Bridging Nutritional and Environmental Assessment Tools: A One Health Integration Using Zinc Supplementation in Weaned Pigs

Zinc is an essential trace mineral for livestock, but excessive use can contribute to ecotoxicity and antimicrobial resistance. The objective of this study was to assess the impact of different zinc oxide (ZnO) levels in diets for weaned pigs on growth performance, mortality, dietary zinc flow, and environmental impacts. A 6-week feeding trial with 432 weaned pigs assessed three dietary treatments: high ZnO (pharmaceutical levels), intermediate ZnO, and low ZnO (EU recommendation). Growth performance for the growing–finishing period was modeled using the NRC (2012), and dietary Zn intake and fecal Zn excretion were estimated. Environmental impacts were analyzed via life cycle assessment (LCA) using SimaPro LCA software. High ZnO improved growth performance and reduced mortality (p < 0.05), but increased nursery fecal zinc excretion, resulting in a total fecal Zn excretion per pig of 54,125 mg, 59,485 mg, and 106,043 mg for low-, intermediate-, and high-ZnO treatments, respectively. In the nursery phase, high-ZnO treatment had the greatest impact on environmental footprint, increasing freshwater ecotoxicity and marine ecotoxicity indicators by 59.6% and 57.9%, respectively. However, high-ZnO-fed pigs had a greater body weight at the end of the nursery phase and were predicted to achieve a higher growth rate per 130 kg market pig, with fewer days to market and by sparing feed. Therefore, high-ZnO-fed pigs had reduced environmental burdens, including global warming potential, ozone depletion, land use, and mineral resource depletion. These findings demonstrate how livestock nutritionists can apply integrated modeling approaches to link animal performance with environmental outcomes within a One Health framework.