Wonderful post, I'm glad @sotall linked it so I found it this morning!
Regarding the calcium needs of laying hens vs growing chickens. What do you recommend in the scenario where we've already got a small established flock of layers and are going to be doubling it this year? Last year we kept the younger chickens in a dog crate in the coop with their own food for as long as possible, but they outgrew the crate before they were full grown so they ate the layer feed along with the older hens. If that's an issue I might have to rethink getting 6 new chicks at once.
I've not tried to raise smaller birds in with larger birds. The bigger birds tend to attack the little ones. I kept them next to and separate from the big ones until they were full grown, which is near laying age. So they were fed non-layer feed.
If you were to put them in together, I'd tend to go with non-layer, make sure there was plenty of oystershell available to the layers, and be very aware of impending behavior problems due to the different feed. You may have to supplement the protein for the layers with animal protein until the younger ones start to lay. Then they can all go on layer. Continuing the animal protein after that point is a good thing to do, as it will prevent behavior problems down the road.
Thanks so much for the response!! I shared this post with the Husband, and because of it, he picked up a couple cans of mackerel at the store! I LOL'd when he showed it to me. We've been having trouble with feather picking, and my internet research had led me to conclude worms were the issue....deworming did seem to solve some other symptoms, but not the picking. This article was a lightbulb moment for me on why anytime I give them assorted kitchen scraps they go like gangbusters after any meat first. They went crazy over the mackerel this afternoon. Fingers crossed they'll grow their fluffy bottom feathers back! I'll definitely be referencing this again as I work to tweak their diet :)
Just make sure you keep it under 1/4 oz/bird/day or you will start with other nutritional problems. They MUST eat ALL their conventional food during the day, and not gorge on meat.
Good to know! I'll go sparingly with it :)