Genetic variation in nodule size at different sites on the skins of slaughter ostriches

Abstract

Nodule size is an important indicator of leather quality in the ostrich leather trade. The present study investigated genetic variation in nodule size at five sites on the skin, namely the neck, back, upper leg, flank and butt. Nodule size increased with an increased chronological age at all sites. Estimates of h² for nodule size ranged from 0.09 ± 0.07 on the flank region to 0.24 ± 0.10 on the upper leg region. Genetic correlations between nodule sizes measured at different sites were generally lower than expected, linked to high standard errors and mostly not significant. These preliminary results seem to suggest that nodule size on different locations of the skin is not necessarily the same genetic trait. Apart from the limitations evident from these results, the objective measurement of nodules on ostrich skins is tedious when done manually, with little prospect for automation. The number of nodules per dm² (nodule density) was considered within skin sites as an indirect criterion for the improvement of nodule size. However, genetic correlations between nodule density and nodule size were negative, variable in size and generally not significantly different from zero or unity. Based on these preliminary results, alternative strategies for the genetic improvement of ostrich skin nodule size should be considered.