What do new born mice eat?

Answer 1

Newborn mice drink milk from the mother's mammary glands until they are old enough to feed by themselves. Mice are weaned at 21 days old. When they get close to this age, they will begin to eat solid food.

Answer 2

They usually would eat milk from their mother, but if your asking about orphans someone would need to feed them goats milk or puppy,kitten or human baby formula (but never feed it cows milk that can make it sick/die)