A Legacy of Progress

Rumensin® has been helping cattle producers build their legacy for over 40 years. We pride ourselves on continuous innovation and research.Learn more about our legacy below.



  • Active ingredient monensin is first discovered


  • Rumensin® is approved by the FDA for feedlot cattle to improve feed efficiency
  • Rumensin 30 is introduced to help cattle producers improve feed efficiency
  • Elanco’s Feed Assay Service is first offered to producers, helping them to ensure proper levels of Rumensin are included in rations


  • Rumensin 60 is introduced with an improved granulated formula


  • Rumensin is approved for dairy and beef replacement heifers


  • Rumensin is approved for use in pasture animals and mature beef cows


  • Rumensin is approved for the prevention and control of coccidiosis in confined cattle and calves


  • Rumensin is approved for lactating and dry dairy cows to improve milk production efficiency*
  • Rumensin is approved in combination with Optaflexx®, Tylan® and Melengestrol Acetate (MGA)


  • Elanco Feed Mixing Study Service and Mixing Demonstrations are introduced to assist producers with proper feed mixing and ration uniformity


Elanco quality means consistent products, complete traceability, and absolute credibility and quality. Learn more about Clinton Manufacturing, our West Central Indiana site, and how Rumensin is made.

*Production of marketable solids-corrected milk per unit of feed intake.
Feeding Directions
Dairy cows: For increased milk production efficiency (production of marketable solids-corrected milk per unit of feed intake):
Total Mixed Rations (“complete feed”): Feed continuously to dry and lactating dairy cows a total mixed ration (“complete feed”) containing 11 to 22 g/ton monensin on a 100% DM basis.
Component Feeding Systems (including top dress): Feed continuously to dry and lactating cows a Type C medicated feed containing 11 to 400 g/ton monensin. The Type C medicated feed must be fed in a minimum of 1.0 lb of feed/cow/day to provide 185 to 660 mg/hd/day monensin to lactating cows or 115 to 410 mg/hd/day monensin to dry cows. This provides cows with similar amounts of monensin they would receive by consuming total mixed rations containing 11 to 22 g/ton monensin on a 100% DM basis.