Submitted to: Meeting Proceedings
Publication Type: Proceedings
Publication Acceptance Date: November 1, 2010
Publication Date: November 11, 2010
Citation: Powell, J.M. 2010. Manure nitrogen excretion and transformation on dairy farms. In: Pereira, O. G., da Forseca, D.M., Obeid, J.A., do Nascimento, D. Jr., editors. Proceedings of the 5th Symposium on Strategic Management of Pasture and 3rd International Symposium on Animal Production Under Grazing, University of Vicosa, Brazil, November 11-13, 2010. pp. 273-292. Technical Abstract: Nitrogen (N) passes through a continuing cycle on dairy farms. On confinement farms, cows are fed conserved forages, grain, protein and mineral supplements, and manure is collected, stored and applied to cropland. Grazing-based dairy farms use intensive rotational grazing to provide fresh forage, generally use less diet supplements than confinement farms, and most manure is deposited directly onto pasture. Manure N recycling back into crops/pasture is highly influenced by the amount of urine N that has been conserved. This paper provides an overview of factors that impact N use efficiency (NUE) in dairy production with a focus on feed N use efficiency (percent of feed N consumption that is secreted into milk) and manure N use efficiency (percent of land-applied manure N that is recycled through crops/pasture). Methods to monitor and evaluate NUE on commercial dairy farm are also discussed.