Mycotoxins in SE Asia aquaculture plant-based meals  

Among possible fish meal alternatives, e.g. animal by-products, fishery by-products, bacteria and algae concentrate, plant ingredients seem to be one of the most promising solutions. Numerous plant raw materials have been successfully tested (Gatlin et al., 2007). It is observed that an interrelationship between nutrition, immunology and disease resistance in fish and shrimp has been essential to evaluate the alternative plant ingredients. It is commonly agreed that a key negative aspect of plant meals are the presence of anti-nutrients that are detrimental to fish. Although there are processes to remove or inactivate many of these compounds, the same is not effective against mycotoxins that are relatively stable to processing conditions.

In order to evaluate the occurrence of mycotoxins in common plant nutrients used for aquaculture feeds production, samples were sourced over a period of two years (January 2015 - December 2016). In first year, 2176 samples of different plant sources were analyzed within the scope of BIOMIN Mycotoxin Survey program. The plant meals selected were: Soy Bean Meal (SBM), Wheat (WH), Wheat Bran (WB), Corn (C), Corn Gluten Meal (CGM), Cottonseed Meal (CSM), Rapeseed/Canola Meal (R/CM) and Rice Bran (RB). In the second year, 157 samples were analyzed, focusing on local plant meals. Common plant meals, alfalfa, broken corn, broken rice, cassava, corn bran, carrot cake, corn dust, full fat soy, ground corn, groundnut cake, peanuts cake, polish rice, rapeseed, sesame, soybean cake, sunflower cake, wheat bran and wheat flour were analyzed.

Mycotoxins were found in most commodities analyzed, showing that mycotoxins might represent a risk for the development of the sector. While in some cases the contamination levels are rather low, in other cases the contamination levels might represent a risk for aquaculture species. Generally, in 2015 samples it was observed that SBM, WH, WB, C, CGM, R/CM and RB were mostly contaminated with Fusarium mycotoxins (ZEN, DON and FUM)- the exception being CSM that was mainly contaminated by AF together with Fusarium toxins (ZEN and DON) in considerable amounts.

Regarding local plant meals, all samples were contaminated with mycotoxins. Corn dust, broken corn, ground corn, groundnut cake and soybean cake presented considerably high values which can, depending on inclusion levels, represent a risk for aquaculture species.