Dozens of horses died at an Oklahoma rodeo stock contracting company after a toxic substance was found inside the feed, according to preliminary tests. | MORE | Investigation underway into what killed dozens of Oklahoma horsesAn estimated 40 to 70 horses have died at Beutler & Son Rodeo Company out of Elk City, which has supplied horses to rodeos all across the country for nearly a century. Livestock Nutrition Center, a company that supplies livestock feed across multiple states, said preliminary tests showed that a load of feed delivered to Beutler & Son Rodeo Company contained monensin, which can be toxic to horses. The incident likely occurred due to a failed cleanout procedure and a sensor malfunction, the feed supplier said in a statement. "We have confirmed this is an isolated incident to this single load of feed from a single facility and no other feed has been impacted and is safe for animal consumption," Ronnie Castlebury, the president of Livestock Nutrition Center, said in the statement. The feed supplier is working with the State Department of Agriculture in Oklahoma and Kansas, as well as the Food and Drug Administration to get to the root cause of the problem and take "any and all corrective actions needed," according to the statement. Get the latest news stories of interest by clicking here.The Oklahoma Department of Agriculture, Food and Forestry received word from a veterinarian on Aug. 23, of a potential issue relating to the single bulk feed order for Beutler & Son Rodeo Company. An inspector visited the ranch on Aug. 26, and found that the feed originated from Kansas. Livestock Nutrition Center has 20 locations in multiple states, including Kansas. "Words are cheap but we are dedicated to assist and support the Beutler family and make this right because our customers and employees expect and deserve it," Castlebury said in the statement. "Our deepest sympathies go out to Mr.'s. Benne and Rhett Beutler and family and everyone affected by the recent tragic event at their ranch. The loss of so many valued animals is devastating."The loss of horses ravaged the rodeo stock company, with lines of generational horses dying. Beutler & Son Rodeo Company was also the main supplier of livestock to the Elk City Rodeo of Champions.The Professional Rodeo Cowboys Association announced that stock companies have stepped up to fill the need left after Beutler & Son Rodeo Company's loss. The rodeo, which began on Friday, was able to go on as planned, and it will end on Sunday. Top HeadlinesLifeguards at South Carolina beach clear water after shark sighting as Labor Day weekend beginsFans celebrate late country music icon Toby Keith during Sooners opening gameOHP: Two dead after separate drownings in Oklahoma lakesOklahoma City park stripped of copper, leaving residents without a place to cool off for Labor Day weekendSchool districts respond to Ryan Walters new guidelines over American flag, Pledge of Allegiance