GENETIC-PARAMETERS FOR AUSTRALIAN MATERNAL AND DUAL-PURPOSE MEATSHEEPBREEDS .3. LIVEWEIGHT, FAT DEPTH AND WOOL PRODUCTION IN COOPWORTH SHEEP

Heritability was estimated for weaning liveweight of 7030 Coopworth sh eep from 10 flocks representing 92 sires by derivative-free restricted maximum likelihood procedures using an animal model. Similar analyses were used for yearling liveweight and greasy fleece weight with over 4000 animals, fat depth on 2184 animals end fibre diameter on 966 anim als. The fixed effects of flock-year-management group, sex, birth type , rearing type and age were significant for most traits. Estimates of heritability were 0.45+/-0.07 for weaning liveweight, 0.38+/-0.07 for yearling liveweight, 0.28+/-0.05 for greasy fleece weight, 0.18+/-0.08 for fibre diameter and 0.13+/-0.04 for ultrasonic fat depth at the C site. The genetic correlations of liveweights with greasy fleece weigh t were positive, but close to zero with fibre diameter. The genetic co rrelation between greasy fleece weight and fibre diameter was 0.42+/-0 .25. Fat depth was highly genetically correlated with liveweights at w eaning (0.53+/-0.22) and yearling (0.64+/-0.20) ages, was highly negat ively correlated with fibre diameter (-0.55+/-0.28) and had a small po sitive genetic correlation with greasy fleece weight (0.15+/-0.34).