|Edrington, Thomas - Tom|
|Genovese, Kenneth - Ken|
|Jung, Yong Soo|
|Nisbet, David - Dave|
Submitted to: Current Issues in Intestinal Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/27/2003
Publication Date: 7/20/2003
Citation: CALLAWAY, T.R., EDRINGTON, T.S., RYCHLIK, J.L., GENOVESE, K.J., POOLE, T.L., JUNG, Y., BISCHOFF, K.M., ANDERSON, R.C., NISBET, D.J. IONOPHORES: THEIR USE AS RUMINANT GROWTH PROMOTANTS AND IMPACT ON FOOD SAFETY. CURRENT ISSUES IN INTESTINAL MICROBIOLOGY. 2003. V. 4. P. 43-51. Interpretive Summary: Ionophores are antibiotics (not related to drugs used in human medicine) that are fed to cattle to improve growth. Ionophore use saves the U. S. cattle industry $1 billion each year. Research results suggest that the use of ionophore antibiotics to enhance livestock production efficiency will not contribute to the unwanted phenomenon of antibiotic resistance. Additionally, they appear to be inconsequential in regard to the occurrence of food borne pathogenic microorganisms in living animals or the meat products derived from these animals.
Technical Abstract: Ionophores (such as monensin, lasalocid, laidlomycin, salinomycin and narasin) are antimicrobial compounds that are commonly fed to ruminant animals to improve feed efficiency. These antimicrobials specifically target the ruminal bacterial population and alter the microbial ecology of the intestinal microbial consortium, resulting in increased carbon and nitrogen retention by the animal, increasing production efficiency. Ionophores transport ions across cell membranes of susceptible bacteria, dissipating ion gradients and uncoupling energy expenditures from growth, killing these bacteria. Not all bacteria are susceptible to ionophores, and several species have been shown to develop several mechanisms of ionophore resistance. The prophylactic use of antimicrobials as growth promotants in food animals has fallen under greater scrutiny due to fears of the spread of antibiotic resistance. Because of the complexity and high degree of specificity of ionophore resistance, it appears that ionophores do not contribute to the development of antibiotic resistance. Ionophore usage also does not appear to provide a competitive advantage to gram-negative food borne pathogenic bacteria. Therefore it appears that ionophores will continue to play a significant role in improving the efficiency of animal production in the future.