Page 1123 - Veterinary Toxicology, Basic and Clinical Principles, 3rd Edition

VetBooks.ir Chapter 76

Zearalenone

Ramesh C. Gupta, Michelle S. Mostrom and Tim J. Evans

INTRODUCTION corn continued, eversion of the uterus, secondary infec-
tions, and death occurred. Mirocha et al. (1971) noted
Zearalenone is a nonsteroidal estrogenic mycotoxin
high death losses in some herds and hypothesized that
produced by several species of Fusarium fungi. The pri-
mortality was related to vaginal and rectal prolapses and
mary producer of zearalenone is Fusarium graminearum
subsequent septicemias; however, the presence of addi-
(teleomorph Gibberella zeae). Additional Fusarium
tional mycotoxins could not be excluded in causing death.
fungi capable of producing zearalenone include F. cul-
Stob et al. (1962) isolated an active metabolite with utero-
morum, F. verticillioides (F. moniliforme), F. sporotri- trophic and anabolic activities from culture of G. zeae
chioides, F. semitectum, F. equiseti,and F. oxysporum.
(F. graminearum).
Contamination of cereal grains by zearalenone has been
The Fusarium compound found in corn with utero-
reported worldwide, primarily in temperate climates.
trophic activity was named zearalenone, previously
Typically, zearalenone concentrations are low in grain
known as F-2, and is chemically described as 6-(10-
contaminated in the field, but increase under storage
hydroxy-6-oxo-trans-1-undecenyl)-β-resorcylic acid lac-
conditions with moisture greater than 30% 40%.
tone (Fig. 76.1). At least seven derivatives of zearalenone
Zearalenone has major effects on reproduction in
have been found that naturally occur in corn. Zearalenone
females (as evidenced by hyperestrogenism), but it
and uterotrophic active derivatives were classified as
affects the male reproductive system as well. Prepubertal
estrogens in the sense that they produce estrus or cornifi-
swine are the most sensitive species. Typical clinical
cation of the vagina of adult mice (Mirocha and
signs of hyperestrogenism are swelling of the vulva,
Christensen, 1974). Zearalenone can be produced on
increase in uterine size and secretions, mammary gland
numerous substrates, including wheat, barley, corn, corn
hyperplasia and secretion, prolonged estrus, anestrus,
silage, rice, rye, sorghum, and occasionally in forages.
increased incidence of pseudopregnancy, infertility,
Production in soybeans is uncommon. Moisture content
decreased libido, and secondary complications of rectal
and the presence of oxygen are critical factors for zearale-
and vaginal prolapses, stillbirths, and small litters.
none production. In laboratory cultures, Fusarium growth
Recent reports suggest that zearalenone is also a signifi-
occurs during a 3-week period at moisture levels over
cant human health concern (EFSA, 2011; Belhassen
20% and temperature between 20 C and 25 C. If the
et al., 2014; Mally et al., 2016). This chapter describes
fungus is stressed by cool temperatures of 8 15 C for
toxicity of zearalenone and its major metabolites in
several weeks, zearalenone can be produced. Production
animals.
of zearalenone in the field is similar to that in the labora-
tory, with alternating moderate and low temperature
weather capable of stimulating zearalenone production.
BACKGROUND
Zearalenone can be produced fairly quickly in the field
Estrogenism in swine was reported in the mid-1920s in during wet weather in the late summer or early fall fol-
the Midwestern United States (McNutt et al., 1928). A lowing hail damage to corn. Very high concentrations of
condition of swelling and eversion of the vagina in young zearalenone, which can occur naturally in some field sam-
gilts and swelling of the prepuce in males was associated ples, generally result from improper storage at high mois-
with consuming moldy corn. Prolapse of the vagina and ture rather than production in the field. Corn stored in a
occasionally the rectum were noted as secondary effects. crib and exposed to winter weather was particularly prone
With replacement of the moldy corn with clean corn, the to fungal invasion and production of zearalenone. In addi-
animals recovered to normal, but if exposure to moldy tion to the cooccurrence of other estrogenic metabolites,
Veterinary Toxicology. DOI: http://dx.doi.org/10.1016/B978-0-12-811410-0.00076-3
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