1 Hunan Province Key Laboratory of Animal Nutritional Physiology and Metabolic Process, Key Laboratory of Agro-ecological Processes in Subtropical Region, Institute of Subtropical Agriculture, Chinese Academy of Sciences, National Engineering Laboratory for Pollution Control and Waste Utilization in Livestock and Poultry Production, Changsha, Hunan 410125, China.
2 Department of Animal Science, Division of Agriculture, University of Arkansas, Fayetteville, AR 72701, USA.
3 Polytechnic Institute of Bragança, Bragança, Portugal.