Breeding ratio and pregnancy in mice

Question
I am trying to breed some regular pet store mice for feeders, because the only place I can get them is over an hour away. But I was wondering what the best female to male ratio is. I was also wondering how to tell if the the female is pregnant. If she should be separated from the others. And also if she starts grabbing pieces of tissue, paper towel rolls and pieces of bedding and putting them all into the one house she shares with the male and another female, if she is building a nest or just being weird.

Answer
Dear Randy,

Two females to one male is a good ratio. But once the girls are pregnant you want to take the male out so he doesn't mate right after she gives birth. The females should get a three week rest between litters. They nest together well. The way to know if mating was successful is that within 24 hours there should be a whitish plug in the v agina. Other than that the nesting is a very good sign that she will have a litter soon. A heavily pregnant mouse will typically look as if she swallowed a pear, but a very small litter may barely show at all.

Best of health to the mice. Remember even feeder mice need love, comfort, and e ntertainment.

Sorry if this is messy, I am on my phone.

Squeaks,

Natasha