HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Kohn, R. A. Articles by Russek-Cohen, E. Search for Related Content PubMed PubMed Citation Articles by Kohn, R. A. Articles by Russek-Cohen, E.

Using blood urea nitrogen to predict nitrogen excretion and efficiency of nitrogen utilization in cattle, sheep, goats, horses, pigs, and rats¹

Department of Animal and Avian Sciences, University of Maryland, College Park 20742

² Correspondence: Animal Sciences Building, #142 (phone: 301-405-4583; fax: 301-314-9059; e-mail: rkohn{at}umd.edu).

The objectives of this study were to evaluate the potential for using blood urea N concentration to predict urinary N excretion rate, and to develop a mathematical model to estimate important variables of N utilization for several different species of farm animals and for rats. Treatment means (n = 251) from 41 research publications were used to develop mathematical relationships. There was a strong linear relationship between blood urea N concentration (mg/100 mL) and rate of N excretion (g•d^–1•kg BW^–1) for all animal species investigated. The N clearance rate of the kidney (L of blood cleared of urea•d^–1•kg BW^–1) was greater for pigs and rats than for herbivores (cattle, sheep, goats, horses). A model was developed to estimate parameters of N utilization. Driving variables for the model included blood urea N concentration (mg/100 mL), BW (kg), milk production rate (kg/d), and ADG (kg/d), and response variables included urinary N excretion rate (g/d), fecal N excretion rate (g/d), rate of N intake (g/d), and N utilization efficiency (N in milk and gain per unit of N intake). Prediction errors varied widely depending on the variable and species of animal, with most of the variation attributed to study differences. Blood urea N concentration (mg/100 mL) can be used to predict relative differences in urinary N excretion rate (g/d) for animals of a similar type and stage of production within a study, but is less reliable across animal types or studies. Blood urea N concentration (mg/100 mL) can be further integrated with estimates of N digestibility (g/g) and N retention (g/d) to predict fecal N (g/d), N intake (g/d), and N utilization efficiency (grams of N in milk and meat per gram of N intake). Target values of blood urea N concentration (mg/100 mL) can be backcalculated from required dietary N (g/d) and expected protein digestibility. Blood urea N can be used in various animal species to quantify N utilization and excretion rates.

Key Words: Blood Urea Nitrogen • Nitrogen Excretion • Nitrogen Utilization Efficiency

This article has been cited by other articles:

				C. Mikolayunas-Sandrock, L. E. Armentano, D. L. Thomas, and Y. M. Berger Effect of protein degradability on milk production of dairy ewes J Dairy Sci, September 1, 2009; 92(9): 4507 - 4513. [Abstract] [Full Text] [PDF]

				G. I. Zanton and A. J. Heinrichs Digestion and nitrogen utilization in dairy heifers limit-fed a low or high forage ration at four levels of nitrogen intake J Dairy Sci, May 1, 2009; 92(5): 2078 - 2094. [Abstract] [Full Text] [PDF]

				P. J. Lammers, B. J. Kerr, T. E. Weber, K. Bregendahl, S. M. Lonergan, K. J. Prusa, D. U. Ahn, W. C. Stoffregen, W. A. Dozier III, and M. S. Honeyman Growth performance, carcass characteristics, meat quality, and tissue histology of growing pigs fed crude glycerin-supplemented diets J Anim Sci, November 1, 2008; 86(11): 2962 - 2970. [Abstract] [Full Text] [PDF]

				J. C. Marini, D. G. Fox, and M. R. Murphy Nitrogen transactions along the gastrointestinal tract of cattle: A meta-analytical approach J Anim Sci, March 1, 2008; 86(3): 660 - 679. [Abstract] [Full Text] [PDF]

				D. M. Butler, N. N. Ranells, D. H. Franklin, M. H. Poore, and J. T. Green Jr. Ground Cover Impacts on Nitrogen Export from Manured Riparian Pasture J. Environ. Qual., January 9, 2007; 36(1): 155 - 162. [Abstract] [Full Text] [PDF]

				D. M. Butler, D. H. Franklin, N. N. Ranells, M. H. Poore, and J. T. Green Jr. Ground Cover Impacts on Sediment and Phosphorus Export from Manured Riparian Pasture J. Environ. Qual., October 27, 2006; 35(6): 2178 - 2185. [Abstract] [Full Text] [PDF]

				X. Hao, P. S. Mir, M. A. Shah, and G. R. Travis Influence of Canola and Sunflower Diet Amendments on Cattle Feedlot Manure J. Environ. Qual., July 5, 2005; 34(4): 1439 - 1445. [Abstract] [Full Text] [PDF]