This is all very interesting. Thanks to all for the info!
I have a question - I currently use an organic starter/grower crumble (manufactured by King) for my 4 chickens (21, 20, 15 and 13 weeks). I had planned to continue using the starter/grow mix indefinitely and add oyster shell (or some other source of calcium) when the older ones started laying (soon, I hope!!!). The protein content of the feed is 22%. It seems like, from what I've read here, a higher protein content isn't optimal if you're going to ferment. So, would I be OK using the current feed, or would it be better to switch to a layer feed, with a lower protein content, when they're all laying? Unfortunately, I don't have any strictly grower feed available where I live. Thanks in advance!
You can always water that feed down a bit and make it stretch by adding some cheaper, lower protein whole grain(s). Barley is a good one and it ferments nicely. If you can't get something like that you can ever add some scratch...say 2/3 grower, 1/2 scratch. The chickens will love the variety and you can make your grower last a bit farther as well.
It doesn't matter what feed you use, really...if it's a high pro mix you can just feed less total feed for them to give them the right amounts. You'll just have to play with it and see what amounts are keeping your flock too heavy on their feet and then just cut back until they are fit and fast on their feet.