Stunning and slaughter

Stunning methods used for poultry include head-only electrical stunning and electrical water bath stunning with high frequency currents (usually 200-1500 Hz) that do not induce cardiac ventricular fibrillation (cardiac arrest). Stun/kill methods include application of 50 Hz sine wave AC through the whole body using either dry electrodes or electrical water baths, and exposure to gas mixtures. Captive bolts and neck dislocation are killing methods used as back-up procedures in poultry processing plants and for on-farm killing during disease outbreaks. Electrical stunning-induced depth and duration of unconsciousness seem to depend upon the waveform and frequency of the electric current. At a given current level, increasing the frequency reduces the effectiveness of stunning and sine wave AC is more effective than pulsed DC. The time to onset of death at slaughter depends upon the blood vessels cut. Stunning with gas mixtures does not provide adequate duration of unconsciousness and therefore stun/killing is preferred. In this regard, exposure to anoxia induced with nitrogen and/or argon appears to be the best option for bird welfare, socio-economic and environmental impact reasons.