Managing Mould and Mycotoxin Risks in Dairy Feed: Practical Guidelines for Producers

By
Tanya Eadie
-
137

Understanding the Risk

  • Mould and mycotoxins in feed can impact cow health, milk production, reproduction, and long-term herd performance.

  • Always rule out other causes before concluding mould or mycotoxins are the issue.

  • Improvements may be seen within 5–10 days after intervention; full recovery from prolonged exposure can take weeks or months.

Immediate Corrective Actions

  • Clean grain: Remove fines, mouldy, lightweight or broken kernels.

  • Reformulate rations: Adjust energy values to reflect reduced nutritional content (5–10% lower).

  • Dilute contaminated feed: Blend with known toxin-free feeds after lab analysis to ensure safe levels.

Safe Feed Inclusion Guidelines

  • Wheat limits:

    • Max 15–20% of Total Ration Dry Matter (TRDM) for dairy cows.

    • Up to 40% TRDM for feedlot cattle, depending on other grain sources and rumen starch breakdown rates.

  • Use lab test data correctly:

    • Convert as-fed mycotoxin values to dry matter (DM) basis for accurate ration formulation.

    • Example: 2.5 ppm DON (as-fed) in 65% moisture feed = 7.1 ppm DON (DM basis).

Calculating Maximum Safe Wheat Inclusion (Based on DON)

  • Formula:
    Safe level in TRDM ÷ Wheat DON level × 100 = % max inclusion in TRDM

  • Example for lactating cows:
    1 ppm ÷ 5 ppm × 100 = 20% max wheat in TRDM

  • Account for high-grain diets (e.g., 60% grain in early lactation):
    20% ÷ 0.6 = 33% max wheat in grain ration

Key Reminders

  • Always use maximum, not average, grain levels when evaluating risk.

  • Palatability issues can further reduce acceptable feed inclusion — monitor feed intake.

  • When in doubt, err on the side of caution and consult with a nutritionist or veterinarian.

Feed Additives and Supplements

  • Binders: Use aluminosilicate or bentonite at 0.5% (or per manufacturer) to bind toxins in the digestive tract. Most effective against aflatoxin; field success seen with Fusarium mycotoxins.

    • Note: No CFIA-registered products in Canada for mycotoxin mitigation claims.

  • Vitamin and mineral support: Increase vitamins A, E, B1 and trace minerals (Selenium, Zinc, Copper, Manganese) by up to 25%. Watch copper levels in sheep feed.

Using Mold Inhibitors

  • Use sodium/calcium propionate or organic acids to prevent further mould growth in stored grain.

    • Add 0.2–0.25% for feeds with 14–17% moisture.

    • Add 0.5–0.6% for feeds with 18–24% moisture.

If Feed-Related Issues Arise

  • Moderate symptoms: Cut inclusion of suspect feed by 50%.

  • Severe symptoms: Remove feed for 1 week; if symptoms improve, test the feed and adjust inclusion or discard based on results.

Critical Considerations

  • Avoid feeding screenings (fines, husk, red dog): Mycotoxins can be up to 5× higher than in whole grain.

  • Distillers grains warning: Mycotoxins concentrate during fermentation (approx. 3× original levels). Always request test results before feeding.

Conclusion
Being proactive with feed testing, cautious with contaminated feed inclusion, and strategic in ration adjustments can significantly reduce mycotoxin risks and safeguard herd health and performance.

RELATED ARTICLESMORE FROM AUTHOR