These are produced from the fungus ergot (Claviceps purpurea) that affects wheat, oats, ryegrass and other grasses by entering the seed and developing into a dark elongated body called a sclerotium. This contains toxic alkaloids, one of which is ergometrine which has the effect of contracting small blood vessel walls, thus restricting the blood supply particularly to the mammary gland and the body extremities.

Clinical signs

Levels of more than 0.1% of the sclerotium in the ration will produce clinical signs. These usually occur over a period of weeks and are associated with poor growth rates, increased respiration and general depression. The most sensitive blood vessels are those found in the mammary glands of maturing pregnant gilts. The restricted blood supply then causes agalactia in lactating animals and gives rise to increased piglet mortality. Lameness is also common due to necrosis and sloughing of the hooves. Tail and ear necrosis are also common.

Diagnosis

There are two methods, the examination of food to identify black/brown sclerotium which can be seen with the naked eye and the laboratory identification of the alkaloids.

Treatment

• There is no specific antidote.
• Remove the affected feed.
• Treat areas of gangrene with antibiotics.
• Some pigs may have to be destroyed on humane grounds.