Fatty acid composition in subcutaneous, intermuscular and intramuscular fat deposits of suckling lamb meat: Effect of milk source

Abstract

A total of 20 Churra suckling lambs from a sheep dairy farm were divided into two groups and reared on ewes’ milk (EM) or milk-replacer (MR). The suckling lambs were slaughtered at ages between 25 and 35 days. Fatty acid profiles of milk source fat as well as subcutaneous (SC), intermuscular (IN) and intramuscular (IR) fat of lamb carcasses were determined, and the effect of the rearing system investigated. As regards fat deposits, proportions of polyunsaturated (PUFA), saturated (SFA) and monounsaturated (MUFA) fatty acids showed high similarity between IN and SC fat, for either of EM or MR samples. However, and only for MR samples, IN fat had lower odd-chain fatty acid (OCFA) and branched-chain fatty acid (BCFA) contents than SC fat. In IR fat, when compared to the other fat deposits, significant differences in all PUFA contents, except for c9t11-C18:2, were found. As for rearing system, a significant effect of dietary fat on the contents of the majority of fatty acids for each fat deposit was observed. Differences in fatty acid contents between the two milk source fats resulted in concomitant differences for those fatty acids in the carcass fat deposits, with the exception of C18:2 n-6, C20:4 n-6, C18:3 n-3 and c9t11-C18:2. Both the n-6 and n-3 fatty acid contents appeared to be influenced by the dietary n-6/ n-3 ratio. Meanwhile, c9t11-C18:2 content was slightly higher in MR carcass fat samples but lower in MR fat. A higher presence of some specific trans-C18:1 fatty acids in MR fat than in EM fat which can be precursors of c9t11-C18:2, might have resulted in a higher endogenous synthesis of c9t11-C18:2, via Δ9-desaturase.