Abdoun, K, Stumpff, F and Martens, H 2006. Ammonia and urea transport across the rumen epithelium: a review. Animal Health Research Reviews 7, 43–59.
Association of Official Analytical Chemists 1990. Official methods of analysis, 15th edition. AOAC, Washington, DC, USA.
Bourg, BM, Tedeschi, LO, Wickersham, TA and Tricarico, JM 2012. Effects of a slow-release urea product on performance, carcass characteristics, and nitrogen balance of steers fed steam-flaked corn. Journal of Animal Science 90, 3914–3923.
Broderick, GA and Kang, JH 1980. Automated simultaneous determination of ammonia and total amino acids in ruminal fluid and in vitro media. Journal of Dairy Science 63, 64–75.
Calomeni, GD, Gardinal, R, Venturelli, BC, de Freitas Júnior, JE, Vendramini, THA, Takiya, CS, de Souza, HN and Rennó, FP 2015. Effects of polymer-coated slow-release urea on performance, ruminal fermentation, and blood metabolites in dairy cows. Revista Brasileira de Zootecnia 44, 327–334.
Cass, J 1994. Urea: calcium compounds as a supplement source of N and Ca for ruminants. MSc thesis, Texas Tech University, TX, USA.
Cherdthong, A and Wanapat, M 2010. Development of urea products as rumen slow-release feed for ruminant production: a review. Australian Journal of Basic and Applied Sciences 4, 2232–2241.
Cherdthong, A and Wanapat, M 2013. Rumen microbes and microbial protein synthesis in Thai native beef cattle fed with feed blocks supplemented with a urea–calcium sulphate mixture. Archives of Animal Nutrition 67, 448–460.
Cherdthong, A, Wanapat, M and Wachirapakorn, C 2011. Effects of urea–calcium mixture in concentrate containing high cassava chip on feed intake, rumen fermentation and performance of lactating dairy cows fed on rice straw. Livestock Science 136, 76–84.
Dehority, BA 2003. Rumen microbiology. Nottingham University Press, Nottingham, UK.
Denman, SE and McSweeney, CS 2005. Quantitative (real-time) PCR. In Methods in gut microbial ecology for ruminants (ed. Makkar, HPS and McSweeney, CS), pp. 105–115. Springer-Verlag, Berlin/Heidelberg, Germany.
Firkins, JL, Yu, Z and Morrison, M 2007. Ruminal nitrogen metabolism: perspectives for integration of microbiology and nutrition for dairy. Journal of Dairy Science 90 (suppl. 1), E1–E16.
Galina, M, Guerrero, M, Puga, C and Haenlein, GF 2004. Effect of a slow-intake urea supplementation on growing kids fed corn stubble or alfalfa with a balanced concentrate. Small Ruminant Research 53, 29–38.
Galo, E, Emanuele, SM, Sniffen, CJ, White, JH and Knapp, JR 2003. Effects of a polymer-coated urea product on nitrogen metabolism in lactating Holstein dairy cattle. Journal of Dairy Science 86, 2154–2162.
Gardinal, R, Calomeni, GD, Cônsolo, NRB, Takiya, CS, Freitas, JE, Gandra, JR, Vendramini, THA, Souza, HN and Rennó, FP 2017. Influence of polymer-coated slow-release urea on total tract apparent digestibility, ruminal fermentation and performance of Nellore steers. Asian-Australasian Journal of Animal Sciences 30, 34–41.
Golombeski, GL, Kalscheur, KF, Hippen, AR and Schingoethe, DJ 2006. Slow-release urea and highly fermentable sugars in diets fed to lactating dairy cows. Journal of Dairy Science 89, 4395–4403.
Highstreet, A, Robinson, PH, Robison, J and Garrett, JG 2010. Response of Holstein cows to replacing urea with a slowly rumen released urea in a diet high in soluble crude protein. Livestock Science 129, 179–185.
Kertz, AF 2010. Review: urea feeding to dairy cattle: a historical perspective and review. The Professional Animal Scientist 26, 257–272.
Koike, S and Kobayashi, Y 2001. Development and use of competitive PCR assays for the rumen cellulolytic bacteria: fibrobacter succinogenes, Ruminococcus albus and Ruminococcus flavefaciens. FEMS Microbiology Letters 204, 361–366.
Livak, KJ and Schmittgen, TD 2001. Analysis of relative gene expression data using real-time quantitative PCR and the 2−ΔΔCT method. Methods 25, 402–408.
Mahmoudi-Abyane, M, Alipour, D and Moghimi, HR 2017. Effect of using different sources of nitrogen on digestibility and nitrogen balance in Mehraban male lambs. Animal Production Research 6, 27–38.
Mirzaei-Alamouti, H, Moradi, S, Shahalizadeh, Z, Razavian, M, Amanlou, H, Harkinezhad, T, Jafari-Anarkooli, I, Deiner, C and Aschenbach, JR 2016. Both monensin and plant extract alter ruminal fermentation in sheep but only monensin affects the expression of genes involved in acid-base transport of the ruminal epithelium. Animal Feed Science and Technology 219, 132–143.
Nocek, JE and Russell, JB 1988. Protein and energy as an integrated system. Relationship of ruminal protein and carbohydrate availability to microbial synthesis and milk production. Journal of Dairy Science 71, 2070–2107.
National Research Council 2007. Nutrient requirements of small ruminants: sheep, goats, cervids, and new world camelids. National Academies Press, Washington, DC, USA.
Pfaffl, MW 2001. A new mathematical model for relative quantification in real-time RT-PCR. Nucleic Acids Research 29, e45.
Pinos-Rodríguez, JM, Peña, LY, González-Muñoz, SS, Bárcena, R and Salem, A 2010. Effects of a slow-release coated urea product on growth performance and ruminal fermentation in beef steers. Italian Journal of Animal Science 9, e4.
Puga, DC, Galina, HM, Peréz-Gil, RF, Sangines, GL, Aguilera, BA, Haenlein, GFW, Barajas, CR and Herrera, HJG 2001. Effect of a controlled-release urea supplementation on feed intake, digestibility, nitrogen balance and ruminal kinetics of sheep fed low quality tropical forage. Small Ruminant Research: The Journal of the International Goat Association 41, 9–18.
Ribeiro, SS, Vasconcelos, JT, Morais, MG, Ítavo, CBCF and Franco, GL 2011. Effects of ruminal infusion of a slow-release polymer-coated urea or conventional urea on apparent nutrient digestibility, in situ degradability, and rumen parameters in cattle fed low-quality hay. Animal Feed Science and Technology 164, 53–61.
Russell, JB 2002. Rumen microbiology and its role in ruminant nutrition. Department of Microbiology, Cornell University, New York, NY, USA.
Russell, JB, Muck, RE and Weimer, PJ 2009. Quantitative analysis of cellulose degradation and growth of cellulolytic bacteria in the rumen. FEMS Microbiology Ecology 67, 183–197.
Sinclair, LA, Blake, CW, Griffin, P and Jones, GH 2012. The partial replacement of soyabean meal and rapeseed meal with feed grade urea or a slow-release urea and its effect on the performance, metabolism and digestibility in dairy cows. Animal 6, 920–927.
Van Soest, PJ 1994. Nutritional ecology of the ruminant. Cornell University Press, Ithaca, NY, USA.
Van Soest, PJ, Robertson, JB and Lewis, BA 1991. Methods for dietary fiber, neutral detergent fiber, and nonstarch polysaccharides in relation to animal nutrition. Journal of Dairy Science 74, 3583–3597.
Sylvester, JT, Karnati, SKR, Yu, Z, Morrison, M and Firkins, JL 2004. Development of an assay to quantify rumen ciliate protozoal biomass in cows using real-time PCR. The Journal of Nutrition 134, 3378–3384.
Taylor-Edwards, CC, Hibbard, G, Kitts, SE, McLeod, KR, Axe, DE, Vanzant, ES, Kristensen, NB and Harmon, DL 2009. Effects of slow-release urea on ruminal digesta characteristics and growth performance in beef steers. Journal of Animal Science 87, 200–208.
Xin, HS, Schaefer, DM, Liu, QP, Axe, DE and Meng, QX 2010. Effects of polyurethane coated urea supplement on in vitro ruminal fermentation, ammonia release dynamics and lactating performance of Holstein dairy cows fed a steam-flaked corn-based diet. Asian-Australasian Journal of Animal Sciences 23, 491–500.