A stunning method that will reliably render an animal insensible to pain and sensation prior to hoisting and bleeding is essential to prevent suffering. Cardiac arrest stunning is more effective than conventional electric stunning. In cardiac arrest stunning, an electric current is passed through both the brain and the heart to produce permanent insensibility. Since the animal is killed by the electricity it cannot revive during hoisting, bleeding, or slaughtering procedures. In contrast, conventional electrical stunning induces reversible insensibility for a short period of time.
Grandin, T. (1985). Cardiac arrest stunning of livestock and poultry. In M.W. Fox & L.D. Mickley (Eds.), Advances in animal welfare science 1985/86 (pp. 1-30). Washington, DC: The Humane Society of the United States.