Effect of level of water intake on water, energy and nitrogen balance and thyroxine secretion in sheep and goats

Abstract

Sheep and goats fed on a diet of oaten chaff were subjected to a 50% reduction and a 50-70% increase in their water intake. Measurements were made of water, energy and nitrogen balance and thyroxine secretion rate. Water restriction decreased feed intake by 25%, but in a lesser proportion than expected from the ad libitum feed to water relationship. This effect was achieved by a reduction in the concentration of water in faeces and by the evaporation of less water. When additional water was given, there was a 10% reduction in feed intake associated with a loss of nitrogen brought about by an increase in urine volume. Again less water was evaporated than expected under this treatment. Thyroxine secretion rate was positively related to energy intake.