The effects of genetic group and sex on residual feed intake, performance, morphometric, testicular, and carcass traits' in lambs.

The aim of this study was to analyze the effects of genetic group and sex on residual feed intake, performance, testicular size, carcass and morphometric traits in Santa Ines purebred and Dorper " Santa Ines crossbred lambs. A total of 32 lambs, with initial body weight of 18 +/- 3.7 kg were used. Analysis of variance, considering the interaction between sex and genetic group of all the traits were performed. Crossbred females (-0.018 +/- 0.06) and purebred males (-0.018 +/- 0.05) were more efficient (p<0.001) in residual feed intake than crossbred males (0.018 +/- 0.04) or purebred females (0.018 +/- 0.04). The most efficient animal in residual feed intake consumed 37.9% less feed (1.179 kg/day) than the least efficient animal (1.899 kg/day). Crossbred, when compared to purebred, showed higher values for body weight, average daily gain, testicle size, carcass traits; had greater muscle accumulation, were more compact and with more aptitude to beef. Purebred were taller, but with lower body length and thoracic perimeter than crossbred. Males had greater muscle accumulation, were more compact and with more aptitude to meat. Crossing of native (Santa Ines) with exotic breed (Dorper) is an alternative to align efficiency in feed use, testicular size, compactness, aptitude for meat and ability for muscle accumulation.