Breeding Mice

Gestation of a mouse is 18-24 days (depending on your source).

Breeding is instanteous when adding a male in with females.  Females come into heat every couple of days.

It is best to have ‘friends’ together.  Female mice will raise babies better when with friends.  Don’t add a fully pregnant mouse to an established colony.

Remove male after 16 days.   Causes less stress to the mom.  And leave him out until her litter has been weaned for 2-3 weeks.   She needs to rebuild her strength as well.

Crowding reduces litter size.

Over breeding reduces litter size.

Handle them frequently but don’t disturb a new litter for the first couple of days.  Let mom get established.  Mind you, I find this less of a problem if you have an experienced momma as part of a colony.