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Feeding Moldy Hay, Acreage Insights for December 2017,
Photo from Minnesota Extension

Moldy hay - no matter how hard you try, eventually you have mold in some of your hay and need to decide about feeding it. Feeding moldy hay to livestock is a tough decision. Although all hay contains some mold, when mold becomes noticeable the decisions become important.

Problems with Moldy Hay
Usually, mold makes hay less palatable, which can result in lower intake or in animals refusing to eat the hay. Many other problems from mold occur because of mycotoxins produced by certain mold fungi. This also is part of the decision problem since not all molds produce mycotoxins and the amount produced by those that do is unpredictable.

Health Effects
Direct negative effects of moldy hay are difficult to document. Horses may be the most sensitive to mold among common livestock. For instance, mold spores often contribute to respiratory and digestive problems like colic or heaves in horses. Cattle apparently are less affected by mold, but certain molds can cause mycotic abortions or aspergillosis. People, too, can be affected by mold spores. Mold can cause a condition called farmer’s lung, where the fungus actually grows in lung tissue. So try to avoid breathing in many of these spores.

Management Decisions
The best course of action often is to minimize feeding moldy hay to more sensitive animals, like horses or pregnant cows. This may require a keen eye or sensitive nose when selecting hay to feed each day. Mixing moldy hay with other feedstuffs can dilute problems sometimes, but be careful that you don’t make your animals sick by tricking them into eating bad hay that they normally would refuse.

Mold is a difficult problem to deal with. Common sense and good observation often are your best decision aids. 

Image of Bruce Anderson
Bruce Anderson
Extension Specialist - Forage

Bruce is a professor of agronomy with the University of Nebraska - Lincoln Department of Agronomy & Horticulture. His specialty is beef systems, including sustainability, profitability, quality, wholesomeness, and health & well-being. Bruce's extension efforts focus on grazing systems, pasture utilization, grazing management, warm season grass pastures, alfalfa production & marketing, grazing maize and other forages.

Bruce is located at:
University of Nebraska - Lincoln
Department of Agronomy and Horticulture
314 Keim Hall
Lincoln NE 68583-0915

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