The Use of Rumensin in Pasture Minerals

By Steve Sachtleben, PhD, PAS – KNG Beef Research and Nutrition
The ionophore Rumensin® (monensin sodium) has been cleared for use in beef cattle for over 35 years. Depending on the feeding situation, the FDA has approved claims in beef cattle for improved feed efficiency, increased rate of weight gain, and the prevention & control of coccidiosis caused by Eimeria bovis and Eimeria zuernii.

For beef cattle on pasture, there is an FDA approval for a free-choice mineral that includes Rumensin. This universal formula is available to all feed suppliers but the nutritional fortification is outdated and would lack the “groceries” needed in today’s pasture situations and genetic pools. Therefore, if this free- choice mineral is not adequate, FDA regulations require us to use “force-fed” products to deliver exact amounts of Rumensin daily or every other day.

This force-fed product must be mixed or formulated into a feed and fed at no less than 1.0 pound per head per day. It must provide no less than 50 mg nor more than 200 mg per head per day. During the first five days, cattle should not receive more than 100 mg of Rumensin in less than 1.0 pound of feed.

As most beef producers offer their cows a free-choice mineral, that method would seem the vehicle to provide the ionophore. However, non-FDA approved minerals must be force fed in no less than 1.0 pound of mixed feed. That feed can be a totally mixed ration (TMR), corn, gluten, silage, distillers, etc.

Framework 365 ADE will be KNG’s delivery vehicle. It will provide 1600 grams of Rumensin per ton of ADE mineral or 200 mg per four ounces of mineral. That four ounces of ADE must be mixed and fed to the animal in no less than 1.0 pound of feed. The ADE mineral with Rumensin cannot be fed free-choice. That would be illegal.