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

The effect of different sources of energy (lipids and carbohydrates) was st udied on 36 Apennine male lambs divided by age, weight and paternity into t hree homogeneous groups receiving three different diets: lambs on diet 1 re ceived ad libitum lucerne hay + concentrate supplemented with barley flakes (9%) (BC); lan;bs on diet 2 received ad libitum lucerne hay + concentrate supplemented with maize oil (5%) (MC) while lambs on diet 3 received only t he concentrate given in diet 2 (MC). The two concentrates were isoenergetic and isonitrogenous. Lambs were slaughtered at 105 days of age. The convers ion indices were similar (4.52, 4.77 and 4.61 Meat FU/kg gain) for the thre e treatments, but the diet 3 led to heavier carcasses (17.57 kg), although with greater adipose covering, and better dressing percentages than the oth er two diets. The histological dissection of the proximal pelvic limb indic ated 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 adequ ate commercial weight at the age of 90-95 days and therefore it seems possi ble to anticipate slaughtering these animals earlier and perhaps obviate th e excessive adiposity of the carcass. In general, this study further confir med the good meat quality of Apennine carcasses slaughtered at 105 days. (C ) 1999 Elsevier Science B.V. All rights reserved.