Ionophores (most common is Rumension) are chemical compounds that are used as feed additives for cattle. They do a great job of improving cattle growth.
The downside of ionophores for a feed company is that it is toxic to horses: deadly toxic. There have been a couple of cases in the news of horses eating feeds that mistakenly had ionophores mixed into the feed, causing some serious problems. You may wonder "Could this happen to the feed I get from J & B?". The answer to that is that is would be highly unlikely. We do not mix any feeds with ionophores. We sell some, but those come to us already packaged and we do not run any of these products thru our mixers. You may wonder about the Purina Horse feeds we sell. Don't worry about that. Purina Mills has a feed mill in Milford Indiana that produces all the horse feeds for this area. That plant is a an ionophore free plant. They make no medicated feeds for any species at this plant. The same is true for the Buckeye Feed plant in Dalton OH.
So while I would never say we would never have a problem, the probability of having a problem is extremely low. I invite you to check out Purina Mills website, www.purinamills.com, and checkout the video they have put together on their FEEDGUARD NUTRITION SYSTEM.