Conjugated Linoleic Acid Content of Beef Finished with Pasture

View the project final report

• 2003 annual report
• 2004 annual report

Commodities

• Animals: bovine

Practices

• Animal Production: grazing - continuous, feed rations
• Farm Business Management: new enterprise development, feasibility study, agricultural finance, market study, value added
• Production Systems: agroecosystems

Cattle were randomly assigned to one of four finishing regimens; pasture, pasture with grain supplement, pasture with grain supplement containing soyoil, and feedlot. Pasture inclusion produced higher levels (P < 0.05) of total CLA than the feedlot diet on an mg/g fat basis for cooked samples while maintaining acceptable eating quality. Meat from all finishing regimes was considered acceptable by consumers. Gains for pasture cattle were poor, partly due to late turnout. Profit potential exists for supplemented pasture systems, but is dependent on sound gains and grazing management and targeted marketing to consumers willing to pay a premium for CLA enhanced beef.

Introduction:

Conjugated linoleic acid (CLA) is a naturally occurring fatty acid found in ruminant animal fats. CLA is a product of ruminal biohydrogenation of polyunsaturated fatty acids (Kelly et al., 1998), and there is strong evidence that CLA has anticarcinogenic properties in laboratory animals (Ip, Scimeca, & Thompson, 1994) as well as be protective against heart disease, diabetes, and obesity (Sumeca and Miller, 2000; Weiss, Martz, & Lorenzen, 2004). The CLA content of beef has been characterized by previous researchers (Shantha, Crum, & Decker, 1994; Ma, Wierzbicki, Field, & Clandinin, 1999); however, these studies used small sample sizes and the tested beef was purchased from retail stores implying that the cattle producing the beef had been fed in a normal production scheme including a high-concentrate finishing diet. CLA content in grass fed cattle was greater in the Semimembranosus muscle compared to cattle on pasture and supplemented with grain (Shantha, Moody, & Tabeidi, 1997). French et al. (2000) reported a linear increase in CLA content with increased percentage of grass in the diet. While these studies indicate the likelihood that beef from pasture-fed or pasture-finished cattle will contain higher concentrations of CLA than feedlot cattle, small sample sizes and the limited selection of muscles for analysis prevent a firm conclusion.

Since beef is not consumed raw, cooking and other processing methods that may alter the original CLA content of the meat also deserve investigation. CLA content in cooked meat patties has been shown to increase on an mg/g of fat basis and mg/100 g of cooked meat basis (Shantha et al., 1994). In order for consumers to receive the health benefits of CLA from meat, there will need to be a maintained and/or elevated amount in the cooked product. In addition, muscles differ in fat concentration based on function and location within the body making it important to investigate more than one muscle.

References
French, P., Stanton, C., Lawless, F., O’Riordan, E. G., Monahan, F. J., Caffrey, P. J., & Moloney, A. P. 2000. Fatty acid composition, including conjugated linoleic acid, of intramuscular fat from steers offered grazed grass, grass silage, or concentrate-based diets. J. Anim. Sci. 78:2849-2855.

Ip, C., Scimeca, J. A., & Thompson, H. J.. 1994. Conjugated linoleic acid: a powerful anticarcinogen from animal fat sources. Cancer 74:1050-1054.

Kelly, M. L., Berry, J. R., Dwyer, D. A., Griinari, J. M., Chouinard, P. Y., Van Amburgh, M. E., & Bauman, D. E. 1998. Dietary fatty acid sources affect conjugated linoleic acid concentrations in milk from lactating dairy cows. J. Nutr. 128:881-885.

Ma, D. W. L., Wierzbicki, A. A., Field, C. J., & Clandinin, M. T. 1999. Conjugated linoleic acid in Canadian dairy and beef products. J. Agric. Food Chem. 47:1956-1960.

Shantha, N. C., Crum, A. D., & Decker, E. A.. 1994. Evaluation of conjugated linoleic acid concentrations in cooked beef. J. Agric. Food Chem. 42:1757-1760.

Shantha, N. C., Moody, W. G., & Tabeidi, Z.. 1997. Conjugated linoleic acid concentration in semi-membranosus muscle of grass- and grain-fed and zeranol-implanted beef cattle. J. Muscle Foods 8:105-110.

Sumeca, J. A. & Miller, G. D. 2000. Potential health benefits of conjugated linoleic acid. J. Amer. College Nutr. 19:472-506.

Weiss, M. F., Martz, F. A., & Lorenzen, C. L. 2004. Conjugated linoleic acid: implicated mechanisms related to cancer, atherosclerosis, and obesity. Professional Animal Scientist 20:127-135.

1. Determine and compare the CLA content of pasture finished beef in the raw and cooked states.

2. Determine the effects of different grain supplementation regimes on CLA content of beef.

3. Determine the economic feasibility of pasture-finished beef for a niche market.

4. Develop educational materials for producers about the management tools and economics involved with increasing the CLA content beef through pasture finishing.