What are you feeding them?
By higher percentage, I guess you mean a higher percentage protein feed?
Very odd time for all to be molting. What is the lighting like in the building?
Chickens are ravenous eaters and if they aren't free ranging, you need to keep feed available all waking hours or they'll eat things you don't want them to eat, like bedding, feces, etc..
The moron that was feeding only corn got out of them, what they put into them, didn't they?
You'll also get the same results if you don't keep an appropriate feed available all day. Since they aren't laying, have been deprived of a complete feed and need to grow feathers - they need a higher protein complete grower feed. 18-20% for now. You can cut back to 18% till they start laying.
Commencement of lay will be determined by body condition(complete nutrition) and day length.
You probably need something like this.
Or you could build a bulk feeder.
Edited by ChickenCanoe - 2/26/16 at 2:50pm