Dun has already given you your answer, but I'm now curious, how long is it in the trailer? When I ship weaned calves or a cull cow sometimes I load them the night before with hay and water in the trailer. I have to leave for the auction yard fairly early the next morning. Never had a problem with one moving around and laying down. If the haul is just a few hours they don't worry about laying down although they turn around a little. My experience is when cows and horses are in a trailer and not tied they like to face toward the back of the trailer.