Bioeconomic assessment of three ages at weaning in cow-calf systems

Early weaning is frequently used for the reestablishment of a cow's physiological conditions in situations of feed restriction and to increase the possibility of conception. However, studies on the systemic impacts of earlier weaning management are scarce, and bioeconomic assessments of beef calves weaned at 30 days of age have not been reported in the scientific literature. Therefore, this study aimed to perform a bioeconomic assessment of cow-calf systems with calves weaned at 30 (W30), 75 (W75), or 180 (W180) days of age. For this, a dynamic deterministic model was created based on a baseline scenario that used only W180, and thereafter the application of W30 and W75 was simulated. In the single application scenarios, W30 was applied only in year one in all cows (HA1), or only in primiparous cows (HP1), and W75 in all cows (EA1), or only in primiparous cows (EP1). In addition, successive application scenarios were simulated in which W30 and W75 were applied every year throughout eight years to intensify the system by increasing the number of dams. Thus, W30 was performed in all cows (HA8), primiparous (HP8), and W75 in all cows (EA8), or only in primiparous cows (EP8). The pregnancy rate breakpoint was simulated to determine which reduction in the pregnancy rate of conventional weaning systems would be necessary to justify the application of each single application scenario. The lowest gross margin per hectare, in the single application scenarios, was observed in the first year owing to the increase in weaning costs, and the highest gross margin per hectare in the second year due to a higher number of weaned calves. In year one, the highest gross margin per hectare was observed in EP1 and lowest in HA1. The pregnancy rate breakpoint for EP1 was 72.6%, whereas for HA1 was 42.3%. Intensification was observed in all successive application scenarios, but with GM/ha lower than CA8. Except for HA1 and HA8, all scenarios generated a positive gross margin per hectare. In conclusion, the single application of W30 only in primiparous and W75 in all cows and only in primiparous were economically viable. In addition, it is possible to intensify the system through consecutive applications of these technologies, although GM/ha was always lower than conventional weaning at 180 days of age. Therefore, adopting technologies that promote the rapid recovery of production and enable the reconstruction of the herd structure, such as W30 and W75, should be considered when unexpected weather events or sudden changes in culling policies occur.