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).
The 2016 Nutriad Mycotoxin Survey covers 66 samples from all over Great Britain and Ireland. More than 500 analyzes were conducted to test for the occurrence of the eight mycotoxins most frequently found in agricultural commodities intended for animal production. The survey provides an 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). All analyzed samples were wheat. Typically, wheat levels of DON and zearalenone tend to be lower in northern England and Scotland; moderate in western England, Wales and Ireland and highest in southern and south-eastern England. All samples (66) were collected almost immediately after the harvest and the probability that some storage mycotoxins will have developed (OTA) was low. Wheat samples were sampled directly from farms or animal feed production sites.
Sample providers were advised to follow the principles of good sampling (Richard, 2000). However, analytical personnel and/or laboratory staff were not involved and, therefore, did not influence any part of this procedure. All six 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 < 0.5 μg/kg; ZEN < 10 μg/kg; DON < 75 μg/kg; FB1 < 125 μg/kg; FB2 < 50 μg/kg; OTA < 1 μg/kg; T-2 toxin < 4 μg/kg and HT-2 toxin < 4 μg/kg.
The results show that 64% of wheat samples were contaminated with DON and none of the samples contained AfB1 or FB1. Only 3 % of samples contained T-2 toxin and such low incidence of contamination was not expected. The average concentrations of all recovered mycotoxins were medium while the highest concentration of DON found in one of the samples reached 1100 μg/kg. Although 12.3% of the samples contained HT-2 toxin, a mycotoxin extremely toxic for poultry, its maximum concentration reached only 32.2 μg/kg and this level is negligible. None of the samples was contaminated with FB1, but this result was expected as it is well known thatFB1 is mostly produced on maize. Only one sample was contaminated with FB2 and OTA. Surprisingly, the results show that 15% of wheat samples were contaminated with ZEN and its maximum concentration found in one sample reached 810 μg/kg.
Table 1 – Mycotoxin contamination of wheat in UK
When comparing mycotoxin contamination of wheat in years 2014, 2015 and 2016 it can clearly be seen that the contamination levels in 2016 are significantly higher than in either of the two previous years. All parameters (% of positive, average of positive and maximum concentration) are higher in 2016.
Figure 1 – Comparison of percentage of positive samples in years 2014, 2015 and 2016 (>LOQ)
Table 2 – Comparison of mycotoxin contamination of wheat in UK in years 2014, 2015 and 2016
The Nutriad 2016 mycotoxin survey concludes that this year’s harvest of wheat in the UK and Ireland is of medium quality (>LOD but below EU recommendation levels) in terms of mycotoxin contamination but the situation is much worse than in last two years. Based on the results of this survey conducted immediately after the 2016 harvest we believe that this year’s wheat crop in the UK and Ireland should not automatically be considered safe for inclusion into finished feed rations for all animal species and a degree of vigilance is prudent.
Vigilance is always advisable in any case as cereals in animal feeds originate from many sources and some continental European cereals and South American soya harvested in 2016 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.