GENETIC-PARAMETERS FOR AUSTRALIAN MATERNAL AND DUAL-PURPOSE MEATSHEEPBREEDS .2. LIVEWEIGHT, WOOL AND REPRODUCTION IN CORRIEDALE SHEEP

Performance of sheep from a large Corriedale stud flock was assessed. Weaning and yearling liveweights, greasy and clean fleece weights, cle an fleece yield and average fibre diameter records on approximately 30 00 animals representing 64 sires were analysed. Also scrotal circumfer ence of 1009 rams representing 27 sires were analysed. Some 3740 repro duction records over 11 years, for 980 ewes representing 114 sires, we re also analysed. Heritability estimates were 0.34+/-0.07 for weaning liveweight, 0.13+/-0.04 for yearling liveweight, 0.32+/-0.07 for greas y and 0.29+/-0.07 for clean fleece weights, 0.53+/-0.10 for clean flee ce yield, 0.56+/-0.10 for yearling and 0.62+/-0.14 for hogget fibre di ameters and 0.15+/-0.11 for scrotal circumference. The genetic correla tions between liveweight and fleece weight ranged from 0.13 to 0.34, a nd those for liveweight and fibre diameter were close to zero. The gen etic correlations of scrotal circumference with liveweight and wool tr aits were positive and moderate. Reproductive performance in the flock was high, with fertility 92% and litter size 1.62, resulting in 148% lambs born and 130% lambs tagged alive of ewes joined. Estimated herit abilities for reproduction traits were 0.03+/-0.02 for lambs born and for lambs tagged, and the component traits, fertility 0.01+/-0.02, lit ter size 0.04+/-0.03 and neonatal lamb survival was zero. Lambing date had a heritability of 0.06+/-0.03. Estimates of repeatability ranged from 0.04+/-0.01 for fertility to 0.07+/-0.02 for lambs tagged and lam bing date. Predicted heritabilities for the average of 3.8 records per ewe generally agreed with those estimated for average ewe lifetime pe rformance, which ranged from 0.02+/-0.08 for fertility to 0.12+/-0.09 for lambs tagged and 0.13+/-0.09 for lambing date.