Variations in wool quality within a sheep arise from inherent differences between sites across the body and between fibres within a site, as well as variationsalong individual fibres that result from nutritional, reproductive and seasonal influences. The Wiltshire sheep is a shedding breed in which there is renewed interest due to the relative values of meat and wool, and the costs of wool production. Staple length, fibre diameter, fibre diameter standard deviation, and medullation were measured on wool grown at seventeen sites across the body of two-tooth Wiltshire rams undergoing a photoperiod-induced wool growth cycle. Staple length was longest on the shoulder (41 ± 2.5 mm) and shortest on the belly (14 ± 1.2 mm). There was an inverse correlation between staple length and fibre diameter with the finest fibres on the shoulder and coarsest on the hip (R²=-0.7, P<0.001). This gradient of increasing fibre diameter was associated with increased variation within-staples (R²=-0.8, P<0.001). Fibre medullation increased from the shoulder to the hip. Short coarse fibres on the front and back legs, along with facial hairs highlight differences in major regional skin domains that are established in utero. Although midside samples were representative for each fleece they did not portray the anterior/posterior and dorsal/ventral gradients observed in all characteristics studied. Understanding the within-fleece variation in wool characteristics is a requirement for producing sheep with more desirable fleece distribution patterns.
Proceedings of the New Zealand Society of Animal Production, Volume 67, Wanaka, 339-344, 2007
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