1. State Key Laboratory of Grassland Agro-Ecosystems, Lanzhou University, Lanzhou, People's Republic of China
2. Key Laboratory of Grassland Livestock Industry Innovation, Ministry of Agriculture and Rural Affairs, Lanzhou, People's Republic of China
3. College of Pastoral Agricultural Science and Technology, Lanzhou University, Lanzhou, People's Republic of China
4. National Demonstration Center for Experimental Grassland Science Education, Lanzhou University, Lanzhou, People's Republic of China