By Jenifer Heyden, PAg, Livestock and Feed Extension Specialist, North Battleford
February 2025
As feed test results make their way to regional offices across the province, testing has indicated the presence of various fusarium-related mycotoxins and ergot alkaloids. Some grazing corn, corn silage and other cereal grain silages have been found to have high levels of the fusarium mycotoxins commonly referred to as DON, T-2 and HT-2. Some grass hay samples tested have had both mycotoxins (DON, T-2, HT-2) and ergot alkaloids in high concentrations. Both mycotoxins and ergot alkaloids present risks to animal health and productivity.
Mycotoxins can be present in hay, greenfeed, silage, pelleted feeds, screenings and whole grains – virtually all feedstuffs that livestock producers rely on for winter feeding. Growing, harvest and storage conditions play a pivotal role in the risk of mycotoxin contamination. Odourless and colourless, these toxins can be hard to detect and may go unnoticed until producers observe issues with fertility, abortions, growth or feed intake that have no obvious cause. Mycotoxins can be produced by different types of fungi such as fusarium and ergot, as well as mould. However, the presence of fungal and mould growth are not good indicators of the type or level of mycotoxins present.
There are many different mycotoxins. The symptoms associated with mycotoxin poisoning are varied. Symptoms may include – but are not limited to – feed refusal, photosensitization, gangrene (tissue death), reduced fertility, abortion and increased susceptibility to disease. The severity of symptoms will depend on the amount of toxin ingested, exposure time, season/temperature, the animal’s stage of production and general health. In addition, some mycotoxins are more potent than others and can cause debilitating issues in very small amounts. Feed sources, such as silage piles, may contain pockets of high levels of mycotoxins, while other areas of the stack may contain little to no toxin.
Deoxynivalenol (DON, or commonly referred to as vomitoxin), T-2 and HT-2 are some of the mycotoxins associated with fusarium pathogens. They occur mostly in cereal grains and corn and as such can also be associated with greenfeed and silage. One symptom of livestock ingesting DON or vomitoxin is an irritated gastrointestinal tract resulting in digestive upset. As a result, cattle will often go off feed or drop consumption drastically, animals may also appear weak or depressed. These mycotoxins can impair reproduction and lead to abortion and may impact immune response.
Ergot alkaloids contaminate cereal grains and forages. In whole cereal grains, screenings and forages with the heads intact, large, purplish-black sclerotia bodies warn producers that the danger of ergot is present. Levels of the alkaloids can vary between sclerotia bodies, making it impossible to know how much toxin is present without testing. Ergot alkaloids can affect feed intake and growth but can also lead to gangrene/necrosis of the extremities resulting in sloughing of ears, hooves and tails, especially in cold weather. In summer, animals subject to ergot alkaloids show signs of heat stress, even at temperatures below 20 degrees Celsius. Abortion, weak calves and severely reduced milk production can also be indicative of ergot alkaloid poisoning. The Canadian Food Inspection Agency recommends maximum ergot alkaloid concentrations of no more than 2.0 to 3.0 parts per million (ppm). Current research in Saskatchewan indicates that the recommended concentrations in cattle feed should be reevaluated and updated.
It’s also important to note that these ergot alkaloids and mycotoxins can have additive effects. Therefore, even if one toxin is below the maximum tolerable level for itself, in combination with the levels of other mycotoxins present, the overall level may be too high for feeding at 100 percent of the ration.
If you have concerns, feedstuffs can be evaluated for mycotoxins and ergot alkaloids through Prairie Diagnostic Services in Saskatoon as well as other feed testing labs across Canada. A livestock and feed extension specialist can help you to determine safe levels to feed and come up with appropriate rations to help minimize risks. For more information about mycotoxins, ergot alkaloids, feed testing or other related topics, contact your local livestock and feed extension specialist or the Agriculture Knowledge Centre at 1-866-457-2377.