I have 6 chickens and they range from 11 weeks to 15 weeks. I have been giving them grower crumbles, but it does not look like they are eating eat. I give them scratch in the morning and at night before they go to bed. They also free range just about all day. I got a 50lb bag of grower over a month ago and they haven't even made a dent in it. Should I stop feeding them grower?