You just turn at the animal, stretch your arms out wide and run at it. Like here.
http://youtu.be/Yhq-8TrRlsM?t=48m54s
If you are going to cross a field with livestock in it please be prepared to move them along if need be. They are beasts of the field and respond to direction. The alternatives are really about how you deal with half a ton of beef muscle which you have given the upper hand to. It is a fairly simple process and these decisions are basic. The alternative is standing on a stile for an hour. Mibbe more.
Take your pick.
More people are killed by rams and sheep than bulls.
Remember that these animals don't understand our etiquette and we don't (generally) understand theirs. It's about personal space etc. - you have to teach them it in a basic and straightforward way.
BTW I once got my OH to walk ahead of me on a walk to "The Bay of the Bag" on the island of Jura. . She had to wave the bull away... because I was too feart - get this - because the bull had looked at me in a funny way... it moved when she told it to...
I once heard a person say how filthy the countryside was - get this - because "the animals sh*t all over the place".