I have 6 ameraucana chicks in the garage now under heat lamps. I have a concrete block dog kennel that is 5' by 6' with a run that is 5' by 8' that I plan on using as my coop. Both have concrete floors. Do chickens need grass to scratch and peck in or will the concrete floor in the run be fine. Would it greatly benefit my chickens if I extend the run another 8 feet into the grass and have half concrete/half grass