Bee, I disagree with you on one thing, feeding Layer to young chicks, and these studies are why.
Avian Gout
http://en.engormix.com/MA-poultry-i.../avian-gout-causes-treatment-t1246/165-p0.htm
British Study – Calcium and Protein
http://www.2ndchance.info/goutGuoHighProtein+Ca.pdf
One bite won’t kill them. It’s not what is in one bite but how much calcium they eat in a day, and that is over a longer period. If they eat a lot of other low-calcium stuff or especially are out foraging with Mama, they are a lot less likely to eat enough Layer to do them harm. It’s not an absolute sure thing that the chicks will get hurt by eating Layer which is essentially what they are feeding these chicks, one study starting from hatch and the other from 5 weeks. They don’t just wait for a chick to fall over dead in these studies. They cut them open to see what is going on inside. If all they eat is Layer at those ages, the results are pretty clear.
Grower is not any more expensive than Layer and has the same percent protein. Oyster shells are dirt cheap. You are a practical woman. I just don’t see the logic in spending the same money and giving them something that might harm them as opposed to spending the same and giving them something that is less likely to harm them.
I agree with you on all that other stuff. My brooder is in the coop and my grow-out pen shares a fence with the adults. I use electric netting for predator protection and young chicks can get through those holes. That’s one big reason I use that grow-out pen, let them get big enough they can’t get out through that netting. We all have different ways to do things.
I take dirt from the adult’s run and feed that to the chicks in the brooder starting from day 2 or 3, depending in when they are settled in. Every 4 or 5 days, I give them some more dirt. That gives them grit, they get any probiotics the adults have, and it gets them started on building up flock immunities. They probably get minerals from that too. I’m convinced they are a lot healthier this way. One of the first things a broody hen teaches her chicks is to eat dirt.
One thing you didn’t mention that I think is pretty important is space. I think most of the problems people have with broody raising chicks with the flock or just integration boils down to them being too crowded. I’m a big believer in giving them as much room as you can.
Some of my broody hens keep their chicks on a tight leash. They keep their chicks really close. Others are much more laid back and let their chicks merge with the rest of the flock. A couple of years back I had a hen wean her chicks at three weeks, left them totally on their with the flock. I’ve never had an adult kill or injure a chick. Like you say, an older hen will sometimes peck a chick to teach it proper flock etiquette, but I really haven’t seen any try to kill a chick. I have seen Mama beat the tar out of a hen that she thought was threatening her chick, and probably more common, teach a juvenile not to get too close to her chicks.