Stephen B Wotton

Changes in the somatosensory evoked potentials and spontaneous electroencephalogram of hens during stunning with a carbon dioxide and argon mixture

A previous investigation indicated that when hens were exposed to 2% oxygen in argon (anoxia) EEG suppression and loss of SEPs occurred at 17 and 29 s after exposure. In this study, hens were exposed to 49% carbon dioxide in air (hypercapnic hypoxia) or 31% carbon dioxide with 2% oxygen in argon (hypercapnic anoxia) and their spontaneous electroencephalogram (EEG) and somatosensory evoked potentials (SEPs) were investigated. The results indicated that EEG suppression and loss of SEPs occurred in 11 and 26 s, respectively, in hypercapnic hypoxia. These events occurred at 11 and 19 s, respectively, after exposure to hypercapnic anoxia. These results indicated that, with regard to preslaughter stunning/killing of chickens, a mixture of 31% carbon dioxide with 2% oxygen in argon resulted in a more rapid loss of evoked responses in the brain when compared with 49% carbon dioxide in air or with 2% oxygen in argon. It is concluded that stunning chickens with low concentrations of carbon dioxide in argon would result in a more rapid loss of consciousness.

CHANGES IN THE SOMATOSENSORY EVOKED POTENTIALS AND SPONTANEOUS ELECTROENCEPHALOGRAM OF HENS DURING STUNNING IN ARGON-INDUCED ANOXIA

This study examined the time to loss of consciousness in hens during stunning in argon-induced anoxia. Somatosensory evoked potentials (SEPs) and the spontaneous electroencephalogram (EEG) were recorded in 12 culled hens prior to and during stunning in less than 2% oxygen (air displaced by argon). An additional 20 hens were stunned with a similar concentration of oxygen and the time to loss of posture, eye closure, and the onset and duration of clonic and tonic convulsions were recorded. A further 10 hens were immersed in less than 2% oxygen for 15-17 s and their response to comb pinching was tested as soon as they had been transferred to atmospheric air. It is concluded that the birds had not lost the primary response in their SEPs by the time they started convulsing, but the reduction in the amplitude of the SEPs, changes in their spontaneous EEG and a negative response to comb pinch before the start of the convulsions indicated that the birds were unconscious when they convulsed.

Captive bolt stunning of cattle: Effects on brain function and role of bolt velocity

Abstract The effects of captive bolt stunning on brain function in adult, anaesthetized cattle were examined. In particular, the role of bolt velocity was considered, using visual evoked responses (VER) as an index of brain damage and to assess the time course to recovery. Bolt velocities of 41, 47, 55 and 58 m/sec were compared. At all velocities examined, shooting with the captive bolt failed to abolish VERs in some animals. Increasing bolt velocity reduced the incidence of animals with VERs present following shooting, and also increased the time to recovery of VERs. Bolt velocities of 55 and 58 m/sec significantly increased the extent and duration of brain damage compared to 41 and 47 m/sec, and this result is discussed from the standpoint of humane stunning.

Effect of electrical stunning on somatosensory evoked responses in the turkey's brain

The effects of head only or waterbath electrical stunning on somatosensory evoked responses in the brain of turkeys were examined. When head only stunning with a sinusoidal AC of 50 Hz was followed within 15 s by neck cutting the evoked responses were absent following the stun. When neck cutting was not performed, the evoked responses returned from 30 s after the stun. When currents between 120 and 250 mA were used in a waterbath stunner some birds retained their evoked responses immediately after the current was applied. The proportion of birds that retained their responses after the stun was not related to the level of the current that was applied.

Changes in the spontaneous and evoked electrical activity in the brain of hens during stunning with 30 per cent carbon dioxide in argon with 5 per cent residual oxygen

Changes in the somatosensory evoked potentials (SEPs) and spontaneous electroencephalogram (EEG) in hens were investigated during stunning with a mixture of 30 per cent carbon dioxide in argon with 5 per cent residual oxygen. The results showed that the SEPs were lost on average in 17 seconds (maximum 28 seconds), which is similar to the 19 seconds (maximum 32 seconds) reported while stunning hens with a mixture of 30 per cent carbon dioxide in argon with 2 per cent residual oxygen. The spontaneous EEG showed suppression and a quiescent phase at 14 and 58 seconds, respectively. It is concluded that a mixture of 30 per cent carbon dioxide in argon with 2 per cent residual oxygen would be ideally suited for batch stunning chickens and any inadvertent increase in the residual oxygen level up to 5 per cent in the stunning atmosphere would not lead to inadequate stunning or recovery of consciousness before neck cutting.

EFFECT OF A 350 HZ DC STUNNING CURRENT ON EVOKED RESPONSES IN THE CHICKEN'S BRAIN

Somatosensory evoked responses in the chickens brain were examined before and after stunning with a 350 Hz pulsed DC. When the current was greater than 120 mA, 93 per cent of the birds lost their evoked responses for at least 60 seconds. On this basis 120 mA per bird is recommended as an acceptable current for commercial use.

A comparison of blood loss during the Halal slaughter of lambs following Traditional Religious Slaughter without stunning, Electric Head-Only Stunning and Post-Cut Electric Head-Only Stunning

Blood lost at exsanguination during the Halal slaughter of lambs was compared between the slaughter methods of Traditional Religious Slaughter without stunning (TRS), Electric Head-Only Stunning (EHOS) and Post-Cut Electric Head-Only Stunning (PCEHOS). Two protocols were examined, Experimental (80 lambs) and Commercial (360 lambs), assessing varying periods of animal orientation during the 4 min bleeding process (upright orientation before vertical hanging). Live-weight, blood weight (Experimental only), carcass weights and by-product weights were recorded. The Experimental protocol highlighted an increase in blood loss at 60s in EHOS and PCEHOS compared to TRS (P<0.001) but by 90 s there was no significant difference. A post-slaughter change in animal orientation from an upright to a vertical hanging position aided the amount of blood loss. The bleeding of lambs is largely completed by 2 min. There were no significant differences (P>0.05) in final blood loss between treatments. This research was undertaken to inform discussion on the merits of different slaughter methods compatible with Halal requirements.

Sensory evaluation of breast fillets from argon‐stunned and electrically‐stimulated broiler carcases processed under commercial conditions

Abstract 1. A comparison of eating quality of breast meat (pectoralis major) filleted at 2 h post‐mortem was made between broilers stunned with argon‐induced anoxia (less than 2% residual oxygen) and broilers which were electrically‐stunned and their carcases electrically‐stimulated under commercial conditions. 2. Fifty breast muscles were filleted from the carcases of argon stunned broilers at 2 h post‐mortem. Fifty breast muscles were also removed at the same time from the carcases of broilers which were electrically‐stunned and electrically‐stimulated. A ‘control’ group of broilers which were electrically‐stunned and electrically‐stimulated and processed under as similar conditions as possible were also filleted after overnight ageing in the air chiller. 3. Sensory analysis was performed using 10 trained panelists, who were asked to rate the fillets on a 1 to 8 hedonic scale for taste, texture, juiciness and overall liking. 4. The mean ranks for texture and overall liking differed between the groups. T...

Humane euthanasia of neonates I: validation of the effectiveness of the Zephyr EXL non-penetrating captive bolt euthanasia system on neonate piglets up to 10.9 kg live-weight

To determine if mechanical blunt force trauma using a non-penetrating captive bolt was a viable method of producing an immediate stun/kill in neonate piglets (Sus scrofa domesticus) as an alternative to manual blunt force trauma, piglets (n=60) were acquired from a local producer and allocated to one of 5 weight ranges Birth weight to 3 kg (n = 12), 3 to 5 kg (n = 11), 5 to 7 kg (n = 13), 7 to 9 kg (n = 13) and 9 to 11 kg (n = 11). These piglets, with an average liveweight of 6.1 kg, were anaesthetized and electroencephalogram (EEG) recording electrodes inserted subdermally over the right cranium to allow recording of Visual Evoked Potentials (VEPs). Following recording of baseline VEPs in the anaesthetized state the piglet was shot once in the frontal-parietal position with a Bock Industries Zephyr EXL non-penetrating captive bolt powered by 120 psi air pressure. Movement scoring, behavioural indices of loss of brain function and VEPs were monitored throughout. VEPs were lost immediately in all piglets shot when the head was resting on a hard surface. This experiment demonstrates that mechanical blunt force trauma using a single shot non-penetrating captive bolt, such as the Zephyr EXL, provides for an immediate stun kill in neonate piglets up to 10.9 kg liveweight. This immediacy of action, combined with reproducible effects will improve the welfare of piglets to be subjected to on-farm euthanasia due to disease, ill-thrift or other commercial concerns.

The stunning and slaughter of cattle within the EU: A review of the current situation with regard to the halal market

The slaughter of animals for the halal market is both ethically and economically significant. There are animal welfare and spiritual requirements that must be met for meat to be considered fit for Muslim consumption. These requirements are enshrined in Islamic law, known commonly as the Shariah law, derived from commandments in the Holy Quran and the Hadith (teachings or traditions of the Prophet of Islam, Mohammed, Peace Be Upon Him). Islamic jurists widely interpret the Shariah law differently, and this has led to debate as to whether pre-slaughter stunning is acceptable for halal slaughter. This paper reviews how these laws are interpreted and implemented and reviews the methods of stunning accepted by proponents of halal stunning. It also describes why some proponents of halal stunning do not accept irreversible stunning methods for producing halal beef within the EU, a situation which has meant that thousands of halal cattle are slaughtered without any form of stunning.