You don't want the pig to die instantly; you want it unconscious and unable to feel pain... but you want the heart still alive. The heart pumps blood which exs

You don't want the pig to die instantly; you want it unconscious and unable to feel pain... but you want the heart still alive. The heart pumps blood which exsanguinates the animal after you slice it's aorta. This allows you to collect the blood for some other use, and removes it from the veins and arteries in the muscle tissue.