Voluntary consumption of low quality roughage by sheep during cold exposure

Abstract

Measurements were made of the feed intakes, heart rates and bad., Y weights of adult sheep with a short fleece (0.3-1.2 cm) that were offered a low quality roughage diet and maintained in a cold environment. Feed intake was higher during cold exposure than under thermoneutral conditions. The increase in feed intake usually began in the second week of cold exposure and maximum intakes were generally shown in the third and fourth weeks. The increases were relatively small, the mean feed intakes in the third and fourth week of cold exposure being 9 to 15 per cent or 1.5-2.3 g organic matter/day/kg body weight above those under thermoneutral conditions. Heart rate values of up to 116 beats per minute during cold exposure indicated that energy expenditure was higher in the cold than under thermoneutral conditions. The increases in energy intake in the cold did not always compensate for the additional energy expenditure and body weight losses of up to 5.5 kg in four weeks of cold exposure were recorded. It was concluded that a regime of ad lib. feeding with low quality roughage would be of limited value in maintaining short fleeced sheep subjected to cold exposure. The data were also considered to be consistent with the conclusion that the intake of the wheaten hay diet was limited by the resistance of the dietary organic matter to removal from the rumen rather than by a metabolic effect of a nutrient deficiency.