Toxins that sneak in through feeds

Farm chicken eating from an automatic feeder. [iStockPhoto]

Ever spotted some ugly mouldy stuff on the chicken feed? That is mycotoxin. The word mycotoxin comes from the Greek letter ‘Mykes’ which means ‘Mould’ and ‘Toxicum’ which refers to ‘toxins’, this essentially means toxins produced from moulds or fungus. Mycotoxins are therefore metabolites of natural fungi plants that get into chickens through the feed they eat. The toxins affect all types of poultry species interfering with their health, performance and productivity. Depending on the target organs in the chickens, the toxins can be classified as hepatoxins (affecting liver), nephrotoxins (affecting kidneys), neurotoxins (affecting nerves), dermatoxins (affecting skin). They can also be classified based on their chemical composition, so you will hear names like aflatoxins, fumonisins, zearalenone and ochratoxin. In Africa, the first three are the most common toxins affecting poultry. Aflatoxins in cereals can develop in growing crops where climate is such that it is stressful to the host plant such as high temperature and drought.  They more commonly develop post-harvest, during storage period, when the storage conditions are such that the water activity remains above the level to permit fungi/mould growth.  This can be due to general climatic conditions, with high ambient temperatures and humidity, or poor ventilation in the storage silos allowing hot spots to develop where water activity builds up. 

Maximum concentration permissible in feed

In ideal situation, no mycotoxins should be allowed in animal feed. However, in real life, traces of mycotoxins do occur because of contamination of raw feedstuff like maize, cottonseed, peanut, corn, sunflower cake, wheat bran all components of final feed. The level generally allowed in the industry should not exceed 20parts per billion for aflatoxins.

Why mycotoxins are bad for your chickens

Feeding birds with higher levels of mycotoxins can result in either the birds refusing to eat such contaminated feed at all resulting into immediate drop in growth and or production or if they end up consuming such feed, will suppress their immunity against diseases.

Aflatoxins, which are the main problem in this part of the world have been demonstrated to be carcinogenic (can cause cancer) potential and damages the livers in both humans and animals. The toxins are known to cause drop in the tissue levels of Vitamin B1, B2, B6, pantothenic acid and choline in the plasma, liver, and bile of chickens. This will result into poor health, immunosuppression, poor production, un-thriftiness and ultimately death.

Food safety concern

One of the major concern of mycotoxins fed to food animals like poultry is the ability to concentrate these toxins in chicken muscles, liver, eggs, and tissues and when consumed by humans may result into poor health.

Economic losses associated with mycotoxins

Here is a summary of the losses farmers are likely to encounter when birds are fed with contaminated feed from suppliers who do not take feed contamination seriously. They include:

  • Reduced feed intake
  • Reduced growth rates and low daily weight gain
  • Poor egg production
  • Poor shell quality, thin shell, low egg weights and low egg energy deposition.
  • Reduced feed conversion efficiencies
  • Reduced fertility and hatchability
  • Reduced immunity and increased incidences of diseases in the flock
  • High mortality
  • Ban in trade of contaminated raw materials.

Broad management of mycotoxins in feed

There are simple ways to mitigate this situation, here are three suggestions

  • Raw material selection for millers and buying complete feed from reputable manufacturers.
  • Routine feed ingredients testing for mycotoxins before incorporating into the final mix.
  • Use of feed additives as binders of the mycotoxins. Mycotoxins and as such can be controlled through binding to bentonite clay products. 

When considering aflatoxin binders, it is also important to consider whether the products are specific or non-specific binders. There is a risk that non-specific binders may also bind some of the essential micro components of the diet coming from the premixes, or even some of the therapeutic additives to the feed.

[The writer is the Head Vet at Kenchic [email protected] or [email protected]]

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