Maternal effects on growth traits of 3872 lambs born from 182 rams and to 2274 ewes during 1994 - 2002 in Moghani Sheep Breeding Station, were investigated using maternal model and restricted maximum likelihood procedures. Traits were birth weight (BWT), and body weights at 3 (BWT3M), 6 (BWT6M), 9 (BWT9M) and 12 (BWT12M) months of age. With or without taking into effect. The maternal effects, six different animal models were fitted and likelihood ratio test applied to determine the most appropriate model. For BWT, direct additive genetic, maternal additive genetic and maternal permanent environmental effects without a fitting of covariance between direct and maternal additive genetic effects were important. For this trait, estimates of direct heritability ( ), maternal heritability ( ) and maternal permanent environmental variance as a proportion of the phenotypic variance ( ) were 0.172 ±0.022, 0.058±0.045 and 0.131±0.038, respectively. For BWT3M and BWT6M, the important sources of variations were direct as well as maternal additive genetic effects. Estimates of and were 0.044±0.037 and 0.075 for BWT3M, and 0.083±0.024 & 0.075±0.040 for BWT6M. None of the maternal effects influenced BWT9M and BWT12M. For these traits, figures were 0.376±0.037 and 0.227±0.059, respectively. Direct additive genetic correlations varied from 0.209 (between BWT and BWT6M) to 0.604 (between BWT and BWT3M). These estimates for maternal additive genetic correlations ranged from 0.574 (between BWT and BWT6M) to 1.000 (between BWT3M and BWT6M). The corresponding estimates for phenotypic correlations varied from 0.168 (between BWT and BWT12M) to 0.843 (between BWT6M and BWT9M)
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