Do cows have regional accents? Well a professor of phonetics, John Wells', attention was drawn to this phenomenon by a Somerset farmer, Mr Lloyd Green, who claims that his bovine charges moo with a distinct Somerset drawl.
To read more on the Professor's response - look at the comments.
(Does that mean that they go mooh arr? And in Scotland do they go "Och aye the moo"?
BTW - "Ooh arr" is West Country speak for "Oh yes," and "Och aye the noo" is part of the Doric dialect in Scotland which I believe means "Oh yes, just now".)