Most soy free feeds I've seen use field peas for that side of the amino acid complex that isn't in grain.Thanks! It seems to be the only alternative on the market if you are avoiding soy.
I don't mind feeds that contain animal protein because that will provide a more complete array of amino acids.
I keep a bag of fishmeal that I mix with lower protein feeds for chicks to bring it up to where they need it. The only time my adult birds get fishmeal is during molt season when they aren't laying but I've never noticed an eggs taste problem.
But poultry nutritionists recommend keeping the amount of fishmeal low for active layers.
For chicks, I mix fishmeal with a 16% organic grower at a ratio of 1:10 which yields 20% crude protein.