Incorporating Subjectively Assessed Sheep and Wool Traits into Genetic Evaluations for Merino Sheep. 1: Phenotypic Variation and Heritabilities

During the last decade, many Australia Merino sheep breeders have adopted selection strategies based on subjectively assessed sheep and wool traits. Pedigree and performance records were obtained from two Merino breeders who collect both objective and subjective information on their sheep. Centre Plus subjectively assessed six sheep and wool traits developed to mimic the Soft Rolling Skin® system, while Petali recorded a single subjective trait based on Elite Wool specifications. This trait was related to wool classing and assessed in the shearing shed for wool-marketing purposes. All objectively and subjectively assessed traits were moderately to highly heritable. Age, birth type, rearing type and age of dam had significant effects on both the objective and subjective traits. The results also indicated that the environment during gestation had larger effects on the sheep and wool qualities later in the sheep's life than that during rearing.