Mycotoxins are naturally occurring, toxic compounds, produced by fungi that infects agricultural crops, particularly cereals and oilseeds. Infection can occur during the growth and storage of crops, but also later on in processed foods and feeds. Decades of extensive research have been dedicated to preventing the occurrence of mycotoxins during plant growth, harvest, storage and processing. Despite the fiercest prevention efforts, the presence of mycotoxins in feed stuffs still appears to be unavoidable.
Trichothecenes are a group of mycotoxins comprised of a large family of structurally related compounds. However, of more than 170 known trichothecenes, only a few appear to be of importance with respects to their actual presence in crops. Trichothecenes are toxic to human beings and animals and can cause both acute and chronic diseases. The toxicity mechanisms of trichothecenes are the inhibition of protein, DNA and RNA synthesis, inhibition of mitochondrial functions, cell division and membrane effects, and immunosuppression. Experimental studies with animals exposed to low doses of trichothecenes have shown that these mycotoxins cause vomiting, diarrhea, gastroenteritis and immune dysfunction. Higher doses also cause severe damage to the lymphoid end epthelial cells of the gastrointestinal mucosa resulting in hemorrhage, endotoxemia and shock. The most common effects of prolonged dietary exposure of experimental animals to deoxynivalenol are feed refusal, decreased weight gain, vomiting, decreased nutritional efficiency and altered immune function with species differences being apparent.
According to the annual mycotoxin survey conducted by animal nutrition additive supplier Biomin, which allows feed and animal producers to assess the risks of using certain feedstuffs/feeds from different regions, trichothecenes are extremely prevalent. For example, the average DON contamination levels have fluctuated slightly over the years; however, deoxynivalenol continues to be one of the major mycotoxins identified. The 2012 survey data included more than 4,000 samples worldwide, of which, DON was found in 64 percent of all samples with an average contamination of over 1,000 pbb in all tested samples. It was the most prevalent mycotoxin in wheat, present in 70 percent of tested samples. As expected, wheat bran samples had higher contamination levels than wheat itself.
Mycotoxin treatment, prevention
Certain treatments have been found to reduce levels of specific mycotoxins in crops. However, no single method has been developed that has proven to be equally effective against the wide variety of mycotoxins that may co-occur in different commodities. Moreover, detoxification processes that are effective in vitro do not necessarily have the same efficacy when tested in vivo.
Pre-harvest: Pre-harvest management, including breeding for resistance and the use of fungicides, has not been efficient in eliminating mycotoxins from crops and crop products.
Physical treatments: Meanwhile, the efficacy of physical treatments (e.g. washing, separation, UV irradiation and solvent extraction) depends on the level of contamination and the distribution of mycotoxins throughout the grain.
The results obtained are uncertain and often connected with high product losses. Thermal processing treatment is usually ineffective while chemical treatments are expensive, time consuming and often result in lower nutritional value and palatability of the feed component treated.
Binders: Another approach to counteracting mycotoxins in feed is the addition of nutritionally inert adsorbent agents with the capacity to bind and immobilize mycotoxins in the gastrointestinal tract, resulting in reduced bioavailability. Due to the fact that mycotoxins vary a lot in their structure, adsorption works well only for a certain group of mycotoxins (e.g. aflatoxins). The efficacy of adsorbents is limited for other less- or non-adsorbable mycotoxins like trichothecenes.
Biotransformation: This method has been shown to be a reliable method for counteracting certain mycotoxins (e.g. deoxynivalenol or DON, ochratoxin A and zearalenone). It implies the conversion of the mycotoxin to a non-toxic metabolite by the action of enzymes or life microbes. The method has been successfully applied since 1991 and continuous research has led to the development of patented microbial feed supplements.
Biomin and biotransformation
A safe bacterial strain (Gen. nov. formerly Eubacterium sp.) was found with the trichothecene-detoxifying activity and named BBSH 797 after a research team that discovered it in 1997.
The European Food Safety Authority (EFSA) has recently adopted a positive scientific opinion on the safety and efficacy of Biomin BBSH 797. With this, BIOMIN has become the first company in the world to receive a positive EFSA-opinion on mycotoxin biotransformation. In their scientific opinion, EFSA concluded that Biomin BBSH 797 (part of the well-established Mycofix product line) is not only safe for animals, humans and the environment, but also demonstrably efficacious in target species.
Following a request from the European Commission, the FEEDAP Panel acknowledged the product's efficacy to reduce the epoxide group of trichothecenes to produce less-toxic and thus, harmless metabolites. The panel concluded the evidence presented in ex vivo and in vivo studies confirms that this efficacy can be realized in animals when the additive is incorporated into trichothecene-contaminated diets.
In 2010, Biomin was the first feed additive company to submit a dossier for an aflatoxin binder and the first to have a positive opinion by EFSA on the approval of a feed additive with mycotoxin-counteracting properties, says Dian Schatzmayr, director of Competence Center Mycotoxins within the BIOMIN Research Center.
According to the company, the dossier for the trichothecene-biotransforming product Biomin BBSH 797 was submitted only a few months after EFSA officially published their guidance document in 2012.
For more information about Biomin BBSH 797, please visit the company's website, www.biomin.net.