Analysis of records of a Perendale flock IV. Estimates of genetic and phenotypic parameters for mature ewes

Heritability and genetic and phenotypic correlation estimates were derived from data on 2-yearold (n = 1724), 3-year-old (n = 1160), 4-year-old (n = 726), and 5-year-old (n = 449) ewes. The traits studied were greasy fleece weight (FW), staple length (SL), mean fibre diameter (FD), quality number (QN), fleece character (FC), and number of lambs weaned (NL W). Pooled averages of the heritabilities, derived by weighting the paternal half-sib (PHS) estimates and 2-, 3-, and 4-year daughter-dam (DDR) estimates according to their standard errors were: FW, 0.47; SL, 0.40; FD, 0.50; QN, 0.35; FC, 0.24; NLW, 0.07; fertility, 0.01; and twinning, 0.09. The estimates of the genetic correlation between FW and NL W averaged around the negligible to low negative range. The phenotypic correlations were similar in sign and magnitude to the genetic correlation.