I have sheep. A small breed. Like rams top out around 80lbs. I don't turn my back on him. No way I'd trust a bull.
And it's not even necessarily meanness (though I think the bull in the link got aggravated). Sometimes it's just playfulness, and even cows are dangerous then.
Just yesterday, I was mowing down a paddock that was starting to seed (the cows won't touch stuff once seed heads form, but will eat the headed grass shortly after cutting it) and pretty much all the cows in the paddock were following me around, and a few of the young heifers were making runs at the tractor, from what I could tell, just for fun, almost like dogs playing. I've seen them do that when I'm in my UTV as well, and again, not out of meanness, but just playfulness. But when the animal weighs as much as a cow, playfulness can be dangerous if you're not protected by a vehicle. Even then, I have areas where T-posts (not flimsy garden posts but the 1/8" steel kind) are set, like the yardage markers on my shooting range, and they have gone through and bent those things at 90deg like they were one of those flexible straws or something. They are powerful animals, even when they don't mean to be.
