AFLATOXINS - NOT A NEW PROBLEM

More is being written and discussed about Aflatoxins, many people have never heard of them and assume they are a new problem (or one invented by vets!). Not so, this is a problem as old as mankind. The only new thing is our ability to detect the problem.

The poultry industry is well aware of the effects of Aflatoxins. The problem was first identified in 1960 after 100,000 turkey poults died following the eating of feed containing Brazilian peanut meal. Deaths extended into many other species (cattle, pigs, sheep and chickens) and all were associated with the Brazilian feed. Some pretty nifty chemistry isolated the toxin and it was identified as coming from a fungus ( Aspergillus flavus ).

Since the identification of Aflatoxins (18 different ones) more very toxic substances (trichothecenes, Ochratoxins, Fumonosins) have been found in fungus and mould growth on feeds from all parts of the world. Scientists have now identified a range of diseases that can be directly related to these toxins and as time goes on more effects will be recognised.

Aflatoxins will grow on most grains including corn, peanuts, wheat and cottonseed. In stored grain, the ideal conditions for aflatoxins are a temperature of 24 - 35°C, and a moisture of 17%. Within 24 hours at these conditions aflatoxins can be produced. Once produced they are almost impossible to eliminate, they can withstand a temperature of 100°C and are very long lasting in the grain. Because they are so potent only very small levels of the aflatoxins are permitted in human food. 20 parts per BILLION is the upper level for human consumption. Surveys of poultry feed in various countries around the world has found levels ranging from 1 - 2000 parts per billion (ppb).

The difficult part of the aflatoxin story is describing the disease that it causes. Unfortunately the disease is dependent on which toxin is eaten, the amount that is eaten, over what period it is eaten and the susceptibility of the individual. As a general rule Aflatoxins cause some degree of liver damage. However a low level intake may only reduce the growth rate or reproduction of a bird without ever killing it. Chicks may die while the adults appear unaffected.

Diagnosis isvery difficult, we must look at tissue samples and try to isolate the toxin from the food.

Precautions you can take to prevent the problem are: only buy clean dry seed: never use seed that smells or looks mouldy: always keep your seed dry (less than 12% moisture): do not store seed for long periods.

New grain protection methods are on their way where grains can be rendered safe by the addition of chemicals that destroy the toxins.

Ref:

1.Leeson,S. Diaz,G .Summers, J.

Poultry metabolic Disorders and Mycotoxins

1995. University Books, Ontario, Canada.



2. Hume,S.

Annual Conference Proceedings, AAVAC.

October 1998, Canberra.