1. College of Animal and Veterinary Sciences, Southwest Minzu University, Chengdu, P.R. China
2. Key Laboratory of Qinghai-Tibetan Plateau Animal Genetic Resource Reservation and Utilization, Ministry of Education, Southwest Minzu University, Chengdu, Sichuan, P.R. China
3. Key Laboratory of Sichuan Province for Qinghai-Tibetan Plateau Animal Genetic Resource Reservation and Exploitation, Chengdu, Sichuan, P.R. China.