Probably mulesing.
"Ranchers perform a barbaric operation-called "mulesing"-where they force live sheep onto their backs, restrain their legs between metal bars, and, without any painkillers whatsoever, slice dinner-plate-sized chunks of flesh from around their tail area. This is done to cause smooth, scarred skin that can't harbor fly eggs. Ironically, the exposed, bloody wounds themselves often get flystrike before they heal."
Poor sheep
From Save The Sheep.