Using the combination of yeast and lactic acid bacteria fermented cornstalks, fresh straw and grass as animal feed to increase the number of beneficial cell microorganisms supporting for intestinal digestion of herbivores be better. The fermentation was carried out under the two phase - semisolid and liquid, thereby yeast biomass after aerobic phase increased to 109, but after the anaerobic biomass decreased to 10 exponent 7. The biomass of lactic acid bacteria increases in all phases of fermentation, bacterial cell count was about 10 exponent 10 after the 2th phase finished. The fermentation process was the biological conversion of plant material into single-cell protein, increased to 53.1 percent protein. Moreover, the biological metabolism has changed amino acid composition of raw materials, increased levels of essential amino acids.