Composite microbial feed additive and preparation method thereof

The present invention discloses a composite microbial feed additive. The composite microbial feed additive is prepared by mixing a lactic acid bacterium fermentation product, a bifidobacterium fermentation product and a bacillus subtilis fermentation product according to a raw material mass ratio of 1:1:1. Composite microorganisms have good stability, can synthesize various nutrients in animal intestinal reproductive processes, enhance digestion and absorption of nutrients, promote growth and development of animals, ensure structural integrity of intestinal tract states by improving height ofintestinal villi, reducing depth of crypts and increasing muscle thickness, maintain the optimal immune states of the intestinal tracts, at the same time can promote high expression of an immune geneMHC I and improve immune performance of body. The present invention also discloses a preparation method of the composite microbial feed additive. The preparation method is simple to operate, strong incontrollability and favora