GENETIC-FACTORS AFFECTING PREWEANING GROW TH OF CROSSBRED SANTA-INES-IN-CEARA STATE

Data of 1,474 cross-bred Santa Ines lambs sired by 48 Santa Ines rams in eight private farms located at Quixada, Quixeramobim, Morada Nova, Crateus and Independencia, CE, Brazil, were analysed and provided esti mates of the genetic parameters for the weights on the pre-weaning pha se. The heritability estimates were of 0.48 +/- 0.10 for weights and b irth, of 0.36 +/- 0.09 for weights at 56 days, of 0.51 +/- 0.10 for we ights at 84 days, of 0.53 +/- 0.11 for weights at 112 days for age, of 0.37 +/- 0.09 for the weight gains from birth to 56 days, of 0.54 +/- 0.11 for the weight gains, from 56 to 84 days, and of 0.56 +/- 0.12 f or the weight gains from birth to 112 days of age. The heritability es timates were high, meaning that selection may promote a genetic change on pre-weaning weights in the population. The genetic correlations we re also midium or high and positive, suggesting that the selection for a particular weight results in improvement on the other weights as we ll, except the genetic correlation between birth and the weight daily gains. The phenotypic and environmental correlations were higher than the genetic and also positive.