Cats are meat eaters, plain and simple. They have to have protein from meat for a strong heart, good vision, and a healthy reproductive system. Cooked beef, chicken, turkey, and small amounts of lean deli meats are a great way to give them that. Raw or spoiled meat could make your cat sick. If you wouldn't eat it, don't give it to your pet. 

Oats have a lot of protein per calorie, and they're easy to make. Many cats like corn, and polenta, a coarsely ground cornmeal, has a good texture for them. You can try brown rice, barley, and wheat berries, but you may need to mash them first. Cats tend to like smaller grains like millet and couscous. Just make sure any grains you give are cooked so your kitty can digest them fully. Whole wheat breadcrumbs are OK, too.