Selection response in New Zealand Romney sheep

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Abstract
Data from a flock selected for wool-free faces, and a random-selected control group derived from the same base flock were analysed. Each flock consisted of 70–80 breeding ewes, mated usually to 4 rams each year. Estimates of the realised heritability of face-cover grade ranged from 0.44 to 0.68. Correlated responses derived from yearling data were generally negligible. Relative to control group means: liveweight, staple length, and fibre fineness increased slightly in both the yearling ewes and rams; clean scoured yield and fibre uniformity increased in the yearling ewes; and fleece weights were slightly lower in both sexes. Data on the lifetime averages of ewes born between 1956 and 1971 indicated that, relative to the control group, staple length and fibre fineness showed small increases.