In this study the data of birth weight (BW), weaning weight (WW) and Yearling weight (YW) of Kermani lambs were used to estimate effects of environmental factors and genetic parameters and correlations among these traits. The data were collected from shahrbabak sheep breeding research station during six years period (1993-1999). The fixed effects were lambing year, sex, litter size and dam age. The age of lamb at weighing was also used as linear and quadratic covariate. Estimates of (co) variance components and genetic parameters were obtained using single and multiple trait animal models. Estimates of direct and maternal habitability’s were 0.10±0.06 and 0.33±0.08, 0.19±0.08 and 0.11±0.07, and 0.14±0.09 and 0.17±0.12 for birth, weaning and yearling weights, respectively. Estimates of correlation between direct and maternal genetic effects for BW, WW and YW were —0.35, 0.56 and —0.20, respectively. Direct and maternal genetic correlations between BW and WW, BW and WW and TW were 0.82 and 0.92, 0.66 and 0.8, 0.92 and 0.80, respectively.
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