That's an artificial mount, essentially the four-legged equivalent of a blow-up doll. And no, that man isn't posing for the requisite "wacky" picture on his dating profile -- someone has to be inside to help "facilitate" the sperm bank deposit by ensuring it lands in the appropriate receptacle.
But, in my experience, bulls get injured with metal or wooden mounts more than with real-life cow ladies, both physically (metal is blunter than a still-living flank steak) and emotionally (cold metal can't comfort bulls through those long, sleepless nights in the barn). So we use a real, live animal. Not a cow, though -- hot bull-on-cow action spreads bovine VD and produces unwanted pregnancies, and bulls are generally pretty bad at getting condom wrappers opened before the mood dies. So we use steers -- bulls that have been neutered. If they don't see anything dangling, most bulls don't notice the difference and are happy to mount the steer. Yup, your hamburger is probably the result of some hot all-male bovine action.
This pre-sex position is called the "tease," for reasons that should be obvious.
Before we act out our all-ungulate re-creations of Sodom, one of us will jump in as the bull mounts the steer and sheath his penis in an artificial cow vagina. It's essentially a soft, lubed-up plastic tube. Here's another picture; you've earned it:
Melisa Rouge / Richard Bowen
The top-most tube is for rabbits, or for steers who are all, "Just the tip tonight; I'm tired."