Occurrence of mycotoxins in aquaculture: preliminary overview of Asian and European plant ingredients and finished feeds
Concern about mycotoxins in aquaculture has been growing, partly due to the gradual replacement of animal-derived proteins, such as fish meal, by plant sources. Over a period of one year, 2,176 samples of different plant protein sources and 25 samples of finished aquaculture feeds were analysed. Samples were tested for aflatoxins (AF; sum of aflatoxin B1, B2, G1 and G2), zearalenone (ZEA), deoxynivalenol (DON), fumonisins (FB; sum of fumonisin B1 and B2), T-2 toxin and ochratoxin A (full toxin screen). The following plant-based meals were analysed: soybean meal (SBM), wheat (WH), wheat bran (WB), maize (C), corn gluten meal (CGM), cottonseed meal (CSM), rapeseed/canola meal (R/CM) and rice bran (RB). The plant raw materials and aquaculture finished feeds were obtained from Asia and Europe. Finished feed samples from Asia were acquired from Vietnam, Indonesia and Myanmar, while from Europe they were sampled from Denmark, Austria, the Netherlands and Germany. Mycotoxins were found in most of the commodities and finished feeds analysed, showing that mycotoxins represent a risk for the development of the aquaculture sector. Generally, in Asian samples we observed that SBM, WH, WB, C, CGM, R/CM and RB were mostly contaminated with Fusarium mycotoxins (ZEA, DON and FB). CSM was contaminated primarily by AF and Fusarium toxins (ZEA and DON) at lower concentrations. European samples were contaminated mainly by Fusarium mycotoxins. The co-occurrence of mycotoxins in all commodities was high, raising the probability of co-occurrence in finished feeds. An accumulation of mycotoxins on the processed plant-based ingredients (e.g. CGM and WB) was observed when compared to the respective whole grains (C and WH, respectively). Compared to results obtained in 2014, finished feeds presented lower contamination levels, but the co-occurrence risk increased.