Aflatoxin M1 contamination in raw milk and its association with herd types in the ten provinces of Southern China

The incidence of aflatoxin M1 (AFM1) contamination in raw milk and its association with herd types was investigated in the ten provinces of Southern China in 2018. A total of 797 raw milk samples were collected from Zhejiang, Jiangxi, Jiangsu, Hunan, Hubei, Hainan, Guangxi, Guangdong, Fujian, and Anhui provinces. The herd types were classified according to their characteristics. Among the 797 samples, 401 were owned by large-scale farms (herd size >500 cows, for dairy cow farming), 303 were owned by milk processing plants (herd size >500 cows, for dairy cow farming + milk processing), and 93 were owned by small farm cooperatives (herd size <= 500 cows, for dairy cow farming). The results revealed the presence of AFM1 in 94 of the 797 samples (11.80%). None of them was above 500 ng/L (Chinese and US limit standard), whereas 0.88% were above 50 ng/L (EU limit standard). The AFM1 concentrations in samples non-compliant with the EU standard were 52, 61, 88, 89.5, 164, 240, and 486 ng/L, respectively. It is important to note that samples exceeding the EU limit were mainly found in the area of Jiangsu and Guangxi provinces, and the herd type of milk processing plants. Hence, it is necessary to monitor and enforce the regulatory compliance of AFM1 levels in the raw milk from these specific areas and herd type.