Lin Bing, 5, is seen at the Dujiangyan base of the China Conservation and Research Center for the Giant Panda in May. [Photo/China Daily]

Keepers and visitors say Mei Sheng is healthy, lively and cute. He likes climbing trees, playing with toy balls and staying on the swing.

"He is expected to be one of the ideal pandas who can have natural sex with female partners and produce offspring," Wang said.

"Two years after he returned from the United States, Mei Sheng had natural sex with a female panda in 2009. But it did not result in a cub," he said.

Missed by many

As pandas are unique to China, people in foreign countries and regions are sad when the cubs born in their cities return home. Some people have gone to Sichuan specially to visit the cubs in the center, Huang said.

Lin Bing was born in Chiangmai, Thailand in 2009. The female panda should have returned home in 2011 but because the Thai people loved her so much, China allowed her to stay in Thailand for two more years.

"About two months after she returned home, some 200 Thai people took a chartered plane to visit her. They were happy to see that the cub had adapted to the new environment in the Bifengxia base of the center," Zhang said.

Fu Long, a male panda, was born in Austria in 2007. He is the first captive panda born in Europe by parents who had natural sex. Fu Long was the talk of the town among Austrians who keenly tracked his naming, first meeting with visitors, first birthday and first walk on snow.

"Last year, Fu Long's Austrian keeper came specially to the Dujiangyan base to visit him," Huang said.

Since the center loaned its first panda to the San Diego Zoo in the US in 1996, China has loaned a total of 33 pandas to other countries and regions. The bears have produced a total of 32 cubs overseas, 22 of which have returned home.