Thanks for your suggestion. I was able to get my feed store to sell me a 50lb bag of pre-mix. Now... if I can just get my measurements correct when I mix my own. ;)
I have a great (cheap) source for a feed base for my chickens. It's basically a ground corn and soybean mix. I add to that oyster shells, and sometimes grit.
The chickens do OK on that but don't quite lay as well as when I buy a mix from the feed store. I'm guessing that I'm missing some...