Zearalenone is structurally similar to estradiol, giving it estrogenic properties. Animals consuming this toxin may exhibit a variety of reproductive problems.

Zearalenone is produced primarily by Fusarium graminearum, but can also be produced by numerous other Fusarium species, including F. culmorum, F. verticillioides, F. avenaceum, F. tricinctum, Fusarium oxysporum, and F. nivale.

Zearalenone occurs most commonly in corn and wheat, but it has also been detected in oats, rice, rye, sorghum, and barley. It occurs worldwide. Production of zearalenone is favored by warm days with cool nights.

The U.S. Food and Drug Administration has no regulations or guidelines on zearalenone in animal feeds.

Zearalenone toxicity causes a variety of reproductive issues, including vaginitis, vaginal secretions, abortions, infertility, and mammary gland enlargement in virgin heifers. No sequestering agents are available for zearalenone, so the only treatment is removal from the contaminated feed. Clinical symptoms of zearalenone toxicity should improve within two to eight weeks after removal of contaminated feed. In the ruminant, zearalenone can be metabolized to α- and β-zearalenol, which can have more potent estrogenic activity if absorbed into the system.

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Hascheck, W.M, C.G. Rousseaux, and M.A. Wallig. 2010. Fundamentals of Toxicologic Pathology, 2^nd ed. London: Elsevier Inc.

Mostrom, M.S. 2011. “Zearalenone Toxicosis.” In Clinical Veterinary Advisor: The Horse, edited by D.A. Wilson, 655–656. London: Elsevier Inc.