Zookeepers were on alert to ensure that the surviving panda cub of twins born on Friday makes it through the crucial first week of its life.
"The first week is the most difficult because it is still very fragile," the zoo's chief vet Baptiste Mulot said this morning.
But the early signs appeared to be good.
"He is breastfeeding from his mother, we'll see if we have to supplement that with milk brought by the two Chinese carers,..." he added.
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Huan Huan "is a very protective mother, which is very good, but that complicates the work of the Chinese carers a bit when it comes to taking the cub away every two hours," said Mulot.
There was joy and pain Friday as the zoo's only female panda gave birth to twins, but one died soon afterwards.
Huan Huan, on loan to Beauval zoo in central France from China, delivered the first cub at 10:18 PM (local time) and the second at 10:32 PM.
"It was too weak to survive. The Chinese experts, who have experience of this, saw it straight away," zoo director Rodolphe Delord said.
"Our veterinary teams did everything they could to save it, but it was too small, too weak."
But he said the second twin, which weighed in at a healthier 142.4 grams, was in "perfect health".
The cub stayed mainly with his mother, but whenever it was taken away from her it was immediately put in an incubator, said chief vet Mulot.
For the moment, the cub is known simply has "Mini Yuan Zi", after its father.
Visitors to the zoo were delighted at the news of the birth.
"I'm so happy that a baby panda was born here because later, I want to work here," said 13-year-old Marion, who made a special trip with her parents from the southern city of Avignon.
Visitors will have to wait three months to see the family in their enclosure, when the baby panda will have opened its eyes and be covered in hair. In the meantime, visitors can watch a film of the pandas on giant screens.
Breeding pandas is notoriously difficult and this is the first time a cub has been born in France.
The female panda is only in heat once a year for about 48 hours. The gestation period for pandas is a mere 50 days.
Huan Huan (meaning "happy") and Yuan Zi ("chubby") are the only giant pandas living in France.
The pair were brought together in February, in the hope they would mate, but it didn't happen. In the end, the zoo performed an artificial insemination.