A decision support model to evaluate the effects of drought and stocking rate on beef cattle properties in Northern Australia

Beef cattle in northern Australia are raised on extensive pastoral properties in a semi-arid tropical climate subject to droughts. The severity of the effect of drought on cattle depends on the stocking rate. Management of herd size is therefore a compromise between harvesting production in average years and the risk of losses in a drought. The authors report on a spreadsheet model that can be used to evaluate herd performance and cashflow using annual rainfall as the only climate input. The model relies on a proxy for pasture availability derived from annual rainfall and stocking rate. This proxy is used for the estimation of reproduction, mortality and liveweight gain. Economic information is calculated to the level of cashflow The model has been used with groups of pastoralists to evaluate the question of drought and stocking rate in terms of economic risk and deterioration of native pastures. It has also been used in consultations with individual pastoralists to help determine which type, and the number, of cattle that should be sacrificed in a drought