Chengdu City, Sichuan Province, southwest China - July 9, 2019 (CCTV - No access Chinese mainland)
1. Giant panda keeper handing cub to mother panda
2. Various of mother panda Cheng Da licking, tending her cub
3. Giant panda keeper walking through doorway, bamboo sticks in basket
4. Various of giant panda keeper feeding Cheng Da
5. SOUNDBITE (Chinese) Mei Yan, giant panda cub keeper:
"I remembered the time she drank milk for the first time. I squatted there all the time until I got cramps. I crouched down there for more than 20 minutes and she only had 0.3 grams of milk."

Chengdu City, Sichuan Province, southwest China - June 11, 2019 (CCTV - No access Chinese mainland)
6. Various of giant panda giving birth
7. Giant panda licking her cub

Chengdu City, Sichuan Province, southwest China - June 13, 2019 (CCTV - No access Chinese mainland)
8. Various of newborn cubs in incubator, keepers taking care of them

Giant panda keepers breathed a sigh of relief on Wednesday as a vulnerable baby panda cub has now gained enough weight to survive after being born underweight at southwest China's Chengdu Research Base of Giant Panda Breeding last month.

The tiny cub named Cheng Lang was smaller than an egg when she was born on June 11 and weighed a minuscule 42.8 grams. After one month of close care and attention from breeders, Cheng Lang has now grown significantly to reach a healthy weight of 510.2 grams.

In the first two weeks after her birth, little Cheng Lang was unable to feed on milk herself and could only eat with the help of keepers.

Mei Yan, one of the giant panda cub keepers responsible for Cheng Lang, recalled the difficulty of nursing the young cub through the early stages.

"I remembered the time she drank milk for the first time. I squatted there all the time until I got cramps. I crouched down there for more than 20 minutes and she only had 0.3 grams of milk," said Mei.

Giant panda cubs usually weigh in at around 150 grams at birth, with those weighing under that figure considered as super light. Prior to Cheng Lang's arrival, the previous record for the smallest cub at the Chengdu Base came in 2006 when a cub weighing 51 grams was born.