Effects of waterbath stunning on the electroencephalograms and physical reflexes of broilers using a pulsed direct current

Abstract

Stunning efficiency of a pulsed direct current was assessed regarding the effect on the electroencephalogram (EEG) and physical reflexes. Four hundred sixty-seven broilers (males and females) were stunned in an electrified waterbath with 60, 80, 100, 120, and 150 mA at frequencies of 70, 100, 200, 400, 800, and 1,500 Hz. Stunning time was 10 s. The EEG recordings lasted for 120 s poststun and simultaneously the occurrence of breathing, spontaneous eye blinking, corneal reflex, and wing flapping was recorded. The EEG records were assessed regarding a profound suppression to less than 10% of the prestun brain power in 2 brain frequency bands, 2 to 30 Hz and 13 to 30 Hz. The EEG results showed a significant effect of stunning frequency for all analyzed parameters. Stunning frequencies of 800 and 1,500 Hz did not achieve adequate stunning results. With a minimum stunning current of 120 mA at frequencies of 70 or 100 Hz or 150 mA at 200 Hz, more than 80% of the animals did not resume breathing. Currents of 80 and 100 mA at 70 or 100 Hz achieved unconsciousness in more than 90% of the birds and birds recovered within 30 to 40 s poststun. Epileptiform activity was found in a relatively low proportion of EEG traces. This could be explained by the long stunning time of 10 s, in which epileptiform activity might have occurred already before the start of EEG recording. Direct current stunning causes less cardiac arrest during stunning, but occurrence of breathing seems more related to cardiac function than to consciousness. A maximum of 30% corneal reflexes and spontaneous eye blinking seems acceptable with a maximum of 15% spontaneous blinking at 15 s poststun. Fourty percent of wing flapping occurred in all effectively stunned groups. Direct current seems to have a different effect on male and female broilers because significantly more male broilers showed reflexes, whereas simultaneously the likelihood of profound EEG suppression was higher. Further investigation of this effect is necessary.

Electrical waterbath stunning: Influence of different waveform and voltage settings on the induction of unconsciousness and death in male and female broiler chickens

“…Pulsed DC, on the other hand, only resulted in a maximum of 40% wing flapping for the highest stunning voltage of 120 V (Figure 3). This level is slightly lower compared with a previous study on pulsed DC stunning of 10 s (Prinz et al, 2010b). It can moreover be observed that the level of wing flapping was higher in females in the present study (Figure 3).…”

“…In their study, a pulsed DC of 70 Hz rendered more than 90% of broilers unconscious with minimum currents of 80 mA. The distinction might be caused by the longer stunning time of 10 s (Prinz, 2009;Prinz et al, 2010b). This might have caused a longer duration of insensibility in the broilers than 4 s of stunning time in the present study.…”

“…Raj (2006) explains the lower stunning efficiency of pulsed DC with the current flow in one direction only, whereas AC flows in positive and negative directions. Results of previous studies (Prinz, 2009;Prinz et al, 2010b), on the other hand, show no difference in stunning efficiency of pulsed DC and rectangular AC waterbath stunning. In their study, a pulsed DC of 70 Hz rendered more than 90% of broilers unconscious with minimum currents of 80 mA.…”

Decapitation in Rats: Latency to Unconsciousness and the ‘Wave of Death’

“…The power in this band is recognized as expressing vigilance and the ability to experience sensory perceptions, including pain, whereas the lack of activity in this band is interpreted as an unequivocal loss of sensibility [6], [7], [8]. The power of the post decapitation EEG in this cognitive band has a time course comparable with the power in the 1–100 Hz band, but the time to half-life is shorter: 3.7 seconds, with a 95% confidence interval between 3.5 to 4.1 seconds (significantly different from the previous 5.5 seconds, t(2)  = 173, p<0.001).…”

Scientific Opinion on the electrical requirements for waterbath stunning equipment applicable for poultry

“…With DC currents, the corneal reflex was not a reliable indicator of unconsciousness and insensibility at any current or frequency. Overall, these observations show that the presence or absence of a corneal reflex is not a reliable indicator of unconsciousness and insensibility, The recovery of corneal reflexes after stunning, together with the return of spontaneous breathing and eye blinking, can be signs of a progressive recovery of brain function (Wenzlawowicz and von Holleben, 2001;Prinz et al, 2010a). On the other hand, a continuing absence of a corneal reflex could be an indicator for approaching brain death or severe brain impairment (Gregory, 1989).…”