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Zearalenone

source: http://www.ansci.cornell.edu/plants/toxicagents/zearalenone.html

Mycotoxins produced by Fusarium spp. are of two general types: 1) the nonestrogenic trichothecenes, including DON, nivalenol, T-2 toxin, and diacetoxyscripenol, and 2) the mycoestrogens, including Zearalenone (ZEN) and zearalenol . Zearalenone and zearalenol are both estrogenic resorcylic acid lactone compounds produced by the fungi Fusarium spp. (Diekman and Green, 1992)

Despite their structural dissimilarity to the steriodal estrogens, ZEN and several of its derivatives possess estrogenic activity. ZEN undergoes a folding such that hydroxyl or potential hydroxyl groups become appropriately orientated to facilitate binding to tissue receptors that normally bind estrogens. Similar binding affinities for ZEN have been determined for the estrogen receptor in sheep and calf uterus.(Diekman and Green, 1992)

Poultry show little reaction to ZEN ingestion. However, swine are strongly affected with symptoms in prepubertal gilts including enlarged mammae, swelling of uterus and vulva, and atrophy of the ovaries. In severe cases, prolapse of the vulva and rectum may occur. Boars exhibit enlarge mammae and atrophied testes.(Flannigan, 1991)

Although cattle are not as sensitive to ZEN as swine, a few experiments have been done to determine whether ZEN affects performance of cattle. Infertility, reduced milk production, and hyperestrogenism in cows have been reported in association with ZEN. Hay containing 14 ppm of ZEN caused infertility in cattle. Holstein cows that consumed 25 to 200 ppm of ZEN for 42 consecutive days exhibited swollen and hyperemic external genitalia but had estrous cycles of normal lengths and normal ovulations. Enlarged mammary glands that exhibited secretory activity were reported in prepubertal heifers that consumed moldy corn with ZEN. Dairy cattle fed a ration that contained 385 to 1925 ppb of ZEN for 7 weeks had normal milk productin. No ZEN residues were found in milk, urine, serum or tissues. Corn that contained 500 ppb of ZEN had no effect on milk or butterfat production. (Diekman and Green, 1992)

Virgin dairy heifers fed 250mg of purified ZEN for three estrous cycles had an average conception rate of 62%, compared with 87% in control heifers. Nonlactating, nonpregnant dairy cows given 500 mg of ZEN daily for two estrous cycles had normal serum concentration of progesterone, normal mating behavior, and normal genital tracts. (Diekman and Green, 1992)

In vivo studies have revealed that ZEN is rapidly metabolized in animals and humans and eliminated mainly as water-soluble glucuronsides. Free and conjugated froms of ZEN have been found in the milk of lactating cows under experimental conditions. That high oral doses of the toxin are required to elicit such a response indicates that consumption of contaminated feed by dairy cows would not result in a health hazard to humans.(Wood, 1992)

References

Cheeke, P.R., (1995) Endogenous Toxins and Mycotoxinz in Forage Grasses and Their Effects on Livestock. J. Anim. Sci. 73:909-918.

Cheeke, P.R. and Shull, L.R. (1985) Mycotoxins (Chap. 12). In: Natural toxicants in feeds and poisonous plants. AVI. pp393-477.

Chu, S.F., (1992) Recent Progress on Analytical Techniques for Mycotoxins in Feedstuffs. J. Anim. Sci. 70:3950-3963.

Diekman, M.A. and Green, M.L., (1992) Mycotoxins and Reproduction in Domestic Livestock. J. Anim. Sci. 70:1615-1627.

Flannigan, Brian, (1991) Mycotoxins (Chap. 10). In: Toxic Substances in Crop Plants. The Royal Society of Chemists.pp226-257.

Price, W.D., Lovell, R.A. and McChesney, D.G., (1993) Naturally Occurring Toxins in Feedstuffs: Center for Veterinary Medicine Perspective. J. Anim. Sci. 71:2556-2562.

Richard, J.L., Bennett, G.A., Ross, P.F. and Nelson, P.E., (1993) Analysis of Naturally Occurring Mycotoxins in Feedstuffs an Food. J. Anim. Sci. 71:2563-2574.

Spainhour, C.B. and Posey, D. (1992) Mycotoxins: A Slient Enemy. Large Animal Veterinarian. Nov./Dec. Page 20-25.

Thompson, Larry. (1996) Lecture for PLPA 652 ('Mycotoxins')

Wood, G.E., (1992) Mycotoxins in Foods and Feeds in the United States. J. Anim. Sci. 70:3941-3949.

Wren, G., (1994) Blaming Mycotoxins Can Be A Risky Venture. Bovine Veterinarian. Nov. Page 4 -10.

source: http://www.oardc.ohio-state.edu/ohiofieldcropdisease/Mycotoxins/mycopagezearalenone.htm

Same text appears also on wikipedia; we don't know which one is the original

ZEARALENONE

Toxin Characteristics

Zearalenone, also known as RAL and F-2 toxin, is a potent estrogenic metabolite produced by some Fusarium species.

   

Several Fusarium species produce toxic substances of considerable concern to livestock and poultry producers: namely, deoxynivalenol, T-2 toxin, HT-2 toxin, diacetoxyscirpenol (DAS) and zearalenone.  

 

Crops and Weather Conditions

 

Zearalenone production does not seem to occur in significant amounts prior to harvest, but under proper environmental conditions, it is readily produced on corn and small grains in storage.

 

Alternating low and moderate temperatures in storage promote production of this toxin. Temperatures between 53-57° F induce the enzymes involved in biosynthesis of this toxic substance, and optimum production occurs at 81° F.

 

The toxin is heat-stable, and it is not destroyed by long storage, roasting, or by the addition of propionic acid or mold retardants.  

 

Impact on Animal Health

 

Zearalenone is the primary toxin causing infertility, abortion or other breeding problems, especially in swine.

 

When contaminated rations are consumed by animals, they develop a condition known as hyperestrogenism.

   

Swine are most sensitive to zearalenone.

Prepuberal gilts are more susceptible than mature swine.

Zearalenone has been associated with infertility and abortion problems in dairy cattle in the Midwestern U.S.  

 

Conception rates may be reduced in dairy heifers when fed greater than 12.5 ppm zearalenone.

 

Poultry in general are more tolerant than swine to zearalenone.

 

The Presence, Effect, and Diagnosis of  Zearalenone in Dairy Cattle

 Background                   

  Mycotoxins are toxic substances that are produced by fungal species.  These fungi can be found in a wide variety of plants and soil types.  Toxigenic fungi are thought to be ubiquitous in the environment.  Several characteristics are thought to be important for fungal growth, but the exact mechanisms of their proliferation are still unknown.  The mycotoxins of major importance in Indiana are zearalenone, aflatoxin, DAS (vomitoxin) and fumonisin.  Because the production of mycotoxins is strongly influenced by weather patterns and climates, the prevalence of each toxin varies with geographical location.

  Zearalenone is naturally produced by the fungus Fusarium roseum and by some isolates of Fusarium moniliforme.  Zearalenone is most commonly reported in the north central cornbelt of the United States and southeastern Canada.  Zearalenone’s estrogenic effects can be attributed to its complex chemical structure which makes it a phytoestrogenic molecule.  Phytoestrogens are estrogenic compounds produced by plants/fungi.  The fungus responsible for zearalenone production, Fusarium spp., has also been shown to produce the nonestrogenic toxins deoxynivalenol and T-2 under appropriate conditions.    Therefore, veterinarians and producers should be aware that mycotoxin contamination can be a multi-factorial problem.

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