Soon enough the babies begin to leave the nest and explore, soon getting into Mom rat's food. It'll soak right in and makes a good supplement. As the babies grow, I gradually introduce lab block along with a wide variety of other foods. I try to keep the protien level somewhat boosted, and I really don't totally take away the kitten or puppy food until the ratties are 3 months old or so because I feel they grow better on it. I discontinue it for older rats because there's too much fat and protien for the nutritional requirements of older rats.
Lab block is a special food made to exactly meet the nutritional requirements of rats.
Adjust this daily to meet the demand. In addition, add variety by giving little bits of fruits and veggies every day. Don't go too heavy on the people food or greasy, salty, or sugary treats, no matter how much the little boogers beg. In general, adult rats need lower levels of protien and fat than do baby rats. This is because they are finished growing.