THE INFLUENCE OF SEVERAL FACTORS IN DETERMINING THE GRAZING BEHAVIOUR OF BORDER LEICESTER × MERINO SHEEP

Over a period of 20 months twenty continuous, 24‐hour, observations were made on the grazing behaviour of Border Leicester × Merino sheep. Distinct seasonal changes were found in the pattern of grazing. Grazing usually began during the dawn period and decreased at dusk. In spring and summer there were two peaks of grazing, but there was only one peak in autumn and winter. The percentage of grazing taking place between 6 a.m. and 6 p.m. varied with season, and was highest in spring and early summer. These seasonal changes in the pattern of grazing appeared to be independent of grazing pressure, or of the nutritional requirements of the sheep. The mean grazing time, for all observations, was 8·2 hours with a standard deviation of 0·97. Decreasing pasture availability increased grazing time, as shown by an increased intensity of grazing. Ruminating times were found to be considerably lower than have been reported for cattle. There was a significant negative correlation between ruminating time and the nitrogen content of available pasture. There was no clear evidence that the number of lambs carried before parturition, or suckled after parturition, had any effect on grazing time. There was no evidence that the behaviour of one sheep influenced that of another, even of a twin, grazing nearby. Consistent differences between sheep were found for ruminating time. The variation in grazing time between sheep, at any one time, was considerably greater than previously reported and differences between sheep were not consistent. Variation in grazing time appeared to be less in flocks of less than 6 sheep than in flocks of 6 to 12 sheep.