I have found that cows can be calmed by "chuffing", that is there have been a number of times when I have had to go very close to cows. As we are all aware, cows often take fright at the last minute, especially when you are close.
I have found that by making a chuff chuff noise of the right pitch, cows seem to relax and take no notice.
It does not help with a stampede!
I know it sounds odd, but it has definately worked.