I am afraid I agree with Fred, to truly economize on feed you will likely have to trim your flock. There is no forage up here in the winter (measured from around November to the end of April most years). "cutting" feed with grains and other foodstuff, and feeding lower protein levels, may decrease costs, but also may decrease production, and in some cases may lead to dietary imbalances affecting the flock's overall health and resistance to disease. You may want to evaluate your hens based on which show the best laying characteristics
http://scratchcradle.wordpress.com/2012/09/09/gms11-breeding-for-type/ - scroll down to The Call of the Hen page
http://www.extension.umn.edu/distribution/livestocksystems/di1182.html
I especially like this one, as it has great pictures -
http://oakridge.ffanow.org/F/oakridge/hens.pdf
http://scratchcradle.wordpress.com/2012/09/09/gms11-breeding-for-type/ - scroll down to The Call of the Hen page
http://www.extension.umn.edu/distribution/livestocksystems/di1182.html
I especially like this one, as it has great pictures -
http://oakridge.ffanow.org/F/oakridge/hens.pdf