For 12 chickens, you would need to have a good and specific reason and feel strongly about committing to making your own feed. Like @Fairview01 says, it is complicated, and most people have the novelty of making their own feed wear off very fast. From all the comments on here, I see a lot of "probably" and "maybe" and "I guess" from you. No offense intended, but it sounds like you were talked into making your own feed and are just trying to figure out what that means. I am here to tell you that it is not worth it for 12 chickens. Unless you develop a strong desire, driven by something specific. Like a hatred of corporations. Or 12 special needs birds who cant eat normal food. The lack of organic commercial feed in your area. Or the need to avoid a certain main ingredient (like corn or soy). Etc...