Regional composition of carcass and tissue composition of cuts from lambs slaughtered with different subcutaneous fat thicknesses

The aim of this study was to evaluate the influence of the subcutaneous fat thickness (SFT) on the regional composition of the carcass, the tissue composition of cuts, and the leg muscularity index of Santa Ines lambs. This experiment involved 24 uncastrated male lambs at approximately 100 days of age and at an average live weight of 22.70 ± 3.75 kg that were kept in the feedlot, where they received a complete pelleted diet formulated to provide a daily gain of 0.30 kg. The animals were slaughtered as they reached the pre-defined SFT of 2.00, 3.00, and 4.00 mm, evaluated by ultrasonography. Lambs slaughtered with 4.00 mm SFT had a heavier shoulder (1.80 kg) and leg (2.99 kg), differing from those slaughtered with 2.00 mm. No significant differences were observed (P > 0.05) between the treatments for the percentages of muscle in the cuts, which averaged 48.38% for the neck, 58.71% for the shoulder, 43.87% for the ribs, 53.56% for the loin, and 64.52% for the leg. Lambs slaughtered with 4.00 and 3.00 mm SFT differed from those slaughtered with 2.00 mm SFT for the percentage of total fat in the shoulder, which averaged 20.10, 19.02, and 15.79%, respectively. The animals slaughtered with 2.00 mm of fat exhibited the highest percentage of bone in the loin (20.23%). Leg muscularity was lower (0.34) in those slaughtered with 2.00 mm of subcutaneous fat. Slaughtering Santa Ines lambs with different subcutaneous fat thicknesses yields different regional compositions of the carcass, tissue compositions of cuts, and leg muscularity indices. It is recommended to slaughter Santa Ines lambs when they reach a subcutaneous fat thickness of 3.00 mm.