I've spent time in Canada on farms and around cattle and never have I come across such aggressive cattle as I did in the UK.
To use my own experience as an example, this may be down to the way the cattle are raised in North America vs. the UK.
My brother has a very large beef herd in Wisconsin. Even though he's got a couple hundred animals, they're handled pretty regularly, are in and out of barns and small pastures for feeding. They get a lot more supplements and shots and things like that. As a result, most of them are very used to people, they're used to traffic noise, and they're even fairly used to dogs/coyotes and other animals around.
My husband has a much smaller herd in Scotland. Same kind of cattle, but they're all grazed on open pasture, only one of them has ever seen the inside of a barn, and other than when they get bales put out for them in winter, or when there are annual health checks, they don't have much close contact with people, so they'd be much more likely to be skittish.
I stand by my earlier post. The best thing to do is just avoid unfamiliar animals. Obviously, that's not always an option. But if you do enter a field with livestock, and they do chase after or crowd you, it's not fair to blame the animals, or the farmer. That's their home, and their livlihood. Enter at your own risk, and keep in mind that if you (or your dog) spook them enough that an animal is injured (i.e. running into fences, etc.) or property is damaged, in some circumstance you could be held liable for damages.