Additive composition for promoting fiber digestion and rumen health of sheep feed as well as preparation method and application of additive composition

The invention discloses an additive composition for promoting fiber digestion and rumen health of sheep feed as well as a preparation method and application of the additive composition. The additive composition is prepared by fermenting a composite raw material matrix and a complex microbial inoculant, wherein the composite raw material matrix comprises hawthorn, malt, pericarpium citri reticulatae, radix stephaniae tetrandrae, bran, soybean meal, rice chaff, calcium carbonate, glucose, sodium chloride, K2HPO4, MgSO4 and MnSO4; the complex microbial inoculants comprise bacillus subtilis, lactobacillus casei and saccharomyces cerevisiae. Tests prove that the digestibility of the fattening Hu sheep to fibers can be improved by adding 2kg/t of the additive-containing feed composition into the complete granular feed of the fattening Hu sheep; the content of globulin in serum can be increased; the isobutyric acid content in rumen fluid is increased, the pH of the rumen fluid is reduced, and the digestive enzyme ac