Dietary manipulation to increase conjugated linoleic acids and other desirable fatty acids in beef: A review

Mir, P. S., Ivan, M., He, M. L., Pink, B., Okine, E., Goonwarde, L., McAllister, T. A., Weselake, R. and Mir, Z. 2003. Dietary manipulation to increase conjugated linoleic acids and other desirable fatty acids in beef: A review. Can. J. Anim. Sci. 83: 673-685. The diet is the source of many essential fatty acids such as linoleic and linolenic acids for all mammals. These fatty acids either, as altered isomers or as other elongated products, have been found to provide unique advantages to human health. Currently two conjugated linoleic acids (CLA) isomers (cis-9, trans-ll C18:2; trans-IO, cis-12 C18:2) and two elongated products of linolenic acid [eicosapentaenoic acid (EPA, C20:5 n-3), docosahexaenoic acid (DHA, C22:6 n-3)] have been recognized for their roles in maintaining human health. Consumers can obtain these functional fatty acids from beef if the feeding management of beef cattle can be altered to include precursor fatty acids. Diet, breed, and gender are important factors that affect total fat content and/ or the fatty acid profile of beef with regard to CLA, EPA, and DHA. Diet provides the precursor fatty acids that are altered and deposited, and breed dictates, the amount of fat that is deposited. These fatty acids can be increased in beef by increasing the forage:concentrate ratio, inclusion of non-fermented forage, and supplementation with various oils or oil seeds. The CLA and vaccenic acid (trans-11 C 18:1) concentration in beef was increased by feeding sunflower oil or seeds, linseed, and soybean oil supplemented diets, while cattle fed linseed and fish oil supplemented diets had increased concentrations of EPA and DHA. Although the concentration of these fatty acids can be increased in beef, there is a need to further the understanding of the mechanism by which they exert positive affects on human health.