4. Discussion
Ten provinces selected in this study are the primary milkproducing regions in China, where the production of raw milk
accounted for 75.1% of the total production in China in 2010. Moreover, these provinces were selected from both southern and northern regions of China, which represented the two typical climates of China. Temperature and humidity are lower in the north than in the south (Table 1). Temperature and humidity had the most important impacts on mycotoxin formation in the feed. Moulds can easily grow and produce toxins in relative high temperatures and humidity environment. Temperature and humidity influence the amount of AFB1 in feed, which in turn determines the concentration of AFM1 in milk. The absence of AFB1 in the feed and AFM1 in the milk in Heilongjiang province and the high incidence of AFB1 in the feed and AFM1 in the milk from Shandong province might be explained by the low temperature and humidity levels in Heilongjiang province compared with the other provinces. The humidity in Shandong province was the highest among the ten provinces, and the average temperature was 25 C (Table 1). Thus, it is more favourable for mould growth and producing toxins, which result in a high incidence of AFB1 in the feed and a high incidence of AFM1 in the milk. Bakirci (2001) pointed out that mould could produce toxins under conditions of 25 C and high humidity.