GENETIC EVALUATION OF PRODUCTION TRAITS BETWEEN AND WITHIN FLOCKS OF MERINO SHEEP .2. COMPONENT TRAITS OF THE HOGGET FLEECE

Components of the fleece and wool quality traits were measured or asse ssed on Merino hogget ewes in an unselected multiple-bloodline flock o ver a 7-year period at Trangie Agricultural Research Centre, N.S.W. Th e traits recorded were face cover score (FC), leg cover score (LC), ne ck fold score (NF), body fold score (BF), wax content (W), suint conte nt (S), vegetable matter content (VM), dust penetration (D), follicle density (N) and follicle ratio (RA). Genetic differences within and be tween flocks of Merino sheep were examined for the traits, and estimat es of heritability and within-flock genetic and phenotypic correlation s and between-flock genetic correlations among the traits were obtaine d. Genetic and phenotypic correlations were also estimated between the se traits and the major wool production traits: greasy fleece weight ( GFW), clean fleece weight (CFW), fibre diameter (FD), body weight (BWT ) and staple length (SL). Significant strain, flock within strain and flock effects were present for all traits. The influence of environmen tal effects (birth-rearing type, age at measurement and age of dam) on the traits was estimated, with the birth-rearing type being significa nt and the largest effect for most traits. Paternal half-sib heritabil ity estimates were 0.44+/-0.06 for FC, 0.35+/-0.06 for LC, 0.24+/-0.05 for NF, 0.23+/-0.05 for BF, 0.38+/-0.07 for W, 0.42+/-0.07 for S, 0.0 6+/-0.04 for VM, 0.22+/-0.06 for D, 0.20+/-0.07 for N and 0.21+/-0.07 for RA. Estimates of within-flock phenotypic and genetic correlations were in broad agreement with available published estimates. The implic ations of the results for Merino breeding programs are discussed.