It isn't anything I have heard of with cattle before. I question the point of it. In a pet show yes, but in a market show or a breed show where your purpose is to judge the animals on their potential to enhance and advance a breed I see this as pretty silly.
I did not see it but my nephew did it a few yrs ago, I believe he had to load and unload from the trailer and walk around and over different things, he thought it was fun and the calf gets exposed to different things before fair. I think it is more for fun.
It's a fun thing usually walk over pipes, over tarp, around cones, tight turn in a keyhole, into trailer, chute and usually a pen where you take off halter then capture again. Usually done by younger showmen. Not really a competitive thing