Ergot alkaloids are one of the oldest known mycotoxins and include the toxins associated with fescue toxicosis.
Species Producing Ergot Alkaloids
Ergot alkaloids are produced by species of Claviceps fungi, and fescue containing Neotyphodium or Epichloë fungi may produce the alkaloids associated with fescue toxicity.
Occurrence of Ergot Alkaloids
Ergot alkaloids are common on rye, dallisgrass, bahiagrass, and fescue. The type of grass may affect the severity of toxicosis (dallisgrass is worse than bahiagrass).
Regulation of Ergot Alkaloids
The U.S. Food and Drug Administration has no regulations or guidelines on ergot alkaloids in animal feeds.
Ergot toxicosis is affected by the source, amount consumed, period of exposure, stage of production, and age of the animal. Fall environments are more optimal for fungal growth, so exposure tends to increase during that time. Toxicosis may cause convulsion, incoordination, staggering, gangrene of the extremities, decreased reproductive performance, and decreased intake. In dairy cattle, decreased milk yield is observed and, although it is rare, abortions may occur. The only treatment is removal of toxic feeds. Because the toxin is located in the spores, deep-plowing fields is recommended because no-till will allow the spore to survive.
Fescue toxicosis is caused by consuming fescue containing the fungus within the plant (endophyte). These fungi produce several toxicants; most of those identified are ergots, but there may be others involved. Fescue toxicosis results in decreased grazing, less weight gain, lower conception rates, reduced milk production, low serum prolactin, rough hair coat, gangrene of the extremities, and increased body temperature. Fescue toxicosis occurs during warmer temperatures, compromising the animal’s ability to dissipate heat. Genetic varieties of endophyte-free fescue are available; however, these are not as hardy as infected varieties. There are also novel fescue varieties that contain the fungus, but the fungus has been genetically selected to not produce the known toxins in appreciable amounts. To prevent spore formation and reduce incidence of toxicosis, fescue may be diluted with other species or systematically grazed.
Whitlow, L.W. and W.M. Hagler, Jr. 2017. Mold and Mycotoxin Issues in Dairy Cattle: Effects, Prevention and Treatment. eXtension. Accessed 7/20/21.
Publication date: Aug. 23, 2021
Other Publications in Guide to Mycotoxins Commonly Found in Animal Feeds
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