Survey of aflatoxin in dairy cow feed and raw milk in China

In August 2010, 200 feed samples for dairy cow and 200 milk samples were collected from ten major milk-producing provinces in China. The feed samples were analysed for Aflatoxin (AF) B1, B2, G1 and G2, using the HPLC method. AFM1 in the milk samples was determined using the ELISA method. AFB1 and AFB2, but not AFG1 and AFG2 were detected in the feed samples. In the feeds, 42% of the samples contained AFB1 in the range of 0.05-3.53 μg/kg, and 36% of the samples were detected positive for AFB2, with the content ranging from 0.03 μg/kg to 0.84 μg/kg. The content of AFB1 was significantly (P < 0.05) higher than that of AFB2 in the feeds, but it was still below the legal limits of 5 μg/kg (in EU) and 10 μg/kg (in China), respectively. The total content of AFs was below the U.S. legal limit of 20 μg/kg. For the milk samples, 32.5% were detected positive for AFM1, in the range of 5.2-59.6 ng/L, far below the legal limit of 500 ng/L in China and the US. However, three samples contained AFM1 at the levels of exceeding 50 ng/L of the EU legal limit. Furthermore, there was no significant (P > 0.05) difference between the north and the south of China in the AF contents in both the dairy cow feed samples and the milk samples.