All my chickens are fed milk (soured as kefir) to make up a full home-mixed diet. Other ingredients are sprouted wheat, sprouted corn and sunflower, alfalfa, soy meal and minerals (kelp, salt, shell grit).
Layer hens don't really want much milk (whether soured or not) because the high phosphorus-to-calcium ratio can cause soft shelled eggs. But I find the chicks do really really well on a diet with a fair bit of soured milk and it seems to help against cocci (combined with gradual exposure).
Edit: oops, also they get fresh garden greens and a treat of liver or other meat about once per week.
I've been "finishing" my last batch of capons with raw milk. I pour it directly over cracked corn, and give it to them. They LOVE it, and are fattening very nicely. I've been giving it to them 1st as a treat and now as about 1/3 of their feed, planning to increase to 1/2 for 1 week and finish with 1week of this exclusively.