Genetic parameters of early growth traits in Mehraban breed of sheep.

Genetic parameters were estimated for birth weight (BWT), weaning weight (WWT) and pre-weaning Average Daily Gain (ADG) using Restricted Maximum Likelihood (REML) procedures. Six different animal models were fitted, differentiated by including or excluding maternal effects. The direct heritability estimates (h2) ranged from 0.26 to 0.53, 0.18 to 0.32 and 0.15 to 0.33 for BWT, WWT and ADG, respectively. The estimates were substantially higher when maternal effects, either genetic or environmental, were ignored from the model. The maternal heritability (m2) for BWT was the highest (0.25) when maternal genetic effect alone was fitted in the basic model. It was decreased to 0.14 when the maternal permanent environmental effect (c2) was employed.