Don't know about »cow« but a bull once attacked me in a field during a school outward bound course.
I always hated outward bound ... cold, wet, uncomfortable I'd rather be curled up with a book.
Walking through a field of large white-and-black beasts, however quietly chewing, was not my idea of a good way to spend an afternoon.
When the bull started running from the other end of the field my classmates and I found a turn of speed I would never have realised I could achieve.
So I suppose I got something out of that encounter. I've always been much better at the sprint than any other sporting event.