Skin wrinkles affect wool characteristics and the time taken to harvest wool from merino and halfbred sheep

Abstract

Aflock of New Zealand Halfbred hoggets and three flocks of Merino hoggets were shorn and wrinkle score determined. There was a small (0.2 μm) decrease in fibre diameter with each unit of increase in wrinkle score (P = 0.003) in one Merino flock (Flock C), but this trend was not significant in the other three flocks. The coefficient of variation of fibre diameter increased with wrinkle score (0.9% per unit increase) in the Halfbred flock (Flock A, P < 0.001) and two of the Merino flocks (P = 0.004 in Flock C, P = 0.005 in Flock D) but the trend was not significant in Flock B. Greasy fleece weight increased significantly with increasing wrinkle score in all four flocks (P = 0.012, < 0.001, < 0.001, and < 0.013 for Flocks A, B, C, and D respectively). Yield was not measured for Flock B, did not change with wrinkle score in the Halfbreds (Flock A), and tended to decrease with wrinkle score in the other two flocks (by 0.4% per unit increase), although the relationship was significant in Flock C only (P = 0.040). The proportional change in yield was small, so the estimated clean fleece weight increased with wrinkle score in the Halfbreds (P = 0.011) and Flock C (P < 0.001) but not Flock D (P = 0.076). Staple length was measured in the Halfbreds, where it did not change with wrinkle score (P = 0.476), and in one flock of Merinos (Flock C) where it decreased by 3.4 mm per unit increase in wrinkle score (P < 0.001). In a second experiment, a flock of adult Merino ewes (n = 296) were shorn and scored for wrinkles. The time taken and the number of blows required to shear each sheep were strongly correlated (R = 0.801), and both increased with wrinkle score, so that the wrinkliest ewes required about 16 more blows (P < 0.001) and 15 more seconds (P< 0.001) to shear than the least wrinkly ewes. In contrast to the hoggets, the adult ewes produced wool that increased in fibre diameter (P = 0.048) by 0.15 μm with each wrinkle score, but was not different in staple length or coefficient of variation of fibre diameter. Greasy fleece weight of these ewes increased (P < 0.001) but yield decreased (P = 0.017) with increasing wrinkle score such that estimated clean fleece weight increased by 288 g (P = 0.004) between the least and most wrinkly ewes. This work suggests that Merino sheep with fewer wrinkles exhibit a slight reduction in fleece weight and little or no change in wool characteristics, but potential improvements in labour costs and animal welfare. © 2005 Taylor & Francis Group, LLC.