I got by last winter on corn stalk bales but just barely. They will eat them about twice as fast as hay bales since the nutrients are so low but it'll buy you some time and definetly stretches your hay supply. I fed ground corn daily anyways so I did not supplement with any tubs. My cows came out of winter in good enough shape for most but I like mine a little fatter going into grass season. Only problem was I didn't bale enough stalks to keep ALL my cows and had to sell some due to the hay shortage that everyone suffered from, but stalks helped a lot!
I tried to unroll them but most fell apart when net was cut off and there were piles of hard stalks to burn this spring that they didn't eat. I would spread out feeding areas and not feed hay till they pretty much cleaned up the stalks that they will eat. About 1/5 of the bale will be wasted, but its cheap feed. I will bale some this fall in hopes to stretch hay again this year, but I think I'll have enough to get by, I just want about 1/2 year supply to carry over next year. It might help to run a brush cutter over stalks to break them up more before baling but I don't know. I cut mine with a disk mower and raked/baled them.
Also I baled some soybean stubble hay to feed, (don't waste your time with that)