NEWBORN RATS

Question
HELLO.  I HAVE A FEMALE RAT AND I PURCHASED ANOTHER FEMALE ABOUT THREE DAYS AGO.  I KNEW SHE WAS PREGNANT AND WAS EXCITED FOR HER LITTER.  SHE GAVE BIRTH THREE DAYS AFTER ME GETTING HER.  I SEPARATED THE OTHER FEMALE AND WAS WONDERING IF I COULD PLACE HER BACK IN THE CAGE WITH THE MOTHER AND HER PUPS.  IF NOT WHEN COULD I PLACE HER BACK IN THERE.  THEY GOT ALONG GREAT WHEN THEY WERE FIRST INTRODUCED.  I HAVE A LARGE 2 STORY FERRET CAGE THEY LIVE IN.  THANKS FOR THE HELP!!

Answer
Nope, I wouldn't introduce the other female back in with the mama until after the babies are weaned - for everyone's safety. Nursing does can be very, very territorial and hormonal; and non-nursing does can act very odd around litters.

Babies wean at 5 weeks. At that point, separate everyone by gender and the other doe can go back in with the female pups and her original cagemate.