Most rats handle the protein ok as long as it is not excessive. Some however can have or develop protein sensitivity. So you just have to be careful. I use dry dog food in my everyday mix. What you need is a high quality Lite or Senior formula (which is lower in protein) I use Nutro Natural Lite, or Chicken Soup senior. Other good brands are Canidae, Solid gold, innova. You want a dog food who's first ingredient is meat, be it beef, chicken lamb ect. ( Mine seem to prefer the lamb and rice variety) Not meat by-product either. Also Corn should NOT be one of the first three ingredients. The less corn and or grain the better. Basically any grocery store food is NOT good. Try a pet supply wholesale or feed store. Also remember not to overdo the fruits. They love them and would eat them nonstop if they could but they are high in sugar. Well I hope this helps!