Abstract

Midside skin and wool samples were taken at hogget shearing in October 1991 from 58 Perendale ewe hoggets which were the progeny of 2 lines of Perendale sheep selected for, or against, loose wool bulk at hogget shearing. Wool from the high line was 50% more bulky, with a 17% lighter clean fleece weight (CFW), 29% shorter staple length (SL), 25% shorter fibre length (FL), 14% greater within sample variation in fibre diameter (SDFD), 72% higher crimp frequency (CFreq), 61% higher proportion of paracortex (Para%), 92% higher follicle curvature grade (FolC) and 7% shallower follicle depth (FolD) than the low line. Character grade (Char) was 14% lower and sulphur content (S) 3% higher in the high line, each approaching 5% significance, while there was no significant difference in live weight (LW) or mean fibre diameter (FD). Bulk was most strongly correlated, in decreasing order, with FolC, CFreq, SL, FL, Para%, CFW, SDFD, Char and FolD. In decreasing order CFreq, Char, FD, SL, FL, Para% and FolD explained a total of 90% of the variation in bulk. With deletion of the subjectively assessed characteristics of FolC and Char, CFreq, SL and FL were the only characteristics selected as being significant, explaining a total of 85% of the variation in bulk. The strong association between bulk and both SL and FL can be considered to be a reflection of associations between the length parameters and other fibre characteristics which impact on bulk rather than a direct effect of the length of fibre being measured for bulk. These data indicate the biological basis of differences in loose wool bulk for coarse wool Perendale sheep are, as for the fine wool Merino, primarily associated with single fibre crimp.

RG, McFarlane, TA Bell, and LR Fletcher

Proceedings of the New Zealand Society of Animal Production, Volume 53, , 255-258, 1993