Association of Official Analytical Chemists. 1999. Official methods of analysis, 16th edition, fifth revision. AOAC Inc., Arlington, VA.
Caldwell, D. R. and Bryant, M. P. 1966. Medium without rumen fluid for non-selective enumeration and isolation of rumen bacteria. Applied Microbiology 14: 794–801.
Callaway, T. R. and Martin, S. A. 1996. Effects of organic acid and monensin treatment on in vitro mixed ruminal microorganism fermentation of cracked corn. Journal of Animal Science 74: 1982–1989.
Callaway, T. R., Martin, S. A., Wampler, J. L., Hill, N. S. and Hill, G. M. 1997. Malate content of forage varieties commonly fed to cattle. Journal of Dairy Science 80: 1651–1655.
Carro, M. D., López, S., Valdés, C. and Ovejero, F. J. 1999. Effect of DL-malate on mixed ruminal microorganism fermentation using the rumen simulation technique (RUSITEC). Animal Feed Science and Technology 79: 279–288.
Carro, M. D. and Miller, E. L. 1999. Effect of supplementing a fibre basal diet with different nitrogen forms on ruminal fermentation and microbial growth in an in vitro semicontinuous culture system (RUSITEC). British Journal of Nutrition 82: 149–157.
Carro, M. D. and Miller, E. L. 2002. Comparison of microbial markers (15N and purine bases) and bacterial isolates for the estimation of rumen microbial protein synthesis. Animal Science 75: 315–321.
Carro, M. D. and Ranilla, M. J. 2003. Effect of the addition of malate on in vitro rumen fermentation of cereal grains. British Journal of Nutrition 89: 279–288.
Carro, M. D., Ranilla, M. J., Giráldez, F. J., Mantecón, A. R. and Balcells, J. 2003. Effect of malate on digestibility and rumen microbial protein synthesis in growing lambs fed a high-concentrate diet. Book of abstracts of the 54th annual meeting of the European Association for Animal Production, no. 9, p. 142. Wageningen Academic Publishers, Wageningen.
Castillo, C., Benedito, J. L., Méndez, J., Pereira, V., López-Alonso, M., Miranda, M. and Hernández, J. 2004. Organic acids as a substitute for monensin in diets for beef cattle. Animal Feed Science and Technology 115: 101–116.
Demeyer, D. I. 1991. Quantitative aspects of microbial metabolism in the rumen and hindgut. In Rumen microbial metabolism and ruminant digestion (ed. Jouany, J. P.), pp. 217–237. INRA Editions, Paris.
Demeyer, D. I. and Henderickx, M. K. 1967. Competitive inhibition of in vitro methane production by mixed rumen bacteria. Archives Internationales de Physiology et de Biochemie 75: 157–159.
Dewhurst, R. J., Davies, D. R. and Merry, R. J. 2000. Microbial protein supply from the rumen. Animal Feed Science and Technology 85: 1–21.
European Commission. 2003. Regulation (EC) no. 1831/2003 of the European Parliament and of the Council of 22 September 2003 on additives for use in animal nutrition. Official Journal of the European Communities L268: 29–43.
Goering, M. K. and Van Soest, P. J. 1970. Forage fiber analysis (apparatus, reagents, procedures and some applications). Agricultural handbook, no. 379. Agricultural Research Services, USDA, Washington, DC.
Gómez, J. A., Tejido, M. L. and Carro, M. D. 2005. Influence of disodium malate on microbial growth and fermentation in Rusitec fermenters receiving medium- and high-concentrate diets. British Journal of Nutrition In press.
Harmeyer, H., Höller, H., Martens, H. and Grabe, C. von. 1976. Estimate of microbial protein synthesis in vitro by the simultaneous use of three different isotopic markers. In Tracer studies on non-protein nitrogen for ruminants III, pp. 69–79. International Atomic Energy Agency, Vienna.
Illg, D. J. and Stern, M. D. 1994. In vitro and in vivo comparisons of diaminopimelic acid and purines for estimating protein synthesis in the rumen. Animal Feed Science and Technology 48: 49–55.
Martin, S. A. 1998. Manipulation of ruminal fermentation with organic acids: a review. Journal of Animal Science 76: 3123–3132.
Martin, S. A. 2004. Effects of DL-malate on in vitro forage fiber digestion by mixed ruminal micro-organisms. Current Microbiology 48: 27–31.
Martin, S. A. and Streeter, M. N. 1995. Effect of malate on in vitro mixed ruminal microorganism fermentation. Journal of Animal Science 73: 2141–2145.
Martin, S. A., Streeter, M. N., Nisbet, D. J., Hill, G. M. and Williams, S. E. 1999. Effects of DL-malate on ruminal metabolism and performance of cattle fed a high-concentrate diet. Journal of Animal Science 77: 1008–1015.
Montaño, M. F., Chai, W., Zinn-Ware, T. E. and Zinn, R. A. 1999. Influence of malic acid supplementation on ruminal pH, lactic acid utilization, and digestive function in steers fed high-concentrate finishing diets. Journal of Animal Science 77: 780–784.
Nisbet, D. J. and Martin, S. A. 1990. Effect of dicarboxylic acids and Aspergillus oryzae fermentation extract on lactate uptake by the ruminal bacterium Selenomonas ruminantium. Applied and Environmental Microbiology 56: 3515–3518.
Nisbet, D. J. and Martin, S. A. 1991. Effect of a Saccharomyces cerevisiae culture on lactate utilization by the ruminal bacterium Selenomonas ruminantium. Journal of Animal Science 69: 4628–4633.
Nisbet, D. J. and Martin, S. A. 1993. Effects of fumarate, L-malate, and an Aspergillus oryzae fermentation extract on D-lactate utilization by the ruminal bacterium Selenomonas ruminantium. Current Microbiology 26: 133–136.
Ranilla, M. J., Carro, M. D., López, S., Newbold, J. C. and Wallace, J. 2001. Influence of N source on the fermentation of fibre from barley straw and sugarbeet pulp by ruminal micro-organisms in vitro. British Journal of Nutrition 86: 717–724.
Russell, J. B. and Van Soest, P. J. 1984. In vitro ruminal fermentation of organic acids common in forage. Applied and Environmental Microbiology 47: 155–159.
Statistical Analysis Systems Institute. 1988. SAS/STAT® user's guide (release 6·03). SAS Institute, Cary, NC.
Taylor, K. A. C. C. 1996. A simple colorimetric assay for muramic acid and lactic acid. Applied Biochemistry and Biotechnology 56: 49–58.
Tejido, M. L., Carro, M. D., Ranilla, M. J. and López, S. 2001. In vitro microbial growth as affected by the type of carbohydrate and the source of nitrogen. Proceedings of the British Society of Animal Science, 2001, p. 152.
Van Soest, P. J., Robertson, J. B. and Lewis, B. A. 1991. Methods for dietary fiber, neutral detergent fiber, and nonstarch polysaccharides in relation to animal nutrition. Journal of Dairy Science 74: 3583–3597.
Weatherburn, M. W. 1967. Phenol-hypochlorite reaction for determination of ammonia. Analytical Chemistry 39: 971–974.