Effect of the length of pasture finishing on trigliceride and phospholipid fatty acid composition of intramuscular fat from lamb meat

Aim of the trial was to study the effect of pasture finishing on fatty acid (FA) composition of intramuscular lamb meat fat, by analyzing total lipids (TL), phospholipids (PL) and triacylglycerols (TG) composition. After weaning (60 days long), 40 Italian Merinizzata lambs were equally allotted into 4 groups according to 4 different feeding regimen: P, 84 days pasture; S, 84 days with a diet composed by concentrate (65% barley, 35% chickpea) and grass hay; PF34, 50 days pasture then 34 days diet S; PF14, 70 days pasture then 14 days diet S. TL content of meat from Sgroup lambs resulted 2 times higher than that from other groups (2.4, 1.5, 1.3 and 1.3 g/100g of meat, in S, PF34, PF14 and P, respectively, P<0.05). The proportion between TG and PL varied according to meat fatness, being higher in C samples and lower in S, PF34, PF14 samples. Feeding regimen strongly affected FA composition of TL, especially in the case of FA which are prefer-entially esterified in TG. The content of PUFA n3 increased with the increase of the length of the grazing period (0.5, 0.5, 1.3 and 2.0 g/100g of FA in S, PF34, PF14 and P, respectively, P<0.0001). The content of PUFA n6 increased as the length of pasture finishing decreased as a consequence of the increase of concentrate supply (10.1, 11.7, 11.7 and 12.5 g/100g of FA in P, PF14, PF34 and S, respectively, P=0.015). Both trends were confirmed with a larger extent in the PL fraction, because PUFA n3 and n6 are preferentially esterified in PL. Feeding regimen dramatically affected n6/n3 ratio (21.7 in S vs 5.2 in P, P<0.0001), but also SFA content (39.8% in S vs 41.6% in P, P<0.001), PUFA content (19.8% in S vs 21.4% in P, P<0.0001) and the PUFA/SFA ratio (0.5 in S vs 0.6 in P, P<0.0001), whereas any effect was revealed on MUFA content.