Abstract: In this study, the best solid-state fermentation condition of wheat bran was optioned by using different ratio of Lactobacillus B, Lactobacillus W, Bacillus subtilis and Saccharomycetes, the digestion of fermentation wheat bran was analyzed by extraction of intestinal digestive enzyme from the grass carp. Experiment was arranged six groups according to the different microbial combination, the unfermented wheat bran acted as control group, and each treatment was repeated 3 times. The best condition was selected through measuring the acidity, bacteria colony and crude protein content of fermentation bran. The digestion of unfermented wheat bran and best fermentation wheat bran was carried out by using the digestive enzyme from the grass crap in vitro, the dry matter and crude protein digestibility and amino acid content were determined. The results showed that the crude protein content of group 3 was the highest, the content was improved by 56.56% compared with the control group. Moreover, the bacteria colonies were reached 7.8×10⁸ CFU/g in 96 h in group 3, which was apparently higher than those in other groups, and the acidity was firstly increased and then decreased. All these exhibited the group 3 were the best one. In addition, the former intestine showed the highest dry matter and crude protein digestibility and amino acid content between unfermented wheat bran group and fermentation wheat bran group, followed by middle intestine, and posterior intestine was minimum, moreover, the digestibility of best fermentation wheat bran was significantly greater than that of unfermented wheat bran in vitro（P＜0.05）.The results indicated that the fermentation wheat bran have the higher nutritional value and digestibility, which can partially replace the protein feed.

Key words: wheat bran; fermentation by multi-strains; enzymolysis; in vitro digestibility