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Ergot in Your Feeds?

Ergot in your feeds can lead to ergotism. This article explain ergotism and the importance of early detection in the treatment of the disease.

The 2011 damp spring weather favored delayed germination and growth of ergot or Claviceps purpurea in plant seed heads.

Claviceps purpurea is a fungus that replaces the ovarian tissue of infected plants. Both cereal grains (for example, rye, triticale, wheat, barley and oats) and a variety of grasses (brome, timothy, quack grasses, blue grasses and others) can develop the ergot body, or sclerotia, in the seed ovary. The dark (purplish-black), hard ergot sclerotia contain toxic ergot alkaloids responsible for the clinical signs of ergotism in animals.

The amount of ergot alkaloids in sclerotia varies widely. Ruminants consuming rations with 0.3 to 1 percent or more sclerotia can develop gangrenous ergotism. Researchers estimate that ergot alkaloid concentrations between 0.2 and 0.8 milligram per kilogram or part per million in the total ration can produce ergotism in livestock.

Ergotism is generally a sporadic disease that can affect ruminants, horses, swine and humans. Clinical signs in cattle are gangrenous or cutaneous ergotism (typically necrosis of the tip of the ears, tail and coronary band above the hoof wall), lameness, elevated body temperature, reduction in feed intake and possibly subfertility. Milk production can decrease in animals exposed to ergot alkaloids.

The key to the successful treatment of ergotism in animals is early recognition of the clinical signs and removal of the animals from ergot-contaminated grains, hay, processed feeds or pastures

The risk of ergotism increases in pregnant and lactating cows. Watch mammary development in susceptible animals for earlier recognition of the disease. Also, visually monitor feed for the presence of C. purpurea sclerotia.

The U.S. Department of Agriculture has set a tolerance of 0.3 percent by weight of ergot sclerotia in grain, but we recommend that ergot body concentrations be less than 0.1 percent in the grain portion of the diet to reduce the risk of ergotism. Avoid using grain screenings (which can contain a higher proportion of ergot bodies) in animal feeds.

Ergot is not a new problem in North Dakota grains. The ergot sclerotia mature at the same rate as plant seeds and can fall to the ground to overwinter and possibly germinate the following year. No-till farming practices, shallow seeding and failure to rotate crops favor ergot development in plants.

Michelle Mostrom, Toxicologist, NDSU Veterinary Diagnostic Lab

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