Grazing Management in the Tropics

Objectives in tropical livestock enterprises are more varied than in most temperate situations. Only in enclosed or fixed area management systems are they generally similar. With communal grazing or nomadic systems, objectives are usually not to maximise profits from sales. Grazing management, other than through the control of stock numbers and animal species combination, is difficult to implement. In fixed area systems, stocking rate (SR) is the major factor influencing production/animal (P/A), production/ha (P/ha) and sustainability of the resource. Long-term profit maximisation from sale of animal products is likely to occur at less than half the SR at which animals just maintain weight. Sustainability issues should therefore be less of a problem where profit maximisation, rather than numbers of animals, is the objective. However, this is not always so. The slopes (b values) of the relation between SR and P/A vary greatly between pastures, indicating different susceptibility to increased SR. Compared with SR, stocking method (SM) has less influence on P/A and P/ha. Continuous grazing (CG) is an acceptable grazing management for most grasslands. Claims that some forms of multipaddock grazing systems markedly improve P/ha have not been substantiated experimentally. A fuller understanding of the effects of defoliation on vigour, competitive ability, seed production and longevity of individual species may help define grazing strategies, based on ecological concepts such as the state and transition model, to restore degraded pastures or maintain productive ones. Such strategies need to be realistically tested. A major challenge is to produce evidence that conservative SRs can be economically and environmentally sustainable and to convince producers.