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environmental disease Sheep, Goat

Ovine mycotoxicoses

Mycotoxins are toxic substances produced by molds that develop on cereals, cakes, hay, straw and silage, both in the field and in storage. They are not destroyed by storage or by usual treatments, and a food can contain them even though the...

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Definition Signs Causes Diagnosis Treatment Prevention Complications When to see a vet Prognosis FAQ Sources Affected species

What is it?

Mycotoxins are toxic substances produced by molds that develop on cereals, cakes, hay, straw and silage, both in the field and in storage.

They are not destroyed by storage or by usual treatments, and a food can contain them even though the mold is no longer visible: this is the main trap. Grain that appears clean may have been contaminated in the field or in a poorly ventilated silo.

The effects are rarely spectacular. Most often, the herd is simply doing worse: the animals eat less, grow more slowly, reproduce poorly, and are less resistant to disease. Parasitism, poor quality food or bad luck are blamed.

Commonly observed signs

These signs are neither exhaustive nor specific. Only a veterinarian can establish a diagnosis.

Related signs — each one links to its page:

Reduced herd feed intake Loss of appetite Stunted growth Weight loss Diarrhea Jaundice Abortion Infertility Fall in milk production Reduction

The picture is often vague and collective, which makes diagnosis difficult.

Decrease in feed consumption throughout the lot, animals sorting, leaving rejects, turning away from the trough for no apparent reason.

Growth stalling in lambs, animals which are declining in status.

Progressive weight loss, dull coat and wool.

Diarrhea that lingers, with no infectious cause found.

Decrease in milk production.

Reproductive problems: irregular heat, poor fertility, abortions, weak lambs at birth.

Swelling and redness of the vulva in young females with certain toxins.

Jaundice and signs of liver damage with others.

Increased sensitivity to all diseases, vaccinations which protect less well: certain toxins directly weaken the immune defenses.

In rarer forms: lesions of the mouth, wounds that do not heal, damage to the extremities, nervous disorders, tremors in animals grazing on damp regrowth.

Worsening sunburns and skin lesions not covered by wool may occur, as certain toxins damage the liver and make the skin very sensitive to light.

When to consult without delay

This list does not replace veterinary advice. It gathers situations that justify a prompt consultation.

Causes and risk factors

Development of mold on food, favored by humidity, heat, grain injuries, insects and poor ventilation.

Cereals harvested damp or poorly dried before storage.

Hay brought in that is not dry enough, which heats up and becomes moldy in the core of the bales.

Poorly ventilated silos, attics and sheds, with condensation, infiltration, or storage on the ground.

Silages that are poorly packed, poorly closed, or whose attack front advances too slowly.

Remains of food left in troughs and feeders, which ferment and mold, especially in hot weather.

Contamination in the field before harvest, particularly during wet years or delayed harvests.

Grazing wet regrowth or decomposing fodder on the ground.

Extended storage life without control.

Prolonged storage of cereals and fodder without ventilation or humidity control.

Harvests carried out in poor conditions, fodder brought in damp.

Damp storage buildings, with infiltrations or leaky roofs.

Troughs and feeders never cleaned, where food accumulates.

Purchases of food without guarantee or traceability, particularly low-price batches.

Animals at the trough receiving the same food for a long time: exposure is continuous.

Growing young, pregnant females and lactating animals, more sensitive.

Hot and humid periods.

Animals already weakened, parasitized or deficient.

Diagnosis and care

Diagnosis is the veterinarian's responsibility, based on clinical examination and laboratory tests. Care is decided case by case.

The diagnosis is difficult and is made with the veterinarian, first ruling out other, more frequent explanations: parasitism, deficiencies, ration errors, infectious diseases.

Report everything about the food: origin, date of purchase, storage conditions, odor, presence of lumps, dust or colored areas. These details are very useful.

The veterinarian examines the storage areas and troughs, which often provides more information than a clinical examination.

Analyzes for mycotoxins can be carried out on suspect foods. Sampling must be done correctly, because contamination is often in pockets: a poorly done sample gives a falsely reassuring result. Get help for this.

Blood tests assess liver and kidney damage.

The improvement of the herd after a change of feed is a major element of orientation: this is often how the diagnosis is confirmed in practice.

Treatment

There is no antidote: the essential measure is to immediately remove the suspect food and replace it with a healthy food. This is the treatment, and it is effective.

Do not attempt to salvage a moldy batch by mixing it with healthy food to dilute the problem: the practice is common and simply exposes all animals for longer.

The veterinarian provides support adapted to the affected organs: treatment of the liver, rehydration, care of skin or oral lesions.

Mycotoxin sensors, incorporated into the ration, exist and can be suggested by the veterinarian or technician; they never replace the removal of contaminated food and their effectiveness varies depending on the toxins.

A good quality ration, rich in fiber, with correct vitamin and mineral intake, helps animals to recover.

Protect animals with skin lesions from sunlight until the liver recovers.

The milk of exposed animals may raise questions: seek the advice of the veterinarian before any consumption or sale.

Treatment depends on the cause and the animal's condition: it must be determined by a veterinarian. No self-medication.

Prevention

Harvesting and storing cereals and dry fodder: this is the key to prevention, much more than any product.

Ventilate storage areas, avoid direct contact with damp ground and walls, repair roofs and infiltrations.

Clean silos, granaries and feeders between batches, and fight against insects and rodents, which damage the grains and open the door to mold.

Never leave aged food in the troughs, especially in hot weather: empty and clean them regularly.

Examine each new batch of food: musty smell, abnormal dust, lumps, colored areas, heat in the heart of the pile should lead to it not being distributed.

Monitor the temperature of silos and piles.

Buy from identified suppliers and be wary of abnormally cheap lots.

Never distribute visibly moldy food, even in small quantities, even mixed.

On farms with recurring problems, talk to the veterinarian about regular food monitoring and the possible benefit of a toxin sensor.

Possible complications

Long-lasting damage to the liver and kidneys.

Infertility, abortions and a wasted reproductive season.

Permanent growth retardation in lambs.

Weakened immune defenses, with a herd that suffers from a series of illnesses and responds poorly to vaccinations.

Serious skin lesions due to sensitivity to light in animals with damaged livers.

Diffuse and lasting economic losses, often wrongly attributed to other causes.

Passage of certain toxins into milk, which raises a food safety issue to discuss with the veterinarian.

Loss of an entire stock of food when contamination is significant.

When to see a veterinarian

Your herd is eating less and has been declining without explanation for several weeks.

The lambs are no longer growing even though the ration seems correct and parasitism is under control.

Abortions or fertility disorders occur in the herd.

Animals present with jaundice or skin lesions in areas poorly covered with wool.

You notice mold, an abnormal odor or heat in stored food: seek advice before distributing it.

The herd is suffering from a series of illnesses even though health management has not changed.

Prognosis

Removal of the contaminated food generally results in a marked improvement within a few weeks, which makes the prognosis favorable in the majority of cases.

Liver and kidney damage already established can leave after-effects.

Lambs whose growth has stalled do not completely catch up.

The consequences on the reproduction of a season are irrecoverable.

At the farm level, the prognosis depends entirely on harvesting and storage conditions: this is where the problem is resolved sustainably.

Frequently asked questions

My food is not visibly moldy, could it be toxic?

Yes, and that's the main pitfall. The contamination may have occurred in the field, and the mold may have disappeared leaving the toxin. A grain that is clean to the eye can therefore pose a problem, while a slightly dusty food does not necessarily contain toxins.

Can I mix a moldy batch with healthy food so I don't waste it?

No. This widespread practice only spreads the problem over more animals and for longer. A suspect batch should not be fed to animals, and the loss of the feed always costs less than the loss of a growing or breeding season.

How do you know if it's really that, and not just worms?

We start by ruling out parasitism and deficiencies, which are more common, with a dropping analysis and a ration assessment. If everything is correct and the herd is still doing poorly, the veterinarian will take an interest in the food and its storage.

Is my sheep's milk safe to eat if the feed was contaminated?

Some toxins do pass into milk. Do not make the decision alone: report the situation to the veterinarian, who will indicate what action to take depending on the type of contamination and the use of the milk.