Diapers won't last long on cows. They go often and a lot-- both #1 and #2
The only way to have something that lasts a few hours is to hang a five gallon pail from their tail.
(I have not tried that.)
While you all are bickering I will take the throne. (Just remembered that I gave up "thrones" for diapers.)
Y'all can have the throne back. I win while wearing diapers.
Besides the above advice this is what I do sometimes;
wear boxer shorts and pull them up a couple inches above your pants and the diaper. Your midriff may show occasionally but seeing boxer top is totally not memorable to most people.