Twenty-four female lambs, all from the Pantaneiro genetic group, slaughtered with 2.0; 3.0 and 4.0 mm of subcutaneous fat thickness measured by ultrasound in Longissimus dorsi, were used. We evaluated quantitative carcass traits, loin and leg muscularity. The lambs were fed with total ration calculated for daily weight gain of 0.3 kg. Ultrasound evaluations (between the 12th and the 13thribs) and weightings were carried out each 14 days; the slaughter occurred as the lambs reached the predetermined fat thickness: 2.0, 3.0 and 4.0 mm regardless of body weight. There was no effect for real income carcass, commercial carcass yield and index of leg compactness. Higher yield of loin for lambs slaughtered at 4.0 mm fat thickness was observed. The thickness of subcutaneous fat did not affect loin eye area, but animals with 4.0 mm had higher measures. There were differences in the proportions of muscle, bone and fat leg between subcutaneous fat thicknesses measured. The leg musculature was not influenced by increasing the thickness of subcutaneous fat. Based on this study and also with the requirements of the consumer market, it is recommended that the slaughter of animals occur with approximately 3.00 mm fat.
females; muscularity; ultrasound; yield