Head-to-Body Stun-Kill

The design of equipment for head-to-body stun-killing depends on the species of animal being killed and is generally semi- or fully-automatic. It is important to make sure that the animals are positioned correctly in the machine, in relation to the electrodes, and to make adjustments for different sized animals. Regular checks must make sure that both an effective stun and cardiac arrest are induced. All automatic stun-kill equipment must be set carefully to the manufacturer’s instructions and both electrodes and placement sites must be clean.

Equipment for pigs automatically places a pair of electrodes on the head, just below the ears, to stun the animal. A third electrode is then placed on the chest of the animal, to deliver a second current that will fibrillate the heart, and thereby cause the death of the animal.

Electrical stunning of cattle can be achieved using three phases sequentially: a three second head-only phase to stun the animal followed by a 15 second cardiac phase to induce ventricular fibrillation (cardiac arrest) and then a four second spinal discharge phase to reduce clonic convulsions. Equipment for cattle should restrain the animal with a neck yoke, chin lift and rump pusher, in order to position the animal for accurate electrode placement (Figure 16). An electrode will then contact the nose and current will flow from the nose to the neck yoke, stunning the animal. A second electrode will then be placed on the brisket and a further current will flow through the body and stop the heart. The type and magnitude of the current delivered varies, dependant on the equipment used. The third phase, nose-to-rump, which disrupts spinal reflexes, is used so that the animal lies motionless once it is released from the restrainer.

head-to-body

Figure 16 Head-to-body stun-kill cattle equipment

In a commercial environment, the interval between stunning and sticking of cattle can be long (up to 60 seconds where the stunned animal has to be shackled and elevated prior to bleeding). Therefore it is essential that all staff should be able to recognise and differentiate between effective and ineffective electrical stunning with subsequent cardiac arrest. A back-up captive-bolt stunner must always be available.


Next: Control Devices and Monitors 

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