[Objects] An object of the present invention is to provide an orally administrable agent for medical use for animals for preventing or treating coccidiosis which is highly safe with no side effects, an agent for a food or a drink for use in the preservation of health, a feed additive, and a feed comprising the same. Another object of the present invention is to provide a method for rearing animals (particularly, livestock and poultry) using the same and a method for controlling coccidiosis using the same.[Means for Resolution] By using a fermentation product of a lactic acid bacterium and/or a whey fermentation product of a propionic acid bacterium as an active ingredient, an agent for preventing or treating coccidiosis, an agent for use in the preservation of health, and a feed additive can be provided.