Birthcoat fibre type arrays of lambs and some adult fleece traits

Abstract

SUMMARYIn a study of two coarse-wool breeds (Awassi and Hamdani) the birthcoat and adult fleece were sampled from six body positions. Mean fibre diameter, mean fibre length, mean staple length and the percentages of fibre types were studied in relation to the birthcoat fibre type arrays.The birthcoat of the two coarse wool breeds showed only plateau and saddle fibre type arrays. In Awassi lambs, plateau arrays were all P3 type whereas in Hamdani 28·6% of the plateau arrays were Po and the rest were P3 indicating a stronger base in the latter. S/P ratios, calculated from fibre types, were 2·22 and 2·27, at birth, and 3·56 and 2·93 at 4–8 weeks of age, in Awassi and Hamdani respectively. Awassi birthcoats showed more precipice within the CT group than those of Hamdani and plateau arrays were more endowed with the precipice than were saddle arrays.A composite sample from the back and mid-side, in Awassi, and from the back and britch, in Hamdani, was found to be most representative of the birthcoat fibre types.In the adult fleece of the Awassi breed, the mean fibre length following plateau arrays exceeded those following saddle arrays.In Hamdani, the saddle arrays developed into coarser fibres in average diameter than those of plateau arrays whereas in Awassi no difference occurred. Awassi plateau arrays were followed by higher within-staple variability in distribution of fibre length than were saddle arrays, whereas in the distribution of fibre diameter there was no difference. In Hamdani, however, saddle arrays were followed by slightly higher within-stable variability in both length and diameter than were plateau arrays.Birthcoat samples that had a transition in the CT group or had saddle array developed into adult fleeces with greater frequency of normal distribution in both fibre length and diameter, within staple. Adult fleeces that showed frequent bimodal distribution of both diameter and length, within staple, were those with birthcoats that had a precipice in length, or in coarseness and length, within their CT group or those with birthcoats that had plateau arrays.