.....Did the fibers in the branches get damaged by that early snow so now they can support any weight?
No, out on pasture yet.
They probably do some good huddling. Individuals rotating out of the windy spots, maybe. Other animals do, IIRC.
The country looks flat, but there is always some terrain relief around somewhere.
If a cow has cover and something to eat they are fine all winter.
40 to 50 below is no problem....as long as they have sufficient calories and protection from the wind.