Objects of the invention are to provide a feed composition, which shows a high antimicrobial activity to a variety of harmful microorganisms, in particular, harmful bacteria such as those belonging to the genus Salmonella, which can show, on the contrary, only a low antibacterial effect on lactic acid bacteria useful for the growth of animals while keeping their good health and which can thus permit the breeding of animals with health, while ensuring a high breeding efficiency as well as a method for breeding animals using the feed composition. The invention provides a feed composition characterized in that it comprises silver-carrying zeolite and a method for breeding an animal wherein if the feed composition having a silver content of 2.5% by mass is administered to the animal, the composition having a silver content of 0.001 to 0.2% by mass is used in the initial breeding stage (term A), the composition having a silver content of less than 0.001% by mass is used in the internal stage (term B), and the composition having a silver content of 0.01 to 0.2% by mass is used after the internal stage and before the shipping date (term C).
