Nutriad Poland 2017: Mycotoxin survey in wheat
Mycotoxins are secondary metabolites produced by filamentous fungi that cause a toxic response (mycotoxicosis) when ingested by farm and companion animals. Fusarium, Aspergillus, and Penicillium are the most abundant moulds that produce these toxins. They contaminate human foods and animal feeds through fungal growth prior to and during harvest, or during improper storage (Bhatnagar et al., 2004).
Picture 1: Barley harvested in central Europe 2017 ©Copyright: Radka Borutova, Nutriad
The 2017 Nutriad Mycotoxin Survey covered 88 wheat samples from across Poland. The survey provided insight into the incidences of aflatoxin B1 (AfB1), zearalenone (ZEN), deoxynivalenol (DON), T-2 toxin, HT-2 toxin, fumonisin B1 (FB1), fumonisin B2 (FB2) and ochratoxin A (OTA). The wheat samples were collected directly from farms or animal feed production sites. Sample providers were advised to follow the principles of good sampling (Richard, 2000). Analytical personnel and laboratory staff were not involved, and therefore did not influence any part of sampling. All 88 samples were collected almost immediately after harvesting and so the probability of storage mycotoxins (OTA) developing was low. More than 700 analyses were conducted to test for the occurrence of the 8 mycotoxins most frequently found in agricultural commodities intended for animal production. All eight mycotoxins were analyzed by liquid chromatography tandem mass spectrometry (LC MS/MS). For the purpose of data analysis, non-detection levels were based on the limits of quantification (LOQ) of the test method for each mycotoxin: AfB1 < 1 μg/kg; ZEN < 10 μg/kg; DON < 50 μg/kg; FB1 < 50 μg/kg; FB2 < 50 μg/kg; OTA < 0,5 μg/kg; T-2 toxin < 20 μg/kg and HT-2 toxin < 50 μg/kg.
The results showed that 83% of the wheat samples were contaminated with DON. None of the samples contained AfB1, FB1, FB2, T-2 toxin and HT-2 toxin. Only 2,3 % of samples contained ZEN, an unexpectedly low incidence of contamination. The average concentrations of the recovered mycotoxins were low. The highest concentration of DON found in one of the samples was 3990 μg/kg. As expected, the results showed that 1,1% of wheat samples were contaminated with OTA and the highest concentration found in one sample was 2 μg/kg.
Table 1 - Mycotoxin contamination of wheat in Poland
The contamination levels of DON and ZEN in wheat in 2017 were much lower than in 2016 (Table 2). However, the percentage of samples contaminated with DON were higher in 2017 than in 2016 (Figure 1 and Table 2). In 2016, there were higher incidences of other mycotoxins compared to 2017 where only 3 mycotoxins types (DON, ZEN, OTA) were detected.
Figure 1 - Comparison of percentage of positive samples (DON and ZEN) in 2016 and 2017.
Table 2 - Comparison of mycotoxin contamination of wheat in Poland in 2016 and 2017.
The Nutriad 2017 mycotoxin survey concluded that the year's harvest of wheat in Poland was of medium quality (>LOD but below EU recommendation levels) in terms of mycotoxin contamination. This is an improvement when compared to last year's harvest. Based on the results of the survey conducted immediately after the 2017 wheat harvest, the 2017 wheat crop in Poland should not automatically be considered safe for inclusion into finished feed rations for all animal species and a degree of vigilance is prudent. Special attention should be paid to the very high incidence of DON found in over 80% of the samples and to the maximum recovered concentration which almost reached 4 mg/kg.
Vigilance is always advisable as cereals in animal feeds originate from many sources. Some continental European cereals and South American soya harvested in 2017 have been shown to be contaminated with medium to high concentrations of mycotoxins.
The last possible line of defense is the detoxification of mycotoxins in vivo. The addition of proven mycotoxin deactivators to animal feeds is a very common method to prevent mycotoxicosis and is an effective strategy to keep mycotoxin risk low under any and all conditions.
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Article made possible through the contribution of Radka Borutova and Nutriad