Questions about death of the animal when different stunning methods are used before Halal or Kosher Slaughter

by Temple Grandin
Department of Animal Science
Colorado State University

(Updated December 2015)

Many religious authorities have questions about the effects of various stunning methods on the death of the animal. Since the 1980s, head only electrical stunning has been used in New Zealand prior to Halal slaughter. When the electrical current is applied across the head only, it causes a temporary loss of consciousness. If the animal is not bled promptly, it will wake up and fully recover. Unconsciousness is induced by causing an epilectic seizure. To prevent the animal from returning to sensibility it must be bled within 15 to 23 seconds (Gregory, 2007; Lambooij, 1982). Head only stunning is completely reversible. In the 1980s, a test was done that showed that cattle stunned with a head only stunner could graze on a pasture after they recovered. When head only electrical stunning is performed, the heart continous to beat (Weaver and Wotton, 2008; Gilbert and Devine, 1982).

There is a second type of electrical stunning that will stop the heart and kill the animal. When it is done correctly, the animal will not recover. It is called cardiac arrest stunning because it stops the heart (Vogel et al, 2010; Gilbert and Devine, 1982). When this method is used, electrodes are applied to BOTH the head and on the body near the heart. Electrode position is the main variable that differentiates head only reversible electric stunning from cardiac arrest stunning. When head only reversible electric stunning is used the electrodes are placed only on the head.

Some religious authorities use heartrate to determine whether or not the animal is dead. When either penetrating or non-penetrating captive bolt is used, the heart will continue to beat for up to 8 to 10 minutes if bleeding is delayed (Vinnic et al, 1983). The heart will continue to beat even when the brain has been destroyed. It will continue to beat until the heart runs out of oxygen. The heart eventually runs out of oxygen because captive bolt stunning stops breathing. However, if cessation of a heartbeat is used as a definition of death, then an animal shot with a captive bolt will be alive for 8 to 10 minutes. This provides sufficient time for death to be induced by a throat cut on the neck. I have received questions about the importance of the brain stem in determining when an animal dies. Structures in the brain stem control rhythmic breathing. One must remember that when the principles of religious slaughter were originally determined, nobody knew what the brain stem was for. At this time, stopping of the heart was the main definition of death. The use of either a non-penetrating or a penetrating captive bolt allows the heart to keep beating, and the animal's heart will be stopped by the knife cut.


Gilbert, K.V. and Devine, C.E. 1982. Effect of electrical stunning methods on petechial haemorrhages and on blood pressure of lambs. Meat Science. 7:197-207.

Gregory, N.G. 2007. Animal Welfare and Meat Production. CABI Publishing. Wallingford, Oxfordshire, UK.

Lambooij, E. 1982. Electrical stunning of Sheep. Meat Science. 6:123-135.

Vinnic, R.J., et al. 1983. Effect of delayed bleeding after captive bolt stunning and heart activity and blood removal in cattle. Journal of Animal Science. 57:628-631.

Vogel, K.D., et al. 2010. Head only electrical stunning followed by cardiac arrest electrical stunning is an effective alternative to head only electrical stunning in pigs. Journal of Animal Science. (E pub ahead of print).

Weaver, A.L. and Wotton, S.B. 2008. The Jarvis Beef Stunner: Effects of a prototype chest electrode. Meat Science. 81:51-56.

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