Biotechnology in Animal Husbandry (Jan 2018)
Analysis of genetic parameters and genetic trends for early growth traits in Iranian Afshari sheep
Abstract
The purpose of the present study was estimation of genetic parameters and genetic trends of early growth traits using Bayesian approach by Gibbs3f90 software in Iranian Afshari sheep. The data set [birth weight (BW), weaning weight (WW) and pre-weaning daily weight gain (PWDG)] were collected during the period 1999 to 2010 from Agriculture Jahad of Zanjan province, Iran. The fitted fixed effects were herd-year-season as interactions, sex (male, female), birth type (single, multiple) and age of dam. Based on Derivative Information Criteria (DIC), for studied traits the most appropriate model was determined. Therefore, based on the most appropriate fitted model, the direct additive heritabilities estimate for BW, WW and PWDG were 0.32±0.02, 0.05±0.01 and 0.24±0.02, respectively. The estimates of maternal heritabilities were 0.17±0.04, 0.07±0.02 and 0.12±0.05 and total heritabilities 0.11±0.05, 0.08±0.02 and 0.08±0.03 for BW, WW and PWDG, respectively. Direct genetic trends were positive for all traits but only significant for BW 0.75±0.31 g/year (P <0.05). Also, maternal genetic trends were for all traits negative and was significant for BW-0.63±0.27 g/year (P <0.05). The moderate estimates of heritabilities for early growth traits indicate that in Afshari sheep faster genetic improvement through selection is possible for these traits. Furthermore, the results genetic trends in this current study indicated that genetic improvement through selection is suitable only for BW in Afshari sheep.
