Use straw blower to get cows barn straw "bedding" done, which enables cows to produce manure. Use manitou MLT 840 alike vehicle to lift straw bales into the straw blower equipment / trailer. Drive the straw blower trailer through cow barn, enable it and it will blow straw to cows bedding.
Baling straw. Use any medium size tractor for example fendt 724 vario with pottinger impress 185vc pro round baler, choose bale size 180cm which is the largest straw round bale size (wrapped silage bales can be only done up to 150cm), then bale straw normally. Next use anderson rbm2000 bale collector to pick up 24 * straw 180cm round bales and haul them to where ever you plan on storing them, for example giants in-game bale storage placeable building which holds 250 bales of various sizes. One anderson rbm2000 trailer load holds 24 round bales, with 180cm round bale size this comes to 24 * 11,000 liters of straw, total of 264,000 liters, in one haul. With anderson rbm2000 the tractor pulling it should not have twin wheels because that prevents proper bale pickup as tractor is not aligned close enough to the bales.
Cow barn straw. Trailer unload icon at the inside of the barn, you cannot simply bring straw bales with an autoloading trailer and drop them at the icon, that doesn't work. Neither does it work if you bring bales there with a telehandler or skid steer, cow barn straw input wont accept BALE type of straw. You need to use Anderson Pro-Chop 150 or Kuhn Primor 15070 M trailers to load straw bales, shred them to pieces and then blow the shredded straw into the cow barn unloading point. Or you could simply dump loose straw from forage wagon etc trailer.
Cow barn straw with anderson pro-chop 150. Once you drop a bale into the pro-chop trailer thingy, nothing happens... this is intended. Now close the back hatch (if you opened it), then drive to the cow barn inner feeding trough thing and now "start overloading straw" action appears and its activated by I key.
Anderson Pro-Chop 150 descriptions state it holds 2 bales, this is most certainly NOT true, it barely holds one bale and even that is half sunk into the trailer. Most likely giants FS22 base game description to Anderson Pro-Chop 150 is wrong, it holds ONE (1) bale and the Kuhm Primor 15070 holds TWO bales.
Harvest wheat, barley and oats which give straw, then bale the straw. Straw is used for animal bedding (cows and pigs) and cow food in Total Mixed Ration (TMR) wagon to mix TMR.
Straw, get a forage wagon, collect straw from harvested fields, then dump it into hay loft placeable building with 250k liter capacity. Then when your animals need straw, just get the same forage wagon, refill from hay loft and dump the straw trailer into cow / pig barn, done. Nice and easy. See also: 180cm straw bales.
Straw for bedding. You can chop straw bales into animal bedding aka loose straw with anderson pro-chop and bigger kuhn primor 15070 M chopper wagons and with TMR mixer wagons as well. When using TMR mixer wagon, have it empty at start, then put only straw bales there and they get chopped to loose straw. Now you can overload the wagon as many bales as you have skill to telehandler load up and actually drive with the overloaded bale haul. Then just use mixer wagon as normally with TMR, only this time its loose straw for animal bedding. Please note that such "top heavy" mixer wagon might not fit through the door into all cattle and cow barns like giants hormann placeables.