Skip to main content Accessibility help
×
Home

Strategies for optimizing nitrogen use by ruminants

  • S. Calsamiglia (a1), A. Ferret (a1), C. K. Reynolds (a2), N. B. Kristensen (a3) and A. M. van Vuuren (a4)...

Abstract

The efficiency of N utilization in ruminants is typically low (around 25%) and highly variable (10% to 40%) compared with the higher efficiency of other production animals. The low efficiency has implications for the production performance and environment. Many efforts have been devoted to improving the efficiency of N utilization in ruminants, and while major improvements in our understanding of N requirements and metabolism have been achieved, the overall efficiency remains low. In general, maximal efficiency of N utilization will only occur at the expense of some losses in production performance. However, optimal production and N utilization may be achieved through the understanding of the key mechanisms involved in the control of N metabolism. Key factors in the rumen include the efficiency of N capture in the rumen (grams of bacterial N per grams of rumen available N) and the modification of protein degradation. Traditionally, protein degradation has been modulated by modifying the feed (physical and chemical treatments). Modifying the rumen microflora involved in peptide degradation and amino acid deamination offers an alternative approach that needs to be addressed. Current evidence indicates that in typical feeding conditions there is limited net recycling of N into the rumen (blood urea-N uptake minus ammonia-N absorption), but understanding the factors controlling urea transport across the rumen wall may reverse the balance to take advantage of the recycling capabilities of ruminants. Finally, there is considerable metabolism of amino acids (AA) in the portal-drained viscera (PDV) and liver. However, most of this process occurs through the uptake of AA from the arterial blood and not during the ‘absorptive’ process. Therefore, AA are available to the peripheral circulation and to the mammary gland before being used by PDV and the liver. In these conditions, the mammary gland plays a key role in determining the efficiency of N utilization because the PDV and liver will use AA in excess of those required by the mammary gland. Protein synthesis in the mammary gland appears to be tightly regulated by local and systemic signals. The understanding of factors regulating AA supply and absorption in the mammary gland, and the synthesis of milk protein should allow the formulation of diets that increase total AA uptake by the mammary gland and thus reduce AA utilization by PDV and the liver. A better understanding of these key processes should allow the development of strategies to improve the efficiency of N utilization in ruminants.

Copyright

Corresponding author

References

Hide All
AFRC 1993. Energy and protein requirements of ruminants. An advisory manual prepared by the AFRC Technical Committee on responses to nutrients. CAB International, Wallingford, UK.
Alemán, G, López, A, Ordaz, G, Torres, N, Tovar, AR 2009. Changes in messenger RNA abundance of amino acid transporters in rat mammary gland during pregnancy, lactation, and weaning. Metabolism Clinical and Experimental 58, 594601.
Arambel, MJ, Bartley, EE, Dufva, GS, Nagaraja, TG, Dayton, AD 1982. Effect of diet on amino and nucleic acids of rumen bacteria and protozoa. Journal of Dairy Science 65, 20952101.
Argyle, JL, Baldwin, RL 1989. Effects of amino acids and peptides on rumen microbial growth yields. Journal of Dairy Science 72, 20172027.
Atasoglu, C, Newbold, CJ, Wallace, RJ 2001. Incorporation of [15N]ammonia by cellulolytic ruminal bacterial Fibrobacter succinogenes BL2, Ruminococcus albus SY3, and Ruminococcus flavefaciens 17. Applied Environmental Microbiology 67, 28192822.
Atasoglu, C, Valdes, C, Newbold, CJ, Wallace, RJ 1999. Influence of peptides and amino acids on fermentation rate and de novo synthesis of amino acids by mixed micro-organisms from the sheep rumen. The British Journal of Nutrition 81, 307314.
Bach, A, Calsamiglia, S, Stern, MD 2005b. Nitrogen metabolism in the rumen. Journal of Dairy Science 88(E. Suppl.), E9E21.
Bach, A, Huntington, GB, Calsamiglia, S, Stern, MD 2000. Nitrogen metabolism of early lactation cows fed diets with two different levels of protein and different amino acid profiles. Journal of Dairy Science 83, 25852595.
Bach, A, Calsamiglia, S, Greathead, HMR, Kamel, C 2005a. Effects of a combination of eugenol and cinnamaldehyde on ruminal protein and energy metabolism in lactating dairy cows. Proceedings Rencontre Recherche Ruminants Paris, Francia 12, 246.
Bates, DB, Gillett, JA, Barao, SA, Bergen, WG 1985. The effect of specific growth rate and stage of growth on nucleic acid-protein values of pure cultures and mixed ruminal bacteria. Journal of Animal Science 61, 713724.
Benson, JA, Reynolds, CK, Humphries, DJ, Rutter, SM, Beever, DE 2001. Effects of abomasal infusion of long-chain fatty acids on intake, feeding behavior and milk production in dairy cows. Journal of Dairy Science 84, 11821191.
Benson, JA, Reynolds, CK, Aikman, PC, Lupoli, B, Beever, DE 2002. Effects of abomasal vegetable oil infusion on splanchnic nutrient metabolism in lactating dairy cows. Journal of Dairy Science 85, 18041814.
Bequette, BJ, Backwell, FRC, Crompton, LA 1998. Current concepts of amino acid and protein metabolism in the mammary gland of the lactating ruminant. Journal of Dairy Science 81, 25102559.
Bequette, BJ, Kyle, CE, Crompton, LA, Buchan, V, Hanigan, MD 2001. Insulin regulates milk production and mammary gland and hind-leg amino acid fluxes and blood flow in lactating goats. Journal of Dairy Science 84, 241255.
Berthiaume, R, Thivierge, MC, Patton, RA, Dubreuil, P, Stevenson, M, McBride, BW, Lapierre, H 2006. Effect of ruminally protected methionine on splanchnic metabolism of amino acids in lactating dairy cows. Journal of Dairy Science 89, 16211634.
Blouin, JP, Bernier, JF, Reynolds, CK, Lobley, GE, Dubreuil, P, Lapierre, H 2002. Effect of supply of metabolizable protein on splanchnic fluxes of nutrients and hormones in lactating dairy cows. Journal of Dairy Science 85, 26182630.
Bödeker, D, Kemkowski, J 1996. Participation of NH4+ in total ammonia absorption across the rumen epithelium of sheep (ovis aries). Comparative Biochemistry and Physiology. Part A: Physiology 114, 305310.
Broderick, GA, Wallace, RJ, Ørskov, ER 1991. Control of rate and extent of protein degradation. In Physiological aspects of digestion and metabolism in ruminants (ed. T Tsuda, Y Sasaki and R Kawashima), pp. 541594. Academic Press, NY.
Busquet, M, Calsamiglia, S, Ferret, A, Kamel, C 2005a. Screening for the effects of plant extracts and secondary plant metabolites on rumen microbial fermentation in a continuous culture system. Animal Feed Science and Technology 123–124, 597613.
Busquet, M, Calsamiglia, S, Ferret, A, Kamel, C 2005b. Effects of cinnamaldehyde and garlic oil on rumen microbial fermentation in a dual flow continuous culture. Journal of Dairy Science 88, 25082516.
Busquet, M, Calsamiglia, S, Ferret, S, Carro, MD, Kamel, C 2005c. Effect of garlic oil and four of its compounds on rumen microbial fermentation. Journal of Dairy Science 88, 43934404.
Calsamiglia, S, Castillejos, L, Busquet, M 2005. Alternatives to antimicrobial growth promoters in cattle. In Recent advances in animal nutrition (ed. PC Garnsworthy and J Wiseman), pp. 129167. Nottingham University Press, Nottingham, UK.
Calsamiglia, S, Cardozo, PW, Ferret, A, Bach, A 2008. Changes on rumen microbial fermentation are due to a combined effect of type of diet and pH. Journal of Animal Science 86, 702711.
Cant, JP 2005. Integration of data in feed evaluation systems. In Quantitative aspects of ruminant digestion and metabolism, 2nd edition (ed. J Dijkstra, J France and JM Forbes), pp. 707726. CABI Publishing, Wallingford, UK.
Cardozo, PW, Calsamiglia, S, Ferret, A, Kamel, C 2004. Effects of natural plant extracts on protein degradation and fermentation profiles in continuous culture. Journal of Animal Science 82, 32303236.
Cardozo, PW, Calsamiglia, S, Ferret, A, Kamel, C 2006. Effects of alfalfa extract, anise, capsicum, and a mixture of cinnamaldehyde and eugenol on ruminal fermentation and protein degradation in beef heifers fed a high-concentrate diet. Journal of Animal Science 84, 28012808.
Casse, EA, Rulquin, H, Huntington, GH 1994. Effect of mesenteric vein infusion of propionate on splanchnic metabolism in primiparous holstein cows. Journal of Dairy Science 77, 32963303.
Chaiyabutr, N, Thammacharoen, S, Komolvanich, S, Chanpongsang, S 2005. Effects of long-term administration of recombinant bovine somatotropin on milk production and plasma insulin-like growth factor and insulin in crossbred Holstein cows. The Journal of Agricultural Science 143, 311318.
Chen, G, Russell, JB 1989. More monensin-sensitive, ammonia-producing bacteria from the rumen. Applied Environmental Microbiology 55, 10521057.
Cotta, MA, Russell, JB 1982. Effect of peptides and amino acids on efficiency of rumen bacterial protein synthesis in continuous culture. Journal of Dairy Science 65, 226234.
De Visser, H, Valk, H, Klop, A, Van der Meulen, J, Bakker, JGM, Huntington, GB 1997. Nutrient fluxes in splanchnic tissue of dairy cows: influence of grass quality. Journal of Dairy Science 80, 16661673.
Delgado-Elorduy, A, Theurer, CB, Huber, JT, Alio, A, Lozano, O, Sadik, M, Cuneo, P, De Young, HD, Simas, IJ, Santos, JEP, Nussio, L, Nussio, C, Webb, KE Jr, Tagari, H 2002a. Splanchnic and mammary nitrogen metabolism by dairy cows fed dry-rolled or steam-flaked sorghum grain. Journal of Dairy Science 85, 148159.
Delgado-Elorduy, A, Theurer, CB, Huber, JT, Alio, A, Lozano, O, Sadik, M, Cuneo, P, De Young, HD, Simas, IJ, Santos, JEP, Nussio, L, Nussio, C, Webb, KE Jr, Tagari, H 2002b. Splanchnic and mammary nitrogen metabolism by dairy cows fed steam-rolled or steam-flaked corn. Journal of Dairy Science 85, 160168.
Dobson, A, Sellers, AF, Thorlacius, SO 1971. Limitation of diffusion by blood flow through bovine ruminal epithelium. American Journal of Physiology 220, 13371343.
Ferme, D, Banjac, M, Calsamiglia, S, Busquet, M, Kamel, C, Avgustin, G 2004. The effects of plant extracts on microbial community structure in a rumen-simulating continuous-culture system as revealed by molecular profiling. Folia Microbiologica 49, 151155.
Feuermann, Y, Shamay, A, Mabjeesh, SJ 2008. Leptin up-regulates the lactogenic effect of prolactin in the bovine mammary gland in vitro. Journal of Dairy Science 91, 41834189.
Firkins, JL, Weiss, WP, Piwonka, EJ 1992. Quantification of intraruminal recycling of microbial nitrogen using nitrogen-15. Journal of Animal Science 70, 32233233.
Graham, C, Simmons, NL 2004. Functional organization of the bovine rumen epithelium. American Journal of Physiology. Regulatory, Integrative and Comparative Physiology 288, R173R181.
Griswold, KE, Hoover, WH, Miller, TK, Thayne, WV 1996. Effect of form of nitrogen on growth of ruminal microbes in continuous culture. Journal of Animal Science 74, 483491.
Han, XT, Xue, B, Hu, LH, Du, JZ 2001. Effect of dietary protein degradability on net fluxes of free and peptide amino acids across the portal-drained viscera of steers. The Journal of Agricultural Science 137, 471481.
Hanigan, MD 2005. Quantitative aspects of ruminant splanchnic metabolism as related to predicting animal performance. Animal Science 80, 2332.
Hatzoglou, M, Fernandez, J, Yaman, I, Closs, E 2004. Regulation of cationic amino acid transport: the story of the CAT-1 transporter. Annual Review of Nutrition 24, 377399.
Hayashi, AA, Nones, K, Roy, NC, McNabb, WC, Mackenzie, DS, Pacheco, D, McCoard, S 2009. Initiation and elongation steps of MRNA translation are involved in the increase in milk protein yield caused by growth hormone administration during lactation. Journal of Dairy Science 92, 18891899.
Hoover, WH, Stokes, SR 1991. Balancing carbohydrates and protein for optimum rumen microbial yield. Journal of Dairy Science 74, 36303644.
Houpt, TR 1959. Utilization of blood urea in ruminants. American Journal of Physiology 197, 115120.
Houpt, TR 1970. Transfer of urea and ammonium to the rumen. In Physiology of digestion and metabolism in the ruminant (ed. AT Phillipson), pp. 119131. Oriel Press, Newcastle Upon Tyne.
Hristov, AN, Huhtanen, P 2008. Nitrogen efficiency in Holstein cows and dietary means to mitigate nitrogen losses from dairy operations. Proceedings of the Cornell Nutrition Conference, Ithaca, NY.
Huhtanen, P, Hristov, AN 2009. A meta-analysis of the effects of dietary protein concentration and degradability on milk protein yield and milk N efficiency in dairy cows. Journal of Dairy Science 92, 32223232.
INRA 2007. Alimentation des bovins, ovins et caprins. Besoins des animaux. Valeur des aliments. Éditeur Quae, Versailles INRA, Paris.
Ipharraguerre, IR, Clark, JH 2005. Impacts of the source and amount of crude protein on the intestinal supply of nitrogen fractions and performance of dairy cows. Journal of Dairy Science 88, E22E37.
Ipharraguerre, IR, Clark, JH, Freeman, DE 2005. Rumen fermentation and intestinal supply of nutrients in dairy cows fed rumen-protected soy products. Journal of Dairy Science 88, 28792892.
Jouany, JP 1996. Effects of rumen protozoa on nitrogen metabolism by ruminants. Journal of Nutrition 126, 1335S1346S.
Karnati, SKR, Sylvester, JT, Ribeiro, CVDM, Gilligan, LE, Firkins, JL 2009. Investigating unsaturated fat, monensin, or bromoethanesulfonate in continuous cultures retaining ruminal protozoa. I. Fermentation, biohydrogenation, and microbial protein synthesis. Journal of Dairy Science 92, 38493860.
Karnati, SKR, Sylvester, JT, Noftsger, SM, Yu, Z, St-Pierre, NR, Firkins, JL 2007. Assessment of ruminal bacterial populations and protozoal generation time in cows fed different methionine sources. Journal of Dairy Science 90, 798809.
Kennedy, PM, Clarke, RTJ, Milligan, LP 1981. Influences of dietary sucrose and urea on transfer of endogenous urea to the rumen of sheep and numbers of epithelial bacteria. The British Journal of Nutrition 46, 533541.
Kohn, RA, Dinneen, MM, Russek-Cohen, E 2005. Using blood urea nitrogen to predict nitrogen excretion and efficiency of nitrogen utilization in cattle, sheep, goats, horses, pigs, and rats. Journal of Animal Science 83, 879889.
Lacasse, P, Prosser, CG 2003. Mammary blood flow does not limit milk yield in lactating goats. Journal of Dairy Science 86, 20942097.
Lacasse, P, Farr, VC, Davis, SR, Prosser, CG 1996. Local secretion of nitric oxide and the control of mammary blood flow. Journal of Dairy Science 79, 13691374.
Lapierre, H, Berthiaume, R, Raggio, G, Thivierge, MC, Doepel, L, Pacheco, D, Dubreuil, P, Lobley, GE 2005. The route of absorbed nitrogen into milk protein. Animal Science 80, 1122.
Lapierre, H, Pacheco, D, Berthiaume, R, Ouellet, DR, Schwab, CG, Dubreuil, P, Holtrop, G, Lobley, GE 2006. What is the true supply of amino acids for a dairy cow? Journal of Dairy Science 89, E1E14.
Larsen, M, Kristensen, NB 2009. Effect of abomasal glucose infusion on splanchnic amino acid metabolism in periparturient dairy cows. Journal of Dairy Science 92, 33063318.
Lescoat, P, Sauvant, D, Danfaer, A 1996. Quantitative aspects of blood and amino acid flows in cattle. Reproduction Nutrition and Development 36, 137174.
Litman, T, Søgaard, R, Zeuthen, T 2009. Ammonia and urea permeability of mammalian aquaporins. Handbook of Experimental Pharmacology 190, 327358.
Mackle, TR, Dwyer, DA, Ingvartsen, KL, Chouinard, PY, Ross, DA, Bauman, DE 2000. Effects of insulin and postruminal supply of protein on use of amino acids by the mammary gland for milk protein synthesis. Journal of Dairy Science 83, 93105.
MacRae, JC, Bruce, LA, Brown, DS, Calder, AG 1997a. Amino acid use by the gastrointestinal tract of sheep given lucerne forage. American Journal of Physiology 273, G1200G1207.
MacRae, JC, Bruce, LA, Brown, DS, Farningham, DA, Franklin, M 1997b. Absorption of amino acids from the intestine and their net flux across the mesenteric- and portal-drained viscera of lambs. Journal of Animal Science 75, 33073314.
Marini, JC, Van Amburgh, ME 2003. Nitrogen metabolism and recycling in Holstein heifers. Journal of Animal Science 81, 545552.
Marini, JC, Klein, JD, Sands, JM, Van Amburgh, ME 2004. Effect of nitrogen intake on nitrogen recycling and urea transporter abundance in lambs. Journal of Animal Science 82, 11571164.
Mateo, RD, Wu, G, Moon, HK, Carroll, JA, Kim, SW 2008. Effects of dietary arginine supplementation during gestation and lactation on the performance of lactating primiparous sows and nursing piglets. Journal of Animal Science 86, 827835.
McAllan, AB 1982. The fate of nucleic acids in ruminants. Proceedings of the Nutrition Society 41, 309316.
Meijer, AJ, Lamers, WH, Chamuleau, RAFM 1990. Nitrogen metabolism and ornithine cycle function. Physiology Reviews 70, 701748.
Menzies, KK, Lefèvre, C, Macmillan, KL, Nicholas, KR 2009. Insulin regulates milk protein synthesis at multiple levels in the bovine mammary gland. Functional & Integrative Genomics 9, 197217.
Mepham, TB 1982. Amino acid utilization by lactating mammary gland. Journal of Dairy Science 65, 287298.
NRC 2001. Nutrient requirements of dairy cattle, 7th revised edition. National Academy Press, Washington, DC.
Parker, DS, Lomax, MA, Seal, CJ, Wilton, JC 1995. Metabolic implications of ammonia production in the ruminant. Proceeding of the Nutrition Society 54, 549563.
Prizant, RL, Barash, I 2008. Negative effects of the amino acids Lys, His, and Thro in S6K1 phosphorylation in mammary epithelial cells. Journal of Cellular Biochemistry 105, 10381047.
Raggio, C, Lemosquet, S, Lobley, GE, Rulquin, H, Lapierre, H 2006. Effect of casein and propionate supply in mammary protein metabolism in lactating dairy cows. Journal of Dairy Science 89, 43404351.
Raggio, G, Pacheco, D, Berthiaume, R, Lobley, GE, Pellerin, D, Allard, G, Dubreuil, P, Lapierre, H 2004. Effect of level of metabolizable protein on splanchnic flux of amino acids in lactating dairy cows. Journal of Dairy Science 87, 34613472.
Rémond, D, Bernard, L, Chauveau, B, Nozie're, P, Poncet, C 2003. Digestion and nutrient net fluxes across the rumen, and the mesenteric and portal-drained viscera in sheep fed with fresh forage twice daily: net balance and dynamic aspects. The British Journal of Nutrition 89, 649666.
Reynolds, CK 2002. Economics of visceral energy metabolism in ruminants: toll keeping or internal revenue service? Journal of Animal Science 80(E. Suppl.), E74E84.
Reynolds, CK 2005. Nitrogen metabolism by splanchnic tissues of ruminants. In Biology of metabolism of growing animals (ed. D Burrin and H Merssman), pp. 197220. Elsevier Science, Oxford, England.
Reynolds, CK 2006a. Splanchnic metabolism of amino acids in ruminants. In Ruminant physiology. Digestion, metabolism and impact of nutrition on gene expression, immunology and stress (ed. K Sejrsen, T Hvelplund and MO Nielsen), pp. 225248. Wageningen Academic Publishers, The Netherlands.
Reynolds, CK 2006b. Production and metabolic effects of site of starch digestion in lactating dairy cattle. Animal Feed Science and Technology 130, 7894.
Reynolds, CK, Kristensen, NB 2008. Nitrogen recycling through the gut and the nitrogen economy of ruminants: an asynchronous symbiosis. Journal of Animal Science 86, E293E305.
Reynolds, CK, Huntington, GB, Tyrrell, HF, Reynolds, PJ 1988. Net portal-drained visceral and hepatic metabolism of glucose, L-lactate and nitrogenous compounds in lactating holstein cows. Journal of Dairy Science 71, 18031812.
Reynolds, CK, Aikman, PC, Lupoli, B, Humphries, DJ, Beever, DE 2003. Splanchnic metabolism of dairy cows during the transition from late gestation through early lactation. Journal of Dairy Science 86, 12011217.
Reynolds, CK, Cammell, SB, Humphries, DJ, Beever, DE, Sutton, JD, Newbold, JR 2001. Effects of post-rumen starch infusion on milk production and energy metabolism in dairy cows. Journal of Dairy Science 84, 22502259.
Røjen, BA, Kristensen, NB 2009. Effect of nitrogen supply on inter-organ urea flux in dairy cows. In Book of abstracts of the 60th annual meeting of the European association for animal production, p. 369. Wageningen Academic Publishers, Wageningen, The Netherlands.
Røjen, BA, Lund, P, Kristensen, NB 2008. Urea and short-chain fatty acids metabolism in holstein cows fed a low-nitrogen grass-based diet. Animal 2, 500513.
Sands, JM 2003. Mammalian urea transporters. Annual Reviews of Physiology 65, 543566.
Satter, LD, Slyter, LL 1974. Effect of ammonia concentration on rumen microbial protein production in vitro. The British Journal of Nutrition 32, 199208.
Schei, I, Danfær, A, Boman, IA, Volden, H 2007a. Post-ruminal or intravenous infusions of carbohydrates or amino acids to dairy cows. 1. Early lactation. Animal 1, 501514.
Schei, I, Danfær, A, Mydland, LT, Volden, H 2007b. Post-ruminal or intravenous infusions of carbohydrates or amino acids to dairy cows. 2. Late lactation. Animal 1, 515522.
Schwab, CG, Huhtanen, P, Hunt, CW, Hvelplund, T 2005. Nitrogen requirements of cattle. In Nitrogen and phosphorus nutrition of cattle (ed. E Pfeffer and A Hristov). CABI Publishing, Wallingford, UK.
Stern, MD, Bach, A, Calsamiglia, S 1997. Alternative techniques for measuring nutrient digestion in ruminants. Journal of Animal Science 75, 22562276.
Stern, MD, Varga, GA, Clark, JH, Firkins, JL, Huber, JT, Palmquist, DL 1994. Evaluation of chemical and physical properties of feeds that affect protein metabolism in the rumen. Journal of Dairy Science 77, 27622786.
Stewart, GS, Graham, C, Cattell, S, Smith, TPL, Simmons, NL, Smith, CP 2005. UT-B is expressed in bovine rumen: potential role in ruminal urea transport. American Journal of Physiology – Regulatory, Integrative and Comparative Physiology 289, R605R612.
Stokes, SR, Hoover, WH, Miller, TK, Manski, RP 1991. Impact of carbohydrate and protein levels on bacterial metabolism in continuous culture. Journal of Dairy Science 74, 860870.
Stoll, B, Burrin, DG, Henry, J, Yu, H, Jahoor, F, Reeds, PJ 1999. Substrate oxidation by the portal drained viscera of fed piglets. American Journal of Physiology 277, E168E175.
Stone, JB, Trimberger, GW, Henderson, CR, Reid, JT, Turk, KL, Loosli, JK 1960. Forage intake and efficiency of feed utilization in dairy cattle. Journal of Dairy Science 43, 12751281.
Sutton, JD, Reynolds, CK 2003. Digestion and absorption of nutrients in the small intestine of lactating ruminants. In Encyclopedia of dairy sciences (ed. H Roginski, P Fox and J Fuquay), pp. 21202127. Academic Press, San Diego.
Tamminga, S 1992. Nutrition management of dairy cows as a contribution to pollution control. Journal of Dairy Science 75, 345357.
Thomas, C 2004. Feed into milk. A new applied feeding system for dairy cattle. Nottingham University Press, UK.
Walker, ND, Newbold, CJ, Wallece, RJ 2005. Nitrogen metabolism in the rumen. In Nitrogen and phosphorus nutrition of cattle (ed. E Pfeffer and A Hristov). CABI Publishing, Wallingford, UK.
Wallace, RJ, Newbold, CJ, Bequette, BJ, MacRae, JC, Lobley, GE 2001. Increasing the flow of protein from ruminal fermentation. Asian-Australian Journal of Animal Science 14, 885893.
Wallace, RJ, McKain, N, McEwan, NR, Miyagawa, E, Chaudhary, LC, King, TP, Walker, ND, Apajalahti, JH, Newbold, CJ 2003. Eubacterium piruvativorans, a novel non-saccharolytic anaerobe from the rumen which ferments pyruvate and amino acids, forms caproate and utilises acetate and propionate. International Journal of Systematic and Evolutionary Microbiology 53, 965970.
Wang, X, Proud, CG 2006. The mTOR pathway in the control of protein synthesis. Physiology 21, 362369.
Waterlow, JC 1999. The mysteries of nitrogen balance. Nutrition Research Review 12, 2554.
Wickersham, TA, Titgemeyer, EC, Cochran, RC, Wickersham, EE, Gnad, DP 2008. Effect of rumen-degradable intake protein supplementation on urea kinetics and microbial use of recycled urea in steers consuming low-quality forage. Journal of Animal Science 86, 30793088.
Williams, AG, Coleman, GS 1997. The rumen protozoa. In The rumen microbial ecosystem, 2nd edition (ed. PN Hobson and CS Stewart), pp. 73139. Chapman & Hall, London.
Windmueller, HG, Spaeth, AE 1980. Respiratory fuels and nitrogen metabolism in vivo in small intestine of rats. Quantitative importance of glutamine, glutamate and aspartate. The Journal of Biological Chemistry 255, 107112.
Yu, F, Bruce, LA, Calder, AG, Milne, E, Coop, RL, Jackson, F, Horgan, GW, MacRae, JC 2000. Subclinical infection with the nematode trichostrongylus colubriformis increases gastrointestinal tract leucine metabolism and reduces availability of leucine for other tissues. Journal of Animal Science 78, 380390.

Keywords

Related content

Powered by UNSILO

Strategies for optimizing nitrogen use by ruminants

  • S. Calsamiglia (a1), A. Ferret (a1), C. K. Reynolds (a2), N. B. Kristensen (a3) and A. M. van Vuuren (a4)...

Metrics

Full text views

Total number of HTML views: 0
Total number of PDF views: 0 *
Loading metrics...

Abstract views

Total abstract views: 0 *
Loading metrics...

* Views captured on Cambridge Core between <date>. This data will be updated every 24 hours.

Usage data cannot currently be displayed.