Investigation on Direct and Maternal Effects on Growth Traits and the Kleiber Ratio in Moghani Sheep

Abstract

The objective of this study was to estimate genetic parameters for growth traits and kleiber ratio in Moghani lambs. Traits included birth weight (BW), weaning weight (WW), 6-month weight (6MW), average daily gain from Birth to Weaning (ADG ), average daily gain from Weaning to 6 months of age (ADG ), 0-3 3-6 Kleiber ratio from Birth to Weaning (KR ) and Kleiber ratio from weaning to 6 months of age (KR ). Data were 0-3 3-6 collected by Moghani Sheep Breeding Station at Jafarabad, Iran, during 1995 to 2008. (Co) variance components and genetic parameters were estimated by univariate and multivariate animal models using Restricted Maximum Likelihood (REML) procedure. The log likelihood ratio test (LRT) was carried out to determination the most suitable model for each trait. The effects of year and season of birth, birth type and sex of lamb were significant for each trait (p<0.01). The age of dam was significant for BW, WW, ADG , ADG , KR and KR (p<0.01). 0-3 3-6 0-3 3-6 Direct heritability estimates for BW, WW and 6MW, ADG , ADG , KR and KR based on most appropriate 0-3 3-6 0-3 3-6 models were 0.104±0.03, 0.098±0.01, 0.085±0.02, 0.212±0.04, 0.023±0.04, 0.132±0.04 and 0.014±0.01, respectively. Estimation of maternal heritability varied from 0.017±0.01 for KR to 0.127±0.03 for ADG . Indeed, estimations 3-6 0-3 of fraction of variance due tomaternal permanent environmental effect were 0.099±0.01, 0.046±0.02 and 0.068±.05 for 6MW, ADG and KR respectively. Direct genetic correlations among different traits ranged from -0.70 for 0-3 0-3 BW and ADG to 0.98 for WW and ADG . 3-6 0-3