IMPROVING THE EFFICIENCY OF DIETARY NITROGEN UTILIZATION IN DAIRY COWS & HEIFERS & REDUCING AMMONIA EMISSIONS

Nitrogen (N) contamination of ground and surface water and air pollution caused by leaching, runoff, and gaseous N emissions from animal feeding operations (AFO) are currently the most important environmental concerns related to animal agriculture. Following recent EPA regulation on ammonia emissions from livestock operation, it becomes increasingly important for the dairy producers to reduce whole-farm N emissions and manage its operation in an environmentally-responsible manner. There is sufficient evidence that low-N feeding and management practices are the most effective method for reducing N and ammonia emissions from AFO. The impact of these practices is multidirectional, including: (1) potential cost savings to the producer (improved income over feed cost); (2) drastic reduction in N imports and surplus on a whole-farm scale and gaseous N emissions from the dairy; and (3) potential beneficial effect on reproductive performance. Therefore, the overall objective of this project is to demonstrate that dairy cows and heifers can be managed on low-crude protein diets without affecting productivity or animal health. This strategy will result in a significant reduction in whole-farm N imports, N losses and ammonia volatilization from manure, and will increase farm profitability though increased income-over-feed cost. This project proposes larger-scale controlled experiments that will add valuable information on the possibility to compensate limiting amino acids deficiency and maintain production in protein-deficient diets fed to high-producing lactating cows. The project will also generate invaluable information on the possibility to reduce N losses and ammonia emissions from dairy manure by decreasing dietary protein concentration.