CHENGDU, Aug. 14 (Xinhua) -- A giant panda in captivity gave birth to two cubs on Monday, bringing the number of newborn cubs to four in just one day.

Fourteen-year-old Eryatou delivered a female cub weighing 218.5 grams at about 7 p.m. at the Chengdu Giant Panda Breeding Center, Sichuan Province, in southwest China.

The arrival of a second female cub, weighing just 98.5 grams, at around 11 p.m. took breeders by surprise.

Eryatou has been able to feed both cubs so far, a rare feat given that most pandas are only able to care for one cub at a time. In the wild environment, only the stronger cub usually survives, and for those raised in captivity, the breeders usually take each of the twins away in turn for a period of time to ensure both receive sufficient milk.

A male and a female were also born earlier on Monday in the same breeding center, the fifth delivery for 12-year-old Jiaozi since 2001.

Chinese panda breeding centers have reported 14 cubs born so far this year, including six pairs of twins.

According to estimates by experts, there are only about 1,590 giant pandas in the wild. The number of giant pandas in captivity stood at about 210 in China.

The mating season of giant panda is mainly from March to May and giant pandas only give birth once a year, usually to one or two cubs.

China has been raising pandas through artificial insemination and breeding for nearly 50 years. However, it began to have more than 10 cubs every year in recent years.

Thirty-four panda cubs were born by artificial insemination in 2006 and 30 of them have survived. Both were record figures.