|Powell, J Mark|
Submitted to: Cornell Nutrition Conference for Feed Manufacturers
Publication Type: Proceedings
Publication Acceptance Date: September 15, 2009
Publication Date: October 20, 2010
Citation: Powell, J.M., Broderick, G.A. 2009. Ammonia Emissions From Dairy Barns: What Have We Learned? Proceedings of Cornell Nutrition Conference for Feed Manufacturers. p 210-219. Technical Abstract: Research, extension, the feed industry and veterinarians have long advocated dairy cow diets that maximize milk production while assuring good animal health and reproduction. Under practical conditions, only 20 to 30% of the crude protein (CP) fed to a dairy cow is converted into milk protein. The remaining feed nitrogen (N) is excreted about equally in urine and feces, although this can be highly influenced by diet. Three-fourths or more of the N in urine can be in the form of urea, which can be converted into ammonia gas and lost to the atmosphere. Loss of N as ammonia is thought to range from 20 to 55% of total N excreted in manure. The increased size and geographic concentration of animal feeding operations makes ammonia emissions of greater than 45.5 kg of ammonia over a 24-h period subject to notification provisions under The Comprehensive Environmental Response, Compensation and Liability Act. We examine impact of dairy cow diets on milk production, feed N use efficiency (proportion of feed N transformed into milk), urine N excretions and ammonia N emissions from dairy barns. We compare the results of various scale methods to estimate ammonia emissions from dairy barns, as well as recent field study results that revealed dairy cattle management impacts on ammonia emission, manure N capture and recycling through crops. We conclude with a synopsis of management practices that enhance feed N use efficiency, reduce urine N excretions and ammonia loss from dairy barns.