"This project will develop a simple diagnostic tool to assess the efficiency of conversion of feed protein into milk and meat protein by ruminants (N-use efficiency; NUE). It addresses the central issue of the relationship between valuable product (milk and meat protein) and waste (urine N, potential pollutant). It is pivotal to European objectives about increasing the supply of healthy, whilst also reducing the environmental effects of ruminant agriculture. The approach is based on measuring the differential fractionation of the stable isotopes of N (Nitrogen-14 and Nitrogen-15) in the metabolic pathways leading to milk or meat protein and urinary Nitrogen respectively. The tool will be used at the large-scale across a range of disciplines that are addressing these problems, including animal nutrition and both plant and animal genetics/genomics – contributing to future multi-disciplinary working. Initial work will develop understanding of dietary factors affecting N fractionation using controlled feeding studies with sheep. Treatments will be designed to alter independently a range of N metabolism pathways (protein degradability, microbial protein synthesis, urea recycling, hepatic ureagenesis and hepatic protein synthesis). We will then apply information about fractionation effects in the different pathways to develop a sampling and analysis protocol to relate isotope measurements to NUE in lactating cows, and ultimately free-grazing cows. The ideal outcome will be a test based solely on milk analysis, since this is easily collected. The project will support recruitment of technicians and postgraduates for the new Animal Bioscience Centre. It will promote the integration of the applicant into EU science through securing the future of the new research centre. I will assist in developing collaborations and student exchanges with centres in Europe, as well as extending useful academic and industry contacts with the New Zealand."