The relationships between crutch cover score and production and easy care traits in Merino sheep.

A preliminary study of the relationship between crutch cover score, measured at hogget and adult age, and production and easy care traits found moderately negative phenotypic correlations between hogget score and hogget fibre diameter and body weight, and a moderately positive phenotypic correlation with hogget face cover. Genetic correlations between hogget crutch cover score and hogget fibre diameter, staple strength, staple length and body weight were moderately to strongly negative and strongly positive for coefficient of variation of fibre diameter and face cover. Correlations with hogget fleece weight, yield, neck and body wrinkle were not significantly different to zero. Heritability of crutch cover score at both ages was high. Strategies to eliminate the need for mulesing by placing selection emphasis on decreased hogget crutch cover should result in genetic gains in hogget performance for body weight, staple strength, staple length and to a lesser degree plainness but attention should be paid to fibre diameter to prevent it from increasing. Better estimates of the genetic correlations between hogget crutch cover score, other hogget traits and adult traits are needed to predict future hogget and adult flock performance, however our preliminary results suggest that selection to reduce hogget crutch cover should give minor gains in adult body weight and reproductive performance, with negligible impact on adult fleece weight in the current flock.