Head-Only Stunning of Turkeys Part 1: The Minimum Voltage Necessary to Break Down the Inherent High Resistance

SIMPLE SUMMARY: Pre-slaughter stunning is required for the humane slaughter of turkeys. For the head-only electrical stunning to be effective, the impedance (resistance) in the tissue of the head of the animal between the two electrodes must be overcome by the level of the voltage used. We have assessed the most appropriate voltage to effectively overcome the impedance and provide an effective stun, and that is also safe for the operator to use. Sinusoidal AC at 150 V and 50 Hz was considered to fulfil those requirements and was used for further testing. ABSTRACT: Pre-slaughter stunning is required for humane slaughter. For turkeys, head-only electrical stunning is most often used by small scale producers. To ensure immediate and effective stunning, the impedance (resistance) of the tissue of the head of the animal situated between the two electrodes needs to be overcome swiftly. The impedance is a function of the voltage and decreases non-linearly with increasing voltage. In this paper, we describe a method to assess the minimum voltage needed at which the impedance no longer decreases, that is likely to produce an effective stun. For ethical reasons, gas stunned, electrically naïve turkeys were used to measure impedance at various levels of voltage and current. Several combinations of voltage and frequency, alternate current (AC), direct current (DC) and pulsed DC, were identified that would be sufficient to achieve the maximum decrease in the impedance, and therefore would allow the highest current and the most effective stun. A minimum, expressed as Root Mean Squared voltage, of 150 V and 50 Hz. would be required in AC, 175 V in pulsed DC at 30% cycle (150 at 50% cycle), and 225 V if voltage spikes of very short duration were used. Sinusoidal AC applied at 150 V, 50 Hz was selected for further testing.