Research On Animal Production

The aim of present study was to estimate genetic and phenotypic trends for body weight traits at some ages in Lori-Bakhtiari lambs. In this study a total of 7721 records on birth weight, 6462 records of one month weight, 7275 records of weaning weight 5745 records of 6 month weight, 3326 records of 9 month weight and 3088 records of 12 month weight of Lori-Bakhtiari sheep was used to reveal the genetic and phenotypic trend of growth traits. The data was collected in Shahrekord sheep breeding station during 1989-2010. The SAS statistical software was used to evaluate the effect of environmental factors. Wombat software was employed to estimate genetic parameters and animals breeding value. Environmental factors, like birth year, sex, birth type and the age of mother were significant factors as fixed effects (P<0.01). Estimation of direct genetic trend for birth weight, one-month weight, weaning weight, 6 month weight, 9 month weight and 12 month weight were as 12±1, 18±2,78±4, 163±8, 183±10 and 205±11 gr per year, respectively and were statistically significant (P<0.01). The phenotypic trend for considered traits was estimated respectively 24±5, 113±17, 272±63, 349±76, 288±10 and 211±99 gr per year and were statistically significant (P<0.01). Estimation of maternal genetic trend for birth weight, one-month weight and weaning weight were as 3±1, 12±2 and 28±2 gr per year, respectively and were statistically significant (P<0.01).