Drought feeding of sheep. 3. The relative importance of components of wool growth in explaining the wool growth differences between strains and diets

Abstract

This paper reports the changes in wool components with differences in wool growth resulting from differences in strain of sheep and diet, and the importance of these in relation to selecting a strain of Merino for the drier pastoral areas. Measurements of body weight, fold score, staple length, fibre diameter and follicle density were taken from Collinsville, Peppin and Bungaree ewes grazing natural pasture at Trangie and also when given a maintenance ration containing different grains, different protein supplements and formaldehyde treatment of these protein supplements. At pasture the Collinsville strain produced more wool with little increase in fibre diameter, when compared with the Peppins, and this resulted in the Collinsville strain being more profitable under pasture conditions than either the Peppins or Bungarees. When given a survival ration, similar changes in wool growth and the components occurred in each strain helping to maintain the profitable advantage of the Collinsvilles. The effect of the dietary treatments on wool growth occurred mainly through changes in fibre diameter and length. It is concluded that the choice of a particular strain of sheep for use in drier areas should not be influenced by the nutritional environment under which they are chosen.