However, note that lactating females do not need to consume milk or dairy products themselves. This goes for all mammals – humans and dogs as well as mice. Dairy produce can be a useful source of protein, but it is not necessary. It is not a natural food for mice.
Fresh water must be available to lactating females at all times. Check frequently that water bottles are not clogged. To be safe, leaving two water bottles in the cage will ensure that water is available even if one clogs.
Do not offer milk, milk substitutes or animal formula to baby or young mice unless there is a serious medical problem, or you are hand-rearing them. Their bodies are designed to thrive on mouse milk, not cow milk. The milk of other species is unnecessary, and could damage their health in the long-run as well as the short-term.
We know that humans fed formula milk are more likely to suffer from a range of health problems; the same almost certainly applies to other mammals.