Some mixing your own chicken feed help links.
http://www.nap.edu/openbook.php?record_id=2114&page=21
http://www.poultryhub.org/nutrition/feed-ingredients/
http://animalscience.ucdavis.edu/avian/feedingchickens.pdf
http://www2.ca.uky.edu/smallflocks/feed_ingredients/grains.html...
http://www.nutrenaworld.com/knowledge-center/poultry/how-much-does-a-chicken-eat/index.jsp
Here is a website that may help for figuring out overall feed. Different grains weigh different amounts per bushel/volume.
You are going to need to figure out exactly what you will feed mix wise to figure...