Improving Nitrogen Utilization in Dairy Cows

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Dairy farming has to be profitable and yet sensitive to environmental concerns. Protein is the most expensive component of dairy rations and excess supply contributes to ground, water and air pollution. Therefore, decreasing both costs and pollution can be achieved through a lower input of dietary protein if feeds were better balanced to provide the required individual amino acids (AA: the building blocks of proteins). Within this overall framework, we are currently studying how AA interact with energetic nutrients, with a focus on glucose, in order to delineate the energy conditions needed to reduce protein supply without any detrimental effect on milk production. Indeed often cows make more milk and milk lactose (which contains glucose) when supplied with protein rather than glucose. Why this happens and whether other nutrients, cheaper or with less impact on environment, can substitute for this role needs to be investigated. The current research program proposes to use state-of-the-art methodology using multi-catheterized cows and glucose labeled with stable isotopes (occurring naturally in the body) to follow how the various tissues use nutrients in response to altered protein and/or energy supply. Our research program aims to develop fundamental knowledge on utilization of nutrients by the gut, the liver and the mammary gland, the major tissues using AA and energy. This unique knowledge will then be integrated into existing programs used by dairy nutritionists and Canadians farmers to balance dairy rations in order to maximize outputs at optimal efficiency. In addition to complementing our knowledge on AA and glucose metabolism, these results can be rapidly transferred to the dairy industry and have an immediate impact on farm practice, with benefits to both the environment and farm economics in Canada.