I live in the Pacific Northwest and love my chickens. My feed is a mix of different seeds and grains. I also mix in organic layer pellets on occasion, but have been known to go months without them. They are really just treats.
Here is my recipe (all is animal-grade except split peas, peanuts, and flax seed):
1/3 organic chick starter and 2/3 of the following:
wheat (white or red)
Black Oil Sunflower Seed
organic cracked or whole corn
oyster shell mixed into the feed each day (flemingoutdoors.com has instructions on how much to give)
grit #3 cherrystone brand
Redmond Mineral conditioner
I aim for 15% protein or so.
They love more grains in the winter.
I have learned that if you give them too many split peas, flax seed, or pumpkin seeds (I used to give pumpkin seeds when I had large fowl in greater quantities), that they will just leave them.
My recipe inspiration comes from www.greenerpasturesfarm.com/chickenfeedrecipe.html
I make sure they have grass to forage on. When I have rotated them to the pen without grass, I use yard scissors to cut them fresh grass almost every day. Keep grass clippings short (2-3 inches) to prevent impacted crop. Giving them greens is essential I have found for their happiness, and also keeps the feed bill down.A VERY important part of their diet is fresh greens.
Please note that there are vitamin deficiencies that can crop up if you don't give them green grass to eat on a regular basis since my recipe doesn't call for artificial vitamins. Another good thing to give them is milk or cooked meat on occasion. I have a poultry nutrition book from decades ago with some good information. It is nice to buy a reference if you like to mix feed.
If I don't mix the oyster shell into the feed, the eggshells become too thin. I also provide a hopper with oyster shell and grit of the two different sizes so they can supplement if needed.
Thank you to all those who have shared their knowledge on BYC regarding diet, and also thanks to Chris09 for teaching about protein content.
"Too many people forget or don't know that by feeding a all grain or high grin diet they increase a higher risk of vitamin B2 (Riboflavin) deficiency since most grains are deficient in vitamin B2." - Chris09
For those of you who wish to mix your own feed, I recommend sourcing everything you can at the feed store. Animal-grade is much cheaper than human-grade.
Also, please note that for baby chicks under 8 weeks I feed organic starter crumbles. They are too small to eat the larger seeds/grains.