By Dr. Othieno Joseph
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,
jothieno43@yahoo.com]
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