The biggest problem with feeding corn is that it is low in protein, and the protein is low in some essential amino acids that chickens need. Corn in itself is fine, but it needs to be balanced with the correct proteins. I would suggest that you feed a small amount of cat food along with the corn, if you don't want to feed layer pellets.
The animal proteins in the cat food will come fairly close to balancing the ration, and the extra fat in the cat food will help the chickens to have more energy.
When your hens are molting, corn is an excellent source of the yellow substance called carotenoids. While hens are laying eggs, the carotenoids gradually are leached out of the hen's beak and legs. It is the substance that causes egg yolks to be yellow. If you notice, pullet eggs have a deeper yellow than the yolks from a hen that has been laying for a year.
When hens molt, the yellow color gradually comes back into their legs and beaks. When the molt is over, the hen will usually have a nice yellow beak and legs, and when she begins to lay eggs again, the yellow gradually disappears again.
My show chickens are fed corn every day. It helps them to keep their legs a nice yellow color. I also feed several other feeds, and try to keep their diet in balance.