Beef producers should consider adding monensin – its trade name Rumensin – to grain supplements for winter forages. It improves beef-cow feed efficiency by 10-15%, says Justin Sexten, University of Missouri Extension beef nutritionist.

“That’s like feeding hay for 90 cows to 100 cows,” Sexten says. “It improves digestion of poor hay. Adding Rumensin to grain fed to cows on winter hay makes economic sense.”

The additive also controls coccidiosis, a disease caused by intestinal parasites that may not show symptoms in cows but can be deadly to weaned calves. Its recommended rate for beef cows is 200 milligrams per head per day, mixed into 1 lb of grain to be fed every day, according to the label.

Monensin is an ionophore that changes the microbial mix in the cow’s rumen and cuts methane production.

“For an easy way to use the supplement, ask your feed dealer to mix it with a grain ration,” Sexten says. “It gives a low-cost gain in feed efficiency. A daily dose costs about 1.8 cents. After adding mixing cost, the treatment costs about 2.5 cents a day.”

Don’t feed grain that containd monensin to horses, as it can be fatal to them.