Effect of production system on fatty acid composition in subcutaneous adipose tissue of Ile de France lambs

A study was conducted on the effect of two different lamb production systems on the fatty acid (FA) composition of subcutaneous fat of 40 purebred Ile de France lambs. In the first production system, ewes and lambs grazed on pasture without concentrate (GS), whereas in the second production system, ewes and lambs were housed indoor and fed silage/hay and concentrate (IS). Twenty lambs (7 females and 13 males) were included in each group. Lambs were slaughtered at 28.75 ± 2.76 kg. The FA were determined by gas chromatography and analysed through ANOVA by considering the following fixed effects: production system, sex and the interaction between production system and sex. Subcutaneous fat of GS lambs had greater proportion of C18:3n-3 (P <0.001), C22:5n-3 (P <0.05) and C22:6n-3 (P <0.05) than IS lambs, which resulted in a higher sum of n-3 polyunsaturated FA in GS compared to IS lambs (2.00 vs. 1.15 g/100 g FAME, P <0.001). Moreover, subcutaneous fat of GS lambs had greater proportion of c9,t11-C18:2 (P <0.001) and sum of detected conjugated linoleic acid isomers than IS lambs (2.21 vs. 0.67 g/100 g FAME, P <0.001). Females had significantly greater proportion of C18:2n-6 (P <0.05) and C18:3n-6 (P <0.001) than males. We can conclude that the GS system where lambs are raised under grazing conditions may provide carcasses with a more acceptable subcutaneous fat, as far as a human health and nutrition perspective is concerned.