Modelled effects of grazing strategies on native grass production, animal intake and growth in Brahman steers

Abstract

Inadequate information about the long-term effects of grazing strategies on native grass production and animal growth poses limitations to sustainable management of beef cattle. A 20-year simulation study was conducted using the Sustainable Grazing Systems model to analyse implications of different stocking rates (SRs) and simple rotational grazing systems (SRGSs) for rangeland-based Brahman steers. Simulations included three SRGSs (two, three and four paddocks per herd) and four SRs that were compared for their effects on grass production, dry matter intake (DMI) and live weight gain (LWG). Stocking rates included a recommended SR of 10 ha livestock unit (LU)⁻¹, 30% high (7 ha LU⁻¹) and, 50% and 100% low (15 and 20 ha LU⁻¹), respectively, SR. Overall, there were no observable differences in the long-term response of grass production and DMI to all treatments for SRGS and SR. In addition, effects of SRGSs on animal production were almost similar across treatments in short and long timeframes, but differential responses of LWG to SRs were more pronounced regardless of time. These findings provide a useful criterion for choosing effective SRs to achieve sustained grass and animal production with lowest risk.