Optimising growth paths of beef cattle in northern Australia for increased profit

Abstract

This project investigated reducing slaughter age of northern cattle through modifications of growth paths using supplements or improved pasture. In a grazing trial at Swans Lagoon steers grazing native pasture were fed from weaning either at low-plane (urea only - Control) or with high-input molasses-based supplement (MUP) in either one or both dry seasons prior to slaughter. A further group were finished on leucaena. Steers fed in only one dry season reached similar slaughter weight to those fed in both with 22% less supplement intake. Hormonal growth promotants (HGPs) given to half the steers continuously from weaning increased growth rate by 8% in most groups, and by 22% whilst steers grazed leucaena, and increased the net value added to steers despite impeding compliance with Meat Standards Australia (MSA). An economic analysis showed that leucaena, but not high-input supplements, increased profitability - the use of improved forages, combined with manipulation of body composition and associated compensatory gain offer the most cost-effective options for reducing slaughter age. Associated pen-feeding studies established that young (8-12 mo) and older (30-33 mo) steers responded similarly (kg extra gain/kg supplement) to additional nutrients and that responses increased in order of MUP, barley/urea and cottonseed meal. Studies indicated that the Australian feeding standards could not currently be relied upon to predict intake of grazing cattle in the tropics.