Citation: Kioumarsi, H., Kioumarsi, S., & Mousavi Eshkelani, S.M. (2025). The Application of Monensin as a Feed Additive in Animal Nutrition. Research Communities by Springer Nature.
 https://communities.springernature.com/posts/the-application-of-monensin-as-a-feed-additive-in-animal-nutrition

Introduction

Monensin is a member of the associate polyether antibiotic ionophore class and acts as an animal growth promoter in some species. Monensin is an FDA-approved feed additive in 21 CFR § 558.355 for cattle, goats, and poultry for specific applications. Monensin is an ionophore antibiotic produced by a sub-species of Streptomyces cinnamonensis and has a positive effect on animal nutrition. It is also the most substantial rationale for the use of supplemental fat in ratio to increase dietary energy. Its applications cover enhancement of feed efficiency to disease prevention and thus having a vital role in contemporary animal husbandry and food production.

How it works

Monensin's action is primarily brought about by altering the fermentative patterns of the rumen by selectively inhibiting Gram-positive bacteria, which optimizes ruminant animal energy metabolism. The drug increases propionate synthesis at the expense of carbon dioxide and methane, optimizing dietary energy to animal growth or lactation yield. Its signature ionophore activity enables the exchange of sodium and potassium ions across microbial cell membranes, resulting in improved feed efficiency and minimal loss of ruminal nitrogen.

Beef and Dairy Cattle

Monensin has been broadly used in beef production to enhance feed efficiency. When supplemented to feed provided to pen-restricted cattle, it typically reduces Dry Matter Intake (DMI) by and improve the growth rate and efficacy. These advantages have always been sustained by multiple meta-analyses, which continue to refine performance measures. In addition to this, these gains help to lower overall input costs in beef production. Monensin is commonly administered routinely in the form of a controlled-release capsule in Europe, primarily to high-risk cows for ketosis. Clinical trials and meta-analyses all indicate strong antiketotic activity, e.g., reduced blood β-hydroxybutyrate concentrations and improved liver function, leading to fewer peripartum health issues.

Poultry and Other Animals

Due to its ability to inhibit protozoa, monensin is continually incorporated into broiler and layer chicken diets as a coccidiostat to prevent coccidiosis and related losses. Its antimicrobial property enables healthier flocks and improved productivity, resulting in higher returns to the producer. Comparative research with other antibiotics, such as virginiamycin, are increasingly explaining its effect on rumen fermentation and animal performance.

Safety

The global regulatory bodies have laid strict limits on monensin usage to ensure animal safety and prevent residue contamination in animal-derived products. In the United States, the maximum permissible dosage for finishing beef cattle is 480 mg per head per day, roughly 1 mg/kg body weight. Research confirms that monensin is poorly absorbed at recommended doses, thereby causing little potential for residue in milk or meat. In regions like the European Union, use in dairy cattle is restricted to specific pharmaceuticals in a bid to offset potential dangers. There are also rules and regulations for the use of monensin in other animals.

Environment and climate changes

Climate actions are important given the rapid changes brought upon by climate change. Monensin is somehow environmentally friendly by decreasing methane emission in ruminants. It changes rumen patterns of fermentation to enhance propionate formation and suppress methanogenesis, enhancing feed efficiency and lowering the ecological footprint of livestock farming. In fact, the application of monensin in animal feed plays a vital role in supporting climate action and net-zero emission strategies. Research has proved that supplementing cattle with monensin reduces enteric methane production without affecting feed intake and productivity levels. Through increased efficiency in feeding and suppressing methane outflows, monensin promotes more efficient animal husbandry that is aligned with global efforts in curbing climate change and attaining net-zero in agriculture.

Limitations

While shown to have benefits, extended monensin use is of concern for microbial resistance in the rumen. Sustained use can destabilize the microbial ecosystem of the rumen, potentially reducing long-term performance and causing cross-resistance to other antimicrobials. Moreover, sustained regulatory pressure on ruminant growth promoters has led to prohibition or restriction in some countries. Monensin use must therefore always be within available residue levels and animal welfare legislation.

Conclusion

Monensin use in animal feeding schedules offers unprecedented benefits in terms of livestock health, productivity, environmental preservation, and economic efficiency. Extensive survey of literature testifies to its effectiveness for improving feed conversion, preventing disease, and minimizing production loss. For ensuring maximum benefit with respect to animal welfare and food safety, rigid compliance with recommended dosing, appropriate treatment duration, and stringent regulatory compliance are essential. However, further research is also needed in this area.

References

Dellaqua, J. V. T., Rigueiro, A. L. N., Silvestre, A. M., Pereira, M. C. S., Felizari, L. D., Demartini, B. L., Dias, E. F. F., Silva, L. A. F., Casali, D. M., Souza, K. L. R., Souza, J. M., & Millen, D. D. (2024). Impact of combined management strategies of monensin and virginiamycin in high energy diets on ruminal fermentation and nutrients utilization. Frontiers in veterinary science, 11, 1325198. https://doi.org/10.3389/fvets.2024.1325198

Khorshidi, K. J., Karimnia, A., Gharaveisi, S., & Kioumarsi, H. (2008). The effect of monensin and supplemental fat on growth performance, blood metabolites and commercial productivity of Zel lamb. Pakistan Journal of Biological Sciences, 11(20), 2395–2400. https://doi.org/10.3923/pjbs.2008.2395.2400

Luo, J., Jiang, J., Duan, H., Zhang, H., Sun, M., Mao, S., & Shen, J. (2024). Comparative effects of nisin and monensin supplementation on growth performance, rumen fermentation, nutrient digestion, and plasma metabolites of fattening Hu sheep. Frontiers in veterinary science, 11, 1441431. https://doi.org/10.3389/fvets.2024.1441431

Mammi, L. M. E., Guadagnini, M., Mechor, G., Cainzos, J. M., Fusaro, I., Palmonari, A., & Formigoni, A. (2021). The Use of Monensin for Ketosis Prevention in Dairy Cows during the Transition Period: A Systematic Review. Animals : an open access journal from MDPI, 11(7), 1988. https://doi.org/10.3390/ani11071988

Ribeiro, R. V., Torres, R. de N. S., Baldassini, W. A., Chardulo, L. A. L., Tedeschi, L. O., & Machado Neto, O. R. (2025). A meta-analysis of the effects of monensin supplementation on beef cattle performance, digestion and ruminal parameters in three feeding systems. Animal Feed Science and Technology, 324, 116301. https://doi.org/10.1016/j.anifeedsci.2025.116301

Rosen, A. R., Kioumarsi, H., & Gholipour Fereidouni, H. (2025). Climate action and net-zero emissions. European Journal of Sustainable Development Research, 9(4), em0334. https://doi.org/10.29333/ejosdr/16864