Factors affecting the variation in fatty acid concentrations in lean beef from grass‐fed cattle in New Zealand and the implications for human health

Abstract

Lean beef from grass‐fed cattle was analysed for fatty acid (FA) content to determine the between‐animal variation and the effects of various traits on FA composition, and indices and FA ratios that have human health implications. In Experiment 1, samples were from three muscles from five bulls, five cows, and five heifers. In Experiment 2, samples were from the m. longissimus lumborum of 50 3/4 Jersey 1/4 Limousin and 50 3/4 Limousin 1/4 Jersey cattle, born over 2 years and sired by two bulls. The heifers and steers grazed on similar pastures until slaughter. In both experiments, after adjusting for differences in total FA content of the meat, there were large coefficients of variation (CV) for trans‐vaccenic, cis‐9 trans‐11 conjugated linoleic, and docosahexaenoic acids and low CV for the saturated (SATFA) and monounsaturated FA (MUFA), and intermediate CV for other FA. There were significant effects of muscle and animal types in Experiment 1 and of breed, sire, sex, and year‐born in Experiment 2 on the composition and content of individual and groups of FA, especially the polyunsaturated FA (PUFA). The n‐6:n‐3, PUFA:SATFA, and MUFA: SATFA ratios, and the indices for atherogenicity and thrombogenicity, traits that have human health implications, were affected by factors in both experiments, but absolute differences were small. The conclusions were that the FA composition of lean grass‐fed beef could be changed by traditional means to improve the human health image of beef, but the impact would be small and progress slow. More progress was likely from selecting for beneficial FA than against undesirable SATFA.