Fred, is it just my foggy memory but I thought you fed an 18% Layer to your laying flock, specially ground at a local mill?
I don’t start mine off on nearly as high a protein feed as Fred, but I’m not growing the large-boned heritage chickens. We are all different with different goals. Fred does love his Barred Rocks. If you saw some photos of them you’d see why.
It depends on the quality of your forage and how long they get to forage, but the more they depend on forage the less it matters what you feed them. What I mean by that, the more they forage the less percentage overall of their diet is the feed, so it is not as significant as if the feed was all they ate. Good quality forage has different grasses and weeds, grass and weed seeds, all kinds of creepy-crawlies, maybe some leaf litter to scratch in, and maybe even cow, hose, or other animal manure for them to enjoy. That way they get a great variety of nutrition. If all you have is a manicured lawn that is a lot better than nothing, just not as good as some people have.
One if the benefits of a high protein diet is that the hens will lay larger eggs and more of them. I’m not a huge fan of that because the larger eggs can possibly lead to egg laying problems. Think along the lines of a woman giving natural birth to a 10 pound baby versus a 7 pound baby. They can do it, my wife gave natural birth to a 10-1/2 pound baby boy. Did the doctor ever mis-guess on that kid’s size! But I think she would have preferred he had been a healthy 8 pounds instead. I’m saying that so you don’t go overboard on trying to get extra huge eggs.
Another advantage with higher protein feeds is they will grow bigger and look better. Feathers are mostly protein. A high protein diet will help make pretty feathers.
Personally I choose to go with a lower protein feed, Grower actually with oyster shell on the side for extra calcium. But I practically always have younger chickens with the flock so they can’t have the higher calcium Layer. When I have very young chicks with a broody hen, they all get a 20% Starter until the chicks get well established. And they get to forage, though my forage is not as high quality as I would like. I don’t need the larger eggs and the higher protein feed is more expensive. With my goals and being naturally cheap, I go with the lower protein feed.