Assessing direct-maternal genetic comp onents a bility in Markhoz goat

A total of ۶۱,۲۸۳ body weeight records between birth and ۴۰۰ days of age obtained from ۳,۴۷۶ Markhoz kids were used in order to estimate variance co mponents and genetic trends of direct and maternal genetic effects. Kids were progeny of ۲۲۳ bucks and ۱,۲۱۷ does raised in Markhoz goat breeding station located in Sanandaj, Iran. The fixed effects were gen der, year of birth (۱۹۹۲-۲۰۱۴), age of dam (two to seven years old)and type ofbirth (single or twin). Random regression moddels based on Legendre polynomials of age at recording included direct and maternaal genetic and permanent environmental effects.Heterogeneous residual variances were considered along age of recording. According to AIC and BIC information criteria and LRT, adding covariance between direct and maternal genetic effects resulted in significant improvement in the level of fit. After examining models with different order of fits, the most suitable model coonsisted of a polynomial of fourth-order for direct genetic effect and third-order for maternal genetic and individual and maternal permanent environmental effects. Thee direct heritabilities ranged from ۰.۲۱ at birth to ۰.۵۵ at ۴۰۰ days of age. The highhest and lowest values for maternal heritability estimates were in birth (۰.۲۵) and ۶۰ days of age (۰.۱۷), respectively.

Keywords:

direct-maternaal genetic effect , genetic correlation , random regression model