Head-cloaca controlled current stunning: assessment of brain and heart activity and meat quality.

1. Behavioural and neural responses of 65 broilers to head-to-cloaca electrical stunning were evaluated and meat quality was assessed on two groups of 25 broilers stunned either head to cloaca, or in a conventional water bath method. 2. On the EEG recordings, a general epileptiform insult was observed when applying a current of 100 mA (100 Hz) or 70 mA (70 Hz) for 1·5 s. This general epileptiform insult shows a tonic, clonic and exhaustion phase followed by spikes of alpha, beta, theta and delta waves with duration of on average 34 ± 12 s and 39 ± 23 s respectively. These birds may have been unconscious for 20 s or longer, according to the correlation dimension analyses. 3. The heart rate decreased significantly (P < 0·05) after stunning and recovered after 60 s. 4. Within a confidence limit of 95%, taking into account the number of animals with a reliable EEG, the chance of an effective stun of all broilers lies between 0·9 and 1·0 with a current of 70 mA (100 Hz for 1·5 s; n = 28) and with 100 mA (100 Hz for 1·5 s; n = 27). 5. The shear force of breast fillets was slightly lower (P < 0·01) 4 d post mortem compared with the conventional water bath stunned group (set at 100 mA, 100 Hz for 10 s). The percentage of fillets and legs without blood splashes was higher, and the percentage with severe blood splashes lower-to-none, for carcases stunned head-cloaca. 6. It can be concluded that broilers are effectively stunned with the head-cloaca method by using a controlled current of 70 mA or 100 mA for 1·5 s. The fillets and legs of bird stunned head-cloaca showed fewer blood splashes in the muscles compared with birds stunned in a conventional water bath.

Animal welfare concerns during the use of the water bath for stunning broilers, hens, and ducks.

European legislation demands that slaughter animals, including poultry, be rendered immediately unconscious and insensible until death occurs through blood loss at slaughter. This study addressed requirements for stunner settings (i.e., voltage, wave oscillation frequency) and response parameters (i.e., applied current, behavior) affecting effective water bath stunning. An inventory of current electrical stunning practice was performed in 10 slaughterhouses in the Netherlands. Thereafter, measurements were performed using a single-bird water bath to examine the effects of stunner settings based on the average technical settings observed in the slaughterhouses. Responses were recorded at 50, 400, and 1,000 Hz on broilers and hens and at 50 and 400 Hz on ducks under controlled laboratory conditions. Effects of voltage settings (broilers: 100 to 400 V; hens: 150 to 300 V; ducks: 150 to 400 V) on current levels (broilers: 45 to 444 mA; hens: 40 to 219 mA; ducks: 64 to 362 mA) and consciousness (response to pain stimulus) were recorded immediately after stunning. Brain and heart activity was monitored using electroencephalogram and electrocardiogram technology. Results show that effective stunning using the conventional water bath almost exclusively produces blood splashing in broilers. Effective stunning current levels did not differ significantly between broilers, hens, and ducks effectively stunned hens tended to require lower currents. Effective stuns at higher frequencies resulted in higher currents. Similar input voltage (V) levels (within and between bird type) resulted in significant variation (P < 0.001) in current levels (mA) required for an effective stun, indicating variability in electrical impedance between individual birds. Body weight and bird type did not affect the probability of an effective stun. Multi-bird water bath usage does not ensure effective stunning and technical adjustments can result in detrimental effects on meat quality. Future legislation should consider wave form, relationships between frequency and current allowing for individual impedance variation and effects on meat quality while safeguarding animal welfare.