MYCOTOXINS ▶▶▶
The hidden threat of mycotoxins in aquaculture
Mycotoxins in aquaculture and fish feed is an emerging and underestimated problem for the industry.
BY PARASKEVI KOLETSI T
The impact of mycotoxins: re- duced growth performance for fish and eco- nomic losses for fish farmers.
here has always been a threat of mycotoxin-con- taminated feeds in the diets of terrestrially farmed animals as a result of the inclusion of high levels of cereals, and this threat has been extended over the
past few decades, as higher levels of cereals have become more commonplace in aquafeeds.
What are mycotoxins? Mycotoxins are chemical compounds produced by soil-borne ‘filamentous fungi’. These lowly mi- crobes are notorious plant pathogens in cereal crops, while their secondary metabolites, mycotoxins, are dangerous feed contaminants for farmed animals. It is possible for fungi to contaminate cereals in the early stages in the field, or later, during transportation and storage.
The hidden threat to farmers The aquafeed industry has made remarkable attempts to de- velop sustainable fish feeds by reducing the inclusion of
traditionally used marine ingredients and replacing them with novel ingredients derived from crops and their byprod- ucts. Thus, the inclusion of plant-based ingredients in fish di- ets, which has some known nutritional limitations, also intro- duces a potential exposure pathway for mycotoxins. To our knowledge, maize and its byproducts are the most highly contaminated with mycotoxins, followed by wheat and soy- bean. If we consider the industry’s long-term goal of reducing the value chain’s dependence on marine ingredients, then we can expect much higher inclusion rates of plant-derived raw materials in aquaculture feeds. Undoubtedly, the higher in- clusion of plantstuffs, in combination with ongoing climate change, may boost the presence of mycotoxins in fish feeds and thus challenge the aquaculture industry to keep contaminants out of fish feed.
Effects on fish health and performance Based on established knowledge from the Alltech 37+ lab database, numerous mycotoxins have been detected in fish feed samples. In most cases, more than one mycotoxin can be simultaneously present in a feed batch, at unpredictable levels and in various combinations. There are indications that some combinations might have synergetic effects on animals. However, the interactions among mycotoxins that co-occur in the feeds are not well understood, as most of
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▶ ALL ABOUT FEED | Volume 28, No. 9, 2020
PHOTO: ALLTECH
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