Analysis of the effects of sire and age on wool quality traits in Romney ewes

Higher prices for sheep meat compared to strong wool have caused dual purpose sheep breeding objectives to align with meat production. The resulting lack of focus on wool breeding has resulted in reduction of the quality and value of strong wool. This dissertation examines the results of a wool breeding trial being conducted with Romney ewes in North Canterbury, New Zealand. Wool trait data collected from the first generation progeny was analysed. The trial aims to increase the value of Romney wool by improving its quality. Key wool traits which affect processing performance and end use were assessed using the Fibrescan objective wool measurement system. Wool staples were side sampled from each of 437 ewes as hoggets and again as two tooths. Sampling date significantly affected mean fibre diameter (MFD), mean curvature, coarse edge (% fleece 10µ > x̄) and the proportion of ewes with wool medullation (p=<0.001). Average changes in wool traits between hoggets and two tooths were as follows. MFD increased 5.5 micron (hogget x̄=31.9, two tooth x̄=37.4). Mean curvature decreased 15.2 Âo/mm (hogget x̄=71.3, two tooth x̄=56.1). Coarse edge increased 1.8% (hogget x̄=8.8%, two tooth x̄=10.5%). The proportion of ewes with medullation decreased (hogget x̄=13.7%, two tooth x̄=6.4%). Sire was recorded for 181 ewes, which allowed the performance of sires to be compared for each wool trait. Sire significantly affected MFD, staple length, mean curvature, and coarse edge (p=<0.001), as well as the coefficient of variation of MFD (CVMFD) (p=0.004). The results agree with previous findings in the literature. The changes in wool traits between hoggets and two tooths have implications for accurately selecting replacement and cull animals in a wool breeding program. The difference in wool traits between sires indicated that these traits can be improved via selective breeding.