An evaluation of classing Merino sheep for fleece rot susceptibility

Two experiments were conducted to evaluate the ability of sheep classers to predict the susceptibility of Merino sheep to fleece rot. A total of 626 hogget ewes, from 15 genotypes known to vary in fleece rot susceptibility, were assessed by 3 classers in each experiment before fleece rot was induced. In all cases the classers were able to identify flocks resistant and susceptible to fleece rot (between-flock correlations between predicted and observed fleece rot susceptibilities ranged from 0.37 to 0.81). Some classers were also able to distinguish between resistant and susceptible sheep within a flock (within-flock phenotypic correlation between predicted and observed fleece rot susceptibilities ranged from 0.05 to 0.39). The potential role of sheep classers in relation to selective breeding against fleece rot is discussed.