Is crimp definition a reflection of variation in fibre curvature?

The relationship between assessed crimp definition and curvature variation as measured by an OFDA was examined in two data sets representing 28 medium (n=1380) and 9 fine (n=530) wool Merino flocks. Flocks of lower average di ameter were characterised by higher average curvature and curvature variati on but these flocks were neither better nor worse in average crimp definiti on compared to flocks of higher average diameter. Within the fine wool floc ks, the correlation between crimp definition and the standard deviation of curvature was highly variable, ranging from -0.47 to 0.50. On average, thou gh, differences in assessed crimp definition between sheep did not reflect differences in curvature variation. Within the medium wool flocks, a decrea se in the standard deviation of curvature was associated with a moderate im provement in assessed crimp definition (0.38). However, mean fibre curvatur e was similarly correlated with crimp definition and also strongly related to the standard deviation of curvature (0.85). After accounting for these a ssociations with mean fibre curvature, it was found that crimp definition d id not reflect variation in fibre curvature, the correlation being 0.05. While it might be thought that curvature variation in greasy wool would be associated with fibre alignment and hence crimp definition, OFDA curvature variation was not shown to provide a useful indirect measure of visually-as sessed crimp definition.