[Comparison of different models for estimating genetic parameters of early growth traits in cashmere goat]

Using data on early growth traits (including birth weight, weaning weight, daily gain, and yearling weight) of cashmere goat from the Aerbasi White Cashmere Goat Breeding Farm in Inner Mongolia, four different animal models for estimating genetic parameters were compared. The four models differ in the way of handling maternal genetic effect and maternal environmental effect: in model I both maternal genetic and environmental effect were excluded, in model II only maternal genetic effect was included, in model III only maternal environmental effect was included, and in model IV both maternal genetic and environmental effect were included. The variance components under different models were estimated with derivative-free restricted maximum likelihood (DFREML) method using the MTDFREML program. The differences between different models were tested by likelihood ratio test. The results show that both maternal genetic and environmental effect have highly significant effect on birth weight. For weaning weight and daily gain the maternal genetic effect is not significant while the maternal environmental effect is highly significant; for yearling weight the maternal genetic effect is significant while the maternal environmental effect is not.