cattle trucks

Because they're always empty.

 

Agreed, did cattle for a few years, pack em in tight and you'll be left with a load of dog meat, they need to have air and keep cool and when they go down they need to be able to stand up again, they'll smother if they can't, also if they stay down the urea in their own pee will also suffocate them, I think you'll find once you take your time , let them settle down they stop moving about and some will sit down and they will get a whole lot easier after a few miles but that's not to say you can go around corners at high speed cos a loaded double deck trailer will have a high center of gravity