Mould and mycotoxins can quietly impact dairy herd performance, especially in years with challenging harvest or storage conditions. While they are not always the root cause of issues, contaminated feed can reduce intake, lower milk production, and affect overall herd health.
Producers should rule out other possible causes first. However, when mould or mycotoxins are suspected, early action can help limit production losses and support recovery.
Watch for performance changes
Mycotoxins can reduce performance quickly. In many cases, milk production begins to recover within five to 10 days after corrective action is taken.
More serious or prolonged exposure can take longer to resolve. In some cases, it may affect organ function or reproductive performance, extending recovery time.
Start with feed management
When issues arise, focus first on feed quality.
- Remove mouldy or damaged grains
- Avoid feeding fines and screenings, where toxins often concentrate
- Test suspect feeds to confirm contamination
Mycotoxins often concentrate in broken kernels and lighter material, increasing risk if these fractions are included in the ration.
Adjust rations carefully
If contamination is confirmed, adjust the ration to reduce risk.
Work with a nutritionist or veterinarian before making changes. This helps ensure adjustments support both production and herd health.
- Dilute contaminated feed with clean ingredients
- Reformulate rations to account for reduced energy in affected feeds
- Monitor feed intake closely, as palatability may decline
Wheat and other grains should be fed cautiously when mycotoxins are present. Safe inclusion levels depend on contamination levels, ration composition, and feeding management.
Don’t overlook lab results
Accurate interpretation of feed tests is critical.
Many lab results are reported on an “as-fed” basis. Producers should convert these values to a dry matter basis to avoid underestimating toxin levels in the ration.
Support the animal
Some nutritional strategies may help reduce the impact of mycotoxins.
These can include:
- Using binding agents in the ration
- Increasing key vitamins and trace minerals
Results can vary, and no products in Canada currently carry approved claims for mycotoxin mitigation. Producers should consult a nutritionist before making adjustments.
Prevent further mould growth
Managing stored feed can help prevent conditions from worsening.
Adding mould inhibitors to grain can slow further mould development, particularly in higher-moisture feeds. However, these treatments do not eliminate toxins already present.
Know when to pull feed
If animals show signs of moderate impact, reducing inclusion of the suspect feed may help.
In more serious cases, remove the feed completely for at least one week. If performance improves, test the feed before deciding whether to reintroduce it.
Be cautious with high-risk feeds
Certain feed ingredients carry higher risk during mycotoxin years:
- Grain screenings and fines
- Distillers grains, where toxin levels can be concentrated
Producers should request test results when sourcing these feeds.
A practical approach
Mycotoxin challenges vary from year to year and farm to farm. A cautious, practical approach is often the most effective.
Regular feed testing, careful ration adjustments, and close monitoring of herd performance can help reduce risk. Working with a nutritionist and veterinarian can also support better outcomes when issues arise.
