Progress In Forage-Based Strategies To Improve The Fatty Acid Composition Of Beef

Nutritional properties of foods are increasingly important factors to consumers. This paper is focused on fatty acid composition of beef and in particular n-3 polyunsaturated fatty acids (PUFA). Exploitation of forage based systems as a route to the production of beef with enhanced product quality characteristics merits further pursuit. Feeding n-3 rich forage increases linolenic acid (18:3n-3) and the longer chain PUFA (EPA, 20:5n-3) and docosahexaenoic acid (DHA; 22:6n-3) in beef lipids. Species-rich pastures and organic systems can influence fatty acid in beef lipids. The range of factors influencing fatty acids in forages such as genotype, conservation method, fertilizer regime are discussed as are opportunities to maximise delivery of n-3 PUFA from forage. Increased focus on breeding for lipids in perennial ryegrass and new knowledge of genes involved in regulating lipid composition is highlighted. Lipolysis and biohydrogenation of dietary PUFA by ruminal micro-organisms is a major limitation to our ability to beneficially enhance the fatty acid composition of beef lipids. Recent progress in understanding the microbial species involved is reviewed along with studies investigating the fate of lipid-rich chloroplasts in the rumen. The levels of n-3 PUFA achieved in beef lipids is assessed relative to those set by the European Food Safety Authority for a food product to be labelled as 'a source of' or 'high in' n-3 PUFA. Currently, it is challenging for forage-fed beef to achieve the necessary levels.