1. Institute
of Environment and Sustainable Development in Agriculture, Chinese Academy of Agricultural Sciences, Beijing 100081, China
2. Key
Laboratory of Energy Conservation and Waste Treatment of Agricultural
Structures, Ministry of Agriculture, Beijing 100081, China
3. Animal Production
and Health Division, Food and Agriculture Organization, 00153 Rome, Italy
4. Animal
Production Systems Group, Wageningen University, P.O. Box 338, Wageningen, The Netherlands
5. Department
of Agricultural and Biosystems Engineering, Iowa State University, Ames, Iowa 50011, United States
6. Institute
of Biological and Environmental Sciences, University of Aberdeen, 23 St. Machar Drive, Aberdeen AB24 3UU, United Kingdom
7. Environment
Centre Wales, School of Environment, Natural Resources and Geography, Deiniol Rd., Bangor University, Bangor LL57 2UW, United Kingdom