Veterinary Medicine Library

Ergot (Claviceps purpurea (Fr.) Tul.)

| Description | Distribution | Conditions of poisoning | Control | Toxic principle | Clinical signs | References


Description

Ergot is a fungus that lives as a parasite in the blossoms of grasses. When the grass heads are nearly mature, it appears as jumbo grains protruding from the heads. Ergot grains, which are fungus bodies and not seeds, are several to many times the size of the grass seed. They are dark violet to almost black and are curved, hard, and hornlike. Ergot varies in abundance from year to year.


Distribution

Ergot is well known as a disease of rye. It also attacks many of the wild grasses that grow along roads, in fencerows, woods, meadows, and pastures, and can often be found on wild rye, quackgrass, redtop, and bromegrass. It occurs throughout Illinois, being more abundant in some years than in others.


Conditions of poisoning

Animals get ergot either in the grain fed them or by grazing on infected grass. Obtained in either way, ergot may cause acute poisoning if a large quantity is eaten at one time. Also, because the effect of ergot is cumulative, poisoning may develop slowly if lesser quantities are eaten regularly. Experiments have shown, however, that a small amount of ergot is not injurious to dairy cattle that are amply provided with a balanced ration.


Control

Do not feed grain or hay that contains ergot. Clean contaminated grain before feeding it. Destroy infested hay. Before planting rye, clean the seed thoroughly either by mechanical means or by immersing it in a 25% salt solution. If using the salt solution, skim off ergots as they rise to the top; then wash the rye seed in water to remove the salt; dry, and plant. If wild grasses are infested, burn them to destroy the ergot.

Besides attacking many kinds of wild grasses, ergot is frequently abundant on rye in rye-fields and on volunteer rye in wheat-fields. Grain from these fields (or screenings used as feed) is very likely to cause poisoning. If there is much ergot in the grain, its effect can be very severe.


Toxic principle


Clinical signs

Ergot poisoning, often called ergotism, produces two distinct types of clinical signs. Acute poisoning, which results from eating a large amount of ergot at one time, causes muscular trembling, discoordination, convulsions, and painful contraction of the muscles. In fatal cases the animal becomes delirious.

The gangrenous type of poisoning, which follows continued feeding on smaller amounts of ergot, causes the animal to become dull and depressed and to develop gangrene of the tail, feet, ears, or teats. Gangrene may vary from rather simple sores around the coronary band or top of the hoof, in the space between the claws, or on the teats to a loosening of the hoof or the sloughing of a larger part of a limb or of the tail, ears, or teats. Before sloughing occurs, a well-marked line of division can be seen between the healthy and gangrenous tissue, similar to the type of lesion that has been observed in selenium poisoning in such western states as Kansas, Nebraska, and Wyoming.

Nausea, vomiting, colic, and diarrhea may occur in both types of poisoning. Even when none of the above signs of ergotism are apparent, the presence of ergot in feed should be suspected whenever pregnant animals have an otherwise inexplicable tendency to abort.

Other References:

Ergot entry in Wikipedia


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