Keyword: Coarse fodder; Microbial ferment agent
The richest polysaccharide material on the earth is cellulose, the biomass of on the world 50% comes from natural cellulose, estimation produces per year a quantity in 100 ～ 50 billion T is controlled (Li Xin, 2000) . The cellulose natural resources of our country is very substantial, annual straw crop is in 570 million T, the 20% ～ that hold world straw total output 30% , use as however the inadequacy of feed 10% (Li Rijiang, 2001) . If can sufficient, effective use these resource, will become alleviate " of the " grain that current mankind faces, the sources of energy, environment 3 big crises, reach one of important ways that implementation agriculture can develop continuously. But because content of straw feed crude fibre is high, protein, mineral content is low, cultivate birds digestive rate is low, dainty sex is poor, restricted its application thereby. Pretreatment must undertake when raise feeds an animal, in order to raise nutrient value and dainty sex. Pretreatment includes method of physics, chemical, biology. Current, use to the degradation of cellulose basically use biology method, use namely can secrete effective enzymatic kind microbial come degradation cellulose.
1 microbial ferment the mechanism of coarse fodder
The bases of the low qualitative coarse fodder such as crop straw is fiber material, neuter catharsis fiber (NDF) the fiber of acidity catharsis of 70% ～ 80%; that takes dry matter about (ADF) the 50% ～ that take dry matter about 60% , and the content of thick albumen is very few, contain 3% ～ only 6% . NDF includes cellulose, semi-cellulose, lignin, it is the main component of plant cell wall, as the ageing of plant cell, cellular wall thickening, NDF becomes the main composition of straw. Pure cellulose can be easier the ground by rumen microbial degradation (Cheason, 1993) , but as a result of lignin thick structure is very difficult by rumen microbial degradation, at the same time the cellular wall of afore-mentioned ageing is put in very strong union key to touch between bases
Fight microbial assimilation, make the cellulose digestive rate in rumen very low (Grent, 1991) .
Accordingly, want to raise the digestive rate of straw, the key is degradation lignin, withhold cellulose. Fermenting in the process, a large number of microbial growth progenitive, secrete all sorts of enzymatic. These are enzymatic pass degradation polysaccharide and lignin, destroy its connective covalent bond, destroyed the cellular wall structure with indigestible straw on one hand, make the cellulose that is together with lignin cross-linking and semi-cellulose dissociate come out; The carbohydrate that makes Neikeli uses straw cell wall again on the other hand and other nutrition material reveal the opportunity that comes out to increase to be contacted with digestive juice, raise straw to digest rate or rate of degradation of rumen dry matter thereby (Min Xiaomei, 2000) . And the growth of biomass of bacterium body self can increase protein content again.