Estimation of Genetic and Phenotypic Trends for Some Growth Traits in Shirvan Kordi Sheep

In this study, 5608 records of Kordi sheep body weights collected during 21 years (1990 to 2010) in Sheep Breeding Station of Shirvan were used to estimate genetic, phenotypic and environmental trends. Best linear unbiased predictions (BLUP) of breeding values were obtained by derivative free restricted maximum likelihood (DFREML) using univariate animal model. Genetic, phenotypic and environmental trends were estimated by regression of average estimated breeding values, average phenotypic values and average difference between phenotypic and breeding values on birth year, respectively. Total genetic progress in 21 years for birth weight (BW), weaning weight (WW), body weight at 6 (6W), 9 (9W) and 12 months of age (12W) were 0.017, 0.890, 1.319, 0.727 and 1.199 kg, respectively. Genetic trends for BW, WW, 6W, 9W and 12W were 4.4±0.5, 64±2, 73±3, 71.56±4 and 98.4±5 gr per year, respectively. The phenotypic trends for BW, WW, 6W, 9W and 12W were 16±2, 328±13, 227±18, 295±23 and 405±28 gr per year, respectively. Estimates of trends were significant for all traits (P < 0.01).