I have just gotten new chicks. 4 are about a week old and 5 are about 3 days old. I had a flock of 18 that lived in a run/coop for 12 years. Most died of old age and my last 4 recently died in a predator attack. Should I start to put little scoops of dirt from the run in with the babies? I heard that was a good idea to get their immune systems started. The weather has been bad so it has really not been raked out so their is poop still in there. Sounds logical but seems a little gross LOL. Thoughts?