Dr. Daniel Rivera, MAFES-South MS Branch Exp. Station
Dr. Thu Dinh, MSU- Dept. of Anim. and Dairy Sci.
Recently, some things were brought to light regarding the use of the terms “Grass fed”, “Natural”, “Organic” and how they relate to conventional beef production. Based upon some discussions with colleagues, we felt that in essence there is a lot of confusion among people, and what we hope to do in the article is clarify some of those misconceptions. Based upon our discussion, we felt that there are two areas that need clarification, the first is the nomenclature or wording used to describe how these animals are produced, and the second regards the flavor and health aspects of conventionally produced beef.
Production Standards .
In essence, these types systems are aimed toward niche markets. The Organic or Natural producer may be trying to market his or her cattle to a particular social demographic, which is willing to pay more for those types of products. Those products cost more since they are more expensive to produce. Data from USDA report that on average these niche systems are less efficient than conventional production systems (Matthews Jr. and Johnson, 2013). These consumers purchase these products based upon perceived value. While there are many claims that these systems are healthier than conventionally produced beef there are no scientific data to prove that claim. Moreover, there have been claims that these systems produce safer (free from pathogens) than conventional beef, however, none of these claims have been verified by scientific data.
Conventional Beef. The majority of beef raised in MS will go towards conventional beef production. In this system, calves raised on farms or ranches will either go directly to a feedyard or they will enter into some type of stockering operation and grown on grass. The direction those calves go will be based upon available resources and marketing dynamics. Stockers will take advantage of the relatively inexpensive gain on grass prior to shipment to the feedyard, and the length of time they are grown on grass is dependent upon forage availability, and marketing decisions.
Once at the feedyard (both stockers and calves) will be gradually adapted to a high concentrate (grain) diet and grown to a final slaughter weight 1200-1300 depending upon the marketing of the cattle (yield versus quality grade). During their stay in the feedyard, in most instances they will be given growth promoting implants and fed diets containing ionophonres. Growth promoting implants are administered to increase efficiency and gain. Ionophores are additives fed that shift rumen bacteria production to increase the energy derived from feed, they also inhibit the growth of coccidia. It should be noted that the efficacy and safety of these products have been rigorously tested by the FDA, and FDA personnel routinely inspect confined feeding operations for adherence to medicated feed usage. Production records (feed batched compared to feed fed) are evaluated to ensure that label adherence is met. All of the technologies used in conventional beef production have been thoroughly scientifically vetted to ensure their safety and efficacy. In essence, most of the beef that is found at the local grocery store was produced in this manner.
Grass Fed Beef. According to USDA, in this system, the animals are simply grown on grass or stored forage (hay). The animals can consume grasses, legumes, or cereal grains in their vegetative state. These animals cannot ever be fed grain, or grain-by products during this process. The USDA does allow for mineral and vitamin supplementation. I have personally seen instances where claim “grass fed” is made but the animals are supplemented feed for a period of time; according to USDA standards those are not grass fed animals. Additionally, no restrictions are made regarding the use of growth promoting implants for grass fed beef, the only requirement is that they are solely fed forage for their entire life until they go to slaughter. Therefore, if the consumer strives to purchase meat produced without growth promoting hormones, grass fed beef may not be the answer.
Natural Beef. This is the tricky one, while some people claim that they have natural beef according to USDA standards, it simply means that the meat is unadulterated (i.e. no artificial colors, no additives or coloring, preservatives, or other artificial ingredient. Therefore according to those standards, most beef purchased is Natural! The tricky part is that USDA also has a Naturally Raised claim.
Naturally Raised. USDA define this by being cattle raised without the use of growth promoting implants, ionophores, no antibiotics, nor are the animals allowed to consume animal by product feed (i.e. feather meal, blood meal, etc.). Cattle are allowed to receive ionophores if they have been used to control parasites, however, the producer must make that claim. There are no other restrictions regarding what they may be fed, therefore these cattle marketed under naturally raised can be fed high grain diets. This is probably the most common niche that we see.
Organic. This one is probably the most difficult one to achieve due to all the restrictions. In essence USDA states that Organic beef is produced without use of antibiotics, ionophores, animal byproducts (think Naturally Raised), however, the land that they are grown on must fall under organic standards (i.e. no chemical pesticides, herbicides, or conventional fertilizer); moreover, any feed fed to these animals must have been grown under organic standards as well (grain produced without chemical pesticides, herbicides or conventional fertilizer). Additionally, cattle grown for slaughter in this program must have been on the program 3 months prior to their birth! When you consider the length of time it takes to get an animal ready for slaughter, and you think about the feed requirements, it is easy to see how this can be difficult to achieve.
Nutritional values and quality of beef, grain-fed vs. grass-fed
All beef cattle are fed with grass at some point in their life. They can be finished on grass or grain, depending on what is best for specific operation, including the marketability of beef from such an operation in a specific market. No beef production system can be sustained by a sole feeding regime. However, the most common myth is that grass-finished beef is safer and healthier than grain-finished beef. Not only does no conclusive evidence support such a claim but also have many nutritional composition studies reported that grass-finished and grain-finished beef had very similar nutritional composition. The reason is that unlike monogastric animals, cattle convert feed to body mass with special help from the microbial population in the rumen.
In terms of nutritional composition, grass-finished beef has been praised for its “healthier” fat, scientifically termed “lipid composition” or “fatty acid composition”. Two publicly recognized components of lipids are cholesterol and fatty acids. We have been analyzing thousands of samples of all kinds of beef and never have we seen any difference in cholesterol content. Cholesterol is part of every cell structure in animal tissues. It is possible that very well-marbled beef has few more milligram cholesterol per 100 g (3.5 oz) of beef compared with very lean beef. This increase is negligible compared with 800 to 1000 mg of cholesterol that our body produces daily just to function properly. Fresh beef has approximately 43 to 84 mg cholesterol/100 g, whereas cooked beef has about 57 to 100 mg/100 g, an increase corresponding to the lost water during cooking. Fatty acid composition is the most interestingly debated issues. It is very important to understand that fatty acids from grass fed to beef cattle, which are touted as plant-origin and being healthier, are NOT the fatty acids that are deposited into beef lean and fat tissues. Bacteria in the rumen are capable of hydrogenating (i.e. adding more hydrogen to the double bonds of fatty acids to make them more saturated) polyunsaturated fatty acids (PUFA; fatty acids with more than one double bonds) from plant sources. The most common product of this biohydrogenation process is vaccenic acid (18:1 trans 11), a fatty acid that has 18 carbons, 1 double bond at carbon 11 with trans configuration. Vaccenic acid is either further saturated in the rumen, forming stearic acid (18:0) or desaturated by desaturase enzyme to 18:2 cis 9, trans 11, one of conjugated linoleic acids (CLA), a collection of fatty acids specific to ruminant products (meat and dairy) that have many documented health benefits. It is true that the more polyunsaturated fatty acids, readily available in grass, are fed to cattle, the more PUFA can pass through the rumen without being biohydrogenated and remain polyunsaturated. However, PUFA are toxic to microbes in the rumen and biohydrogenation is part of the protective mechanism of the microorganisms in the rumen. Effort to delivery more PUFA to small intestines seems to be unsuccessful unless the PUFA are supplemented and protected in encapsulated forms. An increase in PUFA in grass-finished beef is normally in the range of 10 to 25%. However, it is important to note that PUFA only contribute 3-5% of total fatty acids, 60 to 80% of which is linoleic acid (18:2 n-6) and approximately 30% is linolenic acid (18:3 n-3). Therefore, the increase can be calculated at approximately less than 20 mg per 100 g (3.5 oz). We need to keep in mind that most of the increase is of n-3 and n-6 C18 fatty acids, the roles of which in human health are uncertain. The long-chain PUFA n-3 similar to those in fish oils, which have more established roles in cardiovascular health, are NOT significantly different between grass- and grain-finished beef and are found at trace levels in all beef. Conjugated linoleic acids also increase, at a much lower rate than linoleic acids, in grass-finished beef. However, because the fat content of grass-finished beef is normally lower than that of grain-finished beef, such an increase in CLA and n-3 fatty acids becomes negligible. A very interesting fact that has been neglected in many discussions regarding grass- vs. grain-fed is that monounsaturated fatty acids (MUFA), 40 to 45% of total fatty acids and mostly oleic acid with reported benefits in lowering LDL cholesterol (low-density lipoprotein cholesterol or BAD cholesterol) and increasing HDL cholesterol (high-density lipoprotein cholesterol or GOOD cholesterol), is significantly greater in grain-fed beef in term of both percentage and absolute concentration. Moreover, saturated fatty acids (SFA), mostly stearic acid known for having a neutral effect (or NO effect) on LDL cholesterol is present in a similar proportion and/or concentration in both grass- and grain-finished beef. Therefore, grass-finishing increases a negligible amount of n-3 fatty acids that have uncertain health benefits at the great expense of MUFA that are evidently beneficial to human health.
Substituting grass for grain in the diet has been reported to cause off-odor, shortened shelf life, decreased tenderness, darker lean color, and ultimately a less desirable and more difficult to preserve beef. There are a variety of mechanisms such as grass-finished beef being more susceptible to stress, having greater glycogen depletion, higher pH, etc. In all consumer studies that we have conducted, grass-finished beef scored significantly lower than grain-finished beef. Similar findings were reported in both ground and whole muscle beef. In the limit of this paper, we will only discuss the difference in flavor and color profiles. It is obvious that an increase in PUFA, even in a small amount, is detrimental to beef quality. Most PUFA are deposited in the polar lipid fractions such as phospholipids as part of muscle cell membranes or lean tissues. Most PUFA are much less likely to be deposited in beef fat than SFA and MUFA because of the low affinity during the synthesis of triglycerides. PUFA are oxidized more easily than SFA and MUFA because of the effects of double bonds. Therefore, polar lipids, which contribute a significant proportion to the lipid composition of lean beef, are much more susceptible to oxidation, which produces off-odors (ketones and aldehydes) and 4-hydroxynonenal (HNE). HNE binds (or scientifically termed “alkylation”) myoglobin (lean color pigment), which makes myoglobin more susceptible to oxidation, thereby a more rapid beef discoloration. This phenomenon can be easily observed in ground beef, where leaner ground beef (90 to 91% lean) discolors faster and develops more off-flavors as storage progresses.
In closing the various methods that we use to market beef can be complicated. Oftentimes erroneous claims are made regarding “Natural” or “Organic. All these marketing options should be a testament to the ingenuity of the American cattle producer, but one group should not try and move themselves forward at the expense of another. Raising beef cattle on grass needs to be done for the right reason, mostly profit-related. The argument regarding health benefits and sustainability are currently not justifiable by available data. Cattle on different diets will produce meat with different nutritional composition, including other components not discussed in this paper such as minerals, antioxidants, etc. However, the questions are whether the changes are significant enough to make an impact on human health and what the costs are, financially and nutritionally. There are markets for unconventional raised beef, but producers should understand that there are added costs and regulations for these types of products. Consumers should be made aware of the different types of production systems and what they involve, as well as understanding that conventional beef is just as healthy and wholesome as unconventional beef.
Recommended readings and Sources:
Daley, C. a, Abbott, A., Doyle, P. S., Nader, G. a, & Larson, S. (2010). A review of fatty acid profiles and antioxidant content in grass-fed and grain-fed beef. Nutrition Journal, 9, 10. doi:10.1186/1475-2891-9-10
Dinh, T. T. N., Thompson, L. D., Galyean, M. L., Brooks, J. C., Patterson, K. Y., & Boylan, L. M. (2011). Cholesterol Content and Methods for Cholesterol Determination in Meat and Poultry. Comprehensive Reviews in Food Science and Food Safety, 10(5), 269–289. doi:10.1111/j.1541-4337.2011.00158.x
French, P., O’Riordan, E. G., Monahan, F. J., Caffrey, P. J., Mooney, M. T., Troy, D. J., & Moloney, a P. (2001). The eating quality of meat of steers fed grass and/or concentrates. Meat Science, 57(4), 379–86. Retrieved from http://www.ncbi.nlm.nih.gov/pubmed/22061710
Gatellier, P., Mercier, Y., Juin, H., & Renerre, M. (2005). Effect of finishing mode (pasture- or mixed-diet) on lipid composition, colour stability and lipid oxidation in meat from Charolais cattle. Meat Science, 69(1), 175–86. doi:10.1016/j.meatsci.2004.06.022
Harrison, A., & Smith, M. (1978). Nutritional regime effects on quality and yield characteristics of beef. Journal of Animal Science, 383–388. Retrieved from http://www.journalofanimalscience.org/content/47/2/383.short
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Matthews, Jr., K.H., and R. J. Johnson. 2013. Alternative beef production systems, issues and implications. USDA-Economic Research Service. Bulletin LDPM- 218-01. www.ers.usda.gov.
Maughan, C., Tansawat, R., Cornforth, D., Ward, R., & Martini, S. (2012). Development of a beef flavor lexicon and its application to compare the flavor profile and consumer acceptance of rib steaks from grass- or grain-fed cattle. Meat Science, 90(1), 116–121. doi:10.1016/j.meatsci.2011.06.006
Melton, S., & Amiri, M. (1982). Flavor and chemical characteristics of ground beef from grass-, forage-grain-and grain-finished steers. Journal of Animal …, 77–87. Retrieved from http://www.journalofanimalscience.org/content/55/1/77.short
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