It's a commonly held notion that cows aren't the sharpest tacks on the board. They certainly don't understand English, right?
My theory: cows just want us to believe that so we're not expecting them to obey us.
Case in point: when I say, "Time to go to new pasture, ladies," they all get up from their naps, moo loudly, and follow me at a trot. But if I walked out into said new pasture and said, "Time to go to back to the old pasture," everyone would play the deaf-and-dumb-cow card.