Nitrogen use efficiency (NUE) is a growing focus in dairy farming, as it directly impacts environmental sustainability, farm economics, and overall herd health. This study analyzed 278 Holstein-Friesian grazing dairy cows, evaluating how their NUE (nitrogen used and stored divided by nitrogen available) and nitrogen balance (Nbal; nitrogen available minus nitrogen used and stored) influence nitrogen waste and animal well-being.
Researchers categorized cows into four groups based on their NUE and Nbal levels. While cows with high NUE and low Nbal were considered the most desirable—excreting 53 grams less nitrogen daily—they also showed signs of being in greater negative energy balance and had lower body condition scores (BCS). This suggests potential trade-offs in fertility and overall health.
The study confirms that while high NUE is linked to lower nitrogen excretion, the relationship isn’t perfect. Factors like diet composition, metabolic demands, and individual cow variability all play a role. Since excess nitrogen contributes to environmental issues like nitrate leaching and greenhouse gas emissions, optimizing both NUE and Nbal is crucial for more sustainable dairy production.
By understanding these dynamics, dairy farmers can better manage feed efficiency, reduce nitrogen losses, and improve both economic and environmental outcomes.
