It's like a Sharper Image massage chair, but for cows.
This is a video of Paul, a bull living at an animal sanctuary in Germany, using a Happycow cow-cleaning machine.
First of all, it's delightful to see how satisfied Paul is rubbing against the cleaner. Secondly, I'm stoked to have discovered that cow-cleaning machines are a thing that exist. The site for Kerbl, the company that manufactures the Happycow machine, says that "the brush removes dust mites and parasites by rubbing abd [sic] improves the blood circulation to the skin. The skin is becoming more breathable and it stimulates the metabolism." Sounds good to me.
By the way, I would totally use a Happyhuman exfoliating wall-mounted brush if you want to develop one, Kerbl.