Estimation of variance components and genetic parameters for growth traits in New Zealand White rabbit (Oryctolagus cuniculus)

Birth weights and subsequent body weights of individual kits of New Zealand White rabbits were analysed to estimate the impact of direct additive genetic, maternal additive genetic and permanent environmental litter effect on growth traits i.e. birth weight (BW), 15th day body weight (15dW), 30th day body weight (30dW), 90th day body weight (90dW) and 180th day body weight (180dW). The variance components and genetic parameters were estimated using Sire Model and two different animal models. Effect of litter size was significant on all the growth traits except 90dW. Kits born in winter season had significantly higher BW, 30dW and 90dW than the kits born in summer season. The heritability estimate for BW ranged from 0.266 (Sire Model) to 0.540 (Animal Model 2). The permanent effect of litter (c(2)) was highest (0.288-0.310) just before weaning at 30dW and decreased after weaning. The effect of indirectly inherited maternal genetic effect (m(2)) was present at early juvenile stage of growth (15dW, 30dW and 90dW) and was nil for 180dW. Selection for better growth would be more reliable at 180dW because at this age both c(2) and m(2) became lower than in previous stages of growth. Using Animal Model 1, repeatabilities of doe effects on BW, 15dW, 30dW, 90dW and 180dW were 0.35, 0.44, 0.40, 0.35 and 0.01, respectively. Animal Model 1 was better than Animal Model 2 in partitioning of variances when the maternal genetic variance (sigma(2)(m)) was very low or zero.