1. Key Laboratory of Agro-ecological Processes in Subtropical Region, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha, Hunan 410125, China;
2. Observation and Experiment Station of Animal Nutrition and Feed Science in South-Central China, Ministry of Agriculture, Changsha, Hunan 410125, China
3. Hunan Provincial Engineering Research Center for Healthy Livestock and Poultry Production, Changsha, Hunan 410125, China
4. College of Animal Science, South China Agricultural University, Guangzhou 510642, China