When a panda mother gives birth to two cubs, one is almost always rejected, so it needs human intervention to survive, they said. Even a single cub is sometimes rejected or accidentally killed by its mother.
Although a milk substitute for pandas is a long way off, the lead project scientist at the University of Glasgow said the research would move things "in the right direction."
"Bears give birth to tiny, helpless cubs that are unusually small relative to their mothers," Malcolm Kennedy told the BBC. "In the case of pandas the weight ratio can be 1:1,000 or even lower."
Panda cubs are dependent on their mother's first milk, known as colostrum, to protect them from infectious diseases.
"It could be that panda milk is specially adapted to rear such under-developed young," he said. "Indeed, we have found that panda milk takes much longer to convert from colostrum to regular milk than in cows, for example."
Understanding how panda milk differs from dairy and human milk could lead to a modified formula that can better support baby pandas, the researchers said, noting the hand-rearing of pandas in captivity currently involves swapping twins when the mother is distracted or using cows' milk that has been modified for infant dogs.