The objective of the present study was to estimate genetic trends for body weight traits at different ages in Kermani lambs. Data collected from 1993 to 2006 by the Kermani Breeding Station were analyzed. Genetic trends were estimated for birth weight (BW), weaning weight (WW), 6-month weight (6MW), 9-month weight (9MW) and yearling weight (YW). Maximum number of data was 2654 at birth, but only 1124 at yearling. Different appropriate models for investigation of each trait using multivariate analysis were applied. Variance component were estimated using Simplex procedure and breeding values of animals were predicted with Best Linear Unbiased Prediction (BLUP) methodology under multi-trait animal models. Genetic trends of studied traits were estimated by regressing mean of breeding values on birth year. Direct genetic trends were positive and significant for BW (p < 0.05) WW, 6MW, 9MW and YW (p < 0.01) and were 2, 125, 91, 81 and 156 g/year, respectively. Also, maternal trend for BW was positive and highly significant (p < 0.01) and was 3 g/year.
