Hostname: page-component-5d59c44645-n6p7q Total loading time: 0 Render date: 2024-03-01T15:55:10.724Z Has data issue: false hasContentIssue false

Effect of ammonia concentration on rumen microbial protein production in vitro

Published online by Cambridge University Press:  24 July 2007

L. D Satter
Nutrition Institute, ARS, USDA, Beltsville, Maryland, USA
L. L Slyter
Nutrition Institute, ARS, USDA, Beltsville, Maryland, USA
Rights & Permissions [Opens in a new window]


Core share and HTML view are not available for this content. However, as you have access to this content, a full PDF is available via the ‘Save PDF’ action button.

1. The effect of ammonia concentration on microbial protein production was determined in continuous-culture fermentors charged with ruminal contents obtained from steers fed on either a protein-free purified diet, a maize-based all-concentrate diet, or a forage–concentrate (23:77) diet. Urea was infused into the fermentors to maintain various concentrations of ammonia in the incubating mixtures.

2. Under nitrogen-limiting conditions, microbial protein yield measured as tungstic acid-precipitable N (TAPN) increased linearly with supplementary urea until ammonia started to accumulate in the incubating ingesta. Increasing the ammonia concentration beyond 50 mg NH3-N/l had no effect on microbial protein production.

3. The molar proportions of volatile acids produced were not affected by the level of urea supplementation. Total acid production was decreased slightly under N-limiting conditions, but not to the same extent as microbial protein production.

4. Estimated yield of microbial dry matter/mol ATP produced averaged 15·6 when non-limiting N as urea was provided with the purified diet.

5. These results suggest that addition of non-protein N supplements to ruminant rations are warranted only if the prevailing concentration of ruminal ammonia is less than 50 mg NH3-N/l ruminal fluid.

General Nutrition
Copyright © The Nutrition Society 1974



Baldwin, R. L. (1970). Am. J. clin. Nutr. 23, 1508.Google Scholar
Baurngardt, B. R. (1964). Wis. agric. exp. Stn Dairy Dep. Bull. No. 1.Google Scholar
Bryant, M. P. & Robinson, I. M. (1962). J. Bact. 84, 605.Google Scholar
Campling, R. C., Freer, M. & Balch, C. C. (1962). Br. J. Nutr. 16, 115.Google Scholar
Church, D. C. (1969). Digestive Physiology and Nutrition of Ruminants Vol. 1. Corvallis, Oregon: O.S.U. Book Stores Inc.Google Scholar
Cocimano, M. R. & Leng, R. A. (1967). Br. J. Nutr. 21, 353.Google Scholar
Conway, E. J. (1950). Microdiffusion Analysis and Volumetric Error 2nd ed. London: Crosby and Lockwood.Google Scholar
Dehority, B. A., Johnson, R. R., Bentley, O. G. & Moxon, A. L. (1958). Archs Biochem. Biophys. 78, 15.Google Scholar
Draper, N. R. & Smith, H. (1966). Applied Regression Analysis Ch. 5. New York: John Wiley and Sons Inc.Google Scholar
Esdale, W. J., Broderick, G. A. & Satter, L. D. (1968). J. Dairy Sci. 51, 1823.Google Scholar
Henderson, C.Hobson, P. N. & Summers, R. (1969). In Continuous Cultivation of Microorganisms p. 189 [Malek, I, editor]. New York: Academic Press.Google Scholar
Hogan, J. P. & Weston, R. H. (1970). In Physiology of Digestion and Metabolism in the Ruminant p. 474 [Phillipson, A. T., editor] Newcastle upon Tyne: Oriel Press.Google Scholar
Hume, I. D., Moir, R. J. & Somers, M. (1970). Aust J. agric. Res. 21, 283.Google Scholar
Hungate, R. E. (1965). In Physiology of Digestion in the Ruminant p. 314 [Dougherty, R. W., editor]. Washington, DC: Butterworts.Google Scholar
Hungate, R. E. (1966). The Rumen and Its Microbes Ch. 7. New York: Academic Press.Google Scholar
Oltjen, R. R., Slyter, L. L., Williams, E. E. jr & Kern, D. L. (1971). J. Nutr. 101, 101.Google Scholar
Ørskov, E. R., Fraser, C. & McDonald, I (1971). Br. J. Nutr. 25, 243.Google Scholar
Ørskov, E. R., Fraser, C. & McDonald, I. (1972). Br. J. Nutr. 27, 491.Google Scholar
Shultz, T. A. & Shultz, E. (1970). J. Dairy Sci. 53, 781.Google Scholar
Slyter, L. L., Kern, D. L., Weaver, J. M., Oltjen, R. R. & Wilson, R. L. (1971). J. Nutr. 101, 847.Google Scholar
Slyter, L. L., Nelson, W. O. & Wolin, M. J. (1964). Appl. Microbiol. 12, 374.Google Scholar
Slyter, L. L., Oltjen, R. R., Kern, D. L. & Weaver, J. M. (1968). J. Nutr. 94, 185.Google Scholar
Slyter, L. L. & Putnam, P. A. (1967). J. Anim. Sci. 26, 1421.Google Scholar
Walker, D. J. (1965). In Physiology of Digestion in the Ruminant Ch. 6 [Dougherty, R. W., editor]. Washington, DC: Buttenvorths.Google Scholar
Walker, D. J. & Nader, C. J. (1968). Appl. Microbiol. 16, 1124.Google Scholar
Weston, R. H. (1967). Aust. J. agric. Res. 18, 983.Google Scholar
Winter, K. A. & Pigden, W. J. (1971). Can. J. Anim. Sci. 51, 777.Google Scholar