Co-occurrence of mycotoxins, including aflatoxins, trichothecenes, and zearalenone, in Chinese feedstuffs collected in 2013 and 2014

A total of 357 feedstuff samples, including cottonseed meal plus soybean meal (CSM), wheat bran (WB) and dried distillers grain with solubles (DDGS) collected from 14 provinces in China in 2013 and 2014 were analysed for the co-occurrence of mycotoxins, including 4 aflatoxins, 7 trichothecenes, and zearalenone (ZEA), by high-performance liquid chromatography/electrospray ionization tandem mass spectrometry (HPLC/ESI-MS/MS). Deoxynivalenol (DON) was the most prevalent mycotoxin found in Chinese feedstuffs, followed by ZEA and aflatoxin B1 (AFB1). It was found that out of 357 samples, 27 (7.6%), 11 (3.1%) and 5 (1.4%) samples were positive for DON, ZEA and AFB1 at levels exceeding the Chinese regulatory limit of 1000 μg/kg, 500 μg/kg, 50 μg/kg for DON, ZEA, and AFB1, respectively. DON, ZEA, and AFB1 levels ranged from 1,005.5 to 2,893.1 μg/kg, 510.8 to 4,845.9 μg/kg, and 53.9 to 72.9 μg/kg, respectively. These samples were more easily co-contaminated by other mycotoxins, such as DON, ZEA, AFB1, AFB2, 3-acetyldeoxynivalenol (3-ADON), and 15-ADON. CSM was more easily contaminated by aflatoxins than WB and DDGS, and WB was more easily contaminated by DON and ZEA. Besides, 339 samples (95.0%, 339/357) were contaminated by at least two mycotoxins, and 16 samples (4.5%, 16/357) were only contaminated by one mycotoxin, and 2 samples (0.6%, 2/357) were not contaminated by any mycotoxin studied. There were 30, 66, and 66 different mycotoxin combination types in CSM, WB, and DDGS, respectively, but DON+3-ADON+15- ADON+ZEA was the most frequent mycotoxin combination, with a frequency of 13.16% (5/38) in CSM, 17.29% (23/133) in WB, and 18.8% (35/186) in DDGS. These results indicate that mycotoxin co-occurrence is very common in Chinese feedstuffs, and it is very important to conduct multi-mycotoxin monitoring in Chinese feedstuffs.