Title : Mycotoxins in aquaculture: occurrence in feed materials, effects on aquatic species and strategies to counteract them
Mycotoxins are toxic secondary metabolites produced by certain fungi that contaminate a wide variety of grains and other commodities used in animal and human production. Mycotoxins prevalence changes among different regions, although global trade and climate change played a role in homogenizing the contamination profile worldwide. Aquatic species can be quite sensitive to mycotoxins, especially due to the increasing tendency to include plant-derived meals in aquatic diets. Since 2004 Biomin has conducted a survey for the main mycotoxins, namely aflatoxins (Afla), zearalenone (ZEN), deoxynivalenol (DON), T-2 toxin (T-2), fumonisins (FUM) and ochratoxin A (OTA). In 2019, Fusarium mycotoxins were the most prevalent in Asia: FUM, DON and ZEN were detected in 86%, 75% and 69% of samples analyzed, respectively. Alfa remains a concern in Asia as it was detected in 40% of samples analyzed, at average concentrations that are above safety guidelines. OTA and T-2 were detected in 23% and 10% of samples respectively. Concerning the effects of mycotoxins in aquatic species, those are dependent on the species, mode of action of mycotoxins, inclusion rates of contaminated material and duration of exposure. The most common effect observed on aquatic species are reduced growth and increase susceptibility to diseases due to the immunosuppressive effects of mycotoxins. Other effects include histopathological changes, hepatic damages and reproductive issues. Mycotoxins undertake synergistic interactions, thus the simultaneous presence of those secondary metabolites in the same sample, increases the overall toxicity. Synergism is well documented for terrestrial animals, but only a few studies are available in aquaculture. When it comes to mycotoxin counteraction, multiple solutions are available on the market, but only a very limited amount of those is backed up by a scientifically proven mode of action. Binders represent the most common product group, but their efficacy is limited to aflatoxins in the best case and definitely cannot support against other mycotoxins such as trichothecenes, ZEN and FUM. Enzymatic degradation of mycotoxins is the most effective way to completely detoxify mycotoxins in the gastrointestinal tract of the animal, but only a very limited number of enzymes is currently available on the market, with proven mode of action and guaranteed safety. Biomin has developed several solutions for mycotoxin deactivation in aquaculture, to cover all the industry needs. Those products range from combinations of EU authorized binders and enzymes, to single ingredient solutions, with proven identity, safety and efficacy according to the strict conditions imposed by the European Food and Safety Authority (EFSA) and the EU itself. Currently, Biomin is the only company existing on the market with five EU registrations in mycotoxin risk management. The BIOMIN® Mycotoxin Survey is the largest and most cited survey program worldwide and it is the current reference point for mycotoxin contamination assessment among the industry and the scientific community.