Comparison between Merino sheep homozygous (WW) or heterozygous (Ww) for white fleece on the incidence of isolated pigmented wool fibres and types of non-fleece pigmentation

Abstract

Merino sheep known to be homozygous (WW) or heterozygous (Ww) for white fleece were examined for isolated pigmented fibres and various types of non-fleece pigmentation on the adult sheep or pigmented halo-hair on the birth coat.There was no significant difference (P>0-05) between WW and Ww sheep in the occurrence of isolated pigmented fibres. Nevertheless, 17% of the fleece samples contained varying concentrations of pigmented fibres; up to 510 per 10 g scoured staples. Of the various types of macroscopic pigmentation recorded, the scores for pigmented halo-hair (lamb) and pigmented fibres on the horn sites (adult) were the most strongly correlated (r= 0.39 and 0.30, respectively; P<0.001) to the concentration of pigmented fibres in fleece samples. Heterozygous sheep had slightly more black/grey pigmentation for bare skin areas on the nose lips and around eyes ( P< 0.001) or under tail (P<0.05) and in the hooves (P<0.05) than WW sheep, but these differences arc unlikely to be of practical relevance.