Euthanasia and Slaughter of Livestock

Temple Grandin
Department of Animal Science
Colorado State University
Fort Collins, Colorado, 80523, USA

Journal of the American Veterinary Medical Association, Vol. 204 (1994)1354-1360


This paper outlines the basic principles of captive bolt stunning, electric stunning and carbon dioxide anesthesia. It outlines the recommended amperages and currents for electrical stunning and describes how to assess whether or not an animal is rendered insensible. Other subjects that are discussed are preslaughter stress, behavioral principles of handling and ritual slaughter. One of the final conclusions is that the single most important determinant of good animal welfare in a slaughter plant is the attitude of management.

Sufficient amperage must pass through the brain to induce a grand mal epileptic seizure. For large market weight pigs a minimum of 1.25 amps at 250 to 300 volts for 1 second should be used. For sheep a minimum of 1 amp at 375 volts for 3 seconds should be used. Unlike pigs and sheep, cattle must have a stunning current of 2.5 amps passed through the brain before a head to body cardiac arrest current is applied. Available research shows that carbon dioxide stunning is a good euthanasia method for certain genetic types of pigs, and it may possibly cause discomfort in others.

Assessment of insensibility while hanging on the bleed rail in a slaughter plant.

  1. The animal hangs straight down and there is no arched back righting reflex. An animal with an arched back is attempting to right itself
  2. No rhythmic breathing
  3. No eye blinking
  4. No eye reflexes in response to touch
  5. No vocalizations such as squealing or bellowing
  6. Gasping movements are permissible
  7. Ignore uncoordinated reflexive limb movements
  8. If the tongue is hanging straight down and is limp and floppy the animal is insensible.

These eight signs can be used to insure that slaughtered animals are insensible and they will not be able to feel pain.

When ritual slaughter without stunning is being evaluated from a welfare standpoint the variable of the restraint method must be separated from the act of the throat cut. Distressful restraint methods will mask the animals reactions to the throat cut. Observations of hundreds of cattle and calves which were held in a comfortable upright restraint device indicated that there was a slight quiver when the knife first contacted the skin; Invasion of the animals flight zone caused a bigger reaction. The welfare of animals can be greatly improved during ritual slaughter by holding the animal in a device which holds it in a comfortable upright position.

If you would like a reprint of the entire article, write the author at the above address.

Click here to return to the Homepage for more information on animal behavior, welfare, and care.