I use Mazuri 6F for my rodents. I don't have a huge colony yet so my numbers of comparison are pretty small, but I feed this to all my rats. For my pregnant and nursing moms, I also supplement with Pedigree Large Breed dog food for some supplemental protein. The others do not receive the dog food. Once I wean my babies, they no longer receive the dog food either. My females stay of good body weight after they delivery and pups grow large and fast. Out of five litters that I've had born, I've lost no pups after delivery. My holdback rats are also growing nicely and don't appear to be obese or have any health problems.