Effect of dietary inclusion of urea encapsulated in low-trans vegetable fat microspheres on fatty acids intake, carcass traits, quality, and fatty acid composition of lamb meat

This study evaluated the effect of including slow-release urea (SRU) coated from the low-trans vegetable fat (LTFV) microspheres in the diet of lambs on fatty acids intake, carcass traits, meat quality, and fatty acid composition of meat. Thirty-two non-castrated Santa Inês lambs (17.98 ± 2.01 kg of initial weight) were used in a randomized complete block design. Experimental treatments included a control which contained 5 g/kg urea (U_0.5%) and three other treatments in which SRU (60% LTFV and 40% urea) was incorporated at 1.25% (SRU_1.25%); 2% (SRU_2.0%) and 3% (SRU_3.0%) of total diet dry matter (DM). The inclusion of SRU in lamb diets increased linearly (P < 0.05) the intake of ether extract, metabolizable energy, and fatty acids. Carcass traits and physical-chemical composition of the Longissimus muscle were not changed by protected urea addition in lamb diet (P > 0.05). The addition of the protected urea in lamb diet linearly increased proportions of CLA and the 18:1 isomer (cis-12, cis-15, and cis-16) compared to U_0.5%. There was a linear increase in branched-chain fatty acid (BCFA) content (P = 0.048) in Longissimus muscle due SRU inclusion. There were a quadratic increases for the sums of trans-MUFA (P = 0.003) and n-6 PUFA (P = 0.046) and total PUFA (P = 0.037) as SRU was added to lambs diet. Adding urea coated into low-trans vegetable fat microspheres increased the lamb intake of most FA and energy dietary, however, without affecting carcass traits and meat physicochemical composition. The inclusion of protected urea (SRU) in the lamb diet quadratically increases trans-MUFA, n-6 PUFA, and total PUFA concentrations in meat, and lambs fed with SRU at level 1.25% in DM total diet presented greater CLA and trans-MUFA concentrations compared free urea (U_0.5%), which is beneficial from the point of view of the lipid quality of the meat and its relationship with consumer health.