AOAC. 1975. Official Methods of Analysis (12th Ed.). Association of Official Analysis Chemists, Washington, DC.
Chen, X. B., F. D. Deb, Hovell, E. R. Orskov and D. S. Brown 1990. Excretion of purine derivatives by ruminants: effect of exogenous nucleic acid supply on purine derivative excretion by sheep. Br. J. Nutr. 63:131-142.
Fujihara, T., E. R. Orskov, P. J. Reeds and D. J. Kyle. 1987. The effect of protein infusion on urinary excretion of purine derivatives in ruminants nourished by intragastric nutrition. J. Agric. Sci. (Camb). 107:12.
Goering, H. K. and P. J. VanSoest. 1970. Forage fiber analysis. In: Agriculture Handbook No. 379. Agriculture Research Services. Washington, DC. US.
Jones, G. A. and J. D. Milligan. 1975. Influence on some rumen and blood parameter of feeding acetohydroxamic acid in a urea-containing ration for lambs. Can. J. Anim. Sci. 55:39-47.
Khandaker, Z. H. and A. M. M. Tareque. 1997. Effect of rumen degradable protein in straw based ration on purine derivatives excretion and microbial nitrogen supply in cattle. Asian-Aus. J. Anim.Sci. 10: 364-370.
Ludden, P. A., D. L. Harmon, B. T. Larson and D. E. Axe. 2000a. Influence of the novel urease inhibitor N-(n-butyl) thiophosphoric triamide on ruminant nitrogen metabolism:ΙIn vitro urea kinetics and substrate digestion. J. Anim. Sci. 78:181-187.
Ludden, P. A., D. L. Harmon, B. T. Larson and D. E. Axe. 2000b. Influence of the novel urease inhibitor N-(n-butyl) thiophosphoric triamide on ruminant nitrogen metabolism:Ⅱ. Ruminal nitrogen metabolism, diet digestibility and nitrogen balance in lambs. J. Anim. Sci. 78:188-197.
Marsh, W. H., B. Fingerhut and H. Miller. 1965. Automated and manual direct methods for determination of blood urea. Clinical Chem. 11:624-627.
Moore, M. J., W. R. Woods and T. J. Kopfenstein. 1968. Nitrogen metabolism as influenced by acetohydroxamic acid. J. Anim. Sci. 27:1172-1173.
SAS. 1990. SAS/STAT User' Guide. Volume 2, Version 6, Fourth Edition. SAS Institute Inc., SAS Campus Drive, Cary, NC27513.
Satter, L. D. and L. L. Slyter. 1974. Effect of feeding urea supplemented and urea-treated wheat straw on rumen fermentation pattern and fiber digestibility in crossbred cattle. Indian J. Anim. Nutr. 7(2):107-112.
Streeter, C. L., R. R. Oltjen, L. L. Slyter and W. N. Fishbein. 1969. Urea utilization in wethers receiving the urease inhibitor acetohydroxamic acid. J. Anim. Sci. 29:88-93.
Topps, J. H. and R. C. Elliott. 1965. Relationship between concentrations of ruminal nucleic acids and excretion of purine derivatives by sheep. Nature 205:498-499.
Voigt, J., K. Krawielitzki and B. Piatkowski. 1980b. Studies on the effect of phosphoric phenly ester diamide as inhibitor of the rumen urease of dairy cows:2. The metabolism of 15Nurea. Arch.Tierernaehr. 30:825-834.
Voigt, J., K. Krawielitzki and B. Piatkowski. 1980c. Studies on the effect of phosphoric phenly ester diamide as inhibitor of the rumen urease of dairy cows: 3. Digestibility of the nutrients and bacterial protein synthesis. Arch. Tierernaehr. 30:835-840.
Voigt, J., K. Krawielitzki and B. Piatkowski. 1980a. Studies on the effect of phosphoric phenly ester diamide as inhibitor of the rumen urease of dairy cows: 1. Influence of urea hydrolysis ammonia release and fermentation in the rumen. Arch. Tierernaehr. 30:811-823.
Verbic, J., X. B. Chen, N. A. Macleod and E. R. Orskov. 1990. Excretion of purine derivatives by ruminants: effect of microbial nucleic acid infusion on purine derivative excretion by steers. J. Agric. Sci. Camb. 114:243-248.
Whitelaw, F. G., J. S. Milne and S. A. Wright. 1991. Urease inhibition in the sheep rumen and its effect on urea and nitrogen metabolism. Br. J. Nutr. 66:209-225.
Young, E. G. and C. F. Conway. 1942. On the estimation of allantoin by Rimini-Schryner reaction. J. Biol. Chem. 142:839-853.
Zhang, Y. G., A. S. Shan and J. Bao. 2001. Effect of hydroquinone on ruminal urease in the sheep and its inhibition kinetics in vitro. Asian-Aust. J. Anim. Sci. 14:1216-1220.