Mycotoxicosis is a disease affecting poultry resulting from the consumption of feed contaminated with fungi, or exposure to contaminated litter (shavings or straw) within the poultry house. Fungi produce thousands of mycotoxins that are toxic to both birds and animals. These fungi are commonly associated with feed ingredients such as corn and soybeans, infecting plants under stress factors like drought, poor nutrition, late harvest, or lack of pest control. The type and concentration of mycotoxins are influenced by the fungal strain, temperature, and humidity.

The most prominent mycotoxins affecting poultry include:

1. Aflatoxins

One of the most widespread mycotoxins globally with significant economic impact.

• Source: Produced by Aspergillus flavus and Aspergillus parasiticus.
• Occurrence: Produced pre-harvest, post-harvest, or during storage. This toxin is not destroyed by grinding or storage. Hot climates (30–35°C) and high humidity are ideal environments for its growth.
• Biological Effect: Young birds are more susceptible than adults. After ingestion, aflatoxins undergo biotransformation into highly reactive metabolites that interfere with metabolism. These metabolites bind to DNA and RNA, inhibiting protein synthesis and reducing both humoral and cellular immunity.
• Excretion: It is excreted in bile and urine and does not accumulate in body tissues; this explains the rapid recovery of egg production and hatchability once contaminated feed is removed.

Clinical Signs:

• Negative impact on Feed Conversion Ratio (FCR) and weight gain.
• Reduced resistance to diseases such as Salmonella, Coccidiosis, and Gumboro (IBD).
• Affects pigmentation, particularly in brown eggs, leading to pale and inconsistent shell color.
• Decreased egg production, hatchability, and increased embryonic mortality.
• Reduced testicular weight and sperm count.
• Levels exceeding 10 ppm can lead to sudden death.

Post-Mortem Lesions:

• Hepatomegaly (enlarged liver) with a pale, yellowish, and friable appearance.
• Renal enlargement (swollen kidneys).
• Atrophy of the Bursa of Fabricius and Thymus gland.
• Increased hemorrhages and bruising due to decreased clotting factors and increased capillary fragility, leading to ascites.

2. Ochratoxins

Less common than Aflatoxin but more lethal due to its acute toxicity, leading to high mortality rates.

• Source: Produced by Aspergillus ochraceus and Penicillium viridicatum.
• Mechanism: Inhibits protein synthesis and targets renal cells, preventing the normal excretion of uric acid, leading to renal failure and severe damage.
• Symptoms: Dehydration, anemia, decreased pigmentation, and delayed sexual maturity.

Post-Mortem Lesions:

• Pale, enlarged kidneys with white urate deposits (visceral gout).
• Urate deposition on the liver and heart.
• Atrophy of the Bursa and Thymus.
• Hepatomegaly with fatty liver syndrome.

3. Trichothecene Mycotoxins

• Source: Produced by the Fusarium genus. These fungi can grow at various temperatures but secrete toxins specifically in cold conditions (late harvest or cold storage).
• Symptoms: Causes necrosis and ulcerations in the oral cavity, tongue, and esophagus, leading to reduced feed intake and weight loss. It also causes anemia and immunosuppression.

4. Zearalenone Mycotoxin

• Effect: This toxin mimics estrogen, leading to reduced natural estrogen levels, ovarian atrophy, and pathological changes in the oviduct.

Control Strategies

1. Field Level: Avoiding stress factors (drought, poor nutrition), ensuring timely harvest, and implementing pest control.
2. Storage & Transport: Proper drying of grains, insect control, and moisture prevention during maritime transport.
3. Feed Mills: * Strict hygiene during grinding and storage.
   • Adding biological toxin binders and silicates to adsorb toxins.
   • Frequent maintenance of machinery to prevent “carry-over” from old batches.
4. Poultry Farms:
   • Implementing proper feed storage protocols.
   • Adding organic acids to drinking water to inhibit fungal growth.
   • Periodic administration of biological or chemical antimycotoxins in drinking water.
   • Routine sampling and laboratory analysis of feed, with immediate disposal of positive batches.