I have a 1.6 group of mice in a 56qt tub. They are fed and watered daily. Cage is cleaned once weekly. I used to pull only 30 babies per month out of this tub. They've had about 5 group litters. Litter #5 is incredibly small. Only 5-6 babies. They are huge/fat babies, but with only 5-6 and no other females looking pregnant, should I possibly consider feeding off the entire group and replace them?

I was thinking of re-doing my mouse colonies anyway since I'm moving all the mice to tubs. The other group, the offspring of the group mentioned above have okay numbers as far as production. Again it is a 1.6 group. Right now I have probably 10 babies in there, after having fed off 7 pinkies. And 2-3 of the females are still pregnant. So their numbers are okay. I'm thinking of thinning down the number of females so the groups are 1.4. This particular group has had 3-4 litters so far. I lost track of how many, but I know its no more than 4.

The only other "group" I have is a pair. I kept two of their daughters in the group so now it is a 1.4. Original pair have had 3 litters. The daughters have not had any yet.

So what do you think? Should I kill off the first group and replace them? I could keep some of the females from their current litter to raise up but I kind of don't want to wait for them to mature enough to breed.