Yes, I've noticed that about cows. I saw one kick the breath out of a dog. The poor mutt wasn't bothering the cow, he just happened to walk behind her, and Pow! He was very slow getting up.

Then there is the walnut sack saga.
I was on my wife's parents' farm a few years ago when I decided to go up into the pasture and pick up some walnuts. I took a cloth sack with me and climbed over the gate. As soon as the cows saw me, they started walking in my direction. There were about ten of them. So I shook the sack at them to try to discourage them, but they just broke into a trot. Naturally, I took off up the hill at a fast pace and they finally got tired of that and went back to the barn. (Cows will rarely walk straight up or down a hill. They walk around the hill, gaining or losing elevation slowly.) When I finished picking up walnuts, I returned to the house by a circuitous route and mentioned the agressive behavior of the cows to my mother-in-law. She got a big laugh out of it and then told me how her husband takes salt to the cows occasionally and carries it in a cloth sack. Once past the gate, he waves the sack to get their attention, and they come running for the salt. I guess it was just a big misunderstanding between me and the cows.
Howard