1. State Key Laboratory of Grassland and Agro-Ecosystems, School of Life Sciences, International Centre for Tibetan Plateau Ecosystem Management, Lanzhou University, Lanzhou 730000, P.R. China
2. Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou 730000, P.R. China
3. College of Pastoral Agriculture Science and Technology, Lanzhou University, Lanzhou 730000, P.R. China
4. Desert Animal Adaptations and Husbandry, Wyler Department of Dryland Agriculture, Blaustein Institutes for Desert Research, Ben-Gurion University of Negev, Beer Sheva 8410500, Israel
5. Department of Animal Sciences and Industry, Kansas State University, Manhattan 66506