Cattle at rest, not a sign of rain.... really!!

Where do these old wives tales start (Old wives, maybe....LOL) but some are so ridiculous, the best example being that if the cows are lying down it's going to rain!!!
So why isn't it that the cows lie down when they are tired or hot like other animals? Why do cows have this strange affiliation with amateur metereologists, no one ever says about sheep do they? Look the sheep are lying down it's going to be sunny, so why cows, oh and why do people swear by it, without any proof or evidence that it works in the real world!!

No picture has a single meaning.