I was attacked by a mad (as in angry) cow just for walking by on a hike, maybe 20 feet away but not otherwise interacting with her. I hid behind a tree until she went after another cow. Now I give them more space.

My lot backs up to a cow ranch, and I once heard one making the most amazing, and intimidating noises. It was the cow voice you're used to, but "singing" through multiple octives like her soul was being tortured in hell. There are messed up cows just like people.