Grazing Boost

Boost Animal Performance When Forages are Stressed

For producers already supplementing, ionophores offer an easy way to boost performance as forages become stressed.(Progressive Farmer photo by Mike Geissinger)

Whether you're trying to squeeze a profit from stocker cattle or help cows get every bit of good out of drought-hammered forages, ionophores can help.

"Research suggests ionophores improve animal performance in a grazing situation or feedlot," says Auburn University Extension animal scientist Kim Mullenix. "A rule of thumb is they improve gain 10%, almost the same as the increase from implants."

Mullenix says ionophores like Rumensin (monensin) and Bovatec (lasalocid) work by selecting for good bacteria in the rumen, bacteria that produce fewer waste products. That makes animals more efficient. Ionophores are also known for their ability to control bloat, coccidiosis and acidosis.

While they are most often used for young, growing animals, ionophores also work well for brood cows, helping them use the forage they consume more efficiently.

Mix It Up. In a grazing situation, Mullenix says ionophores can be fed in a mineral mix, a liquid supplement or as part of a complete feed.

"Ionophores are a fairly low-cost technology, especially if producers are already feeding supplemental feeds," she notes. "This [past] fall, producers had to go back to byproduct feeds because their winter grazing didn't come up, or they couldn't plant because of the drought. Ionophores are beneficial mixed with those byproduct feeds."

In a study at the University of Florida Institute of Food and Agricultural Sciences (UF / IFAS) Range Cattle Research and Education Center, in Ona, early weaned calves grazed dormant bahiagrass in the winter and received 2% of their body weight in supplement with 20 parts per million (ppm) of monensin added.

"The addition of monensin in the supplement resulted in a significant increase in average daily gain [ADG], from 1.7 to 2 pounds per day," UF / IFAS researcher Joao Vendramini says. When early weaned calves grazed annual ryegrass, the results were variable. However, there was a positive ADG response from monensin in two out of three years of research. Early weaned calves were supplemented with 1% of their body weight in feed, either with or without 20 ppm of monensin.

Camden, Alabama, cattleman Leo Hollinger feels Bovatec does increase feed efficiency of stocker cattle when they're grazing winter annuals. He buys it in a mineral pack and mixes it with grazing minerals, feeding the mix free-choice in mineral feeders. He also uses the ionophore when weaning calves, primarily as a coccidiostat. In addition, he says it helps prevent bloat. "The return on investment is good," he notes.

Read The Label. There are cautions against ionophores. Both Rumensin and Bovatec carry warning labels about feeding them to other species. Horses, especially, should not have access to them or any feed or minerals containing ionophores.

If ionophores are mixed with an antibiotic such as Aureomycin (chlortetracycline), neomycin, tylosin, virginiamycin or oxytetracycline, a Veterinary Feed Directive (VFD) is required for use. However, since neither monensin nor lasalocid are used in human medicine, a VFD isn't required when they are fed without other antimicrobials. Ionophores are classified as an antibiotic, but they aren't therapeutic antibiotics.

Another important note, Rumensin nor Bovatec are approved for use in USDA all-natural beef programs. Corid (amprolium) is approved for some natural beef programs, but it's only labeled for use as a coccidiostat, not a growth promotant.

For More Information:

• Application of Ionophores in Cattle Diets:…

• Bovatec:

• Rumensin:

• Veterinary Feed Directive: