Electrical Waterbath Stunning: Influence of Different Waveform and Voltage Settings on the Induction of Unconsciousness and Death in Broilers21 May 2012
The waveforms required different amounts of current to achieve 90 per cent stunning, according to new research from Germany and the Netherlands. Results with alternating current indicating stun to kill and there was more wing–flapping, and female broilers obtained a significantly lower stunning current than the males.
Stunning effectiveness of male and female broiler chickens was analysed in response to different waveforms at three constant voltage levels, report S. Prinz of the University of Hohenheim in Germany and co–authors there and Radboud University in the Netherlands and OSI Food Solutions in Gunzburg, Germany, in a paper published recently in Poultry Science.
In total, 180 male and female broiler chickens were stunned using a sine wave alternating current (AC) of 50 Hertz (Hz), rectangular AC of 70Hz and pulsed direct current (DC) of 70Hz (duty-cycle 1:1) with a constant voltage of 60, 80 or 120 volts (V), respectively. In each stunning group, 10 male and 10 female birds were stunned for four seconds.
The current obtained by every bird was recorded. For stunning efficiency, the electroencephalogram (EEG) and physical reflexes were recorded and analysed. The EEG was recorded for 120 seconds post–stun. Simultaneously, the occurrence of spontaneous eye blinking, wing flapping and breathing was assessed, and the corneal reflex was tested every 20 seconds post–stun. The EEG was analysed regarding the occurrence of a profound suppression to less than 10 per cent of the pre–stun level in the 2 to 30Hz and 13 to 30Hz bands.
Female broilers obtained a significantly lower stunning current than the males. This resulted in a lower stunning efficiency for females, when the same constant voltage was applied to males and females.
The waveforms required different amounts of currents to achieve a 90 per cent stunning efficiency. A minimum necessary stunning current of 70, 90 and 130mA could be established for sine wave AC, rectangular AC and pulsed DC, respectively.
The low stunning efficiency of pulsed DC might be caused by the short stunning time of four seconds. This effect should be further investigated for DC stunning.
Very few birds stunned with AC resumed breathing following stunning, indicating stun to kill.
Pulsed DC stunning showed a lower effect on the induction of death. The level of wing flapping – indicating convulsions and possible meat quality defects – was higher for the AC treatments.
Prinz S., G. Van Oijen, F. Ehinger, W. Bessei and A. Coenen. 2012. Electrical waterbath stunning: Influence of different waveform and voltage settings on the induction of unconsciousness and death in male and female broiler chickens. Poult. Sci. 91(4):998-1008. doi: 10.3382/ps.2009-00137
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