Always read and follow lable directions. Rumensin is the trade name an ionophore available for producers to use from Elanco Animal Health. It is approved to improve feed efficiency and for the prevention and control of coccidiosis. For cattle fed in confinement (this is important - in confinement) to improve feed efficiency it is fed continuously in complete feed at a rate of 50 to 360 milligrams per head per day [21 CFR 558.255 (f)(3)(i)]. You likely need to be in the 280 mg/hd/da to 360 mg/hd/da when feeding a diet to cull cows destine for slaughter using high energy diets.

The level of ionophore response will be contingent on the energy concentration of the diet. If the diet contains less than 47% TDN you should not expect much response. As the energy content of the diet increases the ionophore response should increase.

For prevention and control of coccidiosis caused by Eimeria bovis and Eimeria zuernii it can be fed at a rate of 0.14 to 0.42 mg/lb of body wt/day and this depends on the severity of the challenge [21 CFR 558.355(f)(3)(vii)].