This paper focuses on dietary approaches to control intramuscular fat deposition to increase beneficial omega-3 polyunsaturated fatty acids (PUFA) and conjugated linoleic acid content and reduce saturated fatty acids in beef. Beef lipid trans-fatty acids are considered, along with relationships between lipids in beef and colour shelf-life and sensory attributes. Ruminal lipolysis and biohydrogenation limit the ability to improve beef lipids. Feeding omega-3 rich forage increases linolenic acid and long-chain PUFA in beef lipids, an effect increased by ruminally-protecting lipids, but consequently may alter flavour characteristics and shelf-life. Antioxidants, particularly ?-tocopherol, stabilise high concentrations of muscle PUFA. Currently, the concentration of long-chain omega-3 PUFA in beef from cattle fed non-ruminally-protected lipids falls below the limit considered by some authorities to be labelled a source of omega-3 PUFA. The mechanisms regulating fatty acid isomer distribution in bovine tissues remain unclear. Further enhancement of beef lipids requires greater understanding of ruminal biohydrogenation.Peer reviewe

. Addition of an extract of lucerne (Medicago sativa L.) to cattle diets -Effects on fatty acid profile, meat quality and eating quality of the M. longissimus muscle. Meat Science, 130,[69][70][71][72][73][74][75][76][77][78][79][80] University of Bristol -Explore Bristol Research General rightsThis document is made available in accordance with publisher policies. Please cite only the published version using the reference above. Full terms of use are available: http://www.bristol.ac.uk/pure/about/ebr-terms AbstractThere is considerable interest in enhancing beneficial fatty acids, particularly 18:3n-3, conjugated linoleic acid and long chain n-3 fatty acids such as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), in beef to provide benefits to human health. Here, the potential to enhance these fatty acids by feeding a n-3 polyunsaturated fatty acid (PUFA)-rich plant extract (PX) from lucerne is presented. Cattle (n=8/diet) were assigned to the following finishing diets: straw and concentrate (S-CC); straw and concentrate containing 25% PX and 2000 IU vitamin E/kg PX-concentrate (S-PXC); grass silage (GS); GS plus 75 g PX/kg dry matter intake (DMI) (GS-LPX) or GS plus 150 g PX/kg DMI (GS-HPX). Addition of PX to concentrates or GS increased the n-3 fatty acid content of loin muscle and had favourable effects on the n-6:n-3 PUFA ratio (P < 0.05), without detrimental effects on loin muscle sensory characteristics.