That depends on how you build your fence, your management, and how determined the bull is. If you have your bulls right next door to a bunch of cycling cows/heifers - probably not. If there is a fair amount of distance - say 70 feet or so - between your pens, yes it can work.
if you are talking about lumber yard 2x6 or similar boards, the important thing is post spacing. If you put posts at 8 ft and push on the middle, a bull just leaning on it may break a board. 6 ft spacing with oak boards (try a sawmill) or 4 ft and store pine may be ok, jmho. I think it is hard to beat used highway guard rail for about $3/ft. Std hole spacing is 6ft-3" apart. Good luck. Jim