Heritability estimates and correlations between subjectively assessed and objectively measured fleece traits in Merino sheep

Abstract

Data from 2801 individuals (born from 1996 to 2002) were used to obtain heritability (h2) estimates for five objectively measured and six linearly assessed type fleece traits (scored on a 1-50 point scale) from the Tygerhoek Merino flock. Correlations of the objective traits with the subjective traits were also derived. Estimates of h2 for the subjective traits accorded with literature estimates, and exceeded 0.2 for wool quality (0.31), wool colour (0.38), yolk (0.25), as well as belly and points (0.25). Corresponding h2 estimates amounted to 0.19 for regularity of crimp score and 0.13 for staple formation score. Genetic correlations of objective traits with subjective traits were either favourable or negligible in the majority of cases. The only exceptions were positive genetic correlations of fibre diameter (FD) and coefficient of variation of FD with staple formation score and belly and points score. Genetic progress in subjective traits thus appears possible, if desired in a selection strategy. © South African Society for Animal Science.