Physiological Effects Of Electrical Stunning

The general principle of electrical stunning is to pass sufficient current through the brain to disrupt the normal electrical activity and cause an epileptic-like fit. During epileptiform brain activity, the neurones fire in a hyper-synchronised way, which leads to neuronal fatigue. Epileptiform brain activity results in immediate unconsciousness and insensibility to pain. The duration of insensibility depends on the size of the current that passes through the brain and the length of time for which the current is applied.

The initial effect on poultry is immediate insensibility, accompanied by arching of the neck, no rhythmic breathing, rigidly extended legs, constant rapid body tremors and the wings held close to the body.  However, the bird may recover to some degree if insufficient current is delivered, or the positioning is incorrect. If there is any uncertainty as to whether a bird has been effectively stunned, it should be re-stunned immediately.

An effective stun can be defined as one which causes immediate insensibility. This condition should persist until death.