Ten days old is a good time to check the sex of the babies because the female babies are developing nipples and their fur is short enough to see them easily. Male rats don’t have nipples.  I also weigh each baby, and Xia’s litter has a nice even weight distribution, although the babies are slightly smaller than average for their age. The total litter weight is 263 grams, almost four times their weight at one day old.

10 days