I like 18-20% but yours is pretty good. If you like that food, keep feeding it. Just add the oyster shell on the side. A lot of people(me included) feed an all flock feed. All flock food is meant for a flock of mixed age chickens or mixed species. I have just five laying hens, no other birds...
I know nothing about that feed but Kalmbach is supposed to be a good company. Is it for laying hens and what's the protein and calcium levels in it? Oyster shell on the side is always a good idea. Whoever wants them can go eat them