Bei Bei munches on bamboo at the zoo on Wednesday. YUAN YUAN / FOR CHINA DAILY

Zoo officials and zookeepers in Washington responded to some observers on Chinese social media that the pandas were "mistreated" following the bear mom's estrus and the cub's weaning.

Bei Bei, born in 2015, is doing well after he was weaned from his parents Mei Xiang and Tian Tian, who moved to the Smithsonian National Zoo in 2000 under a collaboration agreement between China and the US.

"Everyone is doing great," Bryan Amaral, senior curator of mammals at the Smithsonian's National Zoo, said of the three bears. He said that Mei Xiang underwent two artificial inseminations last week, and it's too early to tell if she is pregnant.

There have been reports in Chinese social media that the 18-year-old mother was forced to get pregnant to attract more visitors; that she failed to get enough food; and that there were snakes in her enclosure.

They also said her weaned baby, Bei Bei, was stressed and climbing trees to look for his mother.

"We definitely talked to our Chinese colleagues when we did the artificial insemination," said giant panda keeper Marty Dearie. "We've had a member of the Chinese (counterpart staff) here to assist with that."

Dearie said the highly cooperative relationship between the two countries has benefited pandas in the zoos in the US, in China and those in the wild.

Animal care staff members have closely monitored Mei Xiang and 19-year-old Tian Tian for any behaviors that would indicate the pair were interested in breeding.

The pandas have exhibited such behaviors "at incongruent times", so there has been no natural breeding process this season, the zoo said in a statement.

The zoo received approval for its breeding plans from the China Wildlife and Conservation Association and the US Fish and Wildlife Service, the statement added.

"We follow the best practices that were established through our Chinese colleagues," Dearie said.