7Menke K H, H. Steingass. 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.
8Hu W L, Liu J X, Ye J A,et al. Effect of tea saponin on rumen fermentation in vitro [J]. Animal Feed Science and Technology, 2005, 120:333-339.
9Searle L. The berthelot or indophenol reaction and its use in the analytical chemistry of nitrogen: a review [J]. Analyst,1984,i09: 549-568.
10Menke K H, L. Raab, A. Salewski, et al. The estimation of the di- gestibility and metabolisable energy content of ruminant feed- ingstuffs from the gas production when they are incubated with tureen liquor.[J]. Journal of Agriculture ScienCe,1979,93:217-222.
