Effect of different grazing intensities during the different stages of alpine grassland growth on the body weight gain of Tibetan sheep

• FENG Bin, 
• YANG Xiaoxia, 
• LIU Wenting, 
• ZHANG Yanfen, 
• LIU Yuzhen, 
• YANG Zengzeng, 
• SUN Caicai, 
• LYU Weidong, 
• DONG Quanmin