Using Milk Urea Nitrogen to Predict Nitrogen Excretion and Utilization Efficiency in Lactating Dairy Cows

¹ Department of Animal and Avian Sciences, University of Maryland, College Park 20742

Because animal agriculture has been identified as a major source of nonpoint N pollution, ways to reduce the excretion of N by production animals must be examined. The objective of this research was to develop and evaluate a mathematical model that integrates milk urea N to predict excretion, intake, and utilization efficiency of N in lactating dairy cows. Three separate digestibility and N balance studies (10 diets, 40 cows, and 70 observations) were used to develop the model, and 19 independent studies (93 diets) were used for evaluation. The driving variables for the model were milk urea N (milligrams per deciliter), milk production (kilograms per day), milk protein (percentage), and dietary crude protein (percentage). For the developmental data set, the model accurately predicted N excretion and efficiency with no significant mean or linear bias for most predictions. Residual analysis revealed that a majority of the unexplained model error was associated with variation among cows. For the independent data set, model prediction error was approximately 15% of mean predictions. A mean of at least 10 cows was determined to be appropriate for model predictions. Target milk urea N concentrations were determined from expected urinary N excretion for cows that were fed according to National Research Council recommendations. Target values calculated in this manner were 10 to 16 mg/dl, depending on milk production. Milk urea N is a simple and noninvasive measurement that can be used to monitor N excretion from lactating dairy cows.

Key Words: milk urea nitrogen • nitrogen excretion • modeling

Submitted on October 27, 1997
Accepted on May 25, 1998

This article has been cited by other articles:

				M. Hollmann, K. F. Knowlton, and M. D. Hanigan Evaluation of Solids, Nitrogen, and Phosphorus Excretion Models for Lactating Dairy Cows J Dairy Sci, March 1, 2008; 91(3): 1245 - 1257. [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]

				J. M. Powell, G. A. Broderick, and T. H. Misselbrook Seasonal Diet Affects Ammonia Emissions from Tie-Stall Dairy Barns J Dairy Sci, February 1, 2008; 91(2): 857 - 869. [Abstract] [Full Text] [PDF]

				S. A. Burgos, J. G. Fadel, and E. J. DePeters Prediction of Ammonia Emission from Dairy Cattle Manure Based on Milk Urea Nitrogen: Relation of Milk Urea Nitrogen to Urine Urea Nitrogen Excretion J Dairy Sci, December 1, 2007; 90(12): 5499 - 5508. [Abstract] [Full Text] [PDF]

				L. M. Johnson-VanWieringen, J. H. Harrison, D. Davidson, M. L. Swift, M. A. G. von Keyserlingk, M. Vazquez-Anon, D. Wright, and W. Chalupa Effects of Rumen-Undegradable Protein Sources and Supplemental 2-Hydroxy-4-(Methylthio)-Butanoic Acid and Lysine{middle dot}HCl on Lactation Performance in Dairy Cows J Dairy Sci, November 1, 2007; 90(11): 5176 - 5188. [Abstract] [Full Text] [PDF]

				F. Miglior, A. Sewalem, J. Jamrozik, J. Bohmanova, D. M. Lefebvre, and R. K. Moore Genetic Analysis of Milk Urea Nitrogen and Lactose and Their Relationships with Other Production Traits in Canadian Holstein Cattle J Dairy Sci, May 1, 2007; 90(5): 2468 - 2479. [Abstract] [Full Text] [PDF]

				W. M. Stoop, H. Bovenhuis, and J. A. M. van Arendonk Genetic Parameters for Milk Urea Nitrogen in Relation to Milk Production Traits J Dairy Sci, April 1, 2007; 90(4): 1981 - 1986. [Abstract] [Full Text] [PDF]

				F. Miglior, A. Sewalem, J. Jamrozik, D. M. Lefebvre, and R. K. Moore Analysis of Milk Urea Nitrogen and Lactose and Their Effect on Longevity in Canadian Dairy Cattle J Dairy Sci, December 1, 2006; 89(12): 4886 - 4894. [Abstract] [Full Text] [PDF]

				V. E. Cabrera, A. de Vries, and P. E. Hildebrand Prediction of Nitrogen Excretion in Dairy Farms Located in North Florida: A Comparison of Three Models J Dairy Sci, May 1, 2006; 89(5): 1830 - 1841. [Abstract] [Full Text] [PDF]

				K. F. Kalscheur, R. L. Baldwin VI, B. P. Glenn, and R. A. Kohn Milk Production of Dairy Cows Fed Differing Concentrations of Rumen-Degraded Protein J Dairy Sci, January 1, 2006; 89(1): 249 - 259. [Abstract] [Full Text] [PDF]

				T. D. Nennich, J. H. Harrison, L. M. VanWieringen, N. R. St-Pierre, R. L. Kincaid, M. A. Wattiaux, D. L. Davidson, and E. Block Prediction and Evaluation of Urine and Urinary Nitrogen and Mineral Excretion from Dairy Cattle J Dairy Sci, January 1, 2006; 89(1): 353 - 364. [Abstract] [Full Text] [PDF]

				R. G. Mitchell, G. W. Rogers, C. D. Dechow, J. E. Vallimont, J. B. Cooper, U. Sander-Nielsen, and J. S. Clay Milk Urea Nitrogen Concentration: Heritability and Genetic Correlations with Reproductive Performance and Disease J Dairy Sci, December 1, 2005; 88(12): 4434 - 4440. [Abstract] [Full Text] [PDF]

				S. K. Tallam, A. D. Ealy, K. A. Bryan, and Z. Wu Ovarian Activity and Reproductive Performance of Dairy Cows Fed Different Amounts of Phosphorus J Dairy Sci, October 1, 2005; 88(10): 3609 - 3618. [Abstract] [Full Text] [PDF]

				E. B. Groff and Z. Wu Milk Production and Nitrogen Excretion of Dairy Cows Fed Different Amounts of Protein and Varying Proportions of Alfalfa and Corn Silage J Dairy Sci, October 1, 2005; 88(10): 3619 - 3632. [Abstract] [Full Text] [PDF]

				J. C. Velez and S. S. Donkin Feed Restriction Induces Pyruvate Carboxylase but not Phosphoenolpyruvate Carboxykinase in Dairy Cows J Dairy Sci, August 1, 2005; 88(8): 2938 - 2948. [Abstract] [Full Text] [PDF]

				N. R. St-Pierre and J. T. Sylvester Effects of 2-Hydroxy-4-(Methylthio) Butanoic Acid (HMB) and Its Isopropyl Ester on Milk Production and Composition by Holstein Cows J Dairy Sci, July 1, 2005; 88(7): 2487 - 2497. [Abstract] [Full Text] [PDF]

				R. A. Kohn, M. M. Dinneen, and E. Russek-Cohen Using blood urea nitrogen to predict nitrogen excretion and efficiency of nitrogen utilization in cattle, sheep, goats, horses, pigs, and rats J Anim Sci, April 1, 2005; 83(4): 879 - 889. [Abstract] [Full Text] [PDF]

				D. Hojman, M. Gips, and E. Ezra Association Between Live Body Weight and Milk Urea Concentration in Holstein Cows J Dairy Sci, February 1, 2005; 88(2): 580 - 584. [Abstract] [Full Text] [PDF]

				M. A. Wattiaux and K. L. Karg Protein Level for Alfalfa and Corn Silage-Based Diets: I. Lactational Response and Milk Urea Nitrogen J Dairy Sci, October 1, 2004; 87(10): 3480 - 3491. [Abstract] [Full Text] [PDF]

				K. M. Burkholder, A. D. Guyton, J. M. McKinney, and K. F. Knowlton The Effect of Steam Flaked or Dry Ground Corn and Supplemental Phytic Acid on Nitrogen Partitioning in Lactating Cows and Ammonia Emission from Manure J Dairy Sci, August 1, 2004; 87(8): 2546 - 2553. [Abstract] [Full Text] [PDF]

				A. B. Peterson, K. R. French, E. Russek-Cohen, and R. A. Kohn Comparison of Analytical Methods and the Influence of Milk Components on Milk Urea Nitrogen Recovery J Dairy Sci, June 1, 2004; 87(6): 1747 - 1750. [Abstract] [Full Text] [PDF]

				R. A. Kohn, K. R. French, and E. Russek-Cohen A Comparison of Instruments and Laboratories Used to Measure Milk Urea Nitrogen in Bulk-Tank Milk Samples J Dairy Sci, June 1, 2004; 87(6): 1848 - 1853. [Abstract] [Full Text] [PDF]

				K. Guo, E. Russek-Cohen, M. A.Varner, and R. A. Kohn Effects of Milk Urea Nitrogen and Other Factors on Probability of Conception of Dairy Cows J Dairy Sci, June 1, 2004; 87(6): 1878 - 1885. [Abstract] [Full Text] [PDF]

				E. E. Salado, G. A. Gagliostro, D. Becu-Villalobos, and I. Lacau-Mengido Partial Replacement of Corn Grain by Hydrogenated Oil in Grazing Dairy Cows in Early Lactation J Dairy Sci, May 1, 2004; 87(5): 1265 - 1278. [Abstract] [Full Text] [PDF]

				J. Nousiainen, K. J. Shingfield, and P. Huhtanen Evaluation of Milk Urea Nitrogen as a Diagnostic of Protein Feeding J Dairy Sci, February 1, 2004; 87(2): 386 - 398. [Abstract] [Full Text] [PDF]

				D. J. R. Cherney, J. H. Cherney, and L. E. Chase Influence of Dietary Nonfiber Carbohydrate Concentration and Supplementation of Sucrose on Lactation Performance of Cows Fed Fescue Silage J Dairy Sci, December 1, 2003; 86(12): 3983 - 3991. [Abstract] [Full Text] [PDF]

				R. G. Johnson and A. J. Young The Association Between Milk Urea Nitrogen and DHI Production Variables in Western Commercial Dairy Herds J Dairy Sci, September 1, 2003; 86(9): 3008 - 3015. [Abstract] [Full Text] [PDF]

				A. N. Hristov and J. K. Ropp Effect of Dietary Carbohydrate Composition and Availability on Utilization of Ruminal Ammonia Nitrogen for Milk Protein Synthesis in Dairy Cows J Dairy Sci, July 1, 2003; 86(7): 2416 - 2427. [Abstract] [Full Text] [PDF]

				G. M. Wood, P. J. Boettcher, J. Jamrozik, G. B. Jansen, and D. F. Kelton Estimation of Genetic Parameters for Concentrations of Milk Urea Nitrogen J Dairy Sci, July 1, 2003; 86(7): 2462 - 2469. [Abstract] [Full Text] [PDF]

				S. Davidson, B. A. Hopkins, D. E. Diaz, S. M. Bolt, C. Brownie, V. Fellner, and L. W. Whitlow Effects of Amounts and Degradability of Dietary Protein on Lactation, Nitrogen Utilization, and Excretion in Early Lactation Holstein Cows J Dairy Sci, May 1, 2003; 86(5): 1681 - 1689. [Abstract] [Full Text] [PDF]

				G. A. Broderick Effects of Varying Dietary Protein and Energy Levels on the Production of Lactating Dairy Cows J Dairy Sci, April 1, 2003; 86(4): 1370 - 1381. [Abstract] [Full Text] [PDF]

				S. Godden, R. Bey, J. Reneau, R. Farnsworth, and M. LaValle Field Validation of a Milk-line Sampling Device for Monitoring Milk Component Data J Dairy Sci, September 1, 2002; 85(9): 2192 - 2196. [Abstract] [Full Text] [PDF]

				B. Stefanon, V. Volpe, S. Moscardini, and L. Gruber Using Artificial Neural Networks to Model the Urinary Excretion of Total and Purine Derivative Nitrogen Fractions in Cows J. Nutr., December 1, 2001; 131(12): 3307 - 3315. [Abstract] [Full Text] [PDF]