Chickens should have some type of Animal Protein in there main diet.
I have seen a lot of good show fowl go to crap when fed a "vegetarian" type feed. Most breeders that I know will supplement there feed with some type of Animal Protein even if they are using a good feed that contains Animal Protein.
I myself mix my own feed with grains, protein mixer pellet and I also top dress my birds feed with Raw Goat Milk, and Bil-Jac puppy food. The Raw Goat Milk, and the Bil-Jac puppy food are used as a sores of animal protein.
The ingredients in the Bil-Jac -
Chicken, Chicken By-Products (organs only, source of arginine), Corn Meal, Chicken By-Product Meal, Dried Beet Pulp, Brewers Dried Yeast, Oatmeal and Flaxseed.
Chris