Medical workers perform a checkup on the world's first known surviving panda triplets, at Guangzhou Chimelong Safari Park in Guangdong province. Provided to China Daily

Giant panda triplets born a month ago at a zoo are healthy and putting on weight, a manager said on Thursday.

The cubs were pink when they first appeared but have started to grow black and white fur, said Dong Guixin, general manager of the Guangzhou Chimelong Safari Park in Guangdong province.

The triplets' weight increased from 90.5 grams, 83 grams and 124.4 grams when they were born on July 29 to 1,014.5 grams, 1,013.2 grams and 1,227.6 grams today.

They are the world's first known surviving panda triplets.

"It is a miracle, as the three cubs are very healthy," Dong said. "They are under the watchful eyes of a team of zoo staff 24 hours a day and are expected to meet visitors four months from now."

The triplets are being nursed by their mother, Juxiao, whose name means "chrysanthemum smile".

In addition to mother's milk, each cub is given 300 milliliters of special formula per day.

"The mother cannot feed them all at the same time," said Dong.

"They have become accustomed to the changing feedings and are showing good appetites."

The triplets will start eating bamboo in the near future, he added.

Dong revealed the cubs' genders . The eldest is female and the younger two are male.

"The female cub is quiet after being fed, while the two males are very lively and crawl near their mother," he said.

The zoo has launched a campaign inviting members of the public to suggest names for the cubs.

Panda triplets have only a 1 percent chance of surviving birth, according to the China Conservation and Research Center for the Giant Panda.

There are only four known cases of pandas conceiving triplets, but not all the cubs survived.

In 1999, an 18-year-old panda at the Chengdu Research Base of Giant Panda Breeding conceived three cubs, but only one was born alive.

qiuquanlin@chinadaily.com.cn