6National Research Council. Nutrient Requirements of Dairy Cattle[S]. 7th ed. Washington, D. C. : National Academy Press, 2001.
7van Houtert M F J. The production and metabolism of volatile fatty acids by ruminants fed roughages., a review[J]. Animal Feed Science Technology, 1993, 43(3/4) : 189-225.
8Yang W Z, Beauchemin K A, Rode L M. Effects of grain processing, forage to concentrate ratio, and forage particle size on rumen pH and digestion by dairy cows[J]. Journal of Dairy Science, 2001, 84 (10): 2 203-2 216.
9Kelley R O, Martz F A, Johnson H D. Effect of environmental temperature on ruminal volatile fatty acid levels with controlled feed intake[J].Journal of Dairy Science, 1967, 50(4):531-533.
10Schneider P, Sklan D, Chalupa W, et al. Feeding calcium salts of fatty acids to lactating cows[J]. Journal of Dairy Science, 1988, 71(8): 2 143-2 150.
