The effects of exposure in Blackface sheep with particular reference to the role of the fleece

Abstract

1. The effect of shelter from winter conditions was studied in terms of body-weight change of dry sheep individually fed a maintenance ration. In 2 years, one a mild and the other a hard winter, the exposed group lost weight relative to the sheltered group.2. Within the treatments attempts were made to relate individual weight loss to a variety of fleece components. These results were not conclusive, but they suggest that such components as depth of wool and weight or volume of wool per unit area of skin have some effect in reducing weight loss under climatic stress conditions.3. A method of measuring the insulation provided by the fleece in dry environmental conditions was developed. It was shown that exposure to moderate winds increased the heat flow by between three and five times. The results again suggested that significant differences in insulation could be found between sheep within a breed. It was not possible to demonstrate the overwhelming importance of any single fleece component.