I had bought a new female rat a few months ago and placed her with the original male I had and no babies after a couple months, so I placed her with the male rat my sister had raised up and after a month, se had a litter or 6.
Momma and her babies
http://i49.photobucket.com/albums/f2.../Rats/New1.jpg
The male when my sister "rescued" him from the snake feeding box.
http://i49.photobucket.com/albums/f2...ptiles/Rat.jpg
Here he is today, his name is Rattie. He likes to stay at the front of the tub and "bang" his teeth against it whenever anyone comes near, when you open the tub he pokes his head out wanting someone to pick him up. LOVES to be held.
http://i49.photobucket.com/albums/f2.../Rats/New2.jpg
Since I only need 5 babies from this litter, im letting my sister pick one to raise up.
My other female rat, who ate her entire other little, also had a litter about a week after the other female, her litter was 12.