Milk Urea Nitrogen (MUN) as an Indicator of Environmental Sustainability and Public Health in Dairy Production: A One Health Perspective

Metabolic biomarker for the selection of eco-efficient animals and mitigation of nitrogenous residues"

Resumo

The intensification of dairy production has increased environmental and sanitary concerns related to low nitrogen utilization efficiency and nitrate water contamination. In this context, Milk Urea Nitrogen (MUN) emerges as a metabolic biomarker capable of integrating productive efficiency, environmental sustainability, and public health. Under the One Health perspective, MUN monitoring allows for understanding the interface between animal physiology, milk quality, and water resource security. This study aims to analyze the role of MUN as a bio-strategic indicator at the One Health interface, investigating its relationship with animal metabolic efficiency, milk stability, and environmental impact through nitrate leaching. An integrative literature review was conducted, covering recent studies (2021–2025) that link nitrogen management in dairy farming to planetary sustainability. Evidence demonstrates that MUN is a diagnostic tool with moderate heritability, enabling the selection of "environmentally friendly" animals that exhibit higher nitrogen utilization efficiency (NUE) and lower urinary residue loads. Dietary interventions with bioactive compounds and alternative forages proved effective in reducing MUN and, consequently, the gray water footprint, which can reach up to 11,110 liters of water per liter of milk in high-intensification scenarios. MUN monitoring transcends nutritional adjustment, acting as a sentinel indicator for aquifer preservation and drinking water safety. The integration of genetics and precision nutrition based on MUN is indispensable to decouple dairy production from ecosystem degradation, promoting animal, environmental, and public health in an integrated manner.