An animal feed supplement for use in an animal food composition containing an animal feed having monocalcium phosphate therein is disclosed. The supplement comprises monensin, a solvent, and an alkaline component. The supplement is a mixture, and the alkaline component is present in the animal feed supplement in an amount sufficient to maintain the ability to detect monensin in the animal food composition. An animal food composition, comprising the above described animal feed supplement is disclosed. The animal feed also has monocalcium phosphate therein. The above described animal food composition is useful for preventing or treating coccidiosis in an animal for example a bovine.
