Variation in fibre diameter along the wool staple in sire progeny groups

Abstract

The development of the Optical Fibre Diameter Analyser (the OFDA2000) has greatly facilitated measurement of the variation in fibre diameter (FD) along the staple. This equipment was used to measure fibre diameter profiles on 680 midside wool samples from progeny groups of 17 rams in a sire evaluation test, to determine characteristics of the variation in FD along the staple (SDalong). The SDalong of clean vs greasy samples differed among sire progeny groups, so further analysis focused on clean samples. Over 90% of the variation in SDalong could be accounted for by 3 components; the overall change in diameter across the year (slope), and the maximum and minimum diameters. There were significant differences among progeny groups for SDalong and for all of its components. The average difference in FD between adjacent measurements along the staple differed among sires, but was not a significant component of SDalong. The SDalong was greater in animals with high fleece weight, indicating that sheep thatgrew more wool responded more to the seasonal variation in nutrition. The components of SDalong were also related to staple strength.