Rearing of dairy cattle 5. The effect of stocking rate on animal and herbage production in a grazing system for calves and heifers

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Abstract
SUMMARY A rotational system of grazing, in which Friesian calves grazed the paddock immediately in front of a group consisting of pregnant and non-pregnant young female cattle (heifers), was examined at stocking rates initially of 3·0, 3·5 and 4·0 replacement units per ha (a replacement unit = one calf + one heifer). The stocking rates were reduced towards the end of the season by removing pregnant heifers. Measurements were made of live-weight gains and herbage production and utilization. Increasing the stocking rate from 3·0 to 4·0 units/ha depressed live-weight gain in calves by 18% on average and in heifers by 32%. The stocking rate of 3·5 replacement units/ha produced the greatest amount of live-weight gain per ha. There was a progressive decline in herbage production and consequently live-weight gain from early to late season. Herbage production was also depressed by the increased stocking rate. Although the average utilization of herbage at each grazing was low, ranging from 27 to 37% in calves and 35 to 48% in heifers, the total utilization of herbage over the whole season was high, ranging from 88 to 96%.