Genetic parameters for visually assessed traits and their relationships to wool production and liveweight in Australian Merino sheep

Abstract. Heritability was estimated for a range of visually assessed traits recorded on Merino sheep, together with the phenotypic and genetic correlations among the visually assessed traits and correlations of the visually assessed traits with measuredwool production traits and liveweight. Datawere derived from four research resourceflocks,with a range of 12 958 to57 128 records fromanimalswith 478 to1491 sires for thevarious traits. The estimates of heritabilitywerehigh for thewool quality traits of handle, wool character and wool colour (0.33–0.34) and the conformation traits of face cover, neck wrinkle and body wrinkle (0.42–0.45), moderate for front leg structure (0.18) and low for back leg structure (0.13). Fleece rot score had low heritability (0.14), while classer grade wasmoderately heritable (0.20). Estimates of genetic correlations among the visually assessed wool quality traits were low to moderate in size and positive (0.17–0.47). Genetic correlation estimates among the assessed conformation traits were generally very low, except for the genetic correlations between scores for neck and body wrinkle (0.92 0.01) and front and back leg structure (0.31 0.09). Fleece rot score had low positive genetic correlations with neck and body wrinkle scores (0.18 0.05 and 0.15 0.05, respectively) and classer grade (0.26 0.06). Classer grade was slightly positively correlated with the wool quality traits (0.17–0.45) and leg structure traits (0.21–0.25). The genetic correlations among the visually assessed traits were generally neutral to favourable. The visually assessed woo