Effect of diet energy source on the chemical-physical characteristics of meat and depot fat of lambs carcasses

Chemical-physical analyses of cholesterol content and fatty acid profile of tissues in various anatomical locations of Apennine lambs fed three differ ent diets and slaughtered at 105 days of age are reported. The three diets were (1) a concentrate with barley flakes (BC) and lucerne hay, (2) a conce ntrate with maize oil (MC) and lucerne hay, and (3) only concentrate with m aize oil. Diets had little effect on the physical traits of meat but Diet 3 (MC without hay) had a higher percentage of ether extract both in M. longi ssimus lumborum (3.61%) and in M. semitendinosus (3.01%). Cholesterol conte nt (48.33 mg/100 g) was not affected by diet. The fatty acid profile was af fected by the different diets: the intramuscular fat from lambs on Diet 3 w as more saturated (43.88%) and with less essential fatty acids (omega-3: 0. 92% and omega-6: 10.15%) than the fat of the other two diets (Diet 1: respe ctively, 42.98%, 1.28% and 10.50%; Diet 2: respectively 43.20%, 1.20% and 1 0.67%). M. longissimus lumborum had a dietetically better acid profile than the semitendinosus muscle. Depot and intermuscular fat in Diet 3 showed a positive increase (P less than or equal to 0.05) in the level of unsaturati on (52.31% vs. 50.38% in Diet 1 and 50.96% in Diet 2). A comparison between tissues highlighted a similar composition between the subcutaneous and int ermuscular fats of the proximal pelvic limb that were different (P less tha n or equal to 0.01) from the subcutaneous fat of the loin. Despite these sm all differences, the quality of the meat and of the fat of these lambs was dietetically good. The addition of 5% maize oil to the concentrate did not show any unfavourable physiological side effects in the lambs and modified favourably the subcutaneous and intermuscular fat; the total quantity of un saturates and the good content of stearic acid highlight the good dietetic characteristics. (C) 1999 Elsevier Science B.V. All rights reserved.