GENETIC PARAMETERS FOR SUBJECTIVELY ASSESSED AND OBJECTIVELY MEASURED WOOL AND LIVE WEIGHT TRAITS IN SOUTH AFRICAN MERINOS

Data collected from ~4500 animals maintained at Tygerhoek Experimental farm, were used to derive heritability estimates (h2) for and genetic correlations among live weight at 16 months of age (LW), six objectively measured wool traits and six subjectively assessed wool traits. Direct h2 estimates were 0.38 for LW and ranged from 0.20 (staple strength – SS) to 0.68 (fibre diameter – FD) for objective wool traits. Maternal heritability estimates were 0.05 for LW, 0.10 for clean fleece weight (CFW) and 0.05 for FD respectively. Estimates of h2 ranged from 0.21 (staple formation- STAPL) to 0.49 (quality – QUAL) for subjectively assessed wool traits. Maternal genetic effects were significant for QUAL, regularity of crimp (ROC) and wool colour amounting to 0.06, 0.03 and 0.07 respectively. Genetic correlations (rg) among objective traits accorded with literature values. The rg of LW with subjective wool traits were not significant, with the exception of ROC (0.20). The rg of subjective wool traits with CFW, clean yield, staple length, FD and CV of FD were generally moderate and variable in sign. Among the subjective wool traits only ROC was significantly correlated with SS