Manipulation of fatty acids in muscle lamb

Abstract

Calcium soap fatty acids (CSFA) can increase the energy density of feeds and has been used to improve the level of healthy fatty acids in meat, however there is a paucity of knowledge about the impact on meat quality traits such as colour traits, shear force and collagen. The objective of first study was to determine the effects of CSFA on meat quality traits of lambs when included in a finishing diet. Sixty-three crossbreed lambs were feedlot individually at 24 ± 2.5 kg and slaughtered at 44 ± 1.1 kg. Twenty-nine lambs were fed the Control diet and 34 lambs were fed a diet containing 5.4% CSFA. At 24h postmortem the longissimus lumborum (LL) muscle was collected from the right side of the carcass. The muscle was cut into 2.54-cm thick slices and vacuum-packaged. Samples were stored at -20oC (0 day ageing) and others stored at 2oC for 10 days ageing and then frozen. Cooking loss was reduced (P < 0.05) in CSFA fed lambs, but there was no effect on any other traits (P > 0.05). Shear force was significantly reduced by ageing (P < 0.05), and this was matched by an increase in myofibrillar fragmentation index values with ageing. CSFA decreased EPA and DHA in the longissimus muscle. Algae is a potential candidate to improve the levels of long chain polyunsaturated fatty acids (LC-PUFA) in ruminant meat. In the second study the effect of the supplementation of lambs with algae on the expression of genes that direct the accumulation of LC-PUFA was investigated. The mothers of the lambs were fed with either silage (SLG) or oat/cottonseed (OAT) based diets for six weeks prior to and, three weeks following conception. mRNA levels of FADS1, FADS2, CPT1, SCD, ACC and Fad2 were measured in the liver, muscle and subcutaneous fat from lambs fed a control diet consisting of oat and lupin grains and chopped lucerne (CTRL) or the CTRL diet with algae (DHAgold™) added at 1.92% DM (ALG). The expression of FADS1 in liver tissue was not affected (P > 0.05) by the interaction between dam nutrition and algae supplementation, however it was higher (P < 0.05) when lambs received the ALG ration compared with the CTRL and when their dams were fed SLG compared with OAT diet. The expression of FADS1, FADS2, SCD and ACC genes in lamb muscle was differentially affected by dam nutrition with the highest levels for the SLG+ALG treatment (P < 0.05) compared with other treatments.