Source: We used to make our own but we now rent one of our fields to a farmer and in exchange he makes it for us. So, we not only get free hay... we don't have to do any work except unloading it into the barn.
As far as what type we grow, I have no idea. Whatever kind grows? I'm sure our pasture was seeded a long, long time ago but we get a great crop every year so there's been no need to plow/reseed.