I know a family mixed farm that always grazed their oats for an early bite. I have heard that ‘yearling’ operators in US used to overwinter weaned beef calves on oats behind electric fence. Not sure if the crop ever saw a combine though
Fairly common on the central and southern plains in the US where winter wheat is common. In a bad price year or a damaging frost or drought the crop will be grazed out and something else plant Decent amount of research out there on yield effects and timings.
It’s my understanding that this is also common in areas of South America and Australia.