Genetic parameter estimates for lamb growth traits and greasy fleece weight at first shearing in Turkish Merino sheep

The aim of the current study was to estimate genetic parameters for birth weight (BW), weaning weight (WW), yearling weight (YW), average daily gain from birth to weaning (ADG) and greasy fleece weight at first shearing (GFW), which are essential to design a selection programme for Turkish Merino sheep. Data and pedigree information of Turkish Merino sheep used in this study were collected at Marmara Animal Breeding Research Institute from 1996 to 2001. Genetic parameters were estimated with single- and two-trait analyses using restricted maximum likelihood (REML) with animal models. Estimates of direct heritability were 0.08 for BW, 0.12 for WW, 0.25 for YW, 0.11 for ADG and 0.08 for GFW. Estimates of maternal heritability were 0.09, 0.04, 0.03 and 0.04 for BW, WW, YW and ADG, respectively. Estimates of maternal permanent environmental variance as a proportion of phenotypic variance were 0.19, 0.08 and 0.09 for BW, WW and ADG, respectively. Estimates of direct genetic correlations among growth traits were positive and ranged from 0.56 to 0.98. GFW had a moderate to high positive direct genetic correlation with BW, WW and ADG but not with YW (0.19). Estimates of the correlation between direct and maternal genetic effects were negative and ranged from −0.63 to −0.92 for growth traits.