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Ingestion of Moldy Feedstuffs Can Lead to Fumonisin Toxicity in Horses

By Donald Stotts

STILLWATER - Horse managers who use corn and corn products in equine rations should check with their suppliers to make certain the suppliers' mills are conducting routine tests for fumonisin in their corn products, according to an Oklahoma State University animal scientist.

Fresh, non-moldy feedstuffs are essential for horse rations, as horses are susceptible to health problems caused by ingestion of many known types of molds.

"One type of mold that is causing problems right now is fusarium, which produces the mycotoxin fumonisin," said Dave Freeman, Oklahoma Cooperative Extension Service equine


Freeman said problems with fumonisin have been attributed to ingestion of moldy corn and corn products, especially corn screenings.

"It's not enough for horse managers to just examine equine rations; some problems related to fumonisin cannot be detected visually," Freeman said. "Horse managers need to be sure their suppliers' mills are conducting routine tests for fumonisin in their corn products."

Ingestion of fumonisin leads to a number of clinical symptoms in a horse, most related to neural dysfunction as evidenced by abnormal behavior, loss of motor control and loss of appetite.

"Fumonisin toxicity is almost always fatal to the horse by the time symptoms are observed," Freeman said.

Freeman said horses are among the livestock specie most susceptible to health problems from fumonisin ingestion, making recommendations about "safe intake levels" difficult.

The presence of fumonisin can be detected through various tests; some can be used on-site by feed mills, while others require samples be sent to diagnostic laboratories.

Harvest conditions and shortages in grains may precipitate an increase in corn infestation with fumonisin this year, Freeman said.

"The prevalence of fumonisin-infected corn increases if corn products are harvested too wet, or are stored improperly or for too long a period," he said.

In addition to checking with suppliers to make sure mills are performing routine tests on corn products, horse managers also can help protect against fumonisin toxicity by using grain mixes which contain smaller-than-normal amounts of corn, or mixes which consist of feedstuffs other than corn.

"Lessening the amount of corn will reduce the potential for fumonisin toxicity, even though 'safe' levels cannot be defined," Freeman said.

Grain mixes should be stored in facilities which protect the grains from moisture. Routine cleaning of facilities also will help to decrease the incidence of mold growth or contamination of newly stored products.

"Do not store feed products for more than two weeks," Freeman said. "Most molds require a couple of weeks to grow, so maintaining a short turn-around time on grain mixes can be an easy yet effective management technique for combating contamination."

We would like to take this opportunity to thank Oklahoma State University for allowing us to provide you with this information.


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