Alfalfa doesn’t produce grain, just hay.
You can get way more cattle nutrition from an acre of corn or beans than you can from an acre of alfalfa.
Most legumes, alfalfa and clovers actually add more nitrogen (N) to the soil, especially when tilled in.
Well-established perennial legumes, including red and white clover, have been reported to provide 75 to 200 pounds fixed N per acre. This compares with alfalfa, which provides 150 to 200 pounds fixed N per acre.
I garden 2 big plots (100 by 30 feet) and alternate them with crimson clover each year. This means I have one plot in clover right now, just starting to flower, and the other I tilled in last Fall. Hopefully, my corn and vegies will grow like weeds.
If farmers would do this multiyear planting they’d get more yield per acre, even if it means a reduction in acreage overall.
I think cover crops need to be pushed like counter plowing was in the 1930s.
Corn fed beef are just fatter. It’s not more nutritional than grass.