DATE: 06/06/2012
Have our birds become more vulnerable to disease due to mycotoxins?
A correct mycotoxin risk management program is a key factor for reaching peak performance in animal
husbandry. The health, profits and performance of farm and animal hang in the balance, often affected by these
invisible forces; producers are left wondering why they are under achieving on desired goals.
Animal nutrition company Biomin South Africa chief operations officer Albert van Rensburg explains that
proactively integrating a mycotoxin risk management program with bird management programmes ensures that
producers benefit from better immune functioning, optimal nutrient absorption, feed intake and reproduction.
Acute mycotoxicosis is the term used for poisoning associated with exposures to mycotoxins. “Acute
mycotoxicosis outbreaks are rare events in modern animal production. A mycotoxin is a toxic secondary
metabolite produced by organisms of the fungus kingdom, commonly known as molds. The term
‘mycotoxin’ is usually reserved for the toxic chemical products produced by fungi that readily colonize crops
before or after harvest,” says van Rensburg.
One mold species may produce many different mycotoxins and/or the same mycotoxin as another species.
Any growing crop, including forage and cereals, are susceptible to mold, with Fusarium types being the
main concern. Fusarium molds can produce mycotoxins on the growing plant, and whilst the molds
themselves may not survive the transition from field to feeding trough, the mycotoxins will remain intact,
though invisible to the naked eye.
Feeds may therefore appear and be analysed as high quality, but may harbour a mycotoxin challenge. The
most important mycotoxins being: Aflatoxins, Deoxynivalenol, Ochratoxin A, Fumonisins, Zearalenone,
Patulin and T-2 Toxin.
The symptoms of mycotoxicosis depend on a number of factors, including; the type of mycotoxin causing
contamination, the concentration of the toxin and the length of exposure to the toxin. However, low mycotoxin
doses, which very often go undetected, are responsible for reduced efficiency of production and increased
susceptibility to infectious diseases. “Nonetheless, a more likely scenario is to find mycotoxins at lower levels
interacting with other stressors leading to subclinical losses in performance, increases in incidence of disease and
reduced reproductive performance,” explains van Rensburg.
“To the poultry producer, these subclinical losses are of greater economic importance than losses from acute
effects and are even more difficult to diagnose. Mycotoxins exert their effects through four primary mechanisms,
namely; suppression of the immune system, reduced nutrient absorption and impaired metabolism, feed intake
reduction or feed refusal and alterations in the endocrine and exocrine systems,” he says.
Recognition of the impact of mycotoxins on animal production has been limited by the difficulty of diagnosis.
Symptoms are often nonspecific and the result of a progression of effects, making a diagnosis difficult or
impossible because of the complex clinical results with a wide diversity of symptoms. The difficulty of diagnosis is
increased due to limited research, occurrence of multiple mycotoxins, non-uniform distribution, interactions with
other factors, and problems of sampling and analysis.
Van Rensburg explains that symptoms of mycotoxicosis in farm animals vary depending on the mycotoxins
involved and their interactions with other stress factors. Heat stress, poor ventilation, air quality including high
humidity, dust or airborne pathogens, crowding, viral or bacterial challenges or other stressful conditions lead to an
animal’s increased susceptibility to the effects of mycotoxins. Stressed animals are most affected, perhaps
because their immune systems are already suppressed. There is generally an increase in the incidence of
metabolic disorders and the animals are more susceptible to infectious diseases along with reduced efficacy of
vaccination programs. Even small amounts of mycotoxins in the feed can have a detrimental effect on the immune
“Many investigations are performed in the field of nutrition, genetics and animal welfare to increase farms’
profitability. Nevertheless, animals frequently do not perform according to their capability due to mycotoxins and
much of their economic loss stays unaccounted. Taking all this into account, great awareness must be given to
the interaction of mycotoxins with other main factors,” concludes van Rensburg.
Director : Denis Laurent Giraudoux (Austria) COO: Albert van Rensburg (South Africa)

- Ngage Media Zone