Genetic Analysis of Average Daily Gains and Kleiber Ratios in Moghani Sheep

The objective of the present study was to estimate genetic parameters and trends for average daily gains and Kleiber ratios in Moghani sheep. The included traits were average daily gain from birth to 3 months of age (ADG1), average daily gain from birth to 6 months of age (ADG2), average daily gain from 3 months to 6 months of age (ADG3), average daily gain from 3 months to 9 months of age (ADG4), average daily gain from 3 months to yearling (ADG5) and corresponding Kleiber ratios (KR1, KR2, KR3, KR4 and KR5, respectively). Different univariate and bivariate animal models with additive genetic, maternal genetic, maternal permanent environmental and residual effects were fitted to estimate genetic parameters for the traits. Genetic trends were obtained by regressing the means of predicted breeding values on year of birth for each trait. Direct heritability estimates for ADG1, ADG2, ADG3, ADG4, ADG5, KR1, KR2, KR3, KR4, and KR5 were 0.12, 0.16, 0.14, 0.28, 0.26, 0.11, 0.15, 0.15, 0.26 and 0.19, respectively. Estimates of direct genetic trends were positive for all average daily gains and Kleiber ratios in this study and all these estimates, except for KR5, were significant (P<0.01). The results of this study indicated that improvement of growth traits of Moghani sheep seems feasible in selection programs.