Why did the cow cross the road?

I was cruising along at a good clip, and this guy on the side of the road starts flagging us down to slow down.  I naively yelled out "it's a 65MPH zone"...then I saw 300 head of cattle jogging up the left hand side of the road.  Apparently they were moving from one ranch to the next or something.  But four cars got held up on the road as a bunch of cattle had to cross the street.  And we all had to drive through giant piles of cow crap.