We are feeding chick crumbles. At the moment they are learning how to scratch and have either billed or scratched most of their feed out onto the floor where they are now merrily scratching away. Made the biggest mess
Here's a thread link with my build and a couple other ideas, that might help you with wasted chick feed.
https://www.backyardchickens.com/threads/no-waste-chick-feeder-build.1297528/