Behold; if it goes up by the way of its own border to Beth-shemesh, then he has done us this great evil: but if not, then we shall know that it is not his hand that struck us; it was a chance that happened to us."
"Milch" cows (1 Samuel 6:7; 1 Samuel 6:10) are cows that are still nursing their calves. It would be very unusual for nursing cows to leave their young and head for a town some 10 miles away. Indeed the Philistines regarded this behavior as miraculous and indicative that Yahweh had been punishing them.