Method of preparing feed additive and use of the same for manufacturing composition for promoting growth and preventing and/or curing respiratory disease, inhibiting pathogen growth, inhibiting pathogen infection, or inhibiting inflammation

To provide a feed additive that can be added to an animal feed, and exerts beneficial effects of promoting growth, and preventing respiratory diseases.SOLUTION: A method for adding a feed additive includes: (a) process of preparing a fermentation substrate including coffee powder and an auxiliary material; and (b) process of fermenting a fermentation substrate with Aspergillus oryzae to obtain a feed additive. In the fermentation substrate, the content of coffee powder is 45 wt.% to 80 wt.% relative to the overall weight, a carbon-nitrogen ratio of the fermentation substrate is 35 to 65, an auxiliary material includes corn grains, rice husks, flour of soybeans with husks, crushed rice or a combination thereof. The feed additive includes high specific activity digestive enzyme, and has selective bacteriostatic action and a resistive effect to respiratory pathogens.SELECTED DRAWING: Figure 1