Carcass muscularity and adiposity of different sheep and goat genotypes

SUMMARY Carcass muscularity and adiposity of different goat and sheep genotypes grazing in the Caatinga rangeland were evaluated. A total of 40 uncastrated males, with an initial average age and body weight of 120 days and 18.76 kg, respectively, were used: 10 mixed breed goats (MB), 10 cross Boer goats (½ Boer x ½ MB), 10 MB sheep and 10 cross Dorper sheep (½ Dorper x ½ MB). The cross Dorper had higher mean scores for rib eye area, leg muscularity index, weight of total muscles of the leg and conformation compared to MB goats. There was no significant difference between genotypes for the meat texture. Meat color was darker for goat genotypes than for sheep genotypes. The quantitative aspects of carcass adiposity, renal fat, inguinal fat, and subcutaneous and total leg fat showed to be higher for sheep than for goat genotypes. Carcass finishing and leg compactness index were superior for the cross Dorper genotype. Carcass muscularity and adiposity were better in sheep than in goat genotypes, indicating that sheep have a greater muscle and fat tissue development, giving to them a greater potential for beef production.

本研究对卡廷加放牧牧场中不同基因型山羊与绵羊的胴体肌肉发育及脂肪沉积情况进行了评估。试验共选用40只初始平均日龄为120天、初始平均体重为18.76 kg的未去势公畜，分为4组：10只杂交品种（mixed breed, MB）山羊、10只波尔杂交山羊（½波尔×½MB）、10只杂交品种（MB）绵羊及10只杜泊杂交绵羊（½杜泊×½MB）。与MB山羊相比，杜泊杂交绵羊的眼肌面积、腿部肌肉指数、腿部总肌肉重量及胴体外形评分均更高。不同基因型间的肉质地无显著差异。山羊基因型的肉色较绵羊基因型更深。针对胴体脂肪沉积的量化指标（包括肾周脂肪、腹股沟脂肪、皮下脂肪及腿部总脂肪），绵羊基因型的相关指标均显著高于山羊基因型。杜泊杂交基因型的胴体育肥度与腿部紧凑指数均更优异。绵羊基因型的胴体肌肉发育与脂肪沉积情况均优于山羊基因型，表明绵羊的肌肉与脂肪组织发育更为充分，使其具备更出色的肉羊生产潜力。