Ionophores are commonly added to food and water to control coccidiosis in young calves until the calf’s natural immunity allows them to fight off the infection once they are older. Coccidia are protozoal organisms that cause disease in the calf’s intestinal tract. Bovine Veterinarian, an online farm journal, says that ionophores kill coccidia at a specific stage of growth by interrupting movement of ions through the cell membrane, changing the equilibrium of electrolytes in the cell which leads to protozoal cell death.

The two FDA approved ionophores used for coccidia control in calves are Bovatec® and Rumensin®. Bovatec® is also approved for use in milk and milk replacer. Ionophores also destroy “bad” bacteria in the rumen, letting “good” bacteria grow more aggressively. This allows for increased energy metabolism and production of glucose for energy. Less degradation of amino acids and peptides occurs, allowing more protein to make it to the small intestine to be digested for growth. Ionophores can decrease the chance of bloat. Ionophores also act in the rumen to reduce methane production, improve dry matter use and nitrogen digestibility, thus decreasing environmental waste. Ionophores improve calf health and performance by decreasing disease and improving feed efficiency.