When we bought our ranch, WAY back in 1983.... there was a crossbreed cow that had some 'brahma' in her. She was, to say the least... cranky at all times. She used to actually 'sneak' up on us and attack... once butting my cousin off the ground and into the back of my pickup. Twice catching me off guard and sending me into a cactus once and the other time striking me a half dozen times before I could get to safety. I was sore for a month.
My point is... mountain lions, great sharks.. yup, scary.. but a Mama cow? Terrifying.