Stocking Rate Impacts on the Production and Economic Performance of Steers Grazing Black Speargrass Pastures.

Abstract

A grazing trial conducted in subtropical Queensland examined the effect of four stocking rates (high, medium, low, very low) on beef production, economic returns and pasture stability. Liveweight gains of steers were recorded in legume sown pastures, over a five year period in which severe drought conditions prevailed. Although high stocking rates generated the highest levels of beef production per hectare, moderate rates generated the highest economic returns. The status of the dominant perennial tussock grass (Heteropogon contortus) was used as an indicator of pasture condition. While H, contortus declined in all treatments during the drought, populations were most persistent at the low stocking rate. The results provide clear evidence of a trade-off between ecologically optimal stocking rates and animal production. The highest net profit was derived from the medium stocking rate, which was more than 50% higher than the next most profitable stocking rate. However, at this stocking rate there was evidence of a decline in the dominant grass, H. contortus, which suggests that the medium stocking rate may not be sustainable over the long-term. The highest stocking rate paddocks all required supplementary feeding of stock and were poor both in economic return and ecological condition. The low stocking rate plots had the highest rates of liveweight gain per animal and had low ecological risk, but had low to negative returns on equity and were not sustainable economically. Key words: - stocking rates, black speargrass pastures, economics, range condition, drought.