THE EFFECT OF STOCKING RATE ON THE GRAZING BEHAVIOR OF CORRIEDALE SHEEP

The seasonal variation in the diurnal pattern of grazing, the number of grazing periods each day and the mean intake for each period were assessed at four stocking rates (10, 25, 20 and 25 sheep ha-1) of Corriedale wether sheep (Ovis aries) grazing a mixed pasture with main species of perennial ryegrass (Lolium perenne L.) and subterranean clover (Trifolium subterraneum L.). Most grazing occurred during daylight with a peak of activity in the morning and mid-afternoon. Sheep at the higher stocking rates grazed more intensely throughout the day than did those at lower stocking rates (P < 0.05). There was little difference between the grazing intensities of different stocking rates in the afternoon. Limited grazing occurred about midnight, with more sheep grazing at low than at high stocking rates (P < 0.05). In late summer and autumn, sheep at low stocking rates started grazing earlier (15-30 min) in the morning than did those at high stocking rates but this order was reversed in the spring (P < 0.05). From February to May, the pasture conditions at the low stocking rates allowed faster rates of intake so sheep grazed more frequently with more grazing periods and smaller intakes in each grazing period than did those at high stocking rates. In winter (June and July) longer and less frequent grazing periods were observed at all stocking rates. In spring there was little difference between the stocking rates in the number of grazing periods.