6Sutton J D. Altering milk composition by feeding [ J ].J Dairy Sci, 1989,72:2801～2810.
7Van Houtert M F J. The production and metabolism of volatile fatty acids by ruminants fed roughages : A review [ J ]. Anita Feed Sci Technol, 1993, 43 : 189～225.
8Kennelly J J, Robinson B, Khorasani G R. Influence of carbohydrate source and buffer on rumen fermentation characteristics, milk yield, and milk composition in early-lactation Holstein cows [ J ]. J Dairy Sci,1999, 82 : 2486～2496.
9孟庆翔 译.奶牛营养需要和饲养标准[M].北京:中国农业大学出版社,2002..
10Miettinen H, Huhtanen P. Effects of the ratio of ruminal propionate to butyrate on milk yield and blood metabolites in dairy cows [ J ]. J Dairy Sci, 1996, 79:851～861.
4Bodine T N, Purvis Ⅱ H T. Effects of supplemental energy and/or degradable intake protein on performance, grazing behav ior, intake, digestibility, fecal and blood indices by beef steers grazed on dormant native tallgrass Prairie[J]. Journal of Ani mal Science, 2003, 81:304 -317.
5Menke K H, Raab L, Salewski A, et al. The estimation of the digestibility and metabolisable energy content of ruminant and starch digestion[J]. Small Ruminant Research, 1979, 93: 217-222.
6Menke K H, Steingass H. Estimation of the energetic feed value obtained from chemical analysis and in vitro gas production using rumen fluid[J]. Animal Research and Development, 1988, 28: 7-55.
7AOAC. Association of Official Analytical Chemists Inc, 15th ed[M]. USA: Virginia, 1990.
8Van Soest P J, Robertson J B, Lewis B. Methods for dietary fiber, neutral detergent fiber, and nonstarch polysaccharides in relation to animal nutrition[J]. Journal of Dairy Science, 1991, 74: 3583-3597.
9φrskov E R, McDonald I. The estimation of protein degradability in the rumen from incubation measurements weighed ac cording to rate of passage[J]. Agriculture Science Camb, 1979, 92: 499-503.
10Liu D, Liu J X, Zhu S L, et al. Histological investigation of tissues and cell wall of rice straw influenced by pretreatment with different chemicals and rumen degradation[J]. Journal of Animal Feed Science, 2005, 14: 367-381.
