Journal of Animal Science, Vol 75, Issue 5 1393-1399, Copyright © 1997 by American Society of Animal Science

JOURNAL ARTICLE

Effect of increasing proportion of supplemental nitrogen from urea on intake and utilization of low-quality, tallgrass-prairie forage by beef steers

H. H. Koster, R. C. Cochran, E. C. Titgemeyer, E. S. Vanzant, T. G. Nagaraja, K. K. Kreikemeier and G. St Jean
Department of Animal Sciences and Industry, Kansas State University, Manhattan 66505-1600, USA.

Five Angus x Hereford steers with ruminal and duodenal fistulas were used in a 5 x 5 Latin square to determine effects of increasing the proportion of urea in supplemental degradable intake protein (DIP) on intake, fermentation, and digestion. Steers had ad libitum access to low-quality, tallgrass-prairie forage (2.4% CP, 76% NDF). Supplemental DIP (380 g/d) was from sodium caseinate and(or) urea and was balanced with cornstarch to provide a final supplement (approximately 939 g DM/d) that contained 40% CP. The percentages of supplemental DIP from urea were 0, 25, 50, 75, and 100%. Intake of forage OM was not affected (P > or = .30) by urea level. Ruminal and total tract digestibilities of OM and NDF generally responded in a quadratic manner (P < or = .09) to increasing urea, with the lowest values observed at the highest urea level. As a result, digestible OM intake (DOMI) declined (linear, P = .03) with increasing proportions of urea and tended (quadratic, P = .14) to exhibit the largest proportional decline at the highest urea level. The effects of increasing urea on duodenal N flow, microbial efficiency, ruminal contents, and fluid dilution rate were minimal. Ruminal ammonia N and molar percent acetate increased linearly (P < or = .02), whereas most other VFA (except propionate) decreased (P < or = .05) with increasing urea. In conclusion, although forage OM intake was not altered, OM digestion, NDF digestion, and DOMI were lowest when all supplemental DIP was supplied as urea. Changes in fermentation characteristics reflected the change in source of available nitrogen.

This article has been cited by other articles:

				M. J. Hersom Opportunities to enhance performance and efficiency through nutrient synchrony in forage-fed ruminants J Anim Sci, April 1, 2008; 86(14_suppl): E306 - E317. [Abstract] [Full Text] [PDF]

				T. C. Gilbery, G. P. Lardy, S. A. Soto-Navarro, M. L. Bauer, and J. S. Caton Effects of corn condensed distillers solubles supplementation on ruminal fermentation, digestion, and in situ disappearance in steers consuming low-quality hay J Anim Sci, June 1, 2006; 84(6): 1468 - 1480. [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]

				T. A. Currier, D. W. Bohnert, S. J. Falck, C. S. Schauer, and S. J. Bartle Daily and alternate-day supplementation of urea or biuret to ruminants consuming low-quality forage: II. Effects on site of digestion and microbial efficiency in steers J Anim Sci, May 1, 2004; 82(5): 1518 - 1527. [Abstract] [Full Text] [PDF]

				T. A. Currier, D. W. Bohnert, S. J. Falck, C. S. Schauer, and S. J. Bartle Daily and alternate-day supplementation of urea or biuret to ruminants consuming low-quality forage: III. Effects on ruminal fermentation characteristics in steers J Anim Sci, May 1, 2004; 82(5): 1528 - 1535. [Abstract] [Full Text] [PDF]

				C. G. Farmer, B. C. Woods, R. C. Cochran, J. S. Heldt, C. P. Mathis, K. C. Olson, E. C. Titgemeyer, and T. A. Wickersham Effect of supplementation frequency and supplemental urea level on dormant tallgrass-prairie hay intake and digestion by beef steers and prepartum performance of beef cows grazing dormant tallgrass-prairie J Anim Sci, March 1, 2004; 82(3): 884 - 894. [Abstract] [Full Text] [PDF]

				E. C. Titgemeyer, J. S. Drouillard, R. H. Greenwood, J. W. Ringler, D. J. Bindel, R. D. Hunter, and T. Nutsch Effect of forage quality on digestion and performance responses of cattle to supplementation with cooked molasses blocks J Anim Sci, February 1, 2004; 82(2): 487 - 494. [Abstract] [Full Text] [PDF]