1. Department of Animal Science; School of Agriculture and Biology; Shanghai Jiao Tong University; Shanghai 200240 China
2. Institute of Animal Husbandry and Veterinary Research; Shanghai Academy of Agricultural Sciences; Shanghai 201106 China
3. Shanghai Key Laboratory of Veterinary Biotechnology; Shanghai 200240 China
4. Faculty of Life Science and Technology; Kunming University of Science and Technology; Kunming 650093 Yunnan China