7Menke K H, Raab L, Salewski A, et al. The estimation of the digestibility and metabolizable energy content of ru- minant feeding stuffs from the gas production when they are incubated with rumen liquor in vitro[J]. Journal of Agricultural Science, 1979,93 (1) : 217-222.
8Ramanzin M, Bailoni L, Schiavon S. Effect of forage to concentrate ratio on comparative digestion in sheep, goats and fallow deer [J]. Animal Science, 1997, 64(1) :163-170.
9Tang S X, Tayo G O,Tan Z L, et al. Effects of yeast culture and fibrolytic enzyme supplementation on in vitro fermentation characteristics of low-quality cereal straws[J]. Journal of Animal Science, 2008,86 ( 5 ) 1164-1172.