Ours have free access to a chick starter feed and we give them treats besides. If you offer treats (except for soft things like yogurt or cooked eggs) you should also give them grit. We offer ours a little scratch feed, worms from the garden, boiled or scrambled egg, homemade goat yogurt with probiotics, oatmeal (watch them with this as we found they can drown in it if one gets trampled down and stuck in the sticky food during the feeding frenzy!), and finely chopped fruits and vegetables. Their favorites seem to be strawberries and oranges. We just cut the orange in half and stick the halves in their brooder and 30 chicks will devour a whole orange like that in an hour or less! They also like shredded cabbage a lot (be aware that if you use purple cabbage they will have some strange colored poop for a few hours). They are pretty indifferent to apple slices but shredded carrots go over well, as do bananas and broccoli, and even homemade chicken broth with no salt. Cooked brown rice or whole-grain pasta or cooked beans are tasty treats too. Just be sure what you feed has no salt, as birds don't process salt well, and stay away from sugar, preservatives, etc. Basically all the stuff that is bad for you is extra bad for them because they are so small.