If you're concerned that the skinnier babies aren't getting enough milk from that female due to the fact that's there's 13 competeing for what's available you could try to get the other female with the small litter to take some on. If her small litter is so much bigger you could try it two ways.


- either take some of the large ones from the large litter and move them over...that way the smaller ones don't have bigger littermates to compete with

- move the small ones over to the female that you think has a better milk supply for them

However you do it you can also remove all the young except the smaller ones for a couple of hours a day twice a day (just keep them warm) so the small ones get all the available milk for that period of time each day.

When I have to foster out rat babies I take the fosters and pop them in a small container that is lined with used litter from the new foster mom's enclosure. Then I put in a couple of her own pups and let them co-mingle their scents. Then put them all back in with the female and it usually works really well. Just watch for her to start nursing them and licking their butts and you know it's a go.

Sometimes the runts just don't make it though that's not all that common with rats but it does happen. I have one extremely small rat wean, it was born tiny but is thriving and very healthy...just for some odd reason it's half the size of every other wean in the colony. I've decided to name it Miny Me and see what happens as it grows up since I've never seen one so small that was otherwise healthy.