Nitrogen Dynamics and Use Efficiency in Pasture-Based Grazing Systems: A Synthesis of Ecological and Ruminant Nutrition Perspectives

Summary

This review synthesizes ecological and ruminant nutrition perspectives on nitrogen dynamics in pasture-based grazing systems, integrating evidence on rumen metabolism, microbial processes, and environmental losses. The authors demonstrate that integrated management combining dietary manipulation, forage diversity, and targeted grazing can increase farm-gate nitrogen use efficiency from 20–25% to over 30% whilst maintaining productive performance. The work positions pasture-based ruminant systems as critical leverage points for aligning production with environmental and climate sustainability.

Regional applicability

The findings are directly applicable to United Kingdom pasture-based dairy and beef systems, where similar nitrogen excretion challenges and environmental regulations apply. The strategies reviewed—including forage diversity, dietary optimisation, and sensor-assisted grazing management—align with UK farming conditions and policy drivers around nutrient management and climate targets.

Key measures

Nitrogen use efficiency (NUE), ammonia volatilization, nitrate leaching, nitrous oxide emissions, milk and blood urea nitrogen, microbial protein synthesis, urine patch biogeochemistry

Outcomes reported

The review synthesizes evidence on nitrogen flows in pasture-based ruminant systems, examining rumen metabolism, excreta dynamics, and environmental losses. It evaluates management strategies to improve nitrogen use efficiency while sustaining animal performance and environmental outcomes.

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