Comparison different models for estimation genetics parameter and phenotypic of pre-weaning growth traits and Kleiber ratio in Shal sheep

In this research 6221 records of growth traits of Shal sheep breed from 4060 ewes and 180 rams collected during 1998 to 2009 in Agricultural Research Center of Qazvin province, were used to estimate the genetic and phenotypic parameters. Variance components and genetic parameters were determined for each trait using Maximum Likelihood procedures and various animal models using ASREML software were analyzed. In this study, fitting six different animal models and significant effects on the models were tested by likelihood ratio. In this breed, fit to direct additive genetic without other random effects caused is overestimated direct heritability. Reduce in the estimates result fitting the effects of maternal especially effects maternal additive genetic, with and without in order to genetic covariance effect, showed that a significant portion of phenotypic variance observed of body weight at different ages, especially before weaning due to maternal genetic effect. Direct and maternal heritabilities were estimated Birth Weight (BW), Weaning Weight (WW), Average Daily Gain (ADG) and Kleiber Ratio (KR) 0.13 and 0.12, 0.29 and 0.08, 0.23 and 0.09, 0.14 and 0.07, respectively. Estimates of maternal permanent environmental variance as a portion of phenotypic variance were 0.11, 0.20, 0.04 and 0.16 for BW, WW, ADG, and KR, respectively. Genetic correlation among BW-WW, BW-ADG, BW-KR, WW-ADG, WW-KR and ADG–KR were 0.63, 0.72, 0.56, 0.88, 0.78 and 0.84, respectively.