I mix my own feed too
The only thing I really do different in winter is I increase the molasses, and this year I'm fermenting, and I've decreased my feed consumption by 30% just with the fermenting.
I'm also experimenting with replacing most if the corn with sorghum, so here's the recipe I'm working with at the moment:
40# ALFALFA PELLETS
10# OYSTER SHELL
When I get it at bushel prices, it rounds out to about $.15 per pound, and that lasts me about 45 days for about 40 birds.