Livestock Haulers Gain from NASA Space Technology | Archive content from Trailer Body Builders
This article doesn't include illustrations, maybe you could find those through:
https://www.google.com/#q=livestock+...r+aerodynamics
Long story short—poorly ventilated trailers (all of them) stress the livestock. Vents at the forward 1/3 don't admit air, NACA ducts are good.
Do you own the trailer? Visit the Aerodynamics subforum to find out how to reduce the stress on your transmission.