Fatty Acid Composition in Forage Species and their Influence on Pasture Finished Beef.

There is a growing market for animals raised under organic practices. It is widely asserted that the meat from these animals has a positive influence on human health. The purpose of this research was to determine the variation among and within forage species for fatty acid composition and how these variations might be manipulated to enhance meat quality. The first objective was to determine which forages used in Missouri would provide the best sources for unsaturated fat and omega-3 fatty acids for cattle pastures, and determine if there are any phenotypic traits associated with specific fats. The second objective was to determine if the differences in fatty acids found in forage plants correlate to differences found in the meat of steers finished on three different types of pasture (tall fescue, red clover mixed with tall fescue, or alfalfa mixed with tall fescue). For the first objective, 20 cultivars and/or ecotypes from each of four different forage species (orchardgrass, tall fescue, perennial ryegrass, and alfalfa), were analyzed for fatty acid composition. Significant differences (P<0.05) were found across species and within populations of each forage tested. The phenotypic traits of maturity, color, winterhardiness, and ploidy level correlated poorly to fatty acid concentration, however fall dormancy in alfalfa negatively correlated (r=0.59) to C18:2 concentrations. Additionally, chlorophyll a and total chlorophyll showed a significant (P<0.05) relationship when correlated against all fatty acids but had the greatest correlation (r=0.96 and 0.92) with total fatty acid and α-linolenic acid (C18:3) concentration, respectively. For the second objective, the fatty acid composition in forage also varied significantly across pasture types in palmitic (C16:0), steric (C18:0), oleic (C18:1), linoleic (C18:2), and total fatty acid concentration. However, differences in the fatty acid composition of pastures did not translate to differences in meat quality.