Water and feed intake responses of sheep to drinking water temperature in hot conditions

Abstract

When live-export sheep from Australia arrive in the Middle East during the northern summer months, they may be offered drinking water at temperatures exceeding 40°C. There is little published research to indicate whether drinking water temperature is important in managing heat stress in sheep or its effect on their health and welfare. Three studies were conducted with Merino wethers in climate-controlled rooms to investigate: (i) responses to drinking water temperatures of 20°C, 30°C and 40°C in a cool (20°C) and hot (40°C) environment, (ii) preferences for drinking water temperature at 20°C or 30°C when in a hot or cool environment and (iii) effects of water restriction when offered hot water (40°C) in a hot environment. Sheep assigned to the hot room had significantly higher respiration rates than those assigned to the cool room. In the cool environment, water intakes were the same when water temperatures were 20°C, 30°C or 40°C; however, when the sheep were given a choice between drinking water at 20°C and 30°C, they preferred (P < 0.05) to drink water at 20°C. In the hot environment, water intake increased as drinking water temperature increased, and sheep preferred to drink water at 30°C rather than 20°C. When the availability of 40°C drinking water was restricted (to ~10% of liveweight) in the hot environment, sheep had higher respiration rates than those offered unlimited water.