بررسي اثر عوامل مادري بر صفات توليدي و توليد مثل يك لاين تجارتي گوشتي

Maternal effects on production and reproduction traits in a commercial broiler line

The effect of genetic and non-genetic factors on body weight at 6 weeks (BW6WT), egg weight (EWT), age at sexual maturity (ASM) and egg production from 25 to 50 weeks (EP) of a commercial broiler line were investigated using restricted maximum likelihood procedure through estimation of direct and maternal additive genetic and common environmental variances. Six different animal models were taken into account by including maternal direct additive or environmental effects in the models of analysis. Likelihood ratio test was used to determine the most appropriate model. For BW6WT, maternal additive and common environmental effects together with the covariance between direct and maternal additive genetic effects were significant. For this trait, direct heritability (ha ), maternal heritability (hn, ), maternal environmental variance as a proportion of the phenotypic variance (cʹ-) and the correlation between direct and maternal additive genetic effects ( ram) were 0.350, 0.050, 0.040 and -0.670, respectively. For EWT, ASM and EP, only maternal additive genetic effects were important, in addition to the direct additive genetic effects. The estimates of h] and th,, were 0.470 and 0.130 for EWT, 0.150 and 0.060 for ASM, and 0.240 and 0.05 for EP, respectively. The results of this study indicated that ignoring the maternal effects in the analysis tended to overestimate direct additive genetic variance and heritability for all traits.