Aflatoxicosis In Poultry

Growing fungi (moulds) produce a large number of chemicals as by-products and secrete them into

surrounding substances. Some are toxic to birds. These toxic by-products are called 'mycotoxins' or

'fungal toxins'. Among them, aflatoxin is the most common and also the most important mycotoxin

likely to be consumed by poultry. .

Aflatoxins are highly toxic mycotoxins produced by various species of fungus Aspergillus. The fungus produces aflatoxin in warm, high humidity conditions, such as rainy season. Aflatoxins can withstand extreme environmental conditions and are very heat stable. Aflatoxin contamination is therefore more common in grains in a tropical country like ours. Young birds are more sensitive to aflatoxin than adults.

Harmful Effects of Aflatoxin

I. Affects weight gain

2. Affects feed intake

3. Affects feed conversion efficiency

4. Affects egg production

5. Affects male and female reproductive performance

6. Increases susceptibility to infectious diseases due to immunosuppression. That is, suppression of the immune response.

7. Egg size, yolk weight, and yolk as percentage of total egg size, are decreased.

8. Even less than 100 ppb (parts per billion) in broilers, can result in poor feed conversion and reduced weight gain, which may be due to liver damage and reduced nutrient absorption.

Symptoms

I. In growing birds, there is decreased growth and poor feed conversion.

2. There is also marked decrease in the resistance of birds to infections, such as coccidiosis and Gumboro disease, due to immunosuppression.

3. Affected hens have decreased egg production. Also, the hatchability of eggs is reduced.

Postmortem Findings

I. Liver is greatly enlarged, yellow and friable (easily broken) (Fig. 91).

2. Small haemorrhages may occur due to increased fragility of minute blood vessels. This leads to a condition known as 'bloody thigh syndrome'.

Diagnosis

Symptoms and postmortem findings would indicate aflatoxicosis. Confirmation requires identification of the

level of toxin present in the feed.

Treatment

I. Toxic feed should be removed and replaced with uncontaminated feed.

2. Increase the dietary levels of protein. Increase also the vitamin supplementation.

3. Supply of methionine and other sulphur-containing amino acids should be increased.

4. Poor management, if present, should be improved.

5. Liver tonics may be given.

6. Increase also the supplementation of vitamin E and selenium.

Control

I. Purchase a clean feedstuff. Check the ingredients before purchase.

2. Monitor feed ingredients for levels of mycotoxins.

3. Discard the grains suspected of contamination. That is, mouldy and caked feed.

4. Keep the moisture of grains less than 12%.

5. Sun drying is the best method to prevent mould growth. However, it does not destroy the

toxin.

6. Store the feed and ingredients in well ventilated dry place.

7. Avoid storage of feed for more than a week.

8. Withdraw toxin contaminated feed immediately.

9. The most practical way to control aflatoxicosis is through the effective use of mould inhibitors

and broad-spectrum toxin binders.