A slaughter method that renders animals or birds unconscious with electric current before bleeding. Widely used for swine, sheep and poultry, and effective for cattle too. Done correctly it improves animal welfare and meat quality, for example by reducing the incidence of PSE defects in pork. Systems are generally classed as high-voltage or low-voltage types. Head-only stunning induces a reversible stun suited to lines requiring the animal to be alive at bleeding, whereas head-to-body systems stop the heart. Current, voltage and duration must be tightly controlled: under-stunning compromises welfare, while over-stunning causes blood splash and broken bones that downgrade carcass value.