Reproductive performance of crossbred Santa Inês sheep in Ceará State

[摘要] - The effect of environment and genotype on the Brazilian tropical sheep reproductive performance were evaluated on 480 native ewes, 48 Santa Inês rams and 1.474 F1 lambs from ten private farms in the state of Ceará. The studied traits were mating, fertility, prolificacy and weaning rates, as well as the weight gains at birth, 84 and 112 days, and average daily weight gains from birth to 56, from 56 to 84 and from birth to 112 days. There were effect of breed on the mating, fertility and weaning rates. The F1 ewes were less productive than the natives, but the 1/2 Santa Inês + 1/2 native and 3/4 Santa Inês + 1/4 native lambs had similar growth rates. There were also effect of ewe ages and farm effect on all studied traits, except for ewe ages on weaning rates. Birth year, birth type, farm and ram within the farm, generally, influenced the weights and weight gains in the growth phase. The heritabilities estimated for the weight gain ranged from 0.36 to 0.56, showing that there is a large possibility for improving the weight gain rates of crossbred lambs through mass selection.

[学科分类] 兽医学

[关键词] crossbreeding;weight gain;heritability;weight;reproductive rate    IntroduçãoNa região semi-árida do Nordeste do Brasil;a exploração de ovinos deslanados e crioulos (tipos nativos) é efetuada para produção de carne e pele;porém o desempenho reprodutivo é fraco;principalmente pelas práticas de manejo deficientes;aliadas às limitações de ordem nutricional impostas pelas condições climáticas no semi-árido nordestino e a quase completa inexistência de cuidados sanitários