Cow Calf Producers…Are You Missing Out On EFFICIENCY?

By : Jill J. Dunkel

Supplementing cows for proper nutrition throughout the year is a balancing act between cost, feed and available grazing. Weather, forage conditions and the stage of production for the herd are also major factors.

If a feed additive was available that could reduce forage intake in the cow herd by 8 to 10 percent without reducing performance, would you be interested?

Most ranchers would perk up at that possibility, and ask what is the name of this new supplement on the market. But the fact is, it’s nothing new. It’s monensin, also known as Rumensin.

Ionophores have been around for decades but are more widely known for use in feedlots and growing rations. However, the concept is gaining in popularity in the cowcalf sector.

Nutritionist Levi Trubenbach, Ph.D., with Livestock Nutrition Center, says there is significant data that shows feeding an ionophore to cows reduces their voluntary intake of forage. That can be hay, pasture, corn stalks, etc.

“We conservatively estimate an 8 to 10% reduction in forage intake, without reducing body condition or performance.” Depending on the scenario and location, that can mean several things for a producer.

“It could mean an increase in stocking rate,” he said. “It could mean feeding less hay in the winter, or maybe conserving forage for a secondary stocker enterprise. During a drought, it can help cows perform under conditions with limited forage availability. It’s a big deal.”

David Lalman, Ph.D., Extension Beef Cattle Specialist with Oklahoma State University looked at feeding strategies during a drought, and considered the scenario of limit feeding concentrate diets to beef cows as an alternative to feeding hay.

“In years when hay and forage production is low due to drought, hay prices often escalate,” his research states. “In severe cases, forage may be hard to obtain.” In this scenario, limit feeding concentrates with a very limited amount of roughage is an option.

As part of Lalman’s management tips in a limit feeding scenario, he recommends feeding an ionophore to help prevent acidosis and bloat,  and says that the ionophore will help reduce the amount of feed needed by 7 to 10 percent.

Rumensin is the only ionophore currently labeled to feed cows.

Elanco Beef Cattle Technical Consultant Sara Linneen Ph.D., says. “If the cow is in a physiological stage of production to gain weight, Rumensin will improve daily gain, or the improvement can be increased feed efficiency.”

Considering the cost of the ionophore is approximately 2 cents/cow/day, the return on investment is about 200% if fed half the year, based on improvements in feed efficiency of between 5-10%, Linneen says.

Studies also show an advantage when the ionophore is fed to replacement heifers, with no negative impact on the reproductive performance. In fact, the ionophore-fed heifers reached first estrus faster.

The Value of Supplementation Total feed cost savings per cow with Rumensin during a 112-day supplementation period to increase BCS from 4 to 51

1Lalman, OSU Cowculator v 2.0. Beef Cow Nutrition Evaluation Software. Oklahoma Cooperative Extension Service. CR-3280. Feed requirement data to generate the values in chart are based on the example calculations from the Cowculator. Hay and supplement prices reflect past, present and future cost per ton held at a constant ratio of hay to supplement cost.


Increased feed efficiency is not the only benefit to feeding an ionophore to beef cows. There are health considerations as well, like coccidiosis control, Linneen explains. “Similar to how it works in the stocker and feeder industry, feeding the ionophore will control coccidiosis by killing the bug at three different points in the digestive tract. That also may translate to coccidiosis control for the calf,” she says.

Coccidiosis is shed in the feces, so if a producer is calving in confinement or has baby calves laying around feces possibly in a feeding area, feeding an ionophore to cows may provide a cleaner environment for the calves.

Typically thought of as a feed additive in a total mixed ration, an ionophore can be added to various feeding programs for beef cows.

“It can be formulated to be fed in a cake supplement or anything you hand feed, a block, a mineral or a tub as long as it is hand-fed (not provided free choice),” Linneen says. Monensin is also approved in a liquid form and can be sprayed on roughage. That scenario is most common where producers are processing bales of hay into windrows for cows.

Caution needs to be used in certain settings where horses are grazed with cows since ionophores are toxic to horses.

However, Trubenbach says the ionophore is something producers should really look at adding to their feeding programs. “It adds a lot of value to a diet. I formulate lots of different supplements, complete feeds and premixes, and I almost always recommend an ionophore.”

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