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Analysis showed that more than 80% of the wheat sam- ples, 95% of the maize and 87% of the soybean samples had a positive mycotoxin result.


Pillar 2: Feed formulation In addition to these assessments, there are FDA and EU legal limits for aflatoxins and guidelines on the safe levels of myco- toxins in aquafeed (Table 2). As such, these tolerance levels for specific mycotoxins in different species must be taken into account when formulating the feed for different fish species. There are over 500 different mycotoxins identified, but the most common and prevalent is deoxynivalenol (DON). As stated previously, the meta-analysis highlights the risk of DON to feed intake and performance, and data was also col- lected to quantify the risk of exposure to fish. This approach highlighted the fact that the current recommendations for the limit of DON in fish diets are too high and need to be re- viewed to protect both fish welfare and business profitability.


Pillar 3: Feed manufacturing This information provides an estimated mycotoxin risk of the raw materials and the sensitivity of the targeted species (although it’s the combination of the raw materials and their specific inclusion level that determines the total risk of the feed). Using feed formulation software, the risk equivalent (REQ) is calculated. This is done by comparing the calculated mycotoxin levels of the recipe against the sensitivity of the fish species. With this REQ, the mycotoxin binder inclusion is calculated based on a linear correlation. The main advantage of this system is that the risk is both recipe and species-spe- cific. It is calculated very accurately, i.e., the mycotoxin binder is used at the most efficient ratio.


The importance of continuous testing To accurately assess the risk in aquaculture, continuous testing is crucial. Recently, two separate surveys have been conducted – one in Norway and another survey in the Asia-Pacific region. In the Norway study, a total of 104 samples were collected over a period of 12 months from two salmon farms: Ellingsen Seafood (high fish meal inclusion) and Blom Fiskeoppdrett (low fishmeal inclusion). The samples were sent to an inde- pendent laboratory in Belgium for mycotoxin analysis. The results showed that no mycotoxin contamination was present as a result of good quality control programmes in place at the associated feed mills. Meanwhile, in the Asia-Pacific, a survey was conducted to de- termine the mycotoxin risk in the region. Almost 200 samples were collected from Bangladesh, China, India, Indonesia, Ma- laysia and Vietnam and these were tested in laboratories or locally using the Alltech Rapiread system by using Neogen’s lateral-flow technology. The samples combined complete feeds and the most commonly used aquafeed raw materials. Most of the raw materials, such as maize, wheat and soybean, were imported from either Europe or the Americas. The results of the study revealed that byproducts of maize and wheat had quite high mycotoxin contamination, but more importantly, the survey highlighted significant differences between the highest results and the average results, empha- sising the importance of continuous testing. Additionally, the combined synergistic effects of multiple mycotoxins over a long ingestion period can be more harmful. This can impact feed intake, growth rate and mortality rates and lead to severe economic losses for farmers.


Table 2 – FDA and EU legal limits for aflatoxins and advisory guidelines on safe levels for other mycotoxins in feeds for aquaculture (Commission directive [EU] No. 2003/100/EC; Commission recommendation [EU] No. 2006/576/EC) Legal limits/Advisoryguidelines*


Mycotoxin


Aflatoxin B1 Deoxynivalenol


Fumonisins


Ochratoxin A Zearalenone


FDA


20 ppb 2 ppm


10 ppm (catfish) 5 ppm


ND ND


EU


5 ppm 10 ppb


10 ppm (fish) ND


ND


ND = Not determined FDA = Food and drug Administration EU = European Union


▶ ALL ABOUT FEED | Volume 30, No. 5, 2022


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