Celebrations for the unprecedented birth of four lesser pandas at Beijing Zoo soured this week after keepers discovered that the mother was not able to produce enough milk.

However, the hungry cubs were saved after a public appeal for a lactating dog was answered, in the form of a whippet.

"It was a big surprise to see the birth of four cubs, all alive," said Ye Mingxia, publicity director of the zoo, who said it was the first time a lesser panda has had four cubs in the zoo's 100-year history.

"However, the problem of inadequate breast milk supply came on the second day ," said Ye.

She emphasized that breast milk is a must for newborn mammals due to its rich protein. It cannot be replaced by any other dairy product.

Zoo administrators on Tuesday issued a notice via local media, trying to find a wet nurse.

"We received 33 phone calls offering help on Tuesday, the first day after the notice was published," Ye told China Daily, adding that they were still receiving calls.

After careful consideration, keepers selected the whippet.

"She looks like a deer, and is so beautiful, gentle and friendly. She gave birth to two babies on Sunday and has sufficient milk yield," Ye said.

Both of the dog's puppies died after birth.

The dog will live with the panda cubs for the next two months to feed them, and the owner is welcome to come and visit.

Dogs make good wet nurses for lesser panda cubs because their milk is similar.