Animal feed additive and preparation method thereof

The invention provides an animal feed additive and a preparation method thereof. The animal feed additive is prepared from seven edible and medicinal fungus solid fermentation mycelia including cordyceps militaris, morchella, gloeostereum incarnatum, agaricus blazei murill, ganoderma lucidum, lentinus edodes and flammulina velutipes, and an edible fungus refined fungus chaff biological fermentation feed in a weight ratio of 1 to 2. The animal feed additive has the effects that the animal immune system function can be comprehensively activated in a multi-layer manner, the humoral immunity and the cellular immunity are enhanced, the disease resistance of animals is greatly improved, the body is built, bacteria, fungi, viruses and protozoa can be effectively prevented from invading the bodies of the animals, and the health of the animals is protected. The contained multiple antibacterial active ingredients and interferon inducers can effectively prevent and treat diseases, the survival rate of the animals is imp