A study of some aspects of selection in Romney ram breeding flocks in Canterbury

Abstract

96 questionnaires were sent to Canterbury Romney ram breeders to assess selection practices in these ram breeding flocks. 87% of the 38 respondents were using a recording scheme and it can be assumed that some recording of objective measurements was occurring. The emphasis placed on the use of objective measurements appeared to vary widely, with large numbers of breeders listing subjectively assessed characters as their main criterion for selection. Other aspects of selection in Canterbury ram breeding flocks are discussed. It appears that there is room for improvement in selection practices in a large proportion of flocks, while allowing that there are those striving to maximise selection efficiency, and utilising objective measurement as an effective selection tool. A further refinement to selection practices is fleece testing which would enable animals to be selected on their CFW value as opposed to GFW. Fleece testing allows the breeder to identify outlier animals in their flocks that may be disadvantaged by selection based on GFW. Two flocks of Romney ram hoggets from differing Canterbury environments were midside sampled in order to calculate a CFW value. The correlation between GFW and CFW was 0.869 and 0.930 for flocks A and B respectively. It was calculated that selection based on GFW would only be 84.5% and 95% as efficient as selection based on CFW for flocks A and B respectively. The profitability of fleece testing keeper two-tooth rams for the ram breeding flock was related to the degree of correlation between GFW and CFW. No allowance was made for the effect of superior progeny entering the ram breeding flock or for the increase rate of gain in fleece weight that would occur in the ram buyers flocks. It was noted that there are wider ranging implications than the gains to be made in the ram breeding flock; implications for commercial flocks and the wool industry are discussed.