Emerging mycotoxins: What do we know so far?
How are emerging mycotoxins defined?
When it comes to thinking about mycotoxins, most people will be aware of the more well-known types, such as aflatoxin, deoxynivalenol (DON) and zearalenone (ZEN). However, as the level of research grows and detection methods become more advanced, we are learning more and more about the lesser-known forms of mycotoxins, commonly referred to as ‘emerging mycotoxins.’ While evidence of these toxins is rapidly coming to light, they are currently defined as “mycotoxins that are neither routinely determined, nor legislatively regulated.” However, just like their better-known counterparts, producers need to be vigilant, as these hidden thieves have just as much potential to cause problems for natural immunity, agri-food sustainability and overall production profitability.
Since launching in 2012, the Alltech 37+® mycotoxin testing laboratories have been continually adding new mycotoxins to the testing panel, bringing the total number of detectable mycotoxins to 54. With this advanced analytical capability, emerging mycotoxin contamination is being found in more and more feed samples. This was strongly evidenced in the results of Alltech’s 2020 European Summer Harvest Survey. Based on over 270 samples of feedstuffs from 15 countries, more than 75% of samples showed emerging mycotoxin presence. When Danish feed samples are viewed in isolation, almost 95% of samples submitted contained emerging mycotoxins.
Although more data is being accumulated regarding emerging mycotoxins in animal feedstuffs, there is still a notable lack of in vivo studies measuring how this group of toxins impacts animals health and performance. Of the seven emerging mycotoxins that Alltech 37+ can currently detect, five of these are metabolites of the Fusarium mold, while alternariol comes from the Alternaria mold and phomopsin A is a toxic metabolite of the Phomopsis fungus.
Although in vitro studies found BEA to be toxic to both rodents and poultry, the same results were not observed in an in vivo setting. Effects of BEA on aspects of natural immunity and the bioavailability of pharmaceuticals were suggested by in vitro studies, and some authors highlight the need for further in vivo studies to learn more about these impacts. There is also a lack of in vivo data for other animal species. The European Food Safety Authority (EFSA) concluded that acute exposure to BEA is not a concern for human health. In contrast, no conclusion could be drawn with respect to chronic exposure due to the lack of relevant in vivo toxicity data.
Enniatins A/A1 and B/B1 (ENNs)
When analyzed in in vitro studies, ENNs are found to be toxic, while most in vivo data suggests either no or low toxicity. Similar to BEA, in vitro data does imply some effect on the bioavailability of pharmaceuticals, but more research is required to draw more valid conclusions. EFSA has made the same conclusion as BEA when it comes to the impact on human health — acute exposure is not a concern, while the effects of chronic exposure cannot yet be fully identified due to lack of in vivo toxicity data.
Poultry is found to be most susceptible to the impacts of this mycotoxin, while across all animals, the heart is the organ that exhibits the most damage, including the presence of myocardial lesions. Other conditions frequently noted in animals exposed to MON include muscular weakness, respiratory distress, decreased feed intake, body weight gains and impaired immune function.
Fusaric acid (FA)
Claims state that FA is understudied for its mode actions and effects on livestock. Of the 274 samples collected in the European Summer Harvest Survey, over 40% were found to contain FA. Southern Europe exhibited a particularly strong presence, more than 86% of samples were found to be contaminated here with FA, primarily corn grain. Studies show swine to be particularly susceptible to FA, with animals showing neurochemical changes and vomiting after eating contaminated feeds. Some authors suggest that FA may act synergistically with trichothecenes, such as DON. A 1993 study found little effect of FA on poultry.
The Alternaria mold mainly grows on vegetables, fruit and cereals. In vitro studies suggest AOH exhibits potential genotoxic effects. However, further studies are required to validate any conclusions. Similarly, in vitro data highlights a potential impact on the reproductive organs and immune system, but more in vivo data is necessary to build stronger conclusions.
Phomopsin A is the primary toxic metabolite produced by the Phomopsis mold and is found to be up to five times as toxic as phomopsin B. The Phomopsis mold is most common on lupin crops and seeds and causes lupinosis in cattle and sheep that ingest contaminated feed. The liver is the most impacted organ by this toxin, labeling phomopsin A as a hepatotoxin. However, it also impacts other organs, including the kidneys, adrenal glands, rumen and reticulum. The detection of lesions on affected organs may suggest an issue caused by phomopsin A.
Closing the knowledge gap
While many mycotoxins fall into the ‘emerging’ category, the above are the seven that Alltech 37+ can currently detect. Although notable gaps exist in the industry’s understanding of emerging mycotoxins, advancements in detection methods and further research allow for a deeper comprehension of how these toxins manifest themselves, the impact on animals and the potential solutions to address the presented challenges.
References available on request