Genetic and environmental aspects on the pre-weaning weights in goats af exotic breeds

Abstract

With the objective of studying the effects of sex of kids, kind and order of parturition, breed and sire, and determinating the heritability estimates of the characteristics: weight at birth, at 28,56, and 112 days of age (weaning) on goats of exotic breeds, in the ecologic environment of the semiarid region of Paraiba state, Brazil, a study was conducted with 148 German Alpine and 182 Angio-nubian kids raised at the Pendência Experiment Station in Soledade, PB, Brazil, from 1980 to 1984. The average weights at birth, at 28, 56 and 112 days of age (weaning) analyzed by the Least-squares method were 3.08, 5.75, 8.16 and 11.82 kg, respectively. Sex of kids, kind and order of parturition influenced kids weights, during the growth stages studied (P< 0.01). Breed and the interaction order of parturition x kind of parturition, however, influenced only the weaning weight at level of (P < 0.01) and (P< 0.05), respectively. Dam from third to fifth parturition presented progeny with better body development. German Alpine sires produced descendants with better performance than those of the Angio-nubian. The heritability estimates of these weights, determined by intraclass correlation among paternal half-sibs, were 0.1716 ± 0.0067; 0.1086 ± 0.0054: 0.0093 ± 0.0034 and - 0.0147 ± 0.0029 for Anglo-nubian and 0.0059 ± 0.0063, 0.2155 ± 0,0115; 0.1024 ± 0.0087 and 0.5932 ± 0.0201 for German Alpine. In the German Alpine, except for birth weight, all estimates were considered intermediary to high. This study suggests that the improvement of animal environment must be prometed parallelly with the genetic improvement to increase herd productivity.