Under a settlement with state officials, Western Milling, LLC, will stop producing horse and specialty feeds at its Goshen manufacturing plant and pay $526,500 in fines after feed produced there killed and sickened dozens of horses and cows.

In addition, the company will invest more than $200,000 to buy new manufacturing equipment to elevate its food-safety measures above industry standards, the California Department of Food and Agriculture (CDFA) Feed and Livestock Drugs Inspection Program announced this week.

The agreement follows an investigation by the agency following the deaths in late 2015, which officials determined were caused by a medicated poultry feed additive, monensin, getting mixed in with Western Milling’s cow and horse feeds also manufactured in Goshen.

While beneficial to some poultry and cattle, the antibiotic can be toxic to horses.

In late September 2015, Western Milling voluntarily recalled 1,100 50-pound bags of its Western Blend horse feed after learning horses had died and tests of the feed by the U.S. Food and Drug Administration raised concerns the feed might be the cause.

Several of the horses affected were stabled at Black Fence Farm, a horse boarding and training facility in Clovis. Initial reports in February of last year were that 13 horses had died after eating Western Milling feed and 34 experienced a variety of ailments, including one that suffered a heart attack but survived.   

“In 2016, the same facility improperly mixed the same livestock drug into medicated cattle feed, which contributed to the deaths of several dairy calves,” states the CDFA press release, which doesn’t disclose the number of animals killed and sickened by eating the tainted feed or where those incidents occurred.

But Western Milling’s problems with cross contamination of feed ingredients goes back further, as the Food and Drug Administration’s website shows Western Milling voluntarily recalled horse feed twice in 2011 after state inspectors found monensin in them.

The site also discloses recalls of what was supposed to be non-medicated turkey feed in 2010 and 2011 after monensin was discovered.

Officials at Western Milling didn’t immediately respond Wednesday to an interview request, and CDFA officials didn’t respond immediately to requests seeking more information about how the cross contamination occurred and specifics on what the company will have to do to sufficiently elevate its food-safety standards.

The agreement includes discontinuing production of specialty feeds, those for animals that aren’t major livestock species, including rabbits, but a CDFA official contacted couldn’t immediately provide the list of specialty feeds affected and why Western Milling no longer can make them.

There were reports of several horses sickened at Ross Equestrian, a horse-riding school in Temecula, but its operators couldn’t be immediately reached Wednesday, and a call to Black Fence Farm wasn’t immediately returned.

Calls to lawyers representing owners of at least two dozen horses killed or injured by the contaminated feed also weren’t immediately returned to determine the status of lawsuits filed against Western Milling.