If you want maximum production you want to separate the females as they are pregnant and avoid back to back breeding with rats. (Females can become pregnant again hours after birthing)

Being pregnant while nursing takes it's toll fast not only on the mother but the next litter to come, the litters will be smaller so will the babies.

The other thing that helps in reducing the loss is individual birthing and communal nursing when the pups are 5 days or older.

You need more tubs.

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