Effects of shade use on grazing, drinking, ruminating and postural patterns of Merino sheep

Abstract

Eight animals in a flock of 20 Merino sheep were observed during four 24-h periods in summer (Tamax 31-37¦C) to see whether their voluntary use of shade was related to patterns of foraging and posture. Observations were made at 15-min intervals on the 4 animals that used shade most (31% of the day) and the 4 animals that used shade least (12%). A related experiment revealed no significant differences in body core or skin temperatures or in respiratory rates between the groups. Feeding times, ruminating times and drinks per day were no different in groups making most and least use of shade; day-night patterns of these variables were also indistinguishable. Sheep in the shade stood for 2 h longer per day than sheep in the sun, though they behaved similarly at night. Thus shade use by sheep was not apparently related to patterns of feeding or watering, but was associated with postural modifications that probably have thermoregulatory consequences.