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Compensatory Growth in Cattle: 3. Effect of Stocking Rate at Pasture in Summer on Animal Performance at Pasture and during the Subsequent Winter Period
M. J. Drennan, A. Conway and R. O'Donovan
Irish Journal of Agricultural Research
Vol. 21, No. 1 (1982), pp. 1-11
Published by: TEAGASC-Agriculture and Food Development Authority
Stable URL: http://www.jstor.org/stable/25556011
Page Count: 11
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Fifteen-month-old Friesian steers, weighing 225 kg, were stocked at 3.71 (low), 5.56 (moderate) and 7.41 (high) per ha in three grazing seasons (Experiments 1, 2 and 3). During a subsequent fattening period cattle from each grazing treatment were fed either silage alone or with supplementary barley. In a fourth experiment stocking rates of 4.94 (low/moderate) and 7.41 (high) steers per ha were imposed during the grazing season followed by winter feeding levels of silage alone or with 2.6 or 5.0 kg of supplementary barley per animal daily. From mid-April to August there was no significant effect of stocking rate on liveweight gains in Experiments 1, 2 or 3. However, during this period in Experiment 4, animals at the low/moderate stocking rate gained more (p<0.05) liveweight than those at the high rate. From August until the end of the season (late October/early November) and during the entire grazing season stocking rate significantly affected animal performance in all four experiments. Average liveweight gains during the grazing season (205 days) for Experiments 1, 2 and 3 were 186, 167 and 146 kg for animals at low, moderate and high stocking rates, respectively. The corresponding gains (196 days) in Experiment 4 were 175 and 137 kg (p<0.001) for animals at low/moderate and high stocking rates, respectively. The duration of the winter feeding period varied from 109 to 140 days. For the parameters measured there was no significant interaction between stocking rate at pasture and winter feeding level in any of the four experiments. Stocking rate at pasture had no effect on total winter weight gain in Experiments 1, 2 or 3. In Experiment 4, animals maintained at a high stocking rate (low weight gain) in summer gained more (p<0.05) during the subsequent winter period than those on the low/moderate stocking rate. However, this difference was due to a higher (p<0.01) rate of gain during the first 28 days of the feeding period; and no performance difference was evident during the remaining 81 days. Although there was no effect on total winter gain, significantly higher weight gains were also obtained by previously restricted animals during the first 22 days of winter feeding in Experiment 2. Stocking rate at pasture significantly affected final carcass weight in all four experiments. Animals fed supplementary barley with silage in winter had greater weight gains, final liveweights, carcass weights and killing-out percentages than those fed silage alone. However, increasing the level of barley from 2.6 to 5.0 kg per head daily in Experiment 4 had no significant effect on the foregoing parameters.
Irish Journal of Agricultural Research © 1982 TEAGASC-Agriculture and Food Development Authority