[Inyo-Mono]

Actually, I have noticed this. I always thought cattle did it to keep the sun out of their faces so that they could see predators better.

[oldenuff2no]

The sun has something to do with it but the weather is what usually causes this alignment. Storms come in from the south and a cow well put her behind into the weather. North winds are cold and dry but a cow will still turn her head away from that weather change too.
I was born and raised on a big ranch and every cowboy worth his salt knows all about what a heard of cattle will look like in a storm.
Who ever dreamed up this post doesn't know the north end of a cow from the south end.

[Crystal Cove]

Mark Twain talked about cows always facing north in either The Adventures of Huckleberry Finn or Tom Sawyer. I don’t notice them all facing the same way when I see cows, though.