Factors associated with the prediction of core bulk from fibre diameter and fibre curvature of individual fleeces (Reprinted from the 10th International Wool Textile Conference, Germany, November 2000)

Seventy percent of the New Zealand wool clip is shorn from longwool sheep b reeds coarser than 32 mum. Much of this wool is manufactured into products where increased wool bulk is beneficial to processing and end-product perfo rmance. It is therefore desirable for wool growers to be able to select she ep for breeding, at minimal cost, according to the bulkiness of their wool. This paper reports a series of trials evaluating the effect of several far m related factors on the prediction of core bulk from simultaneous measurem ents of fibre diameter and fibre curvature. There was a significant curvili near relationship between fibre curvature and core bulk over a series of br eeds differing markedly in curvature, and a linear relationship between fib re diameter and core bulk. In subsequent trials utilizing a single breed, b oth relationships were approximately linear. Neither the measurement site o n the body, the sheep's age nor the sheep's sire, significantly affected th e prediction of core bulk from fibre diameter and fibre curvature. The repo rted trials indicate that bulk can be effectively predicted under field con ditions. Calculation of a universal relationship will however be dependent upon the development of a standard test method for the measurement of fibre curvature.