Vicky, I think you hit an important point that my neighbors brought up too. I backed the trailer in to my loading ramp sighting down the left side mirror until the rubber bottom bumper hit.

But I was not quite square and there was about a 4" gap on the other side of the door. The light came through this gap and my bull could see out. I didn't think it was significant but next time I will square it up better.

The heifer went right on but not the bull.  I'm still learning small things like that count a lot with cattle. You and my neighbors must be reading Temple Grandin closer than I have! Thanks for the pointer, I almost forgot about that gap.

Jim at Dawn