Extreme wool production---implications for fitness

Abstract

\"The research reported here examined factors that affect the production of high-value fleeces grown in harsh environments with particular emphasis on how wool production affects fitness of sheep. Data were derived from genetic resource flocks in New South Wales and Western Australia. Sheep with high genetic values for clean fleece weight had less energy reserves than those with low genetic values for clean fleece weight. The small energy reserves of sheep with high genetic values for clean fleece weight were reflected in lower fatness and lower plasma concentrations of glucose and insulin, the extent of which were sufficient to reduce reproductive turnoff. Selection for low fibre-diameter does not exert these effects, but wool yield is associated with fatness. Yield is important to achieve price premiums for fine wool grown in dusty environments, but the dust content of wool with low dust penetration is surprisingly high. Furthermore, the current method of assessment of dust content based on dust penetration does not reflect the ease of processing. These results indicate that fitness characteristics such as reproduction and fatness should be considered in the breeding objective when selecting for increased fleece weight in harsh environments. \"