Definitely not something I wanted to do. This is "Wolfie" our 12month old New Zealand bred Jersey bull. That spiky ring in his nose isn't like one of those tough guy dog collars with the spikes, his is a weaning ring because he is a Momma's boy and instead of thinking about breeding cows and heifers he was still nursing.
There is a certain risk when keeping a bull that he will see you as competition for "his cows" and try to take you out. Jersey bulls, of which I have 3 little ones, have an especially nasty reputation. It probably has more to do with HOW they are raised than a particular breed though. In general ,because of the nature of dairying, calves are taken away shortly after birth and artificially reared on milk replacer, delivered by human hands via a bottle and often they will be isolated in individual pens as well. This leads the bulls to think of themselves on human terms, and when they reach puberty they will start to challenge their human counterparts.
It is recommended, especially for the small holder, that if it is necessary, and A.I. is not available- that you take a few steps to try to reduce the chances of those calves imprinting on you.
Raise the bulls destined for breeding on nurse cows, and/or in a herd situation so he learns cow language and how to be a good cow. Dam or cow raised calves usually have a larger flight zone, and are more leary of people and keep their distance better.
This is what we have done. We are only 12 months into our herd sire experience, and we made sure to never make a pet out of him. We aren't cruel toward him at all, we just remain indifferent and usually made a point to drive him out of our space while he was smaller. We are also prepared to load him on the trailer to the butcher at any moment, when he even hints that he no longer respects us. In all reality it is more a matter of WHEN he turns not IF. This is why I have a succession of younger bulls coming up the line. I don't want to feel like I have to keep a dangerous bull, this way I can just say " See Ya!" and be assured that the next bull is only 3 months away from breeding cows.
Beef bulls are usually safer to use for breeding, probably because they have been raised on a cow, in a herd, with much less human interaction. However, you should never trust ANY bull, don't turn your back on them, don't turn them into a pet. It is also said that people aren't killed nearly as often by the really nasty bulls, because you know they are nasty and untrustworthy and don't give them the opportunity. It is the ones that you falsely believe to be docile or a big pet, that get you when you least expect it. Here's a good read that explains it all better by the reknowned Temple Grandin :