The cool, wet weather we experienced this summer has caused many problems for the farmers in this area. This fall there is one more – there are reports of grain that is contaminated with fusarium mould.  Deoxynivalenol (a.k.a. DON, vomitoxin) is a mycotoxin that can be produced when fusarium moulds contaminate cereal grains, including wheat, barley, and corn. Pigs are more sensitive to DON contamination in their feed than other farm animals. Growing beef cattle, sheep, and poultry have an Agriculture Canada Guideline of 5 ppm, while the guideline for pigs is 1 ppm (1 mg/kg) . The most common symptom pigs show when given DON contaminated feed is a reduction of feed intake and a corresponding decrease in weight gain. Some decrease in feed intake will likely be seen if DON contamination exceeds 1 ppm. In research conducted at the Prairie Swine Centre, feed intake and daily gain of late-nursery pigs decreased 9.1 and 5.2%, respectively, when pigs were fed diets containing 1.57 ppm DON for 22 days. Although pigs may vomit at high levels of DON contamination (~20 ppm) it is more likely that they will refuse feed completely (~12 ppm) before that occurs. Younger animals will be more severely affected than older animals. While the general recommendation for swine is to limit DON in diets for pigs to less than 1 ppm, a maximum of 0.5 is preferable for nursery pigs. While there doesn’t seem to be direct negative reproductive effects from feeding DON contaminated diets to breeding stock, the reduced feed intake itself may be a problem. Therefore, DON contaminated feeds should be avoided in diets for breeding stock whenever possible.