This thread is exactly why the cattle industry will never be chickenized. Look at the diverse ways we all can get a similar job done.
In the deep South grass tends to grow fast and can head fast and can deteriorate fast. Most cows need some sort of winter suppliment. Many use the rye grass option as it will grow all "winter" there. I use the winter term loosely as it is usually warmer there in the winter than some of us get in the summer.
A lot of the Bermuda grass put up as hay looks great, but feed analysis shows low protien (6-9%), and high fiber. Many producers use a lick tank or tubs for ease of delivery, they have off farm jobs and see the cows 1-2 times per week.
Soymeal at 47% protien is usually the cheapest natural protien source in the South, but many get hung up on this protien thing thinking it is all important. A cow can substitute energy for protien. Hand feeding 1/2 pound of soymeal with 3 pounds of shell corn is all the suppliment all but the thinest cows would need. It also works out to be one of the cheapest ways to suppliment.
Farther North, I.E Nebraska sandhills, grass is plentyful but when it dries off is just like straw. Haying like Soapweed does puts up all kinds of roughage with nearly enough food value for cows. If some alfalfa was added to the ration, the cows would need no extra feed. Sometimes a 'cake' or soymeal based pellet is cheaper than alfalfa (per pound of protien). Some producers just feed extra 'cake' instead of pricing corn or mixing corn with the soy. To each his own, but savings can be found.
In the really cold climes, like Montana, Alberta, Sask etc. we rely more on higher quality hays like alfalfa or alfalfa grass mixes. More bedding is used, straw from cereal production and cows tend to eat some of that as it generates heat to digest. Grain suppliments like barley are more common if the alfalfa is poor or got cut late and has lower protien. Much hay in our area will test 15% or better. No suppliments needed for most cows.
Putting a pencil to all feedstuffs make life interesting, and Urea comes in as the cheapest of all protien sources. However it has to be fed with extreme caution and can only make up some of the cows protien requirements. Most of it is digested as by-pass protien. It tests at roughly 281% protien. Too much will kill a cow. Saying it has no value is wrong, it just needs to be understood. Extra energy will be needed to help utilize it.
Brewers grains, distillers grains have had much of the energy taken from them and the protien really climbs. Some have cheap or even free sources of these and they can really be used to cheapen rations. You can feed cows easily 10 pounds or more of this feed with some low quality hay and they do well.
Other feed sources like breadstuffs, beet tops, potatoes, vegetable wastes etc. all have value if transportation costs aren't too high and a steady supply is available.
I have thoroughly enjoyed learning how others feed their cows. Pricing different rations for some, and seeing how good cattle will thrive anywhere they get proper nutrition.
Basically if you can feed your cattle for less than you sell the progeny for, you are doing a good job.