Effect of sample preparation method on the validity of an
early-life predictor of hogget wool bulk in genotypes used to develop
GrowBulk sheep
R.M.W. Sumner
AgResearch, Ruakura Research Centre, Private Bag 3123, Hamilton
Proceedings of the New Zealand Society of Animal Production.
2000 60: 155-158
Selection for wool bulk is normally undertaken in yearlings. In
this study, a mixed-sex group of 170 GrowBulk sheep were wool sampled at
6 and 12 months of age. Measurements of fibre curvature and fibre
diameter following degreasing a wool sample taken at 6 months of age
with either water or solvent, explained 69% and 67% respectively of the
variation in core bulk at 12 months of age. A combination of fibre
curvature and fibre diameter measured following degreasing by either
method was equally effective in predicting core bulk at 12 months of
age. Precision of the predicted core bulk values was equivalent to
direct core bulk measurement. Early-life prediction of core bulk from
measurements of fibre curvature and fibre diameter taken close to the
skin using consistent sample preparation methods, is a low-cost
objective procedure to rank sheep for culling young sheep on wool bulk.
Keywords: NZSAPAB;
wool bulk; fibre curvature; fibre diameter; Romney; Dorset; Texel.
Last Updated 12-07-2000
