Strategies to reduce N and P in animal diets
http://www.extension.umn.edu/agriculture/manure-management-and-air-quality/minimize-nutrient-losses-in-livestock-manure/
Effects of Diet and Feeding Management on Nutrient Content of Manure
http://www.nrcs.usda.gov/Internet/FSE_DOCUMENTS/stelprdb1044377.pdf
Animal Feeding Operations - Best Management Practices (BMPs)
http://www.epa.gov/agriculture/anafobmp.html