In ruminant and poultry nutrition, quality forage and grain are both the biggest cost and the most important source of nutrients. But mycotoxin contamination, which starts in the field before harvest and grows with poor silage compaction, moisture swings or improper storage, pushes livestock operations into an invisible economic loss.
Mycotoxins are toxic secondary metabolites produced by mould fungi (Aspergillus, Fusarium, Penicillium) under stress. They can persist in feed even when there is no change in colour or smell; they suppress immunity, burden the liver and can trigger failure to conceive and embryonic death. In this article we look at the effects of mycotoxins in silage and at strategies to protect your herd.
The 4 Most Common Mycotoxins on Farms
A single feed ingredient or silage pit often contains several mycotoxins at once. This "synergistic toxicity" can multiply the harmful effect.
- Aflatoxin B1 (Aspergillus flavus): One of the most potent natural carcinogens and liver toxins. Aflatoxin B1 eaten by the cow is converted in the liver into aflatoxin M1 and passes into milk. The legal limit in milk is 0.05 ppb (µg/kg); above it, milk can be rejected by the dairy industry.
- Zearalenone, ZEA (Fusarium graminearum): Its chemical structure is very similar to the female sex hormone oestrogen. By binding to oestrogen receptors it can cause false heat, irregular cycles, ovarian cysts, vaginal prolapse and embryonic death, and it lowers the herd's conception rate.
- Deoxynivalenol, DON / vomitoxin (Fusarium culmorum): Blocks protein synthesis in intestinal cells and suppresses appetite. Reduced feed intake, chronic diarrhoea and weight loss are seen.
- T-2 and HT-2 toxins: Trichothecene toxins that cause tissue death (necrosis) in mucous membranes. Mouth sores, intestinal bleeding and immune suppression with a drop in white blood cells are seen.
How Mycotoxins Affect Animal Health
Each toxin has its own target organ and symptoms:
- Aflatoxin B1: Targets the liver and immune system. Liver damage, M1 transfer into milk and vaccine failure may occur.
- Zearalenone: Targets the reproductive system. Failure to conceive, ovarian cysts, vulva swelling and abortion may occur.
- DON (vomitoxin): Targets the gut and appetite. Feed refusal, lost dry matter intake, loose manure and poorer feed efficiency are seen.
- T-2 toxin: Targets the intestinal lining and bone marrow. Mouth ulcers, bloody manure and a drop in white blood cells are seen.
- Fumonisin B1: Targets the liver and respiratory system. Lung oedema, fatty liver and lower yield may occur.
General guidance values for cattle are roughly 250-500 ppb for zearalenone, 1,000-2,000 ppb for DON, below 100 ppb for T-2 toxin and below 5,000 ppb for fumonisin. These values vary with species and stage of lactation. For aflatoxin, the legal limits in feed for dairy animals are much lower; current regulations should be followed.
Why Plain Clay (Bentonite) Falls Short
In the past, mycotoxin control relied mostly on simple inorganic clays such as standard bentonite and zeolite. On their own, they are not enough.
Bentonite and aluminosilicates bind the highly polar aflatoxin B1 well through electrostatic attraction. In contrast, Fusarium toxins such as zearalenone, T-2 and DON are non-polar or weakly polar, and classic clays cannot bind them adequately. The toxin is absorbed from the gut and reaches the liver. Low-quality, high-dose clays can also bind vitamins A, D and E and trace minerals in the ration, causing nutrient deficiencies.
A broad spectrum is essential: Effective mycotoxin control requires high-purity HSCAS (hydrated sodium calcium aluminosilicate), which holds polar toxins, used together with esterified glucomannan (modified yeast cell wall), which captures non-polar toxins.
Frequently Asked Questions
If silage does not smell of mould, is it free of mycotoxins?
No. Mould fungi release toxins when conditions get harder and may die afterwards. Even when the fungus is invisible and the silage smells good, high levels of zearalenone or vomitoxin can be found in the laboratory (with methods such as HPLC). Always send suspect silage for analysis.
Do mycotoxins pass into milk?
Yes. In particular, aflatoxin B1 is converted to aflatoxin M1 in the liver and passes into milk within about 12-24 hours. If M1 is detected in milk, the milk may be rejected by the dairy industry and legal penalties may follow.
How does HepaVital affect milk yield?
When the liver burden is lower and immunity recovers in cows under mycotoxin pressure, feed intake rises. In MCB Vital field observations, about 14 days after starting use, an increase of 1.5-2.2 kg of milk per cow per day was recorded. Results may vary between farms.
How can mycotoxin-related problems be recognised?
Reduced feed intake, unexplained loss of milk yield, failure to conceive, irregular heat and recurring health problems are the first signs. Laboratory analysis of feed and silage samples is needed for a definite diagnosis.
