affect the composition of the beef (Leheska et al., 2014). For example, the study conducted in Mississippi examining native warm-season grasses might find the lipid fatty acid profiles were different than the Australian beef cattle raised on native Australian pasture forages (Kurve et al., 2015 and Ponnampalam et al., 2006). There is also variability within age, gender, and genetic strains between animals (Daley et al., 2010). Perhaps the most obvious of this is comparisons made between countries. Beef cattle raised in the US are typically fatter than cattle in Europe, for example, and reflect an overall difference in production systems and consumer preferences (Enser et al., 1998). To conclusively demonstrate that grass-fed beef contains a significantly different meat characteristic profile, more specific research needs to be conducted over wide geographic areas to ensure that within variabilities, the overall trend stays constant. For example, a nation-wide study conducted in 2014 aimed to include grass-fed beef in the USDA National Nutrient Database for Standard Reference. It compared the fatty-acid composition of grass-fed and conventionally-fed beef (used as a control) that represented 13 states of grass-fed beef production. While the study found that fatty acid amounts were relatively consistent with other studies, the researchers also found that there was no difference in concentrations of PUFA, trans-fatty acids, omega-6 fatty acids, and cholesterol between the grass-fed and control groups (Leheska et al., 2014). This study is an example of further research that should be conducted on a larger scale to eliminate the variabilities that will be found due to feed grown in specific geographical origins, and regional genetic strains of beef cattle.
      Another topic of research that could assist in manipulating carcass qualities for dietary value is ruminal biochemistry. A preliminary study compared RNA extractions taken from the rumen wall of forage-fed versus grain-fed cattle from a homogenous genetic line. They found that 342 genes displayed significant differential expression levels. Of those, 78% had a higher expression level in the grass-fed group. Two of the differentially expressed genes (DEGs) functioned in the vitamin-C transport pathway, which can alter beef color and fatty acid composition, among other carcass characteristics (Yaokun et al., 2015). While this particular study was limited by the number of cattle tested and number of differentially expressed genes analyzed, it called for further research that could project the biochemical differences between grass-fed and grain-fed beef. Understanding the biochemical pathways from feed to rumen to meat qualities would be the next step to developing genetic improvements that could make grass-fed cattle more environmentally efficient (Capper, 2012) and create a leaner product (Yaokun et al., 2015).

    • Conclusion final draft version

      The 2015-2020 Dietary Guildelines for Americans recommends that Americans make an overall shift in their diet towards more nutrient-dense proteins in order to reduce overall caloric intake (USDA & US Dept of Health & Human Services, 2015). Scientific findings that are strongly correlating dietary intake to risk factors for obesity, cardiovascular disease, and more diseases (McNeill, 2014), are pushing producers towards genetic manipulations and changing feeding regimes to create healthier animal products for human consumption. Substantial research conducted since the 1980s indicates that grass-fed beef has a consistently higher total CLA, omega-3 fatty acids, and trans-vaccenic acid on a g/g fat basis, as well as an overall lower fat total (Daley et al., 2010). There are many variabilities within feedstuffs, production management, and animals that create difficulty in comparing different studies to each other (Ponnampalam et al., 2006). The overall trend shows that grass-fed beef can be labeled as lean and lower in total fat than conventionally fed cattle (Clancey, 2006). However, it should be noted that due to the higher overall fat content of grain-fed beef, consumers can achieve a similar intake of desirable CLA, omega-3 FA, trans- vaccenic acid by consuming the higher-fat portions of grain-fed beef (Daley et al., 2010). Therefore, grass-fed beef is most suitable to consumers looking for an overall low-fat diet while maximizing the lipid profiles in their protein sources. In addition, data has been mixed and inconclusive regarding the levels and health benefits of omega-3 fatty acids present in grass-fed beef. The Union of Concerned Scientists concluded in 2006, “until such time as the role of fatty acids in human health is more fully understood and the Food and Nutrition Board of the Institute of Medicine can recommend a dietary intake, grass-fed beef cannot be regarded as beneficial in that regard” (Clancy, 2006).
      In 2005, the recommended average daily consumption of protein foods was around 150 g/day or 5.5 oz/day (depending on age and gender), while in 2010 the average intake in the United States was 1.7 oz/day (McNeill, 2014). Recent data from the Dietary Guidelines for Americans states that overall average intakes of protein foods are close to recommended amounts (USDA & US Dept. of Health & Human Services, 2015). The best conclusive recommendation for American consumers looking to improve their dietary choices is for them to select different types of lean meat that fit their palatability preferences and combine them to create a healthy diet. Grass-fed beef will provide a lower total fat content while still providing a beneficial ratio of “good” fatty acids, at the cost of a sometimes intense grassy flavor, while grain-fed beef can provide the same ratio of fatty acids at the cost of a higher total fat content (Daley et al., 2010). More research is called for to further narrow variabilities, explore opportunities in biochemical manipulation of forages in the ruminant digestive system, and make better recommendations to producers on how to maximize their production output while producing animal products with a desirable panel of carcass characteristics.

    {"cards":[{"_id":"63c969570b61c9f828000049","treeId":"63c969310b61c9f828000047","seq":6245901,"position":1,"parentId":null,"content":"# TITLE\n\n##Big Idea\n\nThesis Statement: Is grass fed beef intrinsically healthier for human consumption than grain fed beef? If so, what characteristics make it that way? Is it more of a quality of the feed, or a quality of their lifestyle? Should humans be recommended to consume grass fed over grain fed beef?\n\nThesis Statement: A growing consumer preference trend for grass-fed beef has [ ] called for `change word` a closer examination in the difference between feeding regimes. Older research focused on general carcass characteristics like color, palatability, and shear force, while newer studies are examining detailed information about fatty acid composition profiles, ratios, and biochemical pathways that feed takes from mouth to meat. While many studies present conflicting evidence, a general trend can be seen that grass-fed beef has a lower total fat content and higher beneficial fatty acid concentration than concentrate-fed beef, although concentrate-fed beef generally has higher palatability, color, and marbling scores. Extrapolation to the implications for human health is difficult since diet recommendations are not universal and differences in forage quality and concentrate composition make lipid profiles change from producer to producer. In general, a consumer wishing to purchase red meat that will supplement a low-saturated-fat diet should look for grass-fed beef. Further research is necessary to conclusively indicate that grass-fed beef has a healthier nutritive value than conventionally-fed beef, and that research will better assist consumers in making informed dietary choices for their meat consumption. \n\n"},{"_id":"64df3577821795a4c6000190","treeId":"63c969310b61c9f828000047","seq":6433797,"position":0.75,"parentId":"63c969570b61c9f828000049","content":""},{"_id":"63c96c4a0b61c9f82800004a","treeId":"63c969310b61c9f828000047","seq":6245905,"position":1,"parentId":"63c969570b61c9f828000049","content":"# Abstract"},{"_id":"63f1ea9381174d7460000053","treeId":"63c969310b61c9f828000047","seq":6245906,"position":1,"parentId":"63c96c4a0b61c9f82800004a","content":"Thesis Statement: A growing consumer preference trend for grass-fed beef has [ ] called for change word a closer examination in the difference between feeding regimes. Older research focused on general carcass characteristics like color, palatability, and shear force, while newer studies are examining detailed information about fatty acid composition profiles, ratios, and biochemical pathways that feed takes from mouth to meat. While many studies present conflicting evidence, a general trend can be seen that grass-fed beef has a lower total fat content and higher beneficial fatty acid concentration than concentrate-fed beef, although concentrate-fed beef generally has higher palatability, color, and marbling scores. Extrapolation to the implications for human health is difficult since diet recommendations are not universal and differences in forage quality and concentrate composition make lipid profiles change from producer to producer. In general, a consumer wishing to purchase red meat that will supplement a low-saturated-fat diet should look for grass-fed beef. Further research is necessary to conclusively indicate that grass-fed beef has a healthier nutritive value than conventionally-fed beef, and that research will better assist consumers in making informed dietary choices for their meat consumption."},{"_id":"63c96de60b61c9f82800004b","treeId":"63c969310b61c9f828000047","seq":6220716,"position":2,"parentId":"63c969570b61c9f828000049","content":"# Introduction"},{"_id":"63c971b80b61c9f828000051","treeId":"63c969310b61c9f828000047","seq":6245440,"position":1,"parentId":"63c96de60b61c9f82800004b","content":"##Definition of Grass Fed and USDA Marketing Claims\n* Consumer preference changes\n* Marketing numbers for grass-fed and the difference in prices-- has this been caused by a change in consumer preference? Is there really a need for the higher price if consumers are buying it for health reasons? "},{"_id":"64043607efedad29ea000051","treeId":"63c969310b61c9f828000047","seq":6258748,"position":1,"parentId":"63c971b80b61c9f828000051","content":"“By definition, grass-fed means an animal has spent its entire life on grass or other green plants, from birth to death” (White, 2014)."},{"_id":"640437daefedad29ea000052","treeId":"63c969310b61c9f828000047","seq":6258739,"position":2,"parentId":"63c971b80b61c9f828000051","content":"As of January 1, 2016, the total of all cattle and calves in the United States was 92.0 million head. This total is up 3% from January 1, 2015 (National Agricultural Statistics Service, 2016)."},{"_id":"640439b0efedad29ea000053","treeId":"63c969310b61c9f828000047","seq":6258667,"position":3,"parentId":"63c971b80b61c9f828000051","content":"The USDA certification of grass-fed beef allowed producers to market their meat with a lucrative premium. In January 2016, the last month that the USDA condoned the certification, the USDA Market News reported the average price of a wholesale grass-fed ribeye steak at $14.50-22.80/lb (Biensen, 2016). A direct-sale grass-fed beef ribeye steaks sold for an average of $19.50/lb (Biensen, 2016). In contrast, the National Retail Report for the week of February 19-25, 2016 reported the weighted average price of a boneless ribeye steak at $9.83 (Agricultural Marketing Service, 2016). These prices limit the sales of grass-fed beef to customers who can afford the premium, and has probably contributed to the controversy surrounding its health claims. Is grass-fed beef worth the pricey premium for better health benefits?"},{"_id":"64047219efedad29ea000057","treeId":"63c969310b61c9f828000047","seq":6433606,"position":1,"parentId":"640439b0efedad29ea000053","content":"##Introduction \n#introduction\n\n[X] catchy opening phrase\n\nAs of January 1, 2016, the total of all cattle and calves in the United States was 92 million head. (National Agricultural Statistics Service, 2016). Beef is the predominantly consumed red meat for most developed nations (McNeill, 2014). The number of beef cattle in the United States is growing (Agricultural Marketing Statistics, 2016) as are nationwide health concerns regarding the traditional American diet high in risk factors for cancers, coronary heart disease, diabetes, and obesity (McNeill, 2014). Beef has come under close scrutiny regarding its nutritive value and implications for human health when consumed with the intent of creating a low-fat diet. Research has been conducted for decades to manipulate meat products that are higher in beneficial fats and low in total fat. At the same time, debates over which fatty acid complexes are considered desirable for human health have been controversial and conceded mixed evidence (Clancey, 2006). A production method utilizing grasses and forages to produce grass-fed beef has shown promising evidence that it could create meat high in omega-3 fatty acids and conjugated linoleic acids while still being lower in total fat content (White, 2014). However, decades of research have conflicted and while a few major generalizations can be made, more research is called for to conclusively determine if grass-fed beef can be considered an overall healthier alternative to conventionally-fed beef. \n\nHistorically, grass-fed beef was the only production method utilized until the 1950s, when new agricultural technology created the feedlot industry. The discovery that high energy grains could simultaneously reduce time cattle spend on feed while pushing a rapid weight gain led to cheaper beef products with more intramuscular fat, or marbling. However, changes in consumer demand and new focuses on nutritive effects of feed regime have incentivized some producers to return to the \"pastoral approach to beef production\" (Daley et al., 2010). \nGrass-fed beef is somewhat self-defining. At the most basic, it is defined as a ruminant fed entirely by grass and forage since weaning (USDA, n.d.). It is considered a life-long production system where the animal spends its entire life eating forages, as opposed to being raised on forages and finished on cereal concentrates or raised entirely on a feedlot system (White, 2014). Before 2016, the USDA certified grass-fed producers who marketed under 49 cattle per year or lambs from 99 ewes per year, and the producer had to guarantee the animals were not fed grain or grain by-products (USDA, n.d.). In 2012, grass-fed beef operations certified by USDA’s Grass Fed Small & Very Small Producer Program contributed 11.5% of all cattle and cow-calf operations in the United States. Grass-fed sheep producers contributed 29.5% of all ewe flock operations and 32.4% of total inventory of ewes and lambs, with 59,127 producers certified by the USDA (USDA, n.d.). Defining grass-fed beef is necessary to compare the differing production systems, feeding regimes, and geographic areas that the beef is produced in the United States. \n\nIf conclusive data could be produced affirming the hypothesis that grass-fed beef is a healthier alternative to conventional, it would further shift consumer preference and therefore incentive for producers to switch production styles. Therefore, it is imperative to fully understand the breadth of variability in studies as well the generalities that can be drawn before making an overall conclusion. The research being performed on grass-fed beef versus concentrate-fed beef could very well have a lasting impact on the types of production systems and therefore the market economics of beef production in the United States. "},{"_id":"640ebe5e7221f33ee9000080","treeId":"63c969310b61c9f828000047","seq":6265957,"position":1,"parentId":"64047219efedad29ea000057","content":""},{"_id":"640ebe757221f33ee9000081","treeId":"63c969310b61c9f828000047","seq":6265958,"position":1,"parentId":"640ebe5e7221f33ee9000080","content":""},{"_id":"64044347efedad29ea000054","treeId":"63c969310b61c9f828000047","seq":6258683,"position":4,"parentId":"63c971b80b61c9f828000051","content":"Before 2016, \"grass-fed beef\" was defined by the Agricultural Marketing Service of the United States Department of Agriculture as a small-scale production system. The producer could market under forty-nine cattle per year or lambs from ninety-nine ewes per year. The animals had to be entirely fed by grass and forage, and could not be fed grain or \"grain by-products\". The two-year certification period also guaranteed that they were raised with continuous access to pasture during appropriate seasons. Meeting those requirements would allow the producer to market their products as USDA Certified Grass-Fed (UDSA, n.d.)\n"},{"_id":"64044477efedad29ea000055","treeId":"63c969310b61c9f828000047","seq":6258684,"position":5,"parentId":"63c971b80b61c9f828000051","content":"In 2012, grass-fed beef operations certified by USDA’s Grass Fed Small & Very Small Producer Program contributed 11.5% of all cattle and cow-calf operations in the United States, or 640,000 head. Sheep producers made up 29.5% of all ewe flock operations and 32.4% of total inventory of ewes and lambs, with 59,127 producers certified by the USDA (USDA, n.d.)."},{"_id":"67df5ce908af5f3c03000093","treeId":"63c969310b61c9f828000047","seq":7342201,"position":2,"parentId":"63c96de60b61c9f82800004b","content":""},{"_id":"67df5ced08af5f3c03000094","treeId":"63c969310b61c9f828000047","seq":7342202,"position":2.5,"parentId":"63c96de60b61c9f82800004b","content":""},{"_id":"63c96e300b61c9f82800004c","treeId":"63c969310b61c9f828000047","seq":6220725,"position":3,"parentId":"63c969570b61c9f828000049","content":"# Discussion"},{"_id":"63c96f8c0b61c9f82800004e","treeId":"63c969310b61c9f828000047","seq":6258841,"position":1,"parentId":"63c96e300b61c9f82800004c","content":"##Why recent studies have been wanting to link grass-fed to human health \n* Overview of how FA and PUFA affect human health\n* 3 factors in determining health from FA- n-6:n-3, P:S, etc.\n* Trans FA and the role they play\n"},{"_id":"64046a81efedad29ea000056","treeId":"63c969310b61c9f828000047","seq":6258716,"position":0.5,"parentId":"63c96f8c0b61c9f82800004e","content":"The USDA certification of grass-fed beef allowed producers to market their meat with a lucrative premium. In January 2016, the last month that the USDA condoned the certification, the USDA Market News reported the average price of a wholesale grass-fed ribeye steak at $14.50-22.80/lb (Biensen, 2016). A direct-sale grass-fed beef ribeye steaks sold for an average of $19.50/lb (Biensen, 2016). In contrast, the National Retail Report for the week of February 19-25, 2016 reported the weighted average price of a boneless ribeye steak at $9.83 (Agricultural Marketing Service, 2016). These prices limit the sales of grass-fed beef to customers who can afford the premium, and has probably contributed to the controversy surrounding its health claims. Is grass-fed beef worth the pricey premium for better health benefits?"},{"_id":"63c9700f0b61c9f82800004f","treeId":"63c969310b61c9f828000047","seq":6258712,"position":1,"parentId":"63c96f8c0b61c9f82800004e","content":"Consumer preferences have changed over time to favor leaner cuts of red meat, driven by newer dietary guidelines that recommend increased consumption of lean proteins and lower fat. Meat production has changed in response and currently approximately two-thirds of the beef sold in the United States meets government guidelines for lean (McNeill, 2014). Nevertheless, misconceptions are still present, especially given the common American dietary pattern of “high intakes of refined grains, sugar and red meat… associated with increased risks for certain types of cancer, coronary heart disease, diabetes, and obesity” (McNeill, 2014).\n\nThe recommended dietary patterns for Americans has changed drastically over the last few decades. In 2011, the World Cancer Research Fund/American Institute for Cancer Research Project released a statement condemning red meat as a correlation factor for colorectal cancer (McNeill, 2014). The statement has since been retracted after more research lead to inconsistent results, but the process of looking for “healthier” and lower-fat red meat had been jumpstarted. As beef is the predominate red meat consumed in most developed nations, beef production systems were examined for meat characteristics that could be manipulated. "},{"_id":"640b5da3d8d572a67f000070","treeId":"63c969310b61c9f828000047","seq":6716574,"position":2,"parentId":"63c96f8c0b61c9f82800004e","content":"Most of the beef produced until the 1940’s was from cattle finished on grass. During the Green Revolution of the ‘50s, the feedlot generation was begun and high energy grains decreased the time cattle spent on feed and improved marbling (intramuscular fat). US consumers have “grown accustomed” to the taste of grain-fed feed, but changes in consumer demand coupled with new research on the effect of feed on nutrient content, “have a number of producers returning to the pastoral approach to beef production despite the inherent inefficiencies” (Daley et al., 2010)."},{"_id":"63c970930b61c9f828000050","treeId":"63c969310b61c9f828000047","seq":6245391,"position":2,"parentId":"63c96e300b61c9f82800004c","content":"##Early Data\n\n* Yellow color in fat\n* Palatability findings\n* How did forage and grass ideas change since the 70s?"},{"_id":"63f1580a81174d746000004f","treeId":"63c969310b61c9f828000047","seq":6244276,"position":1,"parentId":"63c970930b61c9f828000050","content":"Research conducted at the Kansas Agricultural Experiment Station in 1978 was an early example of exploring the growing trend of grass-fed beef. Thirty-eight steers were divided into four separate dietary regimes: grass-fed only (winter forage ration, summer grazing); short-fed (grass-fed and finished for 49 days in a feedlot); long-fed (grass-fed and finished for 98 days in a feedlot) and forage-fed (finished for 98 days in a feedlot on a high forage ration). The study found that increased feeding gave higher marbling scores and quality grades, carcass weight, fat thickness, and overall higher taste panel scores. They concluded, “carcasses from cattle fed the longest time and the highest plane of nutrition had the most desirable quality and palatability characteristics” (Harrison et al., 1978).\nOther carcass characteristics that were assessed showed differences due to feeding as well. Meat from the grass-fed group had the yellowest fat, the least marbling, and “barely graded low Good” for quality scores (Harrison et al., 1978). They found that carcass weight increased with length of feeding, and that grass-fed cattle had the overall lightest carcass weight (Harrison et al., 1978). The study gave overwhelming evidence against the quality of grass-fed beef. All of the carcass qualities tested showed that the long-term feedlot group had highest quality and palatability, and while short-term feeding and forage-feeding had some middle ground, the grass=fed group inevitably ended up with the lowest scores.\n\nThe beef strip steaks from grass-fed group had more yellow fat and less marbling than grain-fed control beef (Leheska et al., 2014). Fat color can be altered as a result of the greater level of vitamins like beta-carotene, or because of the changes in the fatty acid profile (Leheska et al., 2014)."},{"_id":"6405ebb2efedad29ea000058","treeId":"63c969310b61c9f828000047","seq":6266547,"position":1,"parentId":"63f1580a81174d746000004f","content":"##Discussion\n#Discussion\n\n`Early Data`\n\nEarly research comparing grass-fed beef to conventionally-fed beef focused on traditional carcass quality testing that measured gross differences. A Kansas Agricultural Experimental Station study conducted in 1978 divided steers into four separate dietary regimes:grass-fed only (winter forage ration, summer grazing); short-fed (grass-fed and finished for 49 days in a feedlot); long-fed (grass-fed and finished for 98 days in a feedlot); and forage-fed (finished for 98 days in a feedlot on a high forage ration). The study found that increased grain feeding gave higher marbling scores and quality grades, carcass weight, fat thickness, and overall higher taste panel scores. In addition, grass-fed group had the yellowest fat, considered undesirable by consumers, the lowest marbling scores, and the lowest quality grades of the other 3 groups. Overall, the evidence presented was overwhelmingly in favor of long-term grain feeding, and the researchers concluded those carcasses \"had the most desirable quality and palatability characterstics\" (Harrison et al., 1978). \nNewer research has corroborated early findings that grass-fed beef usually has a yellow fat color and generally less marbling than grain-fed. The most desirable color of fat is white, and the yellow color is altered from the ideal as a result of a greater level of beta-carotene, or can be because of changes in the fatty acid profile (Leheska et al., 2014). While yellow fat is typically considered an undesirable trait for consumers, it could potentially be overlooked in exchange for a more nutritive profile. \nA contrast between earlier research and today's studies is the emphasis placed on marbling. The research described prior graded the grass-fed beef group on the lowest amount of marbling which was then seen as undesirable. Today, a lower amount of marbling would contribute to an overall lower fat content which modern consumers are more concerned with (McNeill, 2014). \nThe lower palatability scores found in the prior study have since been correlated with a characteristic \"grassy\" taste of grass-fed beef. This was an early indicator of later studies that focused in on fatty acids, as a 2006 article found that increased omega-3 fatty acids contribute to an \"intense\" flavor that is characteristics of grass-fed beef (Ponnampalam et al., 2006) "},{"_id":"63c9730c0b61c9f828000052","treeId":"63c969310b61c9f828000047","seq":6259511,"position":3,"parentId":"63c96e300b61c9f82800004c","content":"##Recent Findings\n\n* Fatty acid comparisons- `different between studies, might have to dig`\n* Overall carcass quality and carcass weight differences \n* P:S ratio and n-6:n-3 ratio differences\n\n\n"},{"_id":"63e9d73d3e7bb0c93d000038","treeId":"63c969310b61c9f828000047","seq":6259501,"position":1,"parentId":"63c9730c0b61c9f828000052","content":"##Fatty Acid Comparisons\n\n###Areas that allow for error (Enser et al., 1998)\nSeveral factors that will change the ratio of fatty acid composition are the level of fatness, castrated males versus intact, and geographical location of management. An increased level of fatness increases the fatty acid ratio of the total lipid composition. Steers are intrinsically fatter than bulls and therefore have different lipid fatty acid compositions. Grass-fed production systems almost always graze steers because grazing bulls presents management problems and are unable to gain enough fat to reach market weigh on a low-energy diet. However, bulls are most often used in a concentrate management system because of their \"innate leanness and efficiency\". Cattle in the United States are usually raised to a higher fatness content than cattle in Europe, which would also change the lipid composition (Enser et al., 1998). Research that present differences in fatty acid composition ratios must take into account these factors which would skew results.\n\nTrans fatty acids\nCLA and trans-vaccenic acid are shown to have health benefits (Leheska et al., 2014). Not to be confused with normal trans fatty acids?? —— “Naturally occurring and manufactured trans-fatty acids do not function equally because manufactured trans-fatty acids have been associated with a greater risk of coronary heart disease, whereas naturally occuring trans fats have been found to be beneficial to human health” (Leheska et al., 2014). "},{"_id":"64061c3defedad29ea000059","treeId":"63c969310b61c9f828000047","seq":6266539,"position":1,"parentId":"63e9d73d3e7bb0c93d000038","content":"##Discussion\n#Discussion\n`Fatty acid comparisons`\n\nA relatively recent area of focus has been the effort to profile the lipid amount and composition of grass-fed beef. A standard which is comparable between grass-fed meat carcasses across the United States could give valuable insight to which production methods produce a healthier product. Functional lipid components in meat products have a promising relation to improving human health, although research is still pending conclusive evidence. Long-chain omega-3 fatty acids are reportedly linked to improved immune, nervous, and cardiovascular functions in humans, and higher reproductive abilities and meat qualities in ruminant animals (Ponnampalam et al., 2006). A comprehensive literature review determined that while there is promising evidence that shows correlation between different lipid compounds and health benefits, the research is not yet conclusive and requires further work to draw convincing conclusions (Clancey, 2006). \nIn general, three factors of fatty foods determine the nutritional value. The polyunsaturated fatty acids:saturated fatty acids (PUFA:SFA or P:S) ratio should be low. The omega-6:omega-3 fatty acid (n-6:n-3 FA) ratio should also be low. The third factor is total fat content. There is much debate over which factor should be more weighted for overall nutritional health (Enser et al., 1998). However, most research directed at comparing lipid profiles of grass-fed beef has compiled data that fits one of the above factors in order to compare and contrast.\n*Trans* fatty acids have been studied in detail as well. Higher levels of dietary *trans* fatty acids increase serum LDL-cholesterol while decreasing serum HDL-cholesterol levels (Ponnampalam et al., 2006). LDL (low density lipoprotein)-cholesterol is considered the \"bad\" cholesterol as it transports water insoluble lipids in the blood, while HDL (high density lipoprotein)-cholesterol is considered beneficial to cardiovascular health (Clancey, 2006). Generally, manufactured *trans* fatty acids are associated with cardiovascular risk factors, whereas naturally occurring *trans* fatty acids like conjugated linoleic acid (CLA) and *trans*-vaccenic acid have had health benefits (Leheska et al., 2014). Overall, a food considered high in beneficial fats should adhere to the P:S ratio and n-6:n-3 ratio described above, as well as have an adequate amount of CLA and *trans*-vaccenic acid. \n\n\n"},{"_id":"64064f9aefedad29ea00005b","treeId":"63c969310b61c9f828000047","seq":6266585,"position":1,"parentId":"64061c3defedad29ea000059","content":"##Discussion\n#discussion\n\n`Comparing different studies`\n\nIn 1998, a study conducted by researchers in Bristol, UK, examined the fatty acid content and compositions of beef cattle raised on different production systems. Thirty steers were finished on grass pasture for a shorter period of time and measured against ten steers finished for a longer period of time. These groups were measured against a control group of concentrate-fed bulls fed concentrate pellets and given barley straw *ad libitum*. The study also examined lambs grazed on pasture, which is a less common area of research but valuable nonetheless. Samples were measured from several areas in the carcass and analyzed for lipid content and composition. The study found that the grazed steers took longer to finish (harvested at 18 months) than the control bulls which finished by 12.5 months with the same amount of visual fat. The total fatty acid weight was greater in grass-finished steers than control bull group. The grain-fed bulls showed higher levels of omega-6 FA than grass-fed. The P:S ratio was 2-3 times higher in grain-fed group. The study also confirmed that lamb muscle has higher concentrations of omega-3 FA than beef muscle taken from comparative locations in the carcass. The differences in fatty acid percentages were negligent between muscles but the effects of feeding regime remained constant. Grain-fed muscles held 2-3 times the amount of omega-6 FA than grass-fed, and grass-fed held a 2-4 times amount of omega-3 FA (Enser et al., 1998). This study strongly correlated with the notion that grass-fed beef has overall beneficial profiles for omega-6:omega-3 ratios. Although this study is valuable for its comparison of fatty acid profiles, it has problems that make it difficult to compare to other systems. The beef was not considered \"grass-fed\" since the steers in the grass-fed group were only finished on grass pasture, not fed their entire lives (or not explicitly specified). Comparing steers to bulls is problematic since steers are developmentally fatter than bulls and will intrinsically have altering lipid fatty acid composition (Enser et al., 1998). The difficulty in comparing pasture-raised to feedlot-raised cattle is intact versus castrated males. While bulls are usually preferred in a feedlot setting because of their rapid weight gain abilities, they present management problems in pasture and cannot gain enough weight to reach market weight on low-energy diets (Enser et al., 1998). This study has more variability from comparing steers to bulls, but can still draw some generalizations regarding lipid profiles. \n\n"},{"_id":"640ee3077221f33ee9000083","treeId":"63c969310b61c9f828000047","seq":6266518,"position":1,"parentId":"64064f9aefedad29ea00005b","content":""},{"_id":"640678eeefedad29ea00005c","treeId":"63c969310b61c9f828000047","seq":6266590,"position":2,"parentId":"64061c3defedad29ea000059","content":"#discussion\n`Comparing different studies`\nAustralian beef makes an interesting comparison to domestic production systems because only 35-40% of Australian cattle in 2006 were raised in a feedlot production system (Ponnampalam et al., 2006) A study conducted compared the difference between raising cattle entirely on grass diets, raising them under forage conditions and then finishing for 80 days on grain diets (short term grain-fed or STGF), and feeding long-term grain for 150-200 days before slaughter (LTFL). The grass-only group showed a two-fold increase in concentration of omega-3 FA compared to both STGF and LTFL in all primal meat cut areas. Long-term grain feeding significantly increased the total saturated, omega-6 and *trans* fatty acid contents. The muscle showed increase in *trans* fatty acids in the short term grain feeding group and was further increased in the long term grain group, which suggests that length of grain feeding is probably a factor for increased *trans* fatty acids. In effect, changing the diet regimen had a drastic effect on the amount and composition of different fatty acids (Ponampalam et al., 2006). This holds promising implications for health professionals, who have shifted focus to trying to remove saturated fatty acids from red meat and replace them with beneficial fatty acids. \nLike the Enser et al., study, this research has limitations on its comparison to domestic production. The Australian breeds used in this study have genetic strains bred for ability to produce on low-quality ranges, since the majority of cattle are raised on pasture in Australia. A similar study conducted in the United States could given valuable insight to correlating the results with feeding regime and negating the variability of genetic strain and the nutritional value of different forages. "},{"_id":"640b6a5cd8d572a67f000072","treeId":"63c969310b61c9f828000047","seq":6266596,"position":3,"parentId":"64061c3defedad29ea000059","content":"#discussion\n\n`comparing different studies`\nFeedstuffs for ruminant animals ranges due to their innate ability to be able to glean energy from sources that nonruminants cannot. However, the majority of cattle feed is grown, meaning it absorbs some amount of nutrients from the soil it grows it. In the United States alone, forage systems total at least 30 million hectares, with 24 million being perennial forages and 8 million of annual forages (Kurve et al., 2015). The types of grass grown and fed to grass-fed beef will create some amount of variability in the meat characteristics. However, a 2015 study contrasted that conclusion and found that when comparing cattle raised on different grasses in the stocker phase and finished on tall fescue, little to no variability in carcass traits occurred. The study compared 3 different forage treatments from native warm-season grasses in Mississippi, US: Bermuda grass monoculture (BER), Indian grass monoculture (IND), and and Indian grass mix (MIX). They compared fatty acid profiles, tenderness, lipid oxidation, cooking loss, sensory testing, yield grade, and quality grade. There were little to no statistically significant differences between treatments. Interestingly, there were no differences reported in the fatty acid composition between treatments. The averages of the fatty acid composition fell within accepted averages for grass-fed beef. Consumers also rated the meats similarly, with variability due to personal preference and cooking style, but the overall result was that forage-finished beef is deemed acceptable by consumers and the researchers urged farmers to make better use of their pastures to feed cattle during the stocker phase (Kurve et al., 2015). This data could indicate that grasses grown in the same geographic region under the same season and from similar genetic strains (native warm-season grasses) result in overall similar carcass characteristics. However, further research is indicated to compare grasses from from different geographic origins."},{"_id":"640b7a2ed8d572a67f000074","treeId":"63c969310b61c9f828000047","seq":6266598,"position":4,"parentId":"64061c3defedad29ea000059","content":"#discussion\n`comparing different studies`\nA detriment to the production of grass-fed beef is traditionally the longer time it takes for cattle to reach the equivalent carcass weight of concentrate-fed cattle, or the less desirable option of marketing them with a lighter carcass weight. A 2001 study hypothesized that a high carcass growth could be achieved on a grass-based diet without deleterious effect on meat quality. The study compared steers raised on six diets of differing ratios. One diet was completely grass, and then the kg DM of grass decreased and the kg concentrate increased gradually in four diets until the sixth diet was completely concentrate-based. The steers were harvested after 95 days following their diet regimes. Carcass weight gain for the grass-fed group was 360 g/day while the concentrate group averaged 809 g/day. This confirmed previous studies that looked at carcass weight gain rates, but also confirmed that meat quality did not suffer due to the slower weight gain. This study noted an important variability in accuracy: the maturity stage and season at which the grass forage was harvested. The grass utilized was harvested in fall and had lower digestibility and higher crude protein relative to grass grown earlier in the grazing season (French et al., 2001). Higher rate of digestibility could lead to an increase in weight gain rate which could potentially close the gap between grass-fed and grain-fed carcass weights."},{"_id":"640ceaa9b698ea67ef00007e","treeId":"63c969310b61c9f828000047","seq":6264544,"position":2,"parentId":"63c9730c0b61c9f828000052","content":"Increasing the functional lipid components in meat products while decreasing the levels of saturated and trans fatty acids and cholesterol is important because according to the World Review of Nutrition and Dietetics, foods of animal origin are a major source of lipids for human nutrition (Ponnampalam et al., 2006). There are also “potential benefits for human health” linked to intake of conjugated linoleic acid (CLA) from ruminant products, although the research has not shown conclusive evidence yet (Ponnampalam et al., 2006).\n#Implications\nLong chain omega-3 fatty acids are reportedly linked to improved immune, nervous, and cardiovascular functions in humans, and higher reproductive abilities and meat qualities in ruminant animals (Ponnampalam et al., 2006). "},{"_id":"63c975650b61c9f828000053","treeId":"63c969310b61c9f828000047","seq":6716585,"position":4,"parentId":"63c96e300b61c9f82800004c","content":"##Human Health Diet Implications\n\n* Conclusion of what the differences in n-6:n-3, P:S, total FA concentrations mean to human health \n* Red meats can be substituted for fish for a source of n-3\n* trans fatty acid levels in grass fed beef\n\n","deleted":false},{"_id":"63ea08c13e7bb0c93d000039","treeId":"63c969310b61c9f828000047","seq":6259492,"position":1,"parentId":"63c975650b61c9f828000053","content":"###Comparing P:S ratio to n-3:n-6 ratio\nNutritional values of fatty foods depend on three factors: P:S ratio (polyunsaturated fatty acids: saturated fatty acids), n-6:n-3 ratio, and the total fat content (Enser et al., 1998). Generally, beef and lamb have low values (unfavorable) for P:S ratio, and grass-fed beef reduced the ratio where concentrate fed cattle increased it (Enser et al., 1998). However, concentrate-fed beef has a higher n-6:n-3 PUFA ratio, which was shown to be significantly lower in grass-fed (Enser et al., 1998). The controversy lies in deciding which factor is more weighted for overall nutritional health. Ruminant meas and oily fish are the only sources of preformed C20 and C22 PUFA in the diet, so the lower n-3:n-6 ratio could potentially off-set the higher P:S ratio found in grass-fed beef (Enser et al., 1998).\n\n###Trans fatty acids\n\nHigher levels of dietary *trans* fatty acids increase serum LDL-cholesterol which decreasing serum HDL-cholesterol levels (Ponnampalam et al., 2006). They also increase other lipids that are considered risk factors for heart disease (Ponnampalam et al., 2006).\n\nPrevious Recommended Dietary Patterns\nThe recommended dietary patterns for Americans has changed drastically over the last few decades. In 2011, the World Cancer Research Fund/American Institute for Cancer Research Project released a statement condemning red meat as a correlation factor for colorectal cancer (McNeill, 2014). The statement has since been retracted after more research lead to inconsistent results, but the process of looking for “healthier” and lower-fat red meat had been jumpstarted. As beef is the predominate red meat consumed in most developed nations, beef production systems were examined for meat characteristics that could be manipulated. Consumer preferences have changed over time to favor leaner cuts of red meat, driven by newer dietary guidelines that recommend increased consumption of lean proteins and lower fat. Meat production has changed in response and currently approximately two-thirds of the beef sold in the United States meets government guidelines for lean (McNeill, 2014). Nevertheless, misconceptions are still present, especially given the common American dietary pattern of “high intakes of refined grains, sugar and red meat… associated with increased risks for certain types of cancer, coronary heart disease, diabetes, and obesity” (McNeill, 2014). Most Americans are now looking for a lean protein that meets recommendations from the Dietary Guidelines for Americans, published by the USDA & United States Department of Health and Human SErvices. "},{"_id":"640b6651d8d572a67f000071","treeId":"63c969310b61c9f828000047","seq":6263400,"position":2,"parentId":"63c975650b61c9f828000053","content":"The human body cannot synthesize essential fatty acids, yet they are critical to human health, so they must be obtained from food (Daley et al., 2010).\nA healthy diet should reflect a ratio of 4:1 omega-6:omega-3 fatty acids. The typical American diet tends to range from 11-30:1, which has been hypothesized as a factor in the rising rate of inflammatory disorders in the US (Daley et al., 2010)."},{"_id":"6661fb801921ec42eb0000a0","treeId":"63c969310b61c9f828000047","seq":6716590,"position":4.5,"parentId":"63c96e300b61c9f82800004c","content":"#BIG HEADING\n\n##Smaller Heading\n\n###Smallest Heading\n\n**Bold** *Italicize*\n\n`Later- look up different source`\n\n[X] don't forget catchy leaving phrase\n\n#ABBRIEVATION = DEFINITION\n\nSOC \n\n#SOC\n\n#SOC\n\n"},{"_id":"63e988903e7bb0c93d000035","treeId":"63c969310b61c9f828000047","seq":6245456,"position":5,"parentId":"63c96e300b61c9f82800004c","content":"## Future Research: What Needs to Be Done? \n\n* RNA Sequencing study (Yaokun et al., 2015) could help prove that diet changes the biochemistry of the animal, which could open doors for further manipulation of efficiency `could help reduce environmental impact of grass-fed if compare different forages that give overall beneficial impact on microbial populations?`\n* Further manipulating grass-fed diets to give the best overall composition of fatty acids to human health\n* Further studies on mineral differences (iron)\n* For human health purposes: amount of minerals in the meat, which will be largely affected by the minerals in the soil `maybe quote Dr Jones quivira presentation?`\n* ROOM FOR ERROR: How it's difficult to compare and contrast these studies without really digging into the differences between geographic location, genetic variations, microbial populations, feedstuff differences, etc. Going to have to take a very general overview of all statistics given and go with general trends, and even those are changing over time"},{"_id":"63f1093f81174d746000004b","treeId":"63c969310b61c9f828000047","seq":6263561,"position":1,"parentId":"63e988903e7bb0c93d000035","content":"Where does change in fatty acid profile come from\nEvidence from many recent studies has shown that ruminant meat characteristics can be more or less easily manipulated by making drastic change in diets. Taking a closer look at the composition of feedstuffs could give valuable insight into what it making the change in meat qualities, and how we can further manipulate grass-fed diets to give the best [ ] replace word panel of nutritive value. Grasses and legumes are predominantly glycolipids, and the fatty acid content of grass is low and mainly composed of esterified fatty acids (Ponnampalam et al., 2006). Commonly utilized concentrates in cattle feed are less than 5% lipids with the exception of oilseeds which are significantly higher. The lipids that are present in concentrates are almost all storage triglycerides. Cereal grains and cottonseed have high concentrations of n-6 and little n-3 fatty acids. Extrapolating from those numbers, it can be assumed that grass-fed cattle would have a higher proportion of n-3 PUFA than grain-fed, which would show a higher proportion of n-6 in the diets (Ponnampalam et al., 2006)."},{"_id":"640b841fd8d572a67f000076","treeId":"63c969310b61c9f828000047","seq":6266617,"position":1,"parentId":"63f1093f81174d746000004b","content":"##Discussion\n#discussion\n`future research`\n\nAn emerging trend of research to develop more nutrient-dense products has been pushed largely by dietary recommendations from governmental institutes. The World Review of Nutrition and Dietetics officially recommended producers to improve the lipid profile of animal meats through \"optimal\" feeding systems, since most humans source the majority of their lipids through animal foods. Recommendations like this and convincing evidence that feeding systems have a great impact on meat characteristics has led to published research within the last decade that focuses in on nutritive value of grass-fed beef (Ponnampalam et al., 2006). In order to make a broad statement to release to consumers regarding dietary recommendations, it is imperative to critically examine the variabilities of the past research performed and any further research that should be conducted.\n\nStudies that compare the feedstuff of cattle to the meat characteristics should be very specific about the type of feed and other factors. Nutritive value in feedstuffs can be highly variable across geographic locations, genetic strains, crop variety, season, year, and more, which can all affect the characteristics of the meat (Leheska et al., 2014). Comparing a grass-fed group of cattle to a grain-fed group is difficult without further examining the feed. In grass-fed beef, variability arises because of the genetics, forages, and management practices used, which can all affect the composition of the beef (Leheska et al., 2014). For example, the study conducted in Mississippi examining native warm-season grasses might find the lipid fatty acid profiles were different than the Australian beef cattle raised on native Australian pasture forages (Kurve et al., 2015 and Ponnampalam et al., 2006). There is also variability within age, gender, and genetic strains between animals (Daley et al., 2010). Perhaps the most obvious of this is comparisons made between countries. Beef cattle raised in the US are typically fatter than cattle in Europe, for example, and reflect an overall difference in production systems and consumer preferences (Enser et al., 1998). To conclusively demonstrate that grass-fed beef contains a significantly different meat characteristic profile, more specific research needs to be conducted over wide geographic areas to ensure that within variabilities, the overall trend stays constant. For example, a nation-wide study conducted in 2014 aimed to include grass-fed beef in the USDA National Nutrient Database for Standard Reference. It compared the fatty-acid composition of grass-fed and conventionally-fed beef (used as a control) that represented 13 states of grass-fed beef production. While the study found that fatty acid amounts were relatively consistent with other studies, the researchers also found that there was no difference in concentrations of PUFA, *trans*-fatty acids, omega-6 fatty acids, and cholesterol between the grass-fed and control groups (Leheska et al., 2014). This study is an example of further research that should be conducted on a larger scale to eliminate the variabilities that will be found due to feed grown in specific geographical origins, and regional genetic strains of beef cattle. \n\nAnother topic of research that could assist in manipulating carcass qualities for dietary value is ruminal biochemistry. A preliminary study compared RNA extractions taken from the rumen wall of forage-fed versus grain-fed cattle from a homogenous genetic line. They found that 342 genes displayed significant differential expression levels. Of those, 78% had a higher expression level in the grass-fed group. Two of the differentially expressed genes (DEGs) functioned in the vitamin-C transport pathway, which can alter beef color and fatty acid composition, among other carcass characteristics (Yaokun et al., 2015). While this particular study was limited by the number of cattle tested and number of differentially expressed genes analyzed, it called for further research that could project the biochemical differences between grass-fed and grain-fed beef. Understanding the biochemical pathways from feed to rumen to meat qualities would be the next step to developing genetic improvements that could make grass-fed cattle more environmentally efficient (Capper, 2012) and create a leaner product (Yaokun et al., 2015). \n\n"},{"_id":"640b85aad8d572a67f000077","treeId":"63c969310b61c9f828000047","seq":6263563,"position":2,"parentId":"63e988903e7bb0c93d000035","content":"A study conducted in 2015 tested the ruminal environments of four different steers taken from a homogenous genetic line. Two steers were raised on forage feed and two were fed on grain rations. All four steers were raised in a feed lot setting. RNA was extracted from rumen wall samples and read for gene expression level (Yoakun 2015). The researchers were looking to prove that cattle would produce different compositions and flavors of beef when fed under different regimes. They found that 342 genes displayed “significant” differential expression levels. Of those, seventy-eight percent displayed a higher expression level in the grass-fed group. Two of the differentially expressed genes (DEGs) functioned in the vitamin-C transport pathway, which can alter beef color and fatty acid composition, among other carcass characteristics. Three of the DEGs found functioned in glutathione pathways. While details are not yet known, this could potentially explain why other studies have found that grass-fed beef contains higher amounts of glutathione than grain-fed (Yaokun et al., 2015).\nThis particular study was limited by the number of cattle tested, differentially expressed genes analyzed, and by relying on computational strategy that “has not been experimentally validated” (Yaokun et al., 2015). However, further studies of this type could further project the biochemical differences between grass-fed and grain-fed beef. There has been clear evidence that the two meat types share many differences, mainly due to the composition of the feed they are taking in, but little is known about the specific molecular pathways. Understanding the pathways from feed to rumen to meat qualities would be the key to deciphering reliable differences between grass- and grain-fed beef, and techniques like RNA sequencing of ruminal wall samples would be a piece [ ] (replace for better word) of the puzzle."},{"_id":"640b8632d8d572a67f000078","treeId":"63c969310b61c9f828000047","seq":6263564,"position":3,"parentId":"63e988903e7bb0c93d000035","content":"“Development of animal genetic improvement and breeding methodology can bring about leaner beef products” (Yaokun et al., 2015)."},{"_id":"640b8781d8d572a67f000079","treeId":"63c969310b61c9f828000047","seq":6263567,"position":4,"parentId":"63e988903e7bb0c93d000035","content":"Several factors that will change the ratio of fatty acid composition are the level of fatness, castrated males versus intact, and geographical location of management. An increased level of fatness increases the fatty acid ratio of the total lipid composition. Steers are intrinsically fatter than bulls and therefore have different lipid fatty acid compositions. Grass-fed production systems almost always graze steers because grazing bulls presents management problems and are unable to gain enough fat to reach market weigh on a low-energy diet. However, bulls are most often used in a concentrate management system because of their “innate leanness and efficiency”. Cattle in the United States are usually raised to a higher fatness content than cattle in Europe, which would also change the lipid composition (Enser et al., 1998). Research that present differences in fatty acid composition ratios must take into account these factors which would skew results."},{"_id":"640b8ac5d8d572a67f00007a","treeId":"63c969310b61c9f828000047","seq":6263575,"position":5,"parentId":"63e988903e7bb0c93d000035","content":"\"The World Review of Nutrition and Dietetics recommend producers to improve the lipid profile of foods of animal origin through 'optimal' feeding systems, since animal foods are a major source of lipids for humans\" (Ponnampalam et al., 2006). \n\n#Implications\nIncreasing the functional lipid components in meat products while decreasing the levels of saturated and *trans* fatty acids and cholesterol is important because according to the World Review of Nutrition and Dietetics, foods of animal origin are a major source of lipids for human nutrition (Ponnampalam et al., 2006). There are also \"potential benefits for human health\" linked to intake of conjugated linoleic acid (CLA) from ruminant products, although the research has not shown conclusive evidence yet (Ponnampalam et al., 2006). \n\n#Implications\nLong chain omega-3 fatty acids are reportedly linked to improved immune, nervous, and cardiovascular functions in humans, and higher reproductive abilities and meat qualities in ruminant animals (Ponnampalam et al., 2006). If grass-fed beef really does produce a higher quantity and quality of lipid profiles, producers could see an incentive to make the switch to gain higher reproductive production and better premiums for higher meat qualities. \n\n#Introduction \nAgricultural technologies have changed the way we feed our ruminants, especially in the United States and United Kingdom. The increasing use of feedlot production systems coupled with the ability of grain rations to make the ruminant more energy efficient have resulted in a shift in the beef industry to concentrate-based diets. The total of cattle and calves on feedlots in January 2016 was 13.2 million head, which was up 1% from the 2015 total (National Agricultural Statistics Service, 2016). However, Ponnampalam et al., concludes that changing feeding systems have resulted in changing levels of functional lipids, saturated and *trans* fatty acid content in our modern meat animals, which can affect carcass characteristics and the nutritive value of the meat (Ponnamplam et al., 2006). \n\n\"The type of feeding regimens used in beef cattle production can influence the level of essential fats in red meat, due to the variations in the fatty acid composition of diet\" (Ponnampalam et al., 2006). \n\n \n\nA goal for health professionals in recent studies has been to \"reduce and replace\" saturated fatty acids in red meats with beneficial fatty acids, with the hopes that it might change consumer outlook on the health value of red meat (Ponnampalam et al., 2006). The significance of the Ponnampalam study was a \"diet-induced change in functional FA such as n-3 FA, CLA, *trans* fatty acids and ratio of n-6:n-3 FA\". Basically, lipid components of beef meat can be altered by the feeding system.\n\n \"Grass-fed lean beef can be accredited as 'a source' of n-3 PUFA for those who do not consume fish, because the n-3 FA content is similar to that provided by some white fish\" (Ponnampalam et al., 2006). \n"},{"_id":"640b8bd1d8d572a67f00007b","treeId":"63c969310b61c9f828000047","seq":6263578,"position":6,"parentId":"63e988903e7bb0c93d000035","content":"Grass-fed beef production in the US is “highly variable because of the variety of genetics, forages, and management practices used, which affect the fatty acid composition of beef” (Leheska, 2014). In addition, feedstuff nutritive value is highly variable across geographic locations, genetic strains, crop variety, season, year, and more factors, which can all change the end nutritive value of the meat (Leheska, 2014)."},{"_id":"63c96f320b61c9f82800004d","treeId":"63c969310b61c9f828000047","seq":6245461,"position":4,"parentId":"63c969570b61c9f828000049","content":"# Conclusion\n"},{"_id":"64042da2efedad29ea000050","treeId":"63c969310b61c9f828000047","seq":6263588,"position":0.5,"parentId":"63c96f320b61c9f82800004d","content":"Overall, data has been mixed and inconclusive regarding the levels and health benefits of omega-3 fatty acids present in grass-fed beef. Until such time as the role of fatty acids in human health is more fully understood and the Food and Nutrition Board of the Institute of Medicine can recommend a dietary intake, grass-fed beef cannot be regarded as beneficial in that regard (Clancy, 2006). However, there is sufficient evidence to conclude that grass-fed beef can be labeled as lean and lower in total fat than conventionally fed cattle (Clancy, 2006)."},{"_id":"63f1d3b081174d7460000052","treeId":"63c969310b61c9f828000047","seq":6245460,"position":1,"parentId":"63c96f320b61c9f82800004d","content":"##Bringing it all together\n\n* Grass fed beef is not necessarily more healthy\n* What matters is what the animal is fed TMR: a forage component to the diet (or mostly forage with some concentrate supplements) can have a beneficial effect on the total fatty acid profiles\n* If consumers want to tailor their meat choices to a healthy diet, should go generally with grass-fed (only low-fat healthy diet)\n* Overall, need a lot more research to justify the huge premiums and switch from feedlot to pasture"},{"_id":"64063c1befedad29ea00005a","treeId":"63c969310b61c9f828000047","seq":6259494,"position":2,"parentId":"63f1d3b081174d7460000052","content":"In 2005, the recommended average daily consumption of protein foods was around 150 g/day or 5.5 oz/day (depending on age and gender), while in 2010 the average intake in the United States was 1.7 oz/day (McNeill, 2014). Recent data from the Dietary Guidelines for Americans states that overall average intakes of protein foods are close to recommended amounts (USDA & US Dept. of Health & Human Services, 2015). The Dietary Guidelines for Americans also recommends an overall to more nutrient-dense proteins, including more seafood, to reduce overall caloric intake (USDA & Us Depth of Health & Human Services, 2015). "},{"_id":"640cf35eb698ea67ef00007f","treeId":"63c969310b61c9f828000047","seq":6266626,"position":1,"parentId":"64063c1befedad29ea00005a","content":"##Conclusion\n#conclusion\n\nThe 2015-2020 Dietary Guildelines for Americans recommends that Americans make an overall shift in their diet towards more nutrient-dense proteins in order to reduce overall caloric intake (USDA & US Dept of Health & Human Services, 2015). Scientific findings that are strongly correlating dietary intake to risk factors for obesity, cardiovascular disease, and more diseases (McNeill, 2014), are pushing producers towards genetic manipulations and changing feeding regimes to create healthier animal products for human consumption. Substantial research conducted since the 1980s indicates that grass-fed beef has a consistently higher total CLA, omega-3 fatty acids, and *trans*-vaccenic acid on a g/g fat basis, as well as an overall lower fat total (Daley et al., 2010). There are many variabilities within feedstuffs, production management, and animals that create difficulty in comparing different studies to each other (Ponnampalam et al., 2006). The overall trend shows that grass-fed beef can be labeled as lean and lower in total fat than conventionally fed cattle (Clancey, 2006). However, it should be noted that due to the higher overall fat content of grain-fed beef, consumers can achieve a similar intake of desirable CLA, omega-3 FA, trans- vaccenic acid by consuming the higher-fat portions of grain-fed beef (Daley et al., 2010). Therefore, grass-fed beef is most suitable to consumers looking for an overall low-fat diet while maximizing the lipid profiles in their protein sources. In addition, data has been mixed and inconclusive regarding the levels and health benefits of omega-3 fatty acids present in grass-fed beef. Until such time as the role of fatty acids in human health is more fully understood and the Food and Nutrition Board of the Institute of Medicine can recommend a dietary intake, grass-fed beef cannot be regarded as beneficial in that regard (Clancy, 2006).\nIn 2005, the recommended average daily consumption of protein foods was around 150 g/day or 5.5 oz/day (depending on age and gender), while in 2010 the average intake in the United States was 1.7 oz/day (McNeill, 2014). Recent data from the Dietary Guidelines for Americans states that overall average intakes of protein foods are close to recommended amounts (USDA & US Dept. of Health & Human Services, 2015). The best conclusive recommendation for American consumers looking to improve their dietary choices is for them to select different types of lean meat that fit their palatability preferences and combine them to create a healthy diet. Grass-fed beef will provide a lower total fat content while still providing a beneficial ratio of \"good\" fatty acids, at the cost of a sometimes intense grassy flavor, while grain-fed beef can provide the same ratio of fatty acids at the cost of a higher total fat content (Daley et al., 2010). More research is called for to further narrow variabilities, explore opportunities in biochemical manipulation of forages in the ruminant digestive system, and make better recommendations to producers on how to maximize their production output while producing animal products with a desirable panel of carcass characteristics. \n[ ] mic drop\n\n \n"},{"_id":"640f20427221f33ee9000085","treeId":"63c969310b61c9f828000047","seq":6266622,"position":1,"parentId":"640cf35eb698ea67ef00007f","content":""},{"_id":"640f20517221f33ee9000086","treeId":"63c969310b61c9f828000047","seq":6266624,"position":1,"parentId":"640f20427221f33ee9000085","content":""},{"_id":"640ebe817221f33ee9000082","treeId":"63c969310b61c9f828000047","seq":6266629,"position":2,"parentId":"640f20517221f33ee9000086","content":"##Introduction- `final draft version`\n\nAs of January 1, 2016, the total of all cattle and calves in the United States was 92 million head. (National Agricultural Statistics Service, 2016). Beef is the predominantly consumed red meat for most developed nations (McNeill, 2014). The number of beef cattle in the United States is growing (Agricultural Marketing Statistics, 2016) as are nationwide health concerns regarding the traditional American diet high in risk factors for cancers, coronary heart disease, diabetes, and obesity (McNeill, 2014). Beef has come under close scrutiny regarding its nutritive value and implications for human health when consumed with the intent of creating a low-fat diet. Research has been conducted for decades to manipulate meat products that are higher in beneficial fats and low in total fat. At the same time, debates over which fatty acid complexes are considered desirable for human health have been controversial and conceded mixed evidence (Clancey, 2006). A production method utilizing grasses and forages to produce grass-fed beef has shown promising evidence that it could create meat high in omega-3 fatty acids and conjugated linoleic acids while still being lower in total fat content (White, 2014). However, decades of research have conflicted and while a few major generalizations can be made, more research is called for to conclusively determine if grass-fed beef can be considered an overall healthier alternative to conventionally-fed beef.\nHistorically, grass-fed beef was the only production method utilized until the 1950s, when new agricultural technology created the feedlot industry. The discovery that high energy grains could simultaneously reduce time cattle spend on feed while pushing a rapid weight gain led to cheaper beef products with more intramuscular fat, or marbling. However, changes in consumer demand and new focuses on nutritive effects of feed regime have incentivized some producers to return to the “pastoral approach to beef production” (Daley et al., 2010).\nGrass-fed beef is somewhat self-defining. At the most basic, it is defined as a ruminant fed entirely by grass and forage since weaning (USDA, n.d.). It is considered a life-long production system where the animal spends its entire life eating forages, as opposed to being raised on forages and finished on cereal concentrates or raised entirely on a feedlot system (White, 2014). Before 2016, the USDA certified grass-fed producers who marketed under 49 cattle per year or lambs from 99 ewes per year, and the producer had to guarantee the animals were not fed grain or grain by-products (USDA, n.d.). In 2012, grass-fed beef operations certified by USDA’s Grass Fed Small & Very Small Producer Program contributed 11.5% of all cattle and cow-calf operations in the United States. Grass-fed sheep producers contributed 29.5% of all ewe flock operations and 32.4% of total inventory of ewes and lambs, with 59,127 producers certified by the USDA (USDA, n.d.). Defining grass-fed beef is necessary to compare the differing production systems, feeding regimes, and geographic areas that the beef is produced in the United States.\nIf conclusive data could be produced affirming the hypothesis that grass-fed beef is a healthier alternative to conventional, it would further shift consumer preference and therefore incentive for producers to switch production styles. Therefore, it is imperative to fully understand the breadth of variability in studies as well the generalities that can be drawn before making an overall conclusion. The research being performed on grass-fed beef versus concentrate-fed beef could very well have a lasting impact on the types of production systems and therefore the market economics of beef production in the United States.\n"},{"_id":"640ee3147221f33ee9000084","treeId":"63c969310b61c9f828000047","seq":6266632,"position":2.5,"parentId":"640f20517221f33ee9000086","content":"##Discussion- `final draft version`\n\nEarly research comparing grass-fed beef to conventionally-fed beef focused on traditional carcass quality testing that measured gross differences. A Kansas Agricultural Experimental Station study conducted in 1978 divided steers into four separate dietary regimes:grass-fed only (winter forage ration, summer grazing); short-fed (grass-fed and finished for 49 days in a feedlot); long-fed (grass-fed and finished for 98 days in a feedlot); and forage-fed (finished for 98 days in a feedlot on a high forage ration). The study found that increased grain feeding gave higher marbling scores and quality grades, carcass weight, fat thickness, and overall higher taste panel scores. In addition, grass-fed group had the yellowest fat, considered undesirable by consumers, the lowest marbling scores, and the lowest quality grades of the other 3 groups. Overall, the evidence presented was overwhelmingly in favor of long-term grain feeding, and the researchers concluded those carcasses \"had the most desirable quality and palatability characterstics\" (Harrison et al., 1978). \nNewer research has corroborated early findings that grass-fed beef usually has a yellow fat color and generally less marbling than grain-fed. The most desirable color of fat is white, and the yellow color is altered from the ideal as a result of a greater level of beta-carotene, or can be because of changes in the fatty acid profile (Leheska et al., 2014). While yellow fat is typically considered an undesirable trait for consumers, it could potentially be overlooked in exchange for a more nutritive profile. \nA contrast between earlier research and today's studies is the emphasis placed on marbling. The research described prior graded the grass-fed beef group on the lowest amount of marbling which was then seen as undesirable. Today, a lower amount of marbling would contribute to an overall lower fat content which modern consumers are more concerned with (McNeill, 2014). \nThe lower palatability scores found in the prior study have since been correlated with a characteristic \"grassy\" taste of grass-fed beef. This was an early indicator of later studies that focused in on fatty acids, as a 2006 article found that increased omega-3 fatty acids contribute to an \"intense\" flavor that is characteristics of grass-fed beef (Ponnampalam et al., 2006) A relatively recent area of focus has been the effort to profile the lipid amount and composition of grass-fed beef. A standard which is comparable between grass-fed meat carcasses across the United States could give valuable insight to which production methods produce a healthier product. Functional lipid components in meat products have a promising relation to improving human health, although research is still pending conclusive evidence. Long-chain omega-3 fatty acids are reportedly linked to improved immune, nervous, and cardiovascular functions in humans, and higher reproductive abilities and meat qualities in ruminant animals (Ponnampalam et al., 2006). A comprehensive literature review determined that while there is promising evidence that shows correlation between different lipid compounds and health benefits, the research is not yet conclusive and requires further work to draw convincing conclusions (Clancey, 2006). \n\nIn general, three factors of fatty foods determine the nutritional value. The polyunsaturated fatty acids:saturated fatty acids (PUFA:SFA or P:S) ratio should be low. The omega-6:omega-3 fatty acid (n-6:n-3 FA) ratio should also be low. The third factor is total fat content. There is much debate over which factor should be more weighted for overall nutritional health (Enser et al., 1998). However, most research directed at comparing lipid profiles of grass-fed beef has compiled data that fits one of the above factors in order to compare and contrast.\n*Trans* fatty acids have been studied in detail as well. Higher levels of dietary *trans* fatty acids increase serum LDL-cholesterol while decreasing serum HDL-cholesterol levels (Ponnampalam et al., 2006). LDL (low density lipoprotein)-cholesterol is considered the \"bad\" cholesterol as it transports water insoluble lipids in the blood, while HDL (high density lipoprotein)-cholesterol is considered beneficial to cardiovascular health (Clancey, 2006). Generally, manufactured *trans* fatty acids are associated with cardiovascular risk factors, whereas naturally occurring *trans* fatty acids like conjugated linoleic acid (CLA) and *trans*-vaccenic acid have had health benefits (Leheska et al., 2014). Overall, a food considered high in beneficial fats should adhere to the P:S ratio and n-6:n-3 ratio described above, as well as have an adequate amount of CLA and *trans*-vaccenic acid.\n\nIn 1998, a study conducted by researchers in Bristol, UK, examined the fatty acid content and compositions of beef cattle raised on different production systems. Thirty steers were finished on grass pasture for a shorter period of time and measured against ten steers finished for a longer period of time. These groups were measured against a control group of concentrate-fed bulls fed concentrate pellets and given barley straw *ad libitum*. The study also examined lambs grazed on pasture, which is a less common area of research but valuable nonetheless. Samples were measured from several areas in the carcass and analyzed for lipid content and composition. The study found that the grazed steers took longer to finish (harvested at 18 months) than the control bulls which finished by 12.5 months with the same amount of visual fat. The total fatty acid weight was greater in grass-finished steers than control bull group. The grain-fed bulls showed higher levels of omega-6 FA than grass-fed. The P:S ratio was 2-3 times higher in grain-fed group. The study also confirmed that lamb muscle has higher concentrations of omega-3 FA than beef muscle taken from comparative locations in the carcass. The differences in fatty acid percentages were negligent between muscles but the effects of feeding regime remained constant. Grain-fed muscles held 2-3 times the amount of omega-6 FA than grass-fed, and grass-fed held a 2-4 times amount of omega-3 FA (Enser et al., 1998). This study strongly correlated with the notion that grass-fed beef has overall beneficial profiles for omega-6:omega-3 ratios. Although this study is valuable for its comparison of fatty acid profiles, it has problems that make it difficult to compare to other systems. The beef was not considered \"grass-fed\" since the steers in the grass-fed group were only finished on grass pasture, not fed their entire lives (or not explicitly specified). Comparing steers to bulls is problematic since steers are developmentally fatter than bulls and will intrinsically have altering lipid fatty acid composition (Enser et al., 1998). The difficulty in comparing pasture-raised to feedlot-raised cattle is intact versus castrated males. While bulls are usually preferred in a feedlot setting because of their rapid weight gain abilities, they present management problems in pasture and cannot gain enough weight to reach market weight on low-energy diets (Enser et al., 1998). This study has more variability from comparing steers to bulls, but can still draw some generalizations regarding lipid profiles.\n\nAustralian beef makes an interesting comparison to domestic production systems because only 35-40% of Australian cattle in 2006 were raised in a feedlot production system (Ponnampalam et al., 2006) A study conducted compared the difference between raising cattle entirely on grass diets, raising them under forage conditions and then finishing for 80 days on grain diets (short term grain-fed or STGF), and feeding long-term grain for 150-200 days before slaughter (LTFL). The grass-only group showed a two-fold increase in concentration of omega-3 FA compared to both STGF and LTFL in all primal meat cut areas. Long-term grain feeding significantly increased the total saturated, omega-6 and *trans* fatty acid contents. The muscle showed increase in *trans* fatty acids in the short term grain feeding group and was further increased in the long term grain group, which suggests that length of grain feeding is probably a factor for increased *trans* fatty acids. In effect, changing the diet regimen had a drastic effect on the amount and composition of different fatty acids (Ponampalam et al., 2006). This holds promising implications for health professionals, who have shifted focus to trying to remove saturated fatty acids from red meat and replace them with beneficial fatty acids. \nLike the Enser et al., study, this research has limitations on its comparison to domestic production. The Australian breeds used in this study have genetic strains bred for ability to produce on low-quality ranges, since the majority of cattle are raised on pasture in Australia. A similar study conducted in the United States could given valuable insight to correlating the results with feeding regime and negating the variability of genetic strain and the nutritional value of different forages.\n\nFeedstuffs for ruminant animals ranges due to their innate ability to be able to glean energy from sources that nonruminants cannot. However, the majority of cattle feed is grown, meaning it absorbs some amount of nutrients from the soil it grows it. In the United States alone, forage systems total at least 30 million hectares, with 24 million being perennial forages and 8 million of annual forages (Kurve et al., 2015). The types of grass grown and fed to grass-fed beef will create some amount of variability in the meat characteristics. However, a 2015 study contrasted that conclusion and found that when comparing cattle raised on different grasses in the stocker phase and finished on tall fescue, little to no variability in carcass traits occurred. The study compared 3 different forage treatments from native warm-season grasses in Mississippi, US: Bermuda grass monoculture (BER), Indian grass monoculture (IND), and and Indian grass mix (MIX). They compared fatty acid profiles, tenderness, lipid oxidation, cooking loss, sensory testing, yield grade, and quality grade. There were little to no statistically significant differences between treatments. Interestingly, there were no differences reported in the fatty acid composition between treatments. The averages of the fatty acid composition fell within accepted averages for grass-fed beef. Consumers also rated the meats similarly, with variability due to personal preference and cooking style, but the overall result was that forage-finished beef is deemed acceptable by consumers and the researchers urged farmers to make better use of their pastures to feed cattle during the stocker phase (Kurve et al., 2015). This data could indicate that grasses grown in the same geographic region under the same season and from similar genetic strains (native warm-season grasses) result in overall similar carcass characteristics. However, further research is indicated to compare grasses from from different geographic origins.\n\nA detriment to the production of grass-fed beef is traditionally the longer time it takes for cattle to reach the equivalent carcass weight of concentrate-fed cattle, or the less desirable option of marketing them with a lighter carcass weight. A 2001 study hypothesized that a high carcass growth could be achieved on a grass-based diet without deleterious effect on meat quality. The study compared steers raised on six diets of differing ratios. One diet was completely grass, and then the kg DM of grass decreased and the kg concentrate increased gradually in four diets until the sixth diet was completely concentrate-based. The steers were harvested after 95 days following their diet regimes. Carcass weight gain for the grass-fed group was 360 g/day while the concentrate group averaged 809 g/day. This confirmed previous studies that looked at carcass weight gain rates, but also confirmed that meat quality did not suffer due to the slower weight gain. This study noted an important variability in accuracy: the maturity stage and season at which the grass forage was harvested. The grass utilized was harvested in fall and had lower digestibility and higher crude protein relative to grass grown earlier in the grazing season (French et al., 2001). Higher rate of digestibility could lead to an increase in weight gain rate which could potentially close the gap between grass-fed and grain-fed carcass weights.\n\nAn emerging trend of research to develop more nutrient-dense products has been pushed largely by dietary recommendations from governmental institutes. The World Review of Nutrition and Dietetics officially recommended producers to improve the lipid profile of animal meats through “optimal” feeding systems, since most humans source the majority of their lipids through animal foods. Recommendations like this and convincing evidence that feeding systems have a great impact on meat characteristics has led to published research within the last decade that focuses in on nutritive value of grass-fed beef (Ponnampalam et al., 2006). In order to make a broad statement to release to consumers regarding dietary recommendations, it is imperative to critically examine the variabilities of the past research performed and any further research that should be conducted.\nStudies that compare the feedstuff of cattle to the meat characteristics should be very specific about the type of feed and other factors. Nutritive value in feedstuffs can be highly variable across geographic locations, genetic strains, crop variety, season, year, and more, which can all affect the characteristics of the meat (Leheska et al., 2014). Comparing a grass-fed group of cattle to a grain-fed group is difficult without further examining the feed. In grass-fed beef, variability arises because of the genetics, forages, and management practices used, which can all affect the composition of the beef (Leheska et al., 2014). For example, the study conducted in Mississippi examining native warm-season grasses might find the lipid fatty acid profiles were different than the Australian beef cattle raised on native Australian pasture forages (Kurve et al., 2015 and Ponnampalam et al., 2006). There is also variability within age, gender, and genetic strains between animals (Daley et al., 2010). Perhaps the most obvious of this is comparisons made between countries. Beef cattle raised in the US are typically fatter than cattle in Europe, for example, and reflect an overall difference in production systems and consumer preferences (Enser et al., 1998). To conclusively demonstrate that grass-fed beef contains a significantly different meat characteristic profile, more specific research needs to be conducted over wide geographic areas to ensure that within variabilities, the overall trend stays constant. For example, a nation-wide study conducted in 2014 aimed to include grass-fed beef in the USDA National Nutrient Database for Standard Reference. It compared the fatty-acid composition of grass-fed and conventionally-fed beef (used as a control) that represented 13 states of grass-fed beef production. While the study found that fatty acid amounts were relatively consistent with other studies, the researchers also found that there was no difference in concentrations of PUFA, trans-fatty acids, omega-6 fatty acids, and cholesterol between the grass-fed and control groups (Leheska et al., 2014). This study is an example of further research that should be conducted on a larger scale to eliminate the variabilities that will be found due to feed grown in specific geographical origins, and regional genetic strains of beef cattle.\nAnother topic of research that could assist in manipulating carcass qualities for dietary value is ruminal biochemistry. A preliminary study compared RNA extractions taken from the rumen wall of forage-fed versus grain-fed cattle from a homogenous genetic line. They found that 342 genes displayed significant differential expression levels. Of those, 78% had a higher expression level in the grass-fed group. Two of the differentially expressed genes (DEGs) functioned in the vitamin-C transport pathway, which can alter beef color and fatty acid composition, among other carcass characteristics (Yaokun et al., 2015). While this particular study was limited by the number of cattle tested and number of differentially expressed genes analyzed, it called for further research that could project the biochemical differences between grass-fed and grain-fed beef. Understanding the biochemical pathways from feed to rumen to meat qualities would be the next step to developing genetic improvements that could make grass-fed cattle more environmentally efficient (Capper, 2012) and create a leaner product (Yaokun et al., 2015). \n\n\n"},{"_id":"640f205d7221f33ee9000087","treeId":"63c969310b61c9f828000047","seq":6266631,"position":3,"parentId":"640f20517221f33ee9000086","content":"##Conclusion `final draft version`\n\n\nThe 2015-2020 Dietary Guildelines for Americans recommends that Americans make an overall shift in their diet towards more nutrient-dense proteins in order to reduce overall caloric intake (USDA & US Dept of Health & Human Services, 2015). Scientific findings that are strongly correlating dietary intake to risk factors for obesity, cardiovascular disease, and more diseases (McNeill, 2014), are pushing producers towards genetic manipulations and changing feeding regimes to create healthier animal products for human consumption. Substantial research conducted since the 1980s indicates that grass-fed beef has a consistently higher total CLA, omega-3 fatty acids, and *trans*-vaccenic acid on a g/g fat basis, as well as an overall lower fat total (Daley et al., 2010). There are many variabilities within feedstuffs, production management, and animals that create difficulty in comparing different studies to each other (Ponnampalam et al., 2006). The overall trend shows that grass-fed beef can be labeled as lean and lower in total fat than conventionally fed cattle (Clancey, 2006). However, it should be noted that due to the higher overall fat content of grain-fed beef, consumers can achieve a similar intake of desirable CLA, omega-3 FA, trans- vaccenic acid by consuming the higher-fat portions of grain-fed beef (Daley et al., 2010). Therefore, grass-fed beef is most suitable to consumers looking for an overall low-fat diet while maximizing the lipid profiles in their protein sources. In addition, data has been mixed and inconclusive regarding the levels and health benefits of omega-3 fatty acids present in grass-fed beef. The Union of Concerned Scientists concluded in 2006, \"until such time as the role of fatty acids in human health is more fully understood and the Food and Nutrition Board of the Institute of Medicine can recommend a dietary intake, grass-fed beef cannot be regarded as beneficial in that regard\" (Clancy, 2006).\nIn 2005, the recommended average daily consumption of protein foods was around 150 g/day or 5.5 oz/day (depending on age and gender), while in 2010 the average intake in the United States was 1.7 oz/day (McNeill, 2014). Recent data from the Dietary Guidelines for Americans states that overall average intakes of protein foods are close to recommended amounts (USDA & US Dept. of Health & Human Services, 2015). The best conclusive recommendation for American consumers looking to improve their dietary choices is for them to select different types of lean meat that fit their palatability preferences and combine them to create a healthy diet. Grass-fed beef will provide a lower total fat content while still providing a beneficial ratio of \"good\" fatty acids, at the cost of a sometimes intense grassy flavor, while grain-fed beef can provide the same ratio of fatty acids at the cost of a higher total fat content (Daley et al., 2010). More research is called for to further narrow variabilities, explore opportunities in biochemical manipulation of forages in the ruminant digestive system, and make better recommendations to producers on how to maximize their production output while producing animal products with a desirable panel of carcass characteristics. \n\n"},{"_id":"640b8d90d8d572a67f00007c","treeId":"63c969310b61c9f828000047","seq":6263579,"position":4,"parentId":"63f1d3b081174d7460000052","content":"In January 2016, the USDA Agricultural Marketing System (AMS) hosted a conference call to announce the ending of their condonement of the grass-fed certification. The AMS announced that the USDA would no longer recognize a standard definition for grass-fed beef and all marketing claims would have to be verified through third-party organizations or marketed without the backing of a USDA claim (USDA, 2016)."},{"_id":"640ce6beb698ea67ef00007d","treeId":"63c969310b61c9f828000047","seq":6264516,"position":5,"parentId":"63f1d3b081174d7460000052","content":"“The type of feeding regimens used in beef cattle production can influence the level of essential fats in red meat, due to the variations in the fatty acid composition of diet” (Ponnampalam et al., 2006).\nA goal for health professionals in recent studies has been to “reduce and replace” saturated fatty acids in red meats with beneficial fatty acids, with the hopes that it might change consumer outlook on the health value of red meat (Ponnampalam et al., 2006). The significance of the Ponnampalam study was a “diet-induced change in functional FA such as n-3 FA, CLA, trans fatty acids and ratio of n-6:n-3 FA”. Basically, lipid components of beef meat can be altered by the feeding system.\n“Grass-fed lean beef can be accredited as ‘a source’ of n-3 PUFA for those who do not consume fish, because the n-3 FA content is similar to that provided by some white fish” (Ponnampalam et al., 2006)."},{"_id":"640b5c7cd8d572a67f00006f","treeId":"63c969310b61c9f828000047","seq":6264525,"position":6,"parentId":"63f1d3b081174d7460000052","content":"Research performed since the 1980s indicates that grass-fed beef has a consistently higher total CLA, omega-3 fatty acid, and trans-vaccenic acid on a g/g fat basis, as well as an overall lower fat content (Daley et al., 2010). There is some variability within age, gender, and genetic differences within animals but the effect of nutrition remains a significant factor (Daley et al., 2010). However, it should be noted that due to the higher overall fat content of grain-fed beef, consumers can achieve a similar intake of desirable CLA, omega-3 FA, trans- vaccenic acid by consuming the higher-fat portions of grain-fed beef (Daley et al., 2010). Therefore, grass-fed beef is most suitable to consumers looking for an overall low-fat diet while maximizing the lipid profiles in their protein sources."},{"_id":"63c9872906220ef790000047","treeId":"63c969310b61c9f828000047","seq":6220827,"position":5,"parentId":"63c969570b61c9f828000049","content":"# Literature Cited\n"},{"_id":"63c987b206220ef790000048","treeId":"63c969310b61c9f828000047","seq":6225566,"position":1,"parentId":"63c9872906220ef790000047","content":"Yoakun, et al. 2015"},{"_id":"63cef4bece271c669a000049","treeId":"63c969310b61c9f828000047","seq":6433598,"position":1,"parentId":"63c987b206220ef790000048","content":"Ruminal transcriptomic analysis of grass-fed and grain-fed angus beef cattle.\n\n`Rumen functions differently in grass and grain fed environments which results in different compositions and flavors of beef`\n\n\"The RNA sequencing method was used to identify differentially expressed genes in the ruminal wall.... then based on the DEGs list, we performed a computational function analysis and found potential mechanisms contributing to the difference between the two groups\"\n\n\"Two DEGs were involved in teh canonical pathway vitamin-C transport, which may alter beef color, lipid stability, and fatty acid composition between grass-fed and grain-fed cattle.\"\n\nThree DEGs functioned in glutathione pathways, which could explain why previous studies have found that grass-fed beef contains higher amounts of glutathione (Yaokun et al, 2015).\n\nDEG= differentially expressed genes = what the RNA sequencing was trying to identify \n\n`sdfl;kjsdf`\n[X] to do\n**asdflkj**\n\n\n\n\n"},{"_id":"63e9481a3e7bb0c93d000034","treeId":"63c969310b61c9f828000047","seq":6242599,"position":1,"parentId":"63cef4bece271c669a000049","content":"###Summary\nA study conducted in 2015 tested the ruminal environments of four different steers taken from a homogenous genetic line. Two steers were raised on forage feed and two were fed on grain rations. All four steers were raised in a feed lot setting. RNA was extracted from rumen wall samples and read for gene expression level (Yoakun 2015). The researchers were looking to prove that cattle would produce different compositions and flavors of beef when fed under different regimes. They found that 342 genes displayed \"significant\" differential expression levels. Of those, seventy-eight percent displayed a higher expression level in the grass-fed group. Two of the differentially expressed genes (DEGs) functioned in the vitamin-C transport pathway, which can alter beef color and fatty acid composition, among other carcass characteristics. Three of the DEGs found functioned in glutathione pathways. While details are not yet known, this could potentially explain why other studies have found that grass-fed beef contains higher amounts of glutathione than grain-fed (Yaokun et al., 2015). \nThis particular study was limited by the number of cattle tested, differentially expressed genes analyzed, and by relying on computational strategy that \"has not been experimentally validated\" (Yaokun et al., 2015). However, further studies of this type could further project the biochemical differences between grass-fed and grain-fed beef. There has been clear evidence that the two meat types share many differences, mainly due to the composition of the feed they are taking in, but little is known about the specific molecular pathways. Understanding the pathways from feed to rumen to meat qualities would be the key to deciphering reliable differences between grass- and grain-fed beef, and techniques like RNA sequencing of ruminal wall samples would be a piece [ ] (replace for better word) of the puzzle. \n\n###Fluffy Stuff\n\"Flavor, as the combination of taste and aroma, is one of the most important factors affecting consumer preference\" (Yaokun et al., 2015). \n\n\"Development of animal genetic improvement and breeding methodology can bring about leaner beef products\" (Yaokun et al., 2015). \n\n\n\n\n"},{"_id":"63cefb0fce271c669a00008f","treeId":"63c969310b61c9f828000047","seq":6225567,"position":2,"parentId":"63c9872906220ef790000047","content":"Kurve, et al. 2015"},{"_id":"63cefe4bce271c669a000090","treeId":"63c969310b61c9f828000047","seq":6225569,"position":1,"parentId":"63cefb0fce271c669a00008f","content":"The effect of feeding native warm-season grasses during the stocker phase on meat composition, quality characteristics, and sensory properties of loin steaks from forage-finished cattle.\n\n`Test carcass qualities on cattle fed native warm-season grass and forage finished, compares different forage techniques without grain comparison`"},{"_id":"640af11ed8d572a67f00006c","treeId":"63c969310b61c9f828000047","seq":6262996,"position":1,"parentId":"63cefe4bce271c669a000090","content":"Mississippi State University\n\n72 British crossbred steers to 9 pasture plots with 3 different forage treatments that included bermuda grass, Indian grass monoculture, and big blustem, little bluestem,a nd Indian grass and forage finished on tall fescue. Fed native warm-season grass in stocker phase and forage finished on tall fescue. The carcasses did not differ in sensory attributes, average sensory acceptability, color, tenderness, pH, or bacteria counts. There were some differences in aroma, flavor, and texture. Overall, researchers concluded that high-quality forage-fed beef can be produced when cattle are fed mixed native warm season grasses, Indian grass, or Bermuda grass during the stocker phase and then finished on tall fescue.\nThe goal of the study was to compare carcass qualities including fatty acid profile, tenderness, lipid oxidation, cooking loss, sensory testing, yield grade, and quality grade between groups of grass-fed steers on different types of pasture. \nResults: There were mixed results in the comparison of fat percentage, meat pH, and color, however the results were minimal. Interestingly, there were no differences reported in the fatty acid composition among the carcasses from all treatments. The averages of the lipid fatty acid profiles fell within accepted averages for grass-fed beef. Consumers rated the carcasses similarly. Perhaps the most important finding was that the cattle from the Indian treatment had a higher percentage of Select grade carcasses, which was likely related to the higher fat percentage even though no statistical difference existed. The overall result was that forage-finished beef was deemed acceptable by consumers and the research urged farmers to make better use of their pastures to feed cattle during the stocker phase (Kurve et al, 2015). \n\nNo concentrate control groups.\n\n\n##Fluffy Stuff\nAlthough higher omega-3:omega-6 ratios have been reported in grass-fed beef, the actual amounts may not be greater since concentrate-fed beef has a higher total fat percentage (Kurve et al., 2015). \n\nIn 2007, forage systems in the United States totaled at least 24 million hectares of perennial forages and 8 million hectares of annual forage (Kurve et al., 2015). "},{"_id":"640b11d1d8d572a67f00006d","treeId":"63c969310b61c9f828000047","seq":6263159,"position":1,"parentId":"640af11ed8d572a67f00006c","content":"Feedstuffs for ruminant animals ranges due to their innate ability to be able to glean energy from sources that nonruminants cannot. However, the majority of cattle feed is grown, meaning it absorbs some amount of nutrients from the soil it grows it. Thus begins the list of variabilities that falls between feedstuffs grown in different geographical origins, seasons, crop varieties, years, under different management, et cetera. In the United States alone, forage systems total at least 30 million hectares, with 24 million being perennial forages and 8 million of annual forages (Kurve et al., 2015). The types of grass grown and fed to grass-fed beef will create some amount of variability in the meat characteristics. However, a 2015 study contrasted that conclusion and found that between cattle raised on grass in the stocker system and finished on tall fescue, little to no variability in carcass traits occurred. The study compared 3 different forage treatments from native warm-season grasses in Mississippi, US: Bermuda grass monoculture (BER), Indian grass monoculture (IND), and and Indian grass mix (MIX). They compared fatty acid profile, tenderness, lipid oxidation, cooking loss, sensory testing, yield grade, and quality grade. There were little to no statistically significant differences between treatments. Interestingly, there were no differences reported in the fatty acid composition between treatments. The averages of the fatty acid composition fell within accepted averages for grass-fed beef. Consumers also rated the meats similarly, with variability due to personal preference and cooking style, but the overall result was that forage-finished beef is deemed acceptable by consumers and the researchers urged farmers to make better use of their pastures to feed cattle during the stocker phase (Kurve et al., 2015). This data could indicate that grasses grown in the same geographic region under the same season and from similar genetic strains (native warm-season grasses) result in overall similar carcass characteristics. However, further research is indicated to compare grasses from from different geographic origins. "},{"_id":"63cf02f3ce271c669a000091","treeId":"63c969310b61c9f828000047","seq":6225570,"position":3,"parentId":"63c9872906220ef790000047","content":"Enser, et al. 1998"},{"_id":"63cf0476ce271c669a000092","treeId":"63c969310b61c9f828000047","seq":6239364,"position":1,"parentId":"63cf02f3ce271c669a000091","content":"Fatty acid content and composition of UK beef and lamb muscle in relation to production system and implications for human nutrition\n\n`Content and composition of fatty acids from grazed steers vs cereal concentrates and also grass fed lambs`\n\n#PUFA = polyunsaturated fatty acid\n#P:S = PUFA: saturated fatty acid ratio\n\n[ ] `Look at \"Marmer et al 1984 for an 'old' study`","deleted":false},{"_id":"63e9b58b3e7bb0c93d000037","treeId":"63c969310b61c9f828000047","seq":6259518,"position":1,"parentId":"63cf0476ce271c669a000092","content":"##Summary\n\nIn 1998, a study conducted by researchers in Bristol, UK, looked at the fatty acid content and compositions of beef cattle raised on different production systems. Thirty steers were finished on grass pasture for a shorter period of time and measured against ten steers finished for a longer period of time. These groups were measured against a control group of concentrate-fed bulls fed concentrate pellets and given barley straw *ad libitum*. The study also looked at lambs grazed on pasture, which is a less common area of research but valuable nonetheless. Samples were measured from several areas in the carcass and analyzed for lipid content and composition. The study found that the grazed steers took longer to finish (18 months) versus the control bulls which finished by 12.5 months with both groups retaining a similar amount of visual fatness. The total fatty acid weight was greater in grass-finished steers than control bull group. The grain-fed bulls showed higher levels of omega-6 PUFA than grass-fed. The P:S ratio was 2-3 times higher in grain-fed group. The study also confirmed that lamb muscle has higher concentrations of omega-3 PUFA than beef muscle taken from comparative locations in the carcass. The differences in fatty acid percentages were negligent between muscles but the effects of feeding regime remained constant. Grain-fed muscles held 2-3 times the amount of omega-6 PUFA than grass-fed, and grass-fed held a 2-4 times amount of omega-3 PUFA (Enser et al., 1998). This study strongly correlated with the notion that grass-fed beef has overall beneficial profiles for omega-6:omega-3 ratios.\n\nNutritional implications: \nNutritional values of fatty foods depend on three factors: P:S ratio (polyunsaturated fatty acids: saturated fatty acids), n-6:n-3 ratio, and the total fat content (Enser et al., 1998). The UK Food Advisory Committee states that foods below 5g of total fat per 100g are considered \"low-fat\" (Enser et al., 1998). Generally, beef and lamb have low values (unfavorable) for P:S ratio, and grass-fed beef reduced the ratio where concentrate fed cattle increased it (Enser et al., 1998). However, concentrate-fed beef has a higher n-6:n-3 PUFA ratio, which was shown to be significantly lower in grass-fed (Enser et al., 1998). The controversy lies in deciding which factor is more weighted for overall nutritional health. Ruminant meas and oily fish are the only sources of preformed C20 and C22 PUFA in the diet, so the lower n-3:n-6 ratio could potentially off-set the higher P:S ratio found in grass-fed beef (Enser et al., 1998). \n\n\n##Fluffy Stuff\n\"Several studies have shown that the fatty acid composition of ruminant meats is different from that of non-ruminants. The ratio of polyunsaturated to saturated fatty acids is lower because the rumen hydrogenates unsaturated fat from the diet\" (Enser et al., 1998). Nonruminants abosrb and deposit dietary unsaturated fats unchanged. \n\nRatio of n-6:n-3 PUFA is lower in ruminant meats, which is favorable and more closely matches recommended value by British Department of Health of 4:0 or less (Enser et al., 1998).\n\nGrass is higher in n-3 series precursor fatty acid 18:3 (alpha-linolenic) and grains are higher in the n-6 series precursor fatty acid 18:2 (linoleic) (Enser et al., 1998). \n\nSeveral factors that will change the ratio of fatty acid composition are the level of fatness, castrated males versus intact, and geographical location of management. An increased level of fatness increases the fatty acid ratio of the total lipid composition. Steers are intrinsically fatter than bulls and therefore have different lipid fatty acid compositions. Grass-fed production systems almost always graze steers because grazing bulls presents management problems and are unable to gain enough fat to reach market weigh on a low-energy diet. However, bulls are most often used in a concentrate management system because of their \"innate leanness and efficiency\". Cattle in the United States are usually raised to a higher fatness content than cattle in Europe, which would also change the lipid composition (Enser et al., 1998). Research that present differences in fatty acid composition ratios must take into account these factors which would skew results. \n\n \n\n"},{"_id":"63cf06b3ce271c669a000093","treeId":"63c969310b61c9f828000047","seq":6225572,"position":4,"parentId":"63c9872906220ef790000047","content":"Ponnampalam, et al. 2006"},{"_id":"63cf076ace271c669a000094","treeId":"63c969310b61c9f828000047","seq":6242460,"position":1,"parentId":"63cf06b3ce271c669a000093","content":"Effect of feeding systems on omega-3 fatty acids, conjugated linoleic acid and trans fatty acids in Australian beef cuts: potential impact on human health\n\n`Compare grass and grain fed cattle for fatty acid analysis, specifically if grass fed contains more functional lipids`\n\nBeef cattle in Australia\n\n#Functional fatty acids = long-chain omega-3 and conjugated linoleic acids (biological role in cells)\n\n#CLA = conjugated linoleic acids\n#STGF = short term grain-fed\n#LTFL = long term grain-fed"},{"_id":"63f0a3e781174d7460000047","treeId":"63c969310b61c9f828000047","seq":6263574,"position":1,"parentId":"63cf076ace271c669a000094","content":"###Summary\n\nAustralian beef makes an interesting comparison to domestic production systems because only 35-40% of cattle in 2006 were in a feedlot production regime (Ponnampalam et al., 2006) A study conducted by Ponnampalam et al. compared the difference between raising cattle entirely on grass diets, raising them under forage conditions and then finishing for 80 days on grain diets (short term grain-fed or STGF), and feeding long-term grain for 150-200 days before slaughter (LTFL) (Ponnampalam et al., 2006). The study focused primarily on long-chain fatty acids of C14 and above, as they are the \"predominant\" FA present in beef. \n\nThe grass-only group showed a two-fold increase in concentration of omega-3 fatty acids compared to both STGF and LTL. The grass-fed beef group had significantly higher concentrations of long chain omega-3 and total omega-3 fatty acids in all primal meat cut areas than the grain-fed group. Long-term grain feeding significantly increased the total saturated, omega-6 and *trans* fatty acid contents. The muscle showed increase in *trans* fatty acids in the short term grain feeding group and was further increased in the long term grain group, which suggests that length of grain feeding is probably a factor for increased *trans* fatty acids in the meat (Ponnampalam et al., 2006). In effect, changing the diet regimen had a drastic effect on the amount and composition of different fatty acids (Ponampalam et al., 2006). This holds exciting implications for health professionals, which have shifted focus to trying to remove saturated fatty acids from red meat and replace them with beneficial fatty acids. \n\n\nFinding that a change in diet could induces changes in functional FA such as n-3 FA, CLA, *trans* fatty acids and the ratio of n-6:n-3 FA holds promise that a change in feeding system could benefit human health (Ponnampalam et al., 2006). The n-6:n-3 ratio was significantly reduced in the grass-fed beef group compared to grain-fed. \nSHORT VERSION OF RESULTS: The grass-fed beef group had significantly higher concentrations of long chain omega-3 and total omega-3 fatty acids in all primal meat cut areas than the grain-fed group. Long-term grain feeding significantly increased the total saturated, omega-6 and *trans* fatty acid contents. The muscle showed increase in *trans* fatty acids in the short term grain feeding group and was further increased in the long term grain group, which suggests that length of grain feeding is probably a factor for increased *trans* fatty acids in the meat (Ponnampalam et al., 2006). The broad conclusion states that from a human nutritional stance, the \"shift from pasture fed to grain feeding should be discouraged\" (Ponnampalam et al., 2006). \n\n###Where does change in fatty acid profile come from\nEvidence from many recent studies has shown that ruminant meat characteristics can be more or less easily manipulated by making drastic change in diets. Taking a closer look at the composition of feedstuffs could give valuable insight into what it making the change in meat qualities, and how we can further manipulate grass-fed diets to give the best `[ ] replace word` panel of nutritive value. Grasses and legumes are predominantly glycolipids, and the fatty acid content of grass is low and mainly composed of esterified fatty acids (Ponnampalam et al., 2006). Commonly utilized concentrates in cattle feed are less than 5% lipids with the exception of oilseeds which are significantly higher. The lipids that are present in concentrates are almost all storage triglycerides. Cereal grains and cottonseed have high concentrations of n-6 and little n-3 fatty acids. Extrapolating from those numbers, it can be assumed that grass-fed cattle would have a higher proportion of n-3 PUFA than grain-fed, which would show a higher proportion of n-6 in the diets (Ponnampalam et al., 2006). \n\n###Trans fatty acids\n\nHigher levels of dietary *trans* fatty acids increase serum LDL-cholesterol which decreasing serum HDL-cholesterol levels (Ponnampalam et al., 2006). They also increase other lipids that are considered risk factors for heart disease (Ponnampalam et al., 2006).\n\n \n\n###Fluffy Stuff\n\n\"The World Review of Nutrition and Dietetics recommend producers to improve the lipid profile of foods of animal origin through 'optimal' feeding systems, since animal foods are a major source of lipids for humans\" (Ponnampalam et al., 2006). \n\n#Implications\nIncreasing the functional lipid components in meat products while decreasing the levels of saturated and *trans* fatty acids and cholesterol is important because according to the World Review of Nutrition and Dietetics, foods of animal origin are a major source of lipids for human nutrition (Ponnampalam et al., 2006). There are also \"potential benefits for human health\" linked to intake of conjugated linoleic acid (CLA) from ruminant products, although the research has not shown conclusive evidence yet (Ponnampalam et al., 2006). \n\n#Implications\nLong chain omega-3 fatty acids are reportedly linked to improved immune, nervous, and cardiovascular functions in humans, and higher reproductive abilities and meat qualities in ruminant animals (Ponnampalam et al., 2006). If grass-fed beef really does produce a higher quantity and quality of lipid profiles, producers could see an incentive to make the switch to gain higher reproductive production and better premiums for higher meat qualities. \n\n#Introduction \nAgricultural technologies have changed the way we feed our ruminants, especially in the United States and United Kingdom. The increasing use of feedlot production systems coupled with the ability of grain rations to make the ruminant more energy efficient have resulted in a shift in the beef industry to concentrate-based diets. The total of cattle and calves on feedlots in January 2016 was 13.2 million head, which was up 1% from the 2015 total (National Agricultural Statistics Service, 2016). However, Ponnampalam et al., concludes that changing feeding systems have resulted in changing levels of functional lipids, saturated and *trans* fatty acid content in our modern meat animals, which can affect carcass characteristics and the nutritive value of the meat (Ponnamplam et al., 2006). \n\n\"The type of feeding regimens used in beef cattle production can influence the level of essential fats in red meat, due to the variations in the fatty acid composition of diet\" (Ponnampalam et al., 2006). \n\n \n\nA goal for health professionals in recent studies has been to \"reduce and replace\" saturated fatty acids in red meats with beneficial fatty acids, with the hopes that it might change consumer outlook on the health value of red meat (Ponnampalam et al., 2006). The significance of the Ponnampalam study was a \"diet-induced change in functional FA such as n-3 FA, CLA, *trans* fatty acids and ratio of n-6:n-3 FA\". Basically, lipid components of beef meat can be altered by the feeding system.\n\n \"Grass-fed lean beef can be accredited as 'a source' of n-3 PUFA for those who do not consume fish, because the n-3 FA content is similar to that provided by some white fish\" (Ponnampalam et al., 2006). \n\nThe \"intensity of flavor\" increases with increased levels of n-3 in lamb and beef (Ponnampalam et al., 2006). This could explain the flavor described as \"grassy\" by ?? Enser?? \n\n\n\n\n"},{"_id":"63cf095fce271c669a000095","treeId":"63c969310b61c9f828000047","seq":6225574,"position":5,"parentId":"63c9872906220ef790000047","content":"Capper, J.L. 2012"},{"_id":"63f13c1581174d746000004d","treeId":"63c969310b61c9f828000047","seq":6244135,"position":2,"parentId":"63cf095fce271c669a000095","content":"Don't really want to use: not well written and not good research"},{"_id":"63cf0c51ce271c669a000097","treeId":"63c969310b61c9f828000047","seq":6225576,"position":6,"parentId":"63c9872906220ef790000047","content":"Harrison, et al. 1978"},{"_id":"63cf0cc2ce271c669a000098","treeId":"63c969310b61c9f828000047","seq":6225581,"position":1,"parentId":"63cf0c51ce271c669a000097","content":"Nutritional regime effects on quality and yield characteristics of beef\n\n`Roughages are more cost effective given feed grain prices, so comparing carcass characteristics of beef from pasture-finished cattle`"},{"_id":"63f13e7e81174d746000004e","treeId":"63c969310b61c9f828000047","seq":6244192,"position":1,"parentId":"63cf0cc2ce271c669a000098","content":"Research conducted at the Kansas Agricultural Experiment Station in 1978 was an early example of exploring the growing trend of grass-fed beef. Thirty-eight steers were divided into four separate dietary regimes: grass-fed only (winter forage ration, summer grazing); short-fed (grass-fed and finished for 49 days in a feedlot); long-fed (grass-fed and finished for 98 days in a feedlot) and forage-fed (finished for 98 days in a feedlot on a high forage ration). The study found that increased feeding gave higher marbling scores and quality grades, carcass weight, fat thickness, and overall higher taste panel scores. They concluded, \"carcasses from cattle fed the longest time and the highest plane of nutrition had the most desirable quality and palatability characteristics\" (Harrison et al., 1978). \nOther carcass characteristics that were assessed showed differences due to feeding as well. Meat from the grass-fed group had the yellowest fat, the least marbling, and \"barely graded low Good\" for quality scores (Harrison et al., 1978). They found that carcass weight increased with length of feeding, and that grass-fed cattle had the overall lightest carcass weight (Harrison et al., 1978). The study gave overwhelming evidence against the quality of grass-fed beef. All of the carcass qualities tested showed that the long-term feedlot group had highest quality and palatability, and while short-term feeding and forage-feeding had some middle ground, the grass=fed group inevitably ended up with the lowest scores. "},{"_id":"63cf0f7fce271c669a000099","treeId":"63c969310b61c9f828000047","seq":6225584,"position":7,"parentId":"63c9872906220ef790000047","content":"Daley, et al. 2010"},{"_id":"63cf1045ce271c669a00009a","treeId":"63c969310b61c9f828000047","seq":6225585,"position":1,"parentId":"63cf0f7fce271c669a000099","content":"A review of fatty acid profiles and antioxidant content in grass-fed and grain-fed beef\n\n`Grass fed have overall lower fat content, but higher favorable fatty acids- tradeoff is distinct grass flavor and unique cooking qualities`"},{"_id":"640af024d8d572a67f00006b","treeId":"63c969310b61c9f828000047","seq":6263291,"position":1,"parentId":"63cf1045ce271c669a00009a","content":"##Summary\n\n##Fluffy Stuff\n\n\"Research spanning 3 decades suggests that grass-based diets can significantly improve the fatty acid composition and antioxidant content of beef, albeit with variable impacts on overall palatability\" (Daley et al., 2010). Specifically, grass-fed diets increase total conjugated linoleic acid (CLA), omega-3 fatty acids, and *trans*-vaccenic acid on a g/g fat basis, as well as an overall lower total fat.\n\nConsumers may achieve similar intakes of both omega-3 and CLA through the consumption of higher fat grain-fed portions (Daley et al., 2010). \n\nMost of the beef produced until the 1940's was from cattle finished on grass. During the Green Revolution of the '50s, the feedlot generation was begun and high energy grains decreased the time cattle spent on feed and improved marbling (intramuscular fat). US consumers have \"grown accustomed\" to the taste of grain-fed feed, but changes in consumer demand coupled with new research on the effect of feed on nutrient content, \"have a number of producers returning to the pastoral approach to beef production despite the inherent inefficiencies\" (Daley et al., 2010). \n\nThere is genetic, age related and gender differences among meat animals with respect to lipid profiles and ratios, but the effect of animal nutrition is \"quite significant\" (Daley t al., 2010). \n\nThe human body cannot synthesize essential fatty acids, yet they are critical to human health, so they must be obtained from food (Daley et al., 2010). \n\nA healthy diet should reflect a ratio of 4:1 omega-6:omega-3 fatty acids. The typical American diet tends to range from 11-30:1, which has been hypothesized as a factor in the rising rate of inflammatory disorders in the US (Daley et al., 2010). \n\nGrass-fed ruminant species produce 2 to 3 times more CLA than grain-fed ruminants, largely due to a \"more favorable rumen pH\" (Daley et al., 2010). \n\nGrass finishing alters the biochemistry of the beef, so aroma and flavor will be affected (Daley et al., 2010). \n\n\"To maximize the favorable lipid profile and to guarantee the elevated antioxidant content, animals should be finished on 100% grass or pasture-based diets\" (Daley et al, 2010). \n\nHOWEVER: Grain-fed beef consumers can achieve similar intakes of n-3 and CLA with higher fat portions with higher overall palatability scores. (Daley et al., 2010). "},{"_id":"640b52b8d8d572a67f00006e","treeId":"63c969310b61c9f828000047","seq":6263307,"position":1,"parentId":"640af024d8d572a67f00006b","content":"Research performed since the 1980s indicates that grass-fed beef has a consistently higher total CLA, omega-3 fatty acid, and *trans*-vaccenic acid on a g/g fat basis, as well as an overall lower fat content (Daley et al., 2010). There is some variability within age, gender, and genetic differences within animals but the effect of nutrition remains a significant factor (Daley et al., 2010). However, it should be noted that due to the higher overall fat content of grain-fed beef, consumers can achieve a similar intake of desirable CLA, omega-3 FA, *trans*- vaccenic acid by consuming the higher-fat portions of grain-fed beef (Daley et al., 2010). Therefore, grass-fed beef is most suitable to consumers looking for an overall low-fat diet while maximizing the lipid profiles in their protein sources. "},{"_id":"63cf12b2ce271c669a00009b","treeId":"63c969310b61c9f828000047","seq":6225587,"position":8,"parentId":"63c9872906220ef790000047","content":"Leheska, et al. 2014"},{"_id":"63cf1370ce271c669a00009c","treeId":"63c969310b61c9f828000047","seq":6225590,"position":1,"parentId":"63cf12b2ce271c669a00009b","content":"Effects of conventional and grass-feeding systems on the nutrient composition of beef\n\n`Study that encompasses setting standards for grass-fed beef for inclusion in USDA National Nutrient Database for Standard Reference, compared FAs as well as minerals, vitamin B12 and thiamine along with carcass characteristics`"},{"_id":"63f159a781174d7460000050","treeId":"63c969310b61c9f828000047","seq":6244301,"position":1,"parentId":"63cf1370ce271c669a00009c","content":"A nation-wide study conducted to include grass-fed beef in the USDA National Nutrient Database for Standard Reference compared the fatty-acid composition of grass-fed and conventionally-fed beef (used as a control). 13 states were represented in the grass-fed sections, and control beef samples were taken from 3 regions. The findings of the fatty acid comparisons were relatively consistent with other studies, showing that grass-fed samples had significantly less content of monounsaturated fatty acids and a greater content of n-3 and *trans*-vaccenic acids than the conventional control samples. However, the research found that there was no difference in concentrations of PUFA, *trans*-fatty acids, n-6 fatty acids, and cholesterol between the grass-fed and control groups (Leheska et al., 2014). \n\nThe beef strip steaks from grass-fed group had more yellow fat and less marbling than grain-fed control beef (Leheska et al., 2014). Fat color can be altered as a result of the greater level of vitamins like beta-carotene, or because of the changes in the fatty acid profile (Leheska et al., 2014). #olderdata\n\nTotal PUFA between grass-fed and grain-fed control did not differ, but grass-fed samples had greater concentration of n-3 fatty acids than did control, and the control group had a higher ratio of n-6:n-3 fatty acids (Leheska et al., 2014). \n\n#minerals/vitamins An older study from 1983 found that grass-fed steers had greater concentrations of Zn, Fe, P, Na, and K. However, the level of many trace minerals in feed is largely determined by the level in the soil where feed is grown or other environmental factors (Leheska et al., 2014). \n\n###Trans fatty acids\nCLA and *trans*-vaccenic acid are shown to have health benefits (Leheska et al., 2014). `Not to be confused with normal trans fatty acids??` ---- \"Naturally occurring and manufactured trans-fatty acids do not function equally because manufactured trans-fatty acids have been associated with a greater risk of coronary heart disease, whereas naturally occuring trans fats have been found to be beneficial to human health\" (Leheska et al., 2014). \n\n###Fluffy Stuff\n\nGrass-fed beef production in the US is \"highly variable because of the variety of genetics, forages, and management practices used, which affect the fatty acid composition of beef\" (Leheska, 2014). In addition, feedstuff nutritive value is highly variable across geographic locations, genetic strains, crop variety, season, year, and more factors, which can all change the end nutritive value of the meat (Leheska, 2014). \n\n\"There has been an increase in demand for natural meat products, such as grass-fed beef, partially as a result of consumer interest in the fat content of foods\" (Leheska, 2014). [ ] `Food Marketing Institute, 2005 need to look up` "},{"_id":"640cd01db698ea67ef00007c","treeId":"63c969310b61c9f828000047","seq":6264440,"position":1,"parentId":"63f159a781174d7460000050","content":"For example, a nation-wide study conducted in 2014 aimed to include grass-fed beef in the USDA National Nutrient Database for Standard Reference. It compared the fatty-acid composition of grass-fed and conventionally-fed beef (used as a control) that represented 13 states of grass-fed beef production. While the study found that fatty acid amounts were relatively consistent with other studies, the researchers also found that there was no difference in concentrations of PUFA, *trans*-fatty acids, omega-6 fatty acids, and cholesterol between the grass-fed and control groups (Leheska et al., 2014). This study is an example of further research that should be conducted on a larger scale to eliminate the variabilities that will be found due to feed grown in specific geographical origins, and regional genetic strains of beef cattle. "},{"_id":"63cf1671ce271c669a00009d","treeId":"63c969310b61c9f828000047","seq":6259584,"position":9,"parentId":"63c9872906220ef790000047","content":"French, et al. 2001\n\n\n"},{"_id":"63cf16bece271c669a00009e","treeId":"63c969310b61c9f828000047","seq":6225592,"position":1,"parentId":"63cf1671ce271c669a00009d","content":"The eating quality of meat of steers fed grass and/or concentrates\n\n`Measure quality of carcass from cattle finished on grass, or ratio of grass to concentrates, or just concentrates`"},{"_id":"63f18e1f81174d7460000051","treeId":"63c969310b61c9f828000047","seq":6244817,"position":1,"parentId":"63cf16bece271c669a00009e","content":"A frequent finding in studies contrasting grass-fed and concentrate-fed cattle is that grass-fed steers either have a lighter carcass weight or take longer to achieve the equivalent carcass weight than concentrate-fed steers. A study conducted in 2001 found that \"high carcass growth can be achieved on a grass-based diet without a deleterious effect on meat quality\" (French et al., 2001). The study compared steers raised on six diets of differing ratios. One diet was completely grass, and then the kg DM of grass decreased and the kg concentrate increased gradually in four diets until the sixth diet was completely concentrate-based. The steers were harvested after 95 days following their diet regimes. Carcass weight gain for the grass-fed group was 360 g/day while the concentrate group averaged 809 g/day. However, the study found no difference in color or shear force and noted a negligent variation in meat quality (French et al., 2001). This study noted an important variability in accuracy: the maturity stage and season at which the grass forage was harvested. The grass used in the study was harvested in autumn and hence had \"low digestibility and high crude protein relative to that reported for grass earlier in the grazing season\" (French et al., 2001). They concluded that \"only a small proportion of the large variation in both sensory and instrumental assessments of tenderness could be attributed to diet pre-slaughter, carcass growth rate pre-slaughter and carcass fatness\" (French et al., 2001). \n\n###Fluffy Stuff\n\n\"Meat flavour is influenced by a number of factors including animal age and genetics, pre-slaughter dietary regimen, environment, length of post-slaughter aging and the particular primal cut examined\" (French et al., 2001). "},{"_id":"640b6cecd8d572a67f000073","treeId":"63c969310b61c9f828000047","seq":6263533,"position":1,"parentId":"63f18e1f81174d7460000051","content":"A detriment to the production of grass-fed beef is traditionally the longer time it takes for cattle to reach the equivalent carcass weight of concentrate-fed cattle, or the less desirable option of marketing them with a lighter carcass weight. A 2001 study hypothesized that a high carcass growth could be achieved on a grass-based diet without deleterious effect on meat quality. The study compared steers raised on six diets of differing ratios. One diet was completely grass, and then the kg DM of grass decreased and the kg concentrate increased gradually in four diets until the sixth diet was completely concentrate-based. The steers were harvested after 95 days following their diet regimes. Carcass weight gain for the grass-fed group was 360 g/day while the concentrate group averaged 809 g/day. This confirmed previous studies that looked at carcass weight gain rates, but also confirmed that meat quality did not suffer due to the slower weight gain. This study noted an important variability in accuracy: the maturity stage and season at which the grass forage was harvested. The grass utilized was harvested in fall and had lower digestibility and higher crude protein relative to grass grown earlier in the grazing season (French et al., 2001). Higher rate of digestibility could lead to an increase in weight gain rate which could potentially close the gap between grass-fed and grain-fed carcass weights."},{"_id":"63cf2a0dce271c669a0000a0","treeId":"63c969310b61c9f828000047","seq":6225599,"position":10,"parentId":"63c9872906220ef790000047","content":"USDA. 2016"},{"_id":"63cf2a4cce271c669a0000a1","treeId":"63c969310b61c9f828000047","seq":6239067,"position":1,"parentId":"63cf2a0dce271c669a0000a0","content":"###USDA. 2016. Grass Fed Marketing Claim Standard. Available: www.ams.usda.gov/grades-standards/beef/grassfed. Accessed 19 February 2016. \n\nAs of January 12, 2016 the Agricultural Marketing Service no longer stands by the Grass (Forage) Fed Claim for Ruminant Livestock and the Meat Products Derived from Such Livestock. \n\nBasically: The USDA no longer recognizes a standard definition for grass-fed beef. All marketing claims must be verified through third-party organizations (much like the way organic products are certified) or marketed without the backing of a USDA claim. \n\nThis article does not mention WHY it has decided that."},{"_id":"63e8f7f23e7bb0c93d00002d","treeId":"63c969310b61c9f828000047","seq":6239102,"position":1,"parentId":"63cf2a4cce271c669a0000a1","content":"In January 2016, the USDA Agricultural Marketing System (AMS) hosted a conference call to announce the ending of their condonement of the grass-fed certification. The AMS announced that the USDA would no longer recognize a standard definition for grass-fed beef and all marketing claims would have to be verified through third-party organizations or marketed without the backing of a USDA claim (USDA, 2016). \n\n`Why did USDA make such a statement? What was the reason for shutting down the certifications system? WEbsite does not state.`"},{"_id":"63cf35d1ce271c669a0000a2","treeId":"63c969310b61c9f828000047","seq":6225603,"position":11,"parentId":"63c9872906220ef790000047","content":"USDA. n.d."},{"_id":"63cf36e1ce271c669a0000a3","treeId":"63c969310b61c9f828000047","seq":6225604,"position":1,"parentId":"63cf35d1ce271c669a0000a2","content":"###USDA. n.d. Grass Fed Small & Very Small Producer Program. Available: www.ams.usda.gov/services/auditing/grass-fed-SVS. Accessed 19 February 2016. \n\nProgram for \"small-scale livestock producers\" for under 49 cattle/year or lambs produced from 99 ewes/year. Animals must be fed only grass and forage (can be milk fed before weaning). Cannot have grain or grain by-products and have continuous access to pasture during the growing season. 2 year period of certification. Can market cattle/sheep as USDA Certified grass-fed. \n\n2012: small operations had 640,000 or 11.5% of all cattle/calf ops in US and 59,127 sheep producers or 29.5% of all ewe flock ops in US- 32.4% total inventory of ewes and lambs. "},{"_id":"63e8e5f63e7bb0c93d00002b","treeId":"63c969310b61c9f828000047","seq":6258681,"position":1,"parentId":"63cf36e1ce271c669a0000a3","content":"Before 2016, \"grass-fed beef\" was defined by the Agricultural Marketing Service of the United States Department of Agriculture as a small-scale production system. The producer could market under forty-nine cattle per year or lambs from ninety-nine ewes per year. The animals had to be entirely fed by grass and forage, and could not be fed grain or \"grain by-products\". The two-year certification period also guaranteed that they were raised with continuous access to pasture during appropriate seasons. Meeting those requirements would allow the producer to market their products as USDA Certified Grass-Fed (UDSA, n.d.)\n\nIn 2012, grass-fed beef operations certified by USDA's Grass Fed Small & Very Small Producer Program contributed 11.5% of all cattle and cow-calf operations in the United States, or 640,000 head. Sheep producers made up 29.5% of all ewe flock operations and 32.4% of total inventory of ewes and lambs, with 59,127 producers certified by the USDA (USDA, n.d.). "},{"_id":"63cf4408ce271c669a0000a4","treeId":"63c969310b61c9f828000047","seq":6225608,"position":12,"parentId":"63c9872906220ef790000047","content":"Biensen, 2016"},{"_id":"63cf4473ce271c669a0000a5","treeId":"63c969310b61c9f828000047","seq":6225609,"position":1,"parentId":"63cf4408ce271c669a0000a4","content":"###Agricultural Marketing Service. USDA Market News: National Monthly Grass Fed Beef Report (For the month of January). Available: www.ams.usda.gov/mnreports/nw_ls110.txt. Accessed 19 February 2016. \n\n`Alternate citing: Biensen, Nina. 2016. National monthly grass fed beef report for the month of January. Available: www.ams.usda.gov/mnreports/nw_ls110.txt. Accessed 19 February 2016.` \n\nWholesale grass fed beef:\n* Ribeye, bonelss, whole: 11.99-16.18/lb\n* Tenderloin, Whole: 19.29-21.95\n* Ribeye steak: 14.50-22.80/lb\n\ndirect (FOB?) grass fed beef:\n* Ribeye Steak: avg 19.50/lb\n* Tenderloin: avg 28.16/lb \n* Stew meat: avg 10.06/lb\n* Ground beef 90/10, bulk: avg 9.17/lb"},{"_id":"63e8f0623e7bb0c93d00002c","treeId":"63c969310b61c9f828000047","seq":6263551,"position":1,"parentId":"63cf4473ce271c669a0000a5","content":"The USDA certification of grass-fed beef allowed producers to market their meat with a lucrative premium. In January 2016, the last month that the USDA condoned the certification, the USDA Market News reported the average price of a wholesale grass-fed ribeye steak at $14.50-22.80/lb (Biensen, 2016). A direct-sale grass-fed beef ribeye steaks sold for an average of $19.50/lb (Biensen, 2016). In contrast, the National Retail Report for the week of February 19-25, 2016 reported the weighted average price of a boneless ribeye steak at $9.83 (Agricultural Marketing Service, 2016). These prices limit the sales of grass-fed beef to customers who can afford the premium, and has probably contributed to the controversy surrounding its health claims. Is grass-fed beef worth the pricey premium for better health benefits? \n\n[X] Needs a comparison to regular marketed grass-fed beef. Maybe a table showing comparisons?\n`Can't find a table with enough direct comparisons to make a table- grass-fed reported in monthly and retail reported in weekly`"},{"_id":"63e9042f3e7bb0c93d00002e","treeId":"63c969310b61c9f828000047","seq":6239193,"position":13,"parentId":"63c9872906220ef790000047","content":"National Agricultural Statistics Service, 2016."},{"_id":"63e904433e7bb0c93d00002f","treeId":"63c969310b61c9f828000047","seq":6239141,"position":1,"parentId":"63e9042f3e7bb0c93d00002e","content":"###National Agricultural Statistics Service, USDA. Cattle (January 2016). Available: usda.mannlib.cornell.edu/usda/current/Catt/Catt-01-29-2016.pdf. Accessed 21 February 2016.\n\n Total: all cattle & calves in US as of Jan 1, 2016 = 92.0 million head\n * up 3% from Jan 1, 2015\n\nCalf crop up from 2% from 2015. \n\nCattle and calves on feed (feedlots) = 13.2 million head on Jan 1, 2016- up 1% from 2015"},{"_id":"63e90dba3e7bb0c93d000030","treeId":"63c969310b61c9f828000047","seq":6239145,"position":1,"parentId":"63e904433e7bb0c93d00002f","content":"As of January 1, 2016, the total of all cattle and calves in the United States was 92.0 million head. This total is up 3% from January 1, 2015 (National Agricultural Statistics Service, 2016).\n\nAccording to the National Agricultural Statistics Service, cattle and calves on feedlots in the United States totaled 13.2 million head as of January 1, 2016- a number that is 1% up from 2015 (2016). The recent and growing trend of grass-fed beef has not seemed to make a major economic dent in the beef industry. "},{"_id":"63e92e1e3e7bb0c93d000031","treeId":"63c969310b61c9f828000047","seq":6239218,"position":14,"parentId":"63c9872906220ef790000047","content":"Agricultural Marketing Service, 2016."},{"_id":"63e92e4f3e7bb0c93d000032","treeId":"63c969310b61c9f828000047","seq":6239216,"position":1,"parentId":"63e92e1e3e7bb0c93d000031","content":"Agricultural Marketing Service, USDA. National Retail Report- Beef. February 19-25, 2016. Available: www.ams.usda.gov/mnreports.lswbfrtl.pdf. Accessed 21 February 2016. \n\nWeighted average for boneless ribeye steak is $9.83.\n\nGround beef 90% or more: 4.84 \n\nPrices in dollars per pound"},{"_id":"63e93b133e7bb0c93d000033","treeId":"63c969310b61c9f828000047","seq":6239219,"position":1,"parentId":"63e92e4f3e7bb0c93d000032","content":""},{"_id":"63f308c60e3ee512e4000045","treeId":"63c969310b61c9f828000047","seq":6247377,"position":15,"parentId":"63c9872906220ef790000047","content":"Pasiakos, et al., 2015"},{"_id":"63f309430e3ee512e4000046","treeId":"63c969310b61c9f828000047","seq":6247384,"position":1,"parentId":"63f308c60e3ee512e4000045","content":"Sources and Amounts of Animal, Dairy, and Plant Protein Intake of US Adults in 2007-2010\n\nhttp://www.ncbi.nlm.nih.gov/pmc/articles/PMC4555161/\n"},{"_id":"63f30b100e3ee512e4000047","treeId":"63c969310b61c9f828000047","seq":6247385,"position":16,"parentId":"63c9872906220ef790000047","content":"McNeill, 2014."},{"_id":"63f30b8e0e3ee512e4000048","treeId":"63c969310b61c9f828000047","seq":6257727,"position":1,"parentId":"63f30b100e3ee512e4000047","content":"Inclusion of red meat in healthful dietary patterns\n\nhttp://www.sciencedirect.com/science/article/pii/S030917401400196X\n\n###Fluffy Stuff\n\n\"The Western [dietary] pattern is most commonly defined as a diet characterized by high intakes of refined grains, sugar and red meat, and has been shown to be associated with increased risks for certain types of cancer, coronary heart disease, diabetes, and obesity\" (McNeill, 2014). \n\n\"Increased dietary protein has been shown to promote healthy body weight and composition, in part by increasing satiety, and to improve vitality and stamina\" (McNeill, 2014). \n\nIn 2011, the World Cancer Research Fund/American Institute for Cancer Research Project concluded that consumption of red meat and processed meat could correlate with risk factors for colorectal cancer. However, that conclusion has been controversial eventually the research was re-done, leading to inconsistent results (McNeill, 2014). Regardless, the statement was a blow to the beef industry and `started consumers on a path to looking for the healthiest red meat possible.` (McNeill, 2014).\n\nGenerally, red meat is classified as either beef, pork, mutton, or veal (McNeill, 2014). \n\nBeef is the predominate red meat consumed in several developed nations and on the rise worldwide (McNeill, 2014). \n\n\"Consumer preferences for leaner cuts of red meat, driven by dietary guidance in recent decades instructing the increased consumption of lean meats and trimming excess fat from meats, have results in changes in meat production and merchandising that produce meats with 80% less external fat. Currently, appx. 2/3 of the beef sold retail in the US meets the government guidelines for lean\" (McNeill, 2014). \n\n\"The relationship between SFA intake and risk for heart disease is complex, and recent evidence challenges earlier conclusions\" (McNeill, 2014). \n\n\"A broader understanding of the fatty acid profile of lean red meat is important to understand its relationship with cardiovascular heatlh\" (McNeill, 2014). \n\nLean red meat can act equal to lean white meat for lowering total cholesterol and total LCL-cholesterol, when incorporated into an overall low-fat diet (McNeill, 2014). \n\nThe average consumption of beef in 2010 in the United States was 1.7 oz per day (McNeill, 2014). \n\n\"Research regarding red meat as a source of high quality protein and highly bioavailable iron and other nutrients for improving vitality and stamina is emerging\" (McNeill, 2014). \n\nRecommended amounts of daily intake of meat and \"meat alternatives- things like legumes, nuts, seed\" range from 65-250 g/day. 2010 US Dietary Guidelines recommend 150 g/day depending on age and gender (5.5 oz/d) of protein foods (McNeill, 2014). \n\n"},{"_id":"6402f5e72a5a421cba00004b","treeId":"63c969310b61c9f828000047","seq":6257769,"position":1,"parentId":"63f30b8e0e3ee512e4000048","content":"###Previous Recommended Dietary Patterns\n\nThe recommended dietary patterns for Americans has changed drastically over the last few decades. In 2011, the World Cancer Research Fund/American Institute for Cancer Research Project released a statement condemning red meat as a correlation factor for colorectal cancer (McNeill, 2014). The statement has since been retracted after more research lead to inconsistent results, but the process of looking for \"healthier\" and lower-fat red meat had been jumpstarted. As beef is the predominate red meat consumed in most developed nations, beef production systems were examined for meat characteristics that could be manipulated. Consumer preferences have changed over time to favor leaner cuts of red meat, driven by newer dietary guidelines that recommend increased consumption of lean proteins and lower fat. Meat production has changed in response and currently approximately two-thirds of the beef sold in the United States meets government guidelines for lean (McNeill, 2014). Nevertheless, misconceptions are still present, especially given the common American dietary pattern of \"high intakes of refined grains, sugar and red meat... associated with increased risks for certain types of cancer, coronary heart disease, diabetes, and obesity\" (McNeill, 2014). Most Americans are now looking for a lean protein that meets recommendations from the Dietary Guidelines for Americans, published by the USDA & United States Department of Health and Human SErvices. In 2005, the recommended average daily consumption of protein foods was around 150 g/day or 5.5 oz/day (depending on age and gender), while in 2010 the average intake in the United States was 1.7 oz/day (McNeill, 2014). Recent data from the Dietary Guidelines for Americans states that overall average intakes of protein foods are close to recommended amounts (USDA & US Dept. of Health & Human Services, 2015). The Dietary Guidelines for Americans also recommends an overall to more nutrient-dense proteins, including more seafood, to reduce overall caloric intake (USDA & Us Depth of Health & Human Services, 2015). \n\n"},{"_id":"63f31c9d0e3ee512e4000049","treeId":"63c969310b61c9f828000047","seq":6247410,"position":17,"parentId":"63c9872906220ef790000047","content":"USDA & US Dept of Health & Human Services, 2015"},{"_id":"63f31d350e3ee512e400004a","treeId":"63c969310b61c9f828000047","seq":6257724,"position":1,"parentId":"63f31c9d0e3ee512e4000049","content":"Dietary Guidelines for Americans 2015-2015 8th Edition\n\nhttp://health.gov/dietaryguidelines/2015/guidelines/\n\nOverall average intakes of protein foods are close to recommended amounts for all age-sex groups (USDA & US Depth of Health & Human Services, 2015). \n\nRecommends an overall shift to more nutrient-dense proteins, including more seafood, to reduce overall caloric intake. \n\n"},{"_id":"6403820eefedad29ea00004c","treeId":"63c969310b61c9f828000047","seq":6257968,"position":18,"parentId":"63c9872906220ef790000047","content":"White, 2014."},{"_id":"64038c08efedad29ea00004d","treeId":"63c969310b61c9f828000047","seq":6257989,"position":1,"parentId":"6403820eefedad29ea00004c","content":"White, Courtney. 2014. Grass, soil, hope: a journey through carbon country. Chelsea Green Publishing, White River Junction, VT. p. 82.\n\n`original inspiration- needs to be referenced to in Intro`\n\n\"By definition, grass-fed means an animal has spent its entire life on grass or other green plants, from birth to death\" (White, 2014). \n\n\"health benefits of grass-fed over feedlot meat have become widely know. They include the following: more omega-3 fatty acids (\"good\" fats) and fewer omega-6 (\"bad\" fats), fewer saturated fats linked with heart disease, much more conjugated linoleic acid (CLA), a cancer fighter, much more vitamin A, much more vitamin E, higher levels of beta-carotene, higher levels of the B vitamins thiamin and riboflavin, positive effect on enhancing immunity, increasing bone density, and suppressing cancer cells, does not contain traces of added hormones, antibiotics, or other drugs\" \n\n "},{"_id":"6403a492efedad29ea00004e","treeId":"63c969310b61c9f828000047","seq":6258017,"position":19,"parentId":"63c9872906220ef790000047","content":"Clancy, 2006"},{"_id":"6403a4c9efedad29ea00004f","treeId":"63c969310b61c9f828000047","seq":6258658,"position":1,"parentId":"6403a492efedad29ea00004e","content":"Clancy, Kate. Greener pastures; how grass-fed beef and milk contribute to healthy eating. 2006. Union of Concerned Scientists Publications, Cambridge, MA. \n[ ] need pages used\np. 79, 1-4\n\nAn extensive literature review conducted by the Union of Concerned Scientists found that overall, grass-fed ground beef and steak are \"almost always\" lower in total fat, and have higher levels of CLA. They also reported \"sometimes\" higher levels of omega-3 fatty acids (Clancy, 2006).\n\nOverall, data has been mixed and inconclusive regarding the levels and health benefits of omega-3 fatty acids present in grass-fed beef. Until such time as the role of fatty acids in human health is more fully understood and the Food and Nutrition Board of the Institute of Medicine can recommend a dietary intake, grass-fed beef cannot be regarded as beneficial in that regard (Clancy, 2006). However, there is sufficient evidence to conclude that grass-fed beef can be labeled as lean and lower in total fat than conventionally fed cattle (Clancy, 2006). \n\nThe Union for Concerned Scientists recommends to the USDA to \"support more research to identify pasture management strategies that will produce an optimal fat composition in meat and milk from different regions of the United States\" (Clancy, 2006). It also recommends funding more research to specifically look at different types of US pasture systems and their effects on nutrient levels (Clancy, 2006).\n\n#definition \n#LDL #HDL\nLDL: \"bad\" cholesterol because high levels increase risk of heart disease\nHDL: \"good\" cholesterol, transports water-soluble fats in the blood, high levels protect against heart attack \n\n"},{"_id":"64df3566821795a4c600018f","treeId":"63c969310b61c9f828000047","seq":6433799,"position":20,"parentId":"63c9872906220ef790000047","content":""},{"_id":"67df5ca108af5f3c03000092","treeId":"63c969310b61c9f828000047","seq":7342200,"position":6,"parentId":"63c969570b61c9f828000049","content":""}],"tree":{"_id":"63c969310b61c9f828000047","name":"ASCI 355 Literature Review","publicUrl":"asci-355-literature-review"}}