Electroencephalograms and physical reflexes of broilers after electrical waterbath stunning using an alternating current

Abstract

Stunning efficiency of broilers after electrical waterbath stunning with an alternating current was assessed using electroencephalograms (EEG) and physical reflexes. Four hundred eighty-nine broilers (246 males and 243 females) were stunned in an electrical waterbath with a rectangular alternating stunning current of 60, 80, 100, 120, and 150 mA and frequencies of 70, 100, 200, 400, 800, and 1,500 Hz. Stunning time was 10 s. The EEG was recorded for 120 s poststun. Occurrence of spontaneous breathing, eye blinking, and wing flapping and the corneal reflex were recorded. The EEG was analyzed regarding the occurrence of a profound suppression to less than 10% of the prestun level in the 2 to 30-Hz band and 13 to 30-Hz band. The occurrence of epileptiform patterns was assessed and the occurrence of clonic-tonic convulsions was recorded. Statistical analysis showed a highly significant effect of stunning frequency and stunning current for all groups in the EEG analysis. Stunning frequencies above 400 Hz or below 100 mA did not result in profound suppression of brain power to less than 10% of the prestun level in more than 90% of the broilers and can therefore not be recommended. More than 80% of the birds stunned with 70 or 100 Hz at 100 mA or 70, 100, and 200 Hz with 120 and 150 mA did not recover from stunning. The occurrence of epileptiform activity could only be observed in a few birds. It is assumed that this is due to the long stunning time of 10 s and epileptiform activity could have occurred just before EEG recording started. A maximum of 30% of birds with corneal reflexes and spontaneous eye blinking should not be exceeded, whereas at 15 s poststun, not more than 15% of birds should show spontaneous eye blinking. Wing flapping occurred in at least 50% of birds with adequate stunning results. This seems to be related to convulsions and could cause meat quality defects.

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

“…When stunned with at least 800 Hz, all birds recovered from stunning. This corresponds with the findings of Prinz et al (2010), on broilers stunned with an alternating current (AC). In a study of Raj et al (2006a), all broilers recovered from stunning with 800 or 1,400 Hz pulsed DC.…”

“…The profoundly suppressed EEG in both frequency bands for more than 90% of the birds indicate adequate stunning in these groups. This could not be observed for birds stunned with an AC of 80 mA with the same frequencies (Prinz et al, 2010). Similar results have been obtained in the present study for birds stunned with 200 Hz at 120 mA and 400 Hz at 150 mA.…”

“…Furthermore, the state of the eyes of the chickens (open or closed) was recorded immediately after stunning, as well as the occurrence of clonic-tonic convulsions. Convulsions were evaluated as described in Prinz et al (2010).…”

“…The EEG equipment and recording settings used in the present experiment have been described by Prinz et al (2010). All recordings lasted for 120 s poststun.…”

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

“…The efficacy of any waveform needs to be reliably established in a way that can translate to practical situations in the abattoir including meat quality and adequacy of the stun. The application time of the current under commercial conditions is usually around 10 seconds (Prinz, 2010b).…”