Random regression models for estimation of covariance functions growth traits in Iranian Kurdi sheep

Body weight (BW) records (n=11,659) of 4961 Kurdi sheep from 215 sires and 2085 damswere used toestimate the additive genetic, direct and maternal permanent environmental effects on growth from 1 to 300 days of age. The data werecollectedfrom1993 to 2015at a breeding station in North Khorasanprovince; Iran.Genetic parameters for growthtraits were estimated using random regression test-day models. The model 16 with a polynomial of 3 order for fixed effect, 6 order for direct genetic effect, 6 order for direct permanent environmental and 6 order for maternal permanent environmental effects with the lowest Bayesian information criterion (BIC) was considered to be the best model.Genetic correlations ranged from 0.03 to 0.98 for body weight between different days of age. The small value of genetic correlation (0.03) among early (day 1) and late (300 days) weights showed that early weights werenot under the same genetic control as weights at older ages.

Random regression models for estimation of covariance functions growth traits in Iranian Kurdi sheep Keywords:

Kurdi sheep , growth traits , Legendre polynomials