Not sure I agree with that.
Dairy cows are fairly tame becuase they are handled twice a day. But any cow with calf is not, and you don't need to have made the mistake of getting between her and her calf for her to get aggressive. Bullocks can be frisky and for all herds is can depend on the breed, how often they are handled and how much they've been spooked that day. A bull with cows is not a problem. Lone bulls aren't allowed in fields with public access.
Dogs and cows do not mix and will also depend on the above.
Farmers will always have a stick, most don't herd the cows with dogs either.
If I'm with a dog, unless they are dairy, I won't be anywhere near them. I'm jumping walls instead!!