Submitted to: Proceedings of American Registry of Professional Animal Scientists
Publication Type: Proceedings
Publication Acceptance Date: September 1, 2007
Publication Date: October 25, 2007
Citation: Russell, J.B. (2007). Ruminal ionophores, mechanism of action, resistance and the future. Proceedings of American Registry of Professional Animal Scientists (ARPAS) Continuing Education Conference, p 1-10 Coalinga, CA (October 25-26, 2007). Technical Abstract: Ionophores are antibiotics that have an unusual mode of a action that dissipates ion gradients across the cell membranes of sensitive bacteria, and they have been used as feed additives for more than 30 years. Ionophores inhibit bacteria that produce hydrogen, a precursor of methane and bacteria that deaminate amino acids. These effects increase energy and amino acid availability to the animal. Ionophores can also modulate feed intake and inhibit lactic acid producing bacteria. Only some animals can be safely fed ionophores, and ionophores have never been used as antibiotics for human therapy. Many ruminal bacteria are resistant to ionophores even if ionophores are not fed. There is little evidence that ionophore resistance confers an increased resistance to other classes of antibiotics or that ionophore resistance can be spread from one bacterium to another.