Wool characteristics affecting differences among sire progeny groups in staple strength

Abstract

This study aimed to improve the prediction of genetic differences in staple strength (SS) by defining factors that affect differences in SS among progeny groups in 2 sire test trials. The SS was related to mean fibre diameter (FD) and the standard deviation in fibre diameter (SDfd) in both trials (P<0.001), and to staple length in one trial. Sire contributed independently to SS in both trials (P<0.001). Detailed measurements on wools from Flock 2 showed that the relative importance of different components of SS differed among sires (P<0.01); for example, FD had a greater effect on SS in animals with a relatively low SDfd. An equation involving SDfd and FD accounted for only 26% of the variation in SS, but this was increased to 50% of the variation in SS by also incorporating the proportion of fibres greater than 30 m and the amount of unevenness in FD (blobs) measured on clean staples with an OFDA2000. If these findings are robust, they offer a means by which breeders who wish to avoid the expenseof direct measurement of SS may improve the efficiency of their selection for this characteristic.