Try giving them full choice feed for 12 hours straight.....I never let mine run out untill dark. Try it and see if it helps, but don't let them have feed in their down time.
Good Luck,
Jeff Brunty
It sounds like your feeding them too much. Are you feeding them 24 hours / day?
If so what you need to do is take them off of the night feeding schedule. Feed on a 12 hour on and 12 hour off schedule. Time of feeding is up to you but be consistent. For example if your going to feed from 7:00...