Factors Affecting the Secondary Sex Ratio of the Iranian Raeini Goats

Document Type : Original Article

Authors

1 Department of Animal Science, Faculty of Agriculture, Islamic Azad University-Qaemshahr Branch, Qaemshahr, Iran

2 Department Of Animal Science, Faculty of

3 Agriculture, Islamic Azad University-Qaemshahr Branch, Qaemshahr, Iran

Abstract

Commonly,the secondary sex ratio - the animal proportion of the same gender in the population at birth- is equal. This study aimed to identify the environmental and genetic factors affecting the secondary sex ratio of the Iranian Raeini goats. The data from 13563 goats included 7752 males and 5811 females were used to evaluate the effect of genetic and environmental factors by fitting 10 different animal models. In these models, the effects of herd-year of birth, birth type, province, maternal age, permanent environmental (dam and sire) and genetic factors (such as additive, sire, maternal and maternal grandsire) were included. The results showed that the effect of the herd-year of birth and the birth month on the secondary sex ratio were significant (P < 0.001), while the effect of the province, birth type and maternal age were not significant (P > 0.05). By studying the animal models, it could be concluded that the contribution of the genetic factors contributing to the variations of the secondary sex ratio were negligible.

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