Why do cows face one direction when grazing?

A scientific study was done that proves that cows align themselves always to magnetic north or south. It doesn't have to do with the wind. Pretty amazing! :)

think of you witnessed a accident. I grew up on a farm and can assist you to already know first hand that cows do no longer all face an identical course whilst grazing. till the are all eating grass on the exterior of the pasture. ( for the duration of the fence)

the wind blows any noise to them to prevent attack by coyotes/wolves/etc

Butt to the wind, usually! :)

They and horses usually stand so the wind approaches to their rear.

Prolly because they are facing their butts to the wind. Horses do it too- it breaks the wind, kinda like us wearing a windbreaker.