"Fortunately, I didn't have to learn that the hard way. I was really late to work one day, however, because there was a Brahma bull the size of a VW Bus standing right in front of the gate to my property. (It's open range where I live.) He'd found a nice patch of grass right there and no amount of horn honking, shouting, dogs barking, or poking with a stick through the fence could induce him to move until he was good and ready. I just had to sit in the car and wait until he decided to mosey on down the road."
Call me crazy, but isn't this sort of thing the specific reason why cattle prods exist? If I lived in open range territory, I'd invest in one. A REALLY long one.