The Guardian had an article in their Experience series entitled "I was crushed by a cow". in which a herds manager describes how an irate Frisian cow threw him down, face in the mud, knelt on him and pushed her head into his back after he had waved his stick at her and told her to get back.
That cow was cross.
The paramedics who came to his aid were concerned enough to call for an air ambulance to transport the injured man to hospital. He recovered and two weeks later he was back at work.
The cow was destroyed.
There's been a spate of similar incidents; a chap who was killed when his herd turned on him, a vet who was trampled to death. Dog walkers have been killed in fields, because they've held on to their dogs instead of letting them run for their life. Beloved and I were pursued by a herd of heifers across a muddy field. One of them saw us, alerted the others and the whole two dozen of them turned as one animal and came galloping towards us; we ran and stumbled for the stile, me howling in fear. The heifers bellowed the theme tune for Rawhide as they almost caught up with us.
Have they caught on that all we want them for is to eat them, make cheese out of the milk meant for their calves, put their baby girls in cages to become veal and kill their boy offspring at a few days old if they happen to be born into a dairy herd? I hate the sound of a dairy cow howling and crying for her young after they've been taken away. The sound goes on for weeks, as each herd is deprived of its babies.
And to crown it all, we can now interfere with the sex of their offspring; we can now determine that no boys are born into a dairy herd. If that's not enough to turn a mild-mannered, soulful creature like a cow into a vengeful killing machine, I don't know what is.