A different approach is to find GameBird feed with animal protein. Even some of the vegetarian oriented chicken feed makers continue to produce Game Bird feeds with animal protein. The high level of protein can be diluted by feeding some whole grains, scratch, etc. This remains a common approach among many folks.
Our local mill continues to produce feeds with animal protein. I'm grateful. They are a Hubbard Feeds mill, if that helps you.
Prince Feeds are also producers of animal protein products, but they seem to have a smaller market penetration.