Ionophores: 50 years and going strong

Ionophores have been highly significant in the growth of the global poultry meat industry in the 20th and 21st centuries.

During this time, the global human population has risen from around 2 billion in 1920, to approximately 7.5 billion in 2017. Significant contributing factors to this growth include improved healthcare, infrastructure and food availability1.

The increases in food availability includes a proliferation in global poultry meat production. In 1961, 8.9 million tonnes of poultry meat was produced globally. By 2013, this figure had increased to around 110 million tonnes. No other meat sector has come close to matching this expansion2. The result is that in many parts of the world, poultry meat has become an everyday commodity.

The rapid expansion of the poultry meat sector was kick-started in the 1950’s with the introduction of the Vantress White Cornish bird. Prior to this, poultry meat was essentially a by-product of the egg industry. Since this time, improvements in production systems, genetics, nutrition and disease management have contributed to the ongoing progression3.

When considering disease management, coccidiosis represents a significant challenge.

Coccidiosis is a disease associated with the parasite, Eimeria. This parasite is resilient and reproduces rapidly, especially in the ideal conditions of the modern broiler house. Infection severity varies from depressed performance to death4.

Birds develop immunity to Eimeria, however, this takes several lifecycles of the parasite to become established. For modern, fast growing poultry, this delay in immunological development represents a substantial proportion of their lives and consequently, high parasite numbers and a lack of immunity can have a dramatic impact on both birds and producers alike5. Fortunately, ionophore anticoccidial molecules have been discovered to help mitigate this problem.

Lasalocid was first to be identified in 1951. However, it was Monensin that was first to be made commercially available in 1971, subsequent to its discovery in the laboratories of Eli Lilly and Company. Monensin revolutionised the control of coccidiosis in poultry production and it remained an important molecule for many years6. Other commercially viable ionophores were found in quick succession; Salinomycin in 1973, Narasin in 1978 and Maduramycin in 19847, 8, 9. Subsequent ionophore discoveries have shown potent anticoccidial activity, however, in many cases, their use has been limited by unacceptable side effects10.

In 1980 an unexpected, yet hugely significant discovery was made. Combining ionophores with nicarbazin produced greater anticoccidial activity than would be expected from simply adding these individual components together. These synergistic combinations, or ‘potentiated ionophores’, allowed lower inclusion rates of both constituents, thus overcoming negative effects that can be seen with both compound types at higher dose rates7. In 1987, a narasin and nicarbazin combination was shown to have the most potent anticoccidial effect, when compared to other ionophore/nicarbazin formulations6. This combination was subsequently licenced [as Maxiban]and released globally in the early 1990’s.

Ionophores and potentiated ionophores have remained the anticoccidials of choice for the majority of the global poultry industry, due to their ongoing potency and minimal adverse effects11. Without them, the global poultry industry and indeed the world’s protein supply would be very different.


  1. Bavel J.V. (2013). The world population explosion: causes, backgrounds and Projections for the future. FVV in ObGyn, 2013, 5 (4): 281-291
  2. Ritchie H. and Roser M. (2017). Meat and Seafood Production & Consumption. org. Available at:
  3. Farmers weekly (2014). Poultry production through the ages. Available at:
  4. Hernandez-Velasco, X., et al. 2014. Absorption and deposition of xanthophylls in broilers challenged with three dosages of Eimeria acervulina oocysts.  British Poulty Science.  55: 167-175
  5. Kadykalo S. et al. (2018), The value of anticoccidials for sustainable global poultry production, International Journal of Antimicrobial Agents, doi: 10.1016/j.ijantimicag.2017.09.004
  6. D. Chapman, T. K. Jeffers, R. B. Williams (2010); Forty years of monensin for the control of coccidiosis in poultry, Poultry Science, Volume 89, Issue 9, pp 1788–1801
  7. Callender et al, (1980). Anticoccidial combinations and the polyether antibiotics. United States Patent 4,218,438
  8. Kantor S. et al. (1984). CL 259,971: A Potent New Polyether Anticoccidial. 2. Floor-Pen Trials. Poultry Science 63:1506-1511
  9. Mitsuaki Mitani et al (1975). Salinomycin: A new monovalent cation ionophore. Biochemical and Biophysical Research Communications. Vol 66, Iss 4, pp 1231-1236
  10. Kevin D., Meujo D., and Hamann M. (2009). Polyether ionophores: broad-spectrum and promising biologically active molecules for the control of drug-resistant bacteria and parasites. Expert Opin Drug Discov. 4(2): 109–146
  11. Jeffers T.K. (2013). Anticoccidial combo of nicarbazin ionophore. Feedstuffs. Vol. 85, No. 21, May 27, 2013

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