Someone in a previous post was asking for a protein calculator -- how to.
http://homesteadapps.com/app/free/feedcalc/pearsonsquare.php
You can also do it like this
5 pounds corn @ 9.0% = 45%
20 pounds wheat @ 12.5% = 250%
5 pounds oats @ 12.0% = 60%
20 pounds ground alfalfa @ 32.0% = 640%
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50 POUNDS TOTAL 995%
995% / 50 = 19.9%
Feed protein content is 19.9%
Use the above example to calculate your own mix.
Just remember that the commercial breeds are not exactly your backyard hens and have certain nutritional requirements that commercial feed has taken into account.
With that said, I know a few people that use their own blends with similar results as the commercial feeds.
To really save money purchasing the feed in larger quantities. Most feed mill have a recommended blend they can make for you. Usually the more you buy the more you save as far as milling fees go. Many mills charge market price for grain so the price varies from day to day, but it can save if you but in large quantities such as 500 or 1000 pounds.
By the way the futures market for corn looks like it is dropping $1.00 per bushel for Oct/Nov 2011 so a little relief.