Effect of diet energy source on weight gain and carcass characteristics of lambs

Abstract The effect of different sources of energy (lipids and carbohydrates) was studied on 36 Apennine male lambs divided by age, weight and paternity into three homogeneous groups receiving three different diets: lambs on diet 1 received ad libitum lucerne hay + concentrate supplemented with barley flakes (9%) (BC); lambs on diet 2 received ad libitum lucerne hay + concentrate supplemented with maize oil (5%) (MC) while lambs on diet 3 received only the concentrate given in diet 2 (MC). The two concentrates were isoenergetic and isonitrogenous. Lambs were slaughtered at 105 days of age. The conversion indices were similar (4.52, 4.77 and 4.61 Meat FU/kg gain) for the three treatments, but the diet 3 led to heavier carcasses (17.57 kg), although with greater adipose covering, and better dressing percentages than the other two diets. The histological dissection of the proximal pelvic limb indicated a good tissue composition (total lean 56.16%) but confirmed the higher fat percentage (total fat 16.24%), particularly subcutaneous (11.44%), of the group receiving only MC. Animals on diet 3 gave carcasses with an adequate commercial weight at the age of 90–95 days and therefore it seems possible to anticipate slaughtering these animals earlier and perhaps obviate the excessive adiposity of the carcass. In general, this study further confirmed the good meat quality of Apennine carcasses slaughtered at 105 days.