The best nutrition is to give a balanced chicken feed only for 90% of their diet. Many use layer feed or an all flock/flock raiser feed plus crushed oyster shell in a separate container for the layers. Kale is good occasionally. Scratch grains or corn is not necessary and can make some fat. I have pretty much stopped giving scratch grains for treats. I have some overweight Marans, so I switched to Flock Raiser Feed 20% protein which most eat well. They sometimes think they are getting a treat when I put water into a bowl of their feed, LOL.