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 different 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 concentrate with maize oil (MC) and lucerne hay, and (3) only concentrate with maize 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. longissimus lumborum (3.61%) and in M. semitendinosus (3.01%). Cholesterol content (48.33 mg/100 g) was not affected by diet. The fatty acid profile was affected by the different diets: the intramuscular fat from lambs on Diet 3 was 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: respectively, 42.98%, 1.28% and 10.50%; Diet 2: respectively 43.20%, 1.20% and 10.67%). 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 unsaturation (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 intermuscular fats of the proximal pelvic limb that were different (P less than or equal to 0.01) from the subcutaneous fat of the loin. Despite these small 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 unsaturates and the good content of stearic acid highlight the good dietetic characteristics. (C) 1999 Elsevier Science B.V. All rights reserved.