Fertility of Merino sheep classified according to degree of development of face wool and bred by artificial insemination
in ReproductionA large amount of wool on the face (face cover) of Merino sheep has been regarded as a fault by Australian sheep breeders as it has been associated with poor reproduction rates. Fail & Dun (1956) and Drinan & Dun (1967) reported that the degree of face cover was negatively correlated with fertility, but Young, Turner & Dolling (1963) found no evidence of a genetic association. In a review of these factors, Turner & Young (1969) commented that degree of face cover had been related to reduced reproduction rates in various breeds of sheep in Australia, New Zealand and the United States but not in the Soviet Union. The degree of face cover of individual ewes changes with season, and during pregnancy and lactation, with pregnant and lactating ewes showing less face cover than their non-pregnant contemporaries in the same flock (Mullaney, 1965). Physiological status of the ewe could therefore influence phenotypic assessment and may have contributed to the conflict of opinion on the importance of face cover as a criterion of selection.
