From hot and dry conditions to excessive rain and early snow, the country saw all types of weather challenges last year. These weather conditions not only reduce yield but can also increase plant stress and the potential for mould growth and mycotoxin production.
Mycotoxins are a regular concern for producers as they influence feed quality and animal safety. They are produced by certain species of moulds and can have toxic properties that impact ruminant health and performance. The occurrence and concentration of mycotoxins is influenced by many factors, including drought, excess rainfall, hot or cool temperatures, pests and agronomic practices.
Although mycotoxins were first identified over 50 years ago, they are gaining more attention due to changing agricultural practices, improved analytical technology, new scientific research and varying climate conditions. They are seldom found in isolation, and when multiple mycotoxins are consumed, they may have additive, or even synergistic, interactions that increase the overall risk to performance and health. As a result, a cow may have a stronger response than what would be expected if it was only experiencing a single mycotoxin challenge.
2019 Canadian mycotoxin harvest analysis
The silage samples submitted from western Canada appear to have contained multiple mycotoxins, an average of 5.25, particularly from mycotoxins produced by fusarium species of moulds.
Figure 1 shows there were very high levels of type B trichothecenes, emerging mycotoxins, fusaric acid and zearalenones.
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For grain samples submitted from western Canada, corn averaged 6.7 mycotoxins per sample and all grain averaged 6.07.
Figure 2 shows, similar to silage samples, high levels of type B trichothecenes, fusaric acid, emerging mycotoxins and zearalenones.
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In Ontario, the corn silage samples submitted averaged 5.27 mycotoxins.
Figure 4 indicates high levels of multiple mycotoxins, with 100% occurrence of type B trichothecenes and 90.9% of both emerging mycotoxins and fusaric acid.
From the corn silage samples submitted in Ontario, Figure 3 shows the results of high levels of type B trichothecenes and fusaric acid.
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As a result of the late-season rains in many provinces, especially following the dry conditions during summer in the prairies, there is additional potential for mycotoxins such as fumonisins. The production of fumonisins often proliferates under these conditions, as the producing mould prefers low moisture and warm weather when the plant is flowering, followed by rain at harvest.
Effect of mycotoxins on ruminants
When cows consume feed contaminated with mycotoxins, there can be negative effects that result in long-term declines in performance and, ultimately, lower farm profitability. Chronic mycotoxin consumption, in which smaller quantities of contaminated feed are consumed over time, is often more challenging than an acute single dose, as the mycotoxin risk may not be noticed until a loss of production and health has already occurred.
Although the rumen microorganisms can help to degrade some mycotoxins, they may also convert other mycotoxins into more potent forms. Certain mycotoxins can pass through the rumen unchanged to be later absorbed in the small intestine, while other mycotoxins may have antibiotic-like effects directly on the beneficial rumen microorganisms. As a result, the rumen and gastrointestinal tract are main targets of mycotoxins in cows.
Based on the fusarium mycotoxins (DON, ZEA and T-2/HT-2 toxins) detected in 2019’s grain and forage samples, cows may show a multitude of symptoms, such as changes to feeding behaviour, rumen disorders, lesions or haemorrhaging of the gastrointestinal tract, altered conception rates, lower milk production or altered milk components, and increased disease occurrence. Dairy animals may also have poor udder health with increased somatic cell counts or increased incidence of mastitis.
Mycotoxin management on-farm
For feedstuffs harvested in 2019 that are currently being fed, it is important to conduct a mycotoxin analysis that identifies the storage mycotoxins, including penicillium and aspergillus mycotoxin groups, as there is added potential for additional mycotoxins to develop during storage.
Storage measures may be taken to help reduce the risk of further development of mould and mycotoxins, such as:
- Properly dry grains to less than 13% moisture.
- Improve packing density.
- Ensure proper fermentation has occurred.
- Inspect storage quality to minimize moisture, air, insect or pest entry.
- Conduct mycotoxin analysis at harvest and after storage to identify the appropriate management strategy for those feedstuffs on-farm.
Mycotoxins are a challenge to animal and feed production, and employing preventive measures for managing mycotoxins is essential to minimize profit loss. Proper mycotoxin management techniques can reduce the risk of mycotoxins coming from feed materials as well as help to prevent the negative effects mycotoxins can have on dairy cow performance and health. Visit knowmycotoxins.com for more information on mycotoxin management. 
Max Hawkins is in the Mycotoxin Management at Alltech. Email Max Hawkins.
