Diet for compensatory gain of feedlot lambs: commercial composition of carcass cuts and tissues

The effect of diets for compensatory gain on the commercial cut yield and carcasses tissue composition of finished feedlot lambs was determined. A total of 40 Santa Ines lambs, with mean body weight (BW) of 17 +/- 1.7kg and 100 days old were used. The lambs were slaughtered; the left half carcass was sectioned into five primary commercial cuts: neck, shoulder, rib, loin and leg. The leg was dissected into muscle, bone and fat, and then the muscularity of the leg was determined. Muscle hypertrophy was measured by the mean diameter of muscle fibers. The left half carcass, neck, shoulder, rib, loin and leg weight decreased linearly between 0 and 60% of previous food restriction levels, ranging, respectively, from 11497.4 to 8888.5g; from 1453.8 to 1211.4g; from 1955.4 to 1560.9g; from 3420.0 to 2604.6g; from 1669.4 to 1161.6g and from 2998.8 to 2350.0g, as well as loin yield (from 14.5 to 13.1%), leg musculosity index (from 0.42 to 0,39) and muscle fiber diameter (from 46.0 to 43.4 mu m). Food restriction followed by refeeding promoted decreasing in the weight of cuts and did not affect the yield, and it also decreased the proportion of fat in the carcass, resulting in lighter cuts and leaner meat.