Battle the Bad Bacteria

Your secret weapon? Ionophores

by Melissa Albertson

photo by Malloree Barnes

As you consider all the different products available to help increase the performance for your herd, you can’t ignore the proven benefits of feeding ionophores: improved feed utilization, increased gain, prevention and control of coccidiosis, and cost effectiveness. Even so, while ionophore use is extremely common in feedlot finishing diets, they still are an underutilized product in grazing operations.

“The beef business is about turning grass and feed into high quality beef,” says Dr. John Groves, a highly respected veterinarian in Eldon, Missouri, who specializes in beef cattle production medicine.  Groves encourages producers to use ionophores. “Any technology that makes that process more efficient makes sense on many levels.” 

Overview & Safety Considerations

Ask a rancher if they use an ionophore and you might hear, “An i-on-o-what?” But it’s not because ionophores are new to the beef industry. As a feed additive, ionophores were approved for use in feedlot cattle more than 35 years ago.  Since then, countless yards have benefited from the increased efficiency, improved rate of gain, as well as the proven coccidiostat function provided by ionophores in their rations.   

When feeding ionophores, it’s important to follow the recommended inclusion rates, which allow for use in beef cattle self-feeder strategies without concern for toxicity. However, they are not labeled as safe for other common livestock species, such as sheep, goats and especially horses.  This makes for an important caution for ranchers managing cattle and horses in a co-grazing situation.

“Horses are the most sensitive to ionophores, but all animals are susceptible,” says Groves. “This toxicity is usually well known, and the only time I have seen a problem in my 19 years of practice was associated with accidental direct feeding of a premix. Overall I consider them very safe, especially considering how long they’ve been used in the beef industry.” 


How Ionophores Work

Cattle digest feed in the rumen most efficiently when the levels of good and bad bacteria are well-balanced. Ionophores create this balance by killing bad bacteria that cause undesirable health conditions like acidodis and bloat.  A healthy balance of good bacteria allows feed to be metabolized more efficiently and contributes to the overall health of the animal.

This newly-created efficiency then tells the animal’s body it doesn’t have to eat as much to get the usable energy it needs.  Rather, it can be more satisfied on reduced feed intake. But whoa!  Instead of thinking of “less is less” (less intake - less gain - less profit), think “less is more” (less feed required - less costs - more profit.)  

Justin Sexten, a State Extension Specialist in Beef Nutrition with the University of Missouri-Columbia, explains it this way, “If you’re feeding a supplement every day, and can include an ionophore with this to get more out of your forages, then effectively it’s like taking 100 cows and making them 90 due to reduced maintenance requirements.”


Benefits & Considerations

Benefits of ionophore use in feedlot diets have long been established, but they also are common in stocker operations as well.  According to industry estimates, ionophores can increase average daily gains between 7-8% in stocker cattle – a net return of $10-$15/head in today’s market. In addition to stockers, Sexten sees the benefit of ionophores in a sometimes overlooked, but similar class of beef cattle – replacement heifers.

“Most everyone will have 20-25% of their cow herd in replacement heifers, which are managed much in the same way as a set of stockers,” says Sexten. “Research shows ionophores hasten puberty in replacement heifers, and this can be especially beneficial in continental-type cattle that are later maturing. You get feed efficiency, control coccidiosis, and as an added bonus, get earlier puberty. It’s just another way to try to get more bang for your buck.”

Ionophores also have benefits in breeding cattle, such as growing and developing bulls. Ken Holloway operates Coyote Hills Ranch headquartered in Chattanooga, Oklahoma.  Holloway has raised top-end Limousin cattle since the early ‘70s. He feeds his bulls an ionophore through a blended ration developed by his feed supplier, Livestock Nutrition Center. 

“I learned about ionophores many years ago and went to the nutritionist at Livestock Nutrition and told them I wanted to include it. They agreed it was a good idea and we’ve been using it since,” said Holloway. “You just don’t second guess yourself when you get good results.”

When producers ask Sexten to help create a nutrition plan for their cattle, one of his first questions is, “Do you feed an ionophore?” If the producer says no, his next is “why not?” because it reduces maintenance requirements and increases growth. He feels two primary reasons ionophores may be overlooked are awareness of the product and its cost-to-benefit ratio, as well as the perceived ease of including an ionophore in daily rations.

“If you buy a truckload of distiller’s grain, but don’t have good mixing capabilities, it’s unfeasible to properly mix in the small amount of an ionophore premix. This can result in intake problems and can be more trouble than it’s worth,” he says.

To make it easier, producers can have feed suppliers mix ionophores with their commodity/bulk pellet feed, or purchase a complete ration that includes an ionophore. Ionophores also can be added to free-choice mineral mixes, blocks and protein supplements, such as range cubes.

Jim White, a ruminant nutritionist for MFA Inc., a Midwest farm supply and marketing cooperative, likes to illustrate to customers the benefits of ionophores with this example:

Nutritionist: “What does a pound of corn cost?”
Customer: “Somewhere between 11 to 15 cents, depending who has it and where you want it.”

Nutritionist: “Would you buy corn if I sold it to you for 3 cents a pound?”

Customer: “Yes!”
Nutritionist: “Well, I don’t have corn that cheap, but for about 3 cents a pound, an ionophore is going to improve the energy value of your feed by about the same amount as a pound corn.”

Knowing the nutrient value in your forages is especially important for ionophores to work best. To see the benefit of the product, the proper nutrients must be available to your cattle – in that, ionophores can help maximize the pasture you have, but they cannot mask poor quality forages. 

“What ionophores do is set the body up to be more productive. Therefore, if you don’t provide the nutrients to the animal once you’ve added ionophores, you don’t get the payoff,” says Sexten. “Protein in the animal’s body needs to be at a certain level for optimal rumen fermentation. So, for example, in forages that go dormant or are overly mature, the nutrient value may not provide this level of protein, and this can hinder the effectiveness of the ionophore. In this case, you need to provide a protein supplement that helps the cattle get to that level to see the benefit from the ionophore.”

Adding an ionophore to your feeding strategy can help your cattle all the way around – in improved herd health and increased efficiency – which can mean more pounds of beef for more profit in today’s beef market. 

“Margins in the cattle business on a per head basis have shrunk over time,” says Groves. “If you choose to make your cattle approximately 10% less efficient by not feeding an ionophore, you better have a very good reason.”

Quick Glance at Ionophores


  • Improve feed efficiency
  • Increases gains
  • Reduces acidodis and bloat
  • Helps prevent and control coccidiosis


  • Toxic to horses – do not feed in co-grazing pastures
  • Will not treat a coccidiosis outbreak
  • Read label and follow the recommended inclusion rates
  • Unsure of best option – talk to an industry resource

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