From a WSJ piece about purity testing American bison DNA:
One by one, the bison are pushed into a squeeze chute, which holds them steady so ranch hands can work on them. As the calf thrashes and flails, Mr. Collins works the front end, trying to hold the head and shoulders steady so the microchip can be inserted. It's a messy job. "They blow snot," he says.
The ranch hand at the rear end doesn't have it much better.
The branding iron on the rump sends smoke curling into the air, and with it, the throat-clogging smell of burning hair. It is then that the designated tail-puller must thrust his arm into the chute—taking care not to get crushed against the wall by the 300-pound calf. The tail hairs are well-rooted, so it takes as many as a dozen firm tugs to unloose them.
It's then best to remove hand, pliers and hairs all at once, for often the bison "will start pooping, and their tail acts as a manure spreader," Mr. Hamilton says. "It gives you that manly smell."