I still prefer flaking off big-squares off a flat-bed truck, and towing a trailer behind it to haul more bales if/when necessary...just have to 'giver her hell' in soggy/muddy pastures sometimes.
Feeding 'cake' is great, but in heavy snow, it's sometimes tough to drive in such a way to get the feeder to put it in the tire-tracks...and then alot of it gets trampled by over-eager 'welfare' cows, who get trained to follow the truck, rather than EAT what hits the ground.
...anyways I DO recall seeing a round-bale processor that hooked-up to back of tractor....and unless my memory is going bad on me, the whole deal worked off of conveyor-belt system, and held upwards of 9 round-bales (or more ?) had it's own hydraulic loading system...and he got all the cows (on the main place) fed in one shot. We did the rest off flat-bed trucks.
...last time I saw this was where I worked on the Padlock Ranch, a few yrs ago; and the boss himself was the only one who took it out to feed with...never trusted the rest of us with it, for good reason...when I asked why, he simply showed me the shipping-receipt he signed when ranch HQ had it sent out by Semi-flatbed the year before I got there...
...it was upwards of $80,000 brand new.
A 'Heston' model I think ? ? ? it was Red and Yellow, and very long...that's all I know.