What is the difference between Purina Flock Raiser and feed specific to layers? I read something on here about switching chicks from chick feed to layer too early, which caused kidney failure, I think, due to too much calcium. Someone mentioned that this Flock Raiser was good for any age chicken. I always followed the directions on the bag and switched the young ones off chick starter at about eight weeks. All the young ones are on layer now, and the only hen from the older batch (from June) is laying perfectly. I haven't seen any health issues at all that would be related to kidneys, as far as I know (two roosters have a slight respiratory infection). I'm just curious to clear this up in case we do get any more chicks. Thanks!