Addressing productivity of supplementation of weaners and replacement females in the seasonally dry rangelands of northern Australia: a modelling approach.

Context: Increasing cow reproduction rates and annual liveweight gain present the best opportunity for maximising profitability of cattle herds in the seasonally dry rangelands of northern Australia. Herd-management and feed-base strategies exist and target heifer reproduction, liveweight of steers, and herd structure to increase whole-of-herd productivity. Aims: To use a desk-top model to determine the effect of supplementation in the first or second dry season after weaning on the break-even thresholds of the long-term productivity and profitability of an entire beef enterprise in response to changes in supplement costs and steer prices. Methods: Whole-of-herd desktop analyses were conducted using an Excel© version of the Breedcow Dynama software on a modelled cattle breeding herd in the Victoria River District and Katherine regions of the Northern Territory, Australia. Key results: Gross margins across the entire herd were increased in response to supplementation of weaners to achieve an extra 0.3 kg/day liveweight gain in the first dry season, with a break-even threshold of AU$678/t of supplement when steer prices were AU$3.50/kg liveweight. A concentrated supplementation period of heifers in the second dry season after weaning to achieve 0.8 kg/day had a break-even threshold of AU$696/t at the same price structure. Conclusions: At recent steer prices and supplement costs, feeding all weaners in the first dry season after weaning, or just the heifer cohort for a short duration in the second dry season after weaning increased gross margins across the entire cattle herd and altered herd structure. The application of a sensitivity analysis demonstrated the steer price and supplement-cost thresholds, at which weaner supplementation is likely to be profitable. Implications: These results have provided evidence and a framework for decision-making to assess the potential financial benefits associated with weaner and yearling heifer supplementation. The approach and results will assist producers to make tactical or strategic decisions on the adoption of weaner supplementation and the development of novel feeding systems in cattle breeding herds located in the seasonally dry rangelands of northern Australia within prevailing economic conditions. Moreover, they have provided target supplement costs by which to identify potential new supplements or feeding scenarios. Increasing heifer re-conception rates and increased annual liveweight gain present the best opportunity for maximising profitability in northern Australian beef cattle herds. A desktop analysis was undertaken to investigate the impact of weaner and yearling heifer supplementation on herd structure and gross margins. Break-even thresholds for supplementation were established for steer prices and supplement costs within the recent economic environment. [ABSTRACT FROM AUTHOR]