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Much of the effort expended on nutrient management has focused on the post-excretion product. It is important to keep in mind that management of the diet can have important impacts on quantitative and qualitative aspects of the excreted nutrients. Surveys of nutritionists and extension specialists show that dairy producers are advised to feed 0.45 to 0.50% phosphorus (P) (DM basis) in their lactating cow diets. This is 20% in excess of NRC (2001) requirements. Feeding to requirement would reduce P excretion by 25 to 30% and would reduce solubility and potential for runoff of the P that is applied to fields. Nitrogen (N) excretion by dairy cows can also be decreased, but by a lesser amount. Balancing ruminally undegraded and degraded protein and use of protected methionine along with strategic selection of protein supplements that are relatively rich in lysine, may permit a 10 to 15% reduction in total N …