PURPOSE: To provide the subject composition free from the danger of anaerobic treatment and contamination with pathogenic microorganisms, etc., having excellent Salmonella inhibiting performance and useful as an antisalmonella feed and feed additive, an agent for preventing infection with Salmonella, etc.

CONSTITUTION: The objective composition contains butter milk as an active component. For example, cow's milk is separated into defatted milk and cream by centrifugal separation, the cream is separated into butter and butter milk by churning process comprising the vigorous agitation of the cream and the butter milk is used as an active component of the objective composition.