A red thread is tied on the ear of a male sheep to be marked as a breeding sheep on the riverside of Nam Co, southwest China's Tibet Autonomous Region, May 5, 2016. A sheep castration ceremony, which has been observed for more than 1,000 years by the herdsmen living in the northern part of Tibet region, was held on the riverside of Nam Co. In order to breed sheep of the best quality, despite a few robust male sheep, most of the male sheep of more than 5 months old here will be castrated and bred as mutton sheep. (Photo: Xinhua/Chogo)
