My rats are on a gluten-free diet. I looked up what crops rats actually attack in the wild, and replicate it as much as I can here. Right now they get dog food, but that will be replaced with crickets and other insects and grubs - as natural as possible to replicate their wild ancestor's diet - Brown Rice, some squash seeds, Fresh corn, fresh fruits and vegetables(or baby food if we have no fruits or vegetables in the house), melon, and berries. I also offer grass and clover every so often in case they're having a day where they want to eat it.