Pasture growth curves and grazing management

Abstract

Growth curves, published by Brougham (1956), of pastures growing in winter at Palmerston North, New Zealand, were analysed. The mathematical models were examined by computer runs in which the various parameters were varied within likely limits. The results obtained suggest that the following principles may be applied to the management of pastures similar to those studied. The average rate of regrowth increases to a maximum after removal of grazing animals, but this maximum is not sharply defined. The optimum number of subdivisions in a rotational grazing system is probably less than ten, unless considerations other than pasture growth are important. The optimum length of intervals between grazings, and of grazing periods, for a given level of subdivision, are not sharply defined. Following dry autumns, management should generally aim at maximum pasture production rather than most rapid relief of present stress, provided this policy does not endanger animal or financial survival. Systems of grazing management may therefore vary within fairly wide limits, without serious loss of pasture production, provided pasture stability and animal welfare are not jeopardized.