For a long time, off and on, my family has planted and grown oat hay on a field adjacent to the vineyard. When I was growing up, we fed it to my horses and our cattle (we probably had 30 head when I was younger).
I remember the cattle fondly - finding the new babies where their mothers hid them in the grass while they grazed. Being able to pet the youngsters before they developed any fear of humans was a thrilling thing as a child. I also remember doctoring them, running them through the corral and head catch for their check-ups and fix-ups and carefully avoiding the bull (he was mean).
As for the hay, after it was harvested I remember my parents would place me on top of the growing stack on the trailer. It was a whole family chore. They would lift the bales up to me and I was responsible for stacking them neatly on top. In that way we'd slowly circle the field, collecting bales as we went around, then taking them, pulling them off the trailer, and restacking them in the barn.
Here are some images of our most recent hay adventure. To be honest, I think I was stronger as a kid! To much desk jockeying in my recent life...