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How farmers can keep aflatoxin threat at bay

By Dr. Othieno Joseph
Don’t feed mouldy cereals or feeds to animals.

I am a dairy farmer and I have a question. During a recent farmers’ seminar on feed making, the presenter made a remark that poor storage of feeds can lead to production of aflatoxins which are harmful to humans and animals. What are aflatoxins and how can I make sure they don’t contaminate my feeds? [Kipsang, Eldoret] 

What are Aflatoxins

Dear Kipsang, aflatoxins are naturally occurring toxin produced by certain types of moulds.  The moulds grow on crops under warm and humid conditions.  The moulds that produces aflatoxins prefers to grow on peanuts, groundnuts, wheat, maize, beans and rice when not stored well. They can also grow on hay or silage when not stored under good conditions. Aflatoxins are carcinogenic (cancer causing) and are colourless chemicals hence cannot be seen with naked eyes. Moulds that produce aflatoxins can be seen with naked eyes. Lab tests are used to test the presence and quantity of aflatoxins in feeds.

Sources of Aflatoxin

The aflatoxin producing fungi normally grow on crops when they are still in the field, during harvesting or during storage. In the field, the aflatoxin producing moulds flourish under stressful conditions like drought. It is common for farmers to feed animals on such crops that have failed due to drought; effectively putting them into the human food chain later when these animals or their products are eaten by man. Feed damaged by insects favour growth of moulds. The mould is also found in soils, decaying vegetation, hay and silage. High temperatures and moisture content like those in silage favour the growth of aflatoxin-producing moulds.

How do Aflatoxins get into human food chain?

Human beings get exposed to aflatoxins when they continually consume plant products that are contaminated by aflatoxins directly. The other way is through consumption of meat or milk or milk products from animals continually fed feeds contaminated with aflatoxins. Farm hands and the farmers can be exposed to aflatoxins through inhalation of aflatoxins containing dust. Animals exposure to aflatoxins will have low weight gain due to reduced feed intake and low feed conversion rates.

What can farmers do?

Prevention of mould growth on feeds can be done through physical, chemical or biological means.  Reduction of moisture in freshly harvested feeds and those in storage helps to halt the growth of moulds.  Sun drying or mechanical dryers can be used to lower moisture. Harvesting of pastures for animal feeds can be staggered so that farm hands are not overwhelmed resulting in improper storage that creates favourable conditions for mould growth.

There are chemical compounds that can be used to halt the growth of aflatoxins. There are also chemical compounds that can be mixed with contaminated feeds to bind the toxins in a form that makes them harmless.  They are available in Agrovets. Dried and ground garlic, onion, cinnamon and pepper can also stop the growth of moulds in stored feeds. These products also prevent insects from damaging stored feeds. Don’t feed mouldy cereals or feeds to animals. Do not give your animals rotten or mouldy cereals. When you do this you are exposing the animal to aflatoxins.

[The writer is the winner of Vet of the Year Award (VOYA) 2016 and works with the Kenya Tsetse and Trypanosomiasis Eradication Council, [email protected]]

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