Most of my chicks are 5 weeks old. Between 3 breeds, I've noticed that my rocks are growing faster. They are fully feathered already with my RIR close behind. Anyway, the rocks seem to be growing really, really fast all of the sudden. They have to duck to walk under the perch in the brooder cage I have for them. Do chickens go through growth spurts? I've been giving them chick feed from the family farm store and letting them roam in the yard to eat what they find... I'm kind of glad I don't have to clothe them, I'd have gone broke with their growth rate. Is this normal?