Seriously Noel, all joking aside, I would be too Very Upset if my girls were chased by them.
You have so many options here, local police citing public safety, livestock growers association for lack of responsibility, reeve or mayor complaint department, DNR for health issues and safety of persons and property maybe???
Gosh, even local media, IF you want to that is...
A few good digital photos, attached to emails to government offices at least.
If I were you I would try all and every office & drive your neighbor into lawful compliance, before someone gets really hurt.
PM sent....