The basic assumption being that by stunning the animal prior to cutting the throat it is less painful.  This has been disproved by recent scientific finding, yet the practice continues.

Stunning is not allowed as an Islamic method of slaughtering as it causes harm the animal as well restricts spilling of the blood from the animal once the blade is applied to it blood vessels.

The Islamic method of slaughtering does not touch the nervous system at all; rather it allows the brain to function and thereby keeps the heart working expelling as much blood as possible.

A COMPARISON OF SLAUGHTERING METHODS

Experimental studies in Europe have deduced the following.

Islamic Method of slaughtering

1. The first three seconds from the time of dhabh as recorded on the EEG did not show any change from the graph before slaughter,

2. Thus indicating that the animal did not feel any pain during or immediately  after the incision

3. For the following 3 seconds, the EEG recorded a condition of deep sleep - unconsciousness. This is due to the large quantity of blood gushing out from the body.

4. After the above-mentioned 6 seconds, the EEG recorded zero level, showing no feeling of pain at all.

5. As the brain message (EEG) dropped to zero level, the heart was still pounding and the body convulsing vigorously (a reflex action of the spinal cord) driving a maximum amount of blood from the body thus resulting I in hygienic meat-for the consumer.

Non-Islamic Method of slaughtering (i.e. Bolt)

1. The animals were apparently unconscious soon after stunning.

2. EEG showed severe pain immediately after stunning.

3. The hearts of animals stunned by C.B.P. stopped beating earlier as compared to the Islamic Method

4. Resulting in the retention of more blood in the meat. This in turn is unhygienic for the consumer.

Study conclusion:

The Islamic slaughtering is the most humane method of slaughter and that captive bolt stunning, practiced in the West, causes severe pain to the animal.