Genetic and non-genetic effects on the growth and mortality of Alpine, Nubian and crossbred kids

Abstract

Birth weight (BW), weaning weight (WW), market weight (MW), preweaning (ADG1) and postweaning (ADG2) rates of gain, and kid mortality from birth to 15 d of age (KM-15) and from 16 d to weaning age (KM-90) of 395 purebred and crossbred kids born between 1987 to 1992 were studied. Breed and regression models were used in the analysis of the data. Fixed effects included in the breed model were the genetic group of kid, year, age of dam, type of birth, sex, and type of birth and rearing. Genetic group of kid was partitioned to direct genetic, breed maternal, direct heterosis and maternal heterosis in the regression model. Estimates for direct genetic effect were small ( P > 0.05) and negative, indicative of the nonsignificant superiority of Nubian over Alpine. The maternal superiority of the Alpine breed over the Nubian was 0.26 ± 0.12, 1.4 ± 0.6 and 2.2 ± 0.9 kg for BW, WW, and MW, respectively, and 14.4 ± 6 g/d for ADG1. Direct heterosis estimates were significant and positive for BW (0.24 ± 0.09 kg), WW (1.9 ± 0.5 kg) and ADG1 (19.8 ± 5 g/d) and significant, but negative, for KM-15 (−10 ± 5%). Heterotic effects observed were primarily due to dominance. Favorable maternal heterosis was evident for WW and KM-90. Year effect was evident in all traits. Age of dam had a significant ( P < 0.05) effect on BW, WW, ADG1 and ADG2. Sex of kid was an important source of variation in all traits except WW and KM-90. Single or multiple born kids, reared as singles were heavier ( P < 0.05) at weaning and marketing and grew faster in ADG1 than multiple born and reared kids.