1. Faculty of Animal Science and Technology; Gansu Agricultural University; Gansu 730070 Lanzhou China
2. Ministry of Agriculture Laboratory of Quality and Safety Risk Assessment for Dairy Products (Beijing); Institute of Animal Science; Chinese Academy of Agricultural Sciences; Beijing 100193 China
3. College of Animal Science and Technology; Hunan Agricultural University; Changsha Hunan Province China
4. Ministry of Agriculture - Milk and Dairy Product Inspection Center (Beijing); Beijing 100193 China