Dominant mutation(s) for low fibre curvature in the wool of sheep

Two sires judged to have phenotypically lustrous wool as neonates were mated to ewes that did not exhibit lustre in their fleece as adults. Around half their progeny were lustrous as neonates. Wool characteristics of these progeny were measured on an optically based fibre diameter analyser (OFDA) when they were weaned and again as yearlings. There was a profound difference in mean fibre curvature (P<0.001) such that the lustrous phenotype had less curvature in both sire groups (22.8, 24.5°/mm) compared with the non-lustrous (67.5, 56.2°/mm) as lambs, and 29.8, 28.1°/mm compared with 74.1, 55.0°/mm as yearlings. Curvature of the sire groups was significantly different in concert with breed mix, Merino in one sire and Romney in the other, but only when their fleece was not lustrous. The greasy fleece of the lustrous yearlings was significantly lighter (1.8 vs 3.0 kg, P<0.05) than their non-lustrous contemporaries, while there was no significant difference in fibre diameter between the two phenotypes as lambs or yearlings. Fibre curvature is inexpensive to measure and well-defined, whereas lustre is a qualitatively assessed trait. These findings suggest “low fibre curvature” would be a more appropriate name for the trait than “lustre”.