Head-only Electrical Stunning Research Articles

Assessment of Return to Consciousness After Electrical Stunning in Lambs

AbstractThe return to consciousness of 24 electrically stunned lambs was assessed by measurement of physiological reflexes and electroencephalography (EEG) recordings. The physical activity of the lambs after head-only electrical stunning included one tonic phase and two clonic phases. The tonic phase began immediately after the stun and ended 10 s after the stun; the first clonic phase started immediately after the tonic phase and ended 36 s after the stun, and the second clonic phase started immediately after the first clonic phase and ended 70 s after the stun. During the tonic phase and the first clonic phase, electrical activity recordings of the brain showed a dramatic increase in the relative power spectra of alpha and beta frequencies. Both frequencies returned to pre-stun levels with the end of the first clonic phase. During the second clonic phase, the relative power spectrum of theta frequency was higher than that before stunning. These results suggest that during the tonic phase and the first clonic phase, the animal was unconscious, whereas during the second clonic phase the return of some conscious function began. Spontaneous breathing returned at about 29 s post-stun, whereas the corneal reflex returned at about 38 s. It is therefore suggested that the return of spontaneous breathing is the safest indicator that the animal is close to recovering consciousness.

Effects of feed deprivation and electrical, gas, and captive needle stunning on early postmortem muscle metabolism and subsequent meat quality

The general method for stunning poultry before slaughter is by immersion of a chicken's head into an electrified waterbath. This method results in carcass and meat quality deficiencies. The major problems are hemorrhages and a delay in onset of rigor mortis, which increases the risk of cold shortening with early deboning. In two experiments, this study examines the early postmortem metabolism in the breast muscle and its effect on ultimate meat quality. The first experiment describes the effects of 5 h feed deprivation on the availability of glycogen from the liver and the breast muscle, of waterbath and head-only electrical stunning on pH and metabolite levels up to 6 h in unprocessed muscle, and the consequences on meat quality. The second experiment compares the same measurements after waterbath and head-only electrical stunning, CO2/O2/N2 and Ar/CO2 gases, and captive needle stunning. Metabolic degradation halted after 6 h without processing or after 4 h under conventional conditions after waterbath and CO2/O2/N2 stunning. With other stunning methods, this occurrence is at a faster rate, largely depending on muscle activity. Muscle glycogen does not need to be exhausted for energy generation to cease. If glycogen is a limiting factor, as found with head-only stunning, pH drops too rapidly and affects water-holding capacity and color. Hemorrhage scores were higher with electrical stunning than with other stunning methods. Gas stunning affected color and, to a lesser extent, water-holding capacity. Captive needle stunning scored between gas and electrical stunning on most measurements.

Electrical stunning of cattle

Cattle are normally stunned electrically by three sequential cycles, first a three-second head-only cycle, to stun the animal, secondly a 15-second cardiac cycle, to induce ventricular fibrillation (cardiac arrest), and...

Factors affecting the effectiveness of head-only electrical stunning in sheep

The effects of factors such as the position of the tongs, the presence of wool, and the wetness of the skin on the efficiency of the head-only stunning procedure, and...

The effect of the sticking method on the welfare of slaughter pigs

A project was undertaken to investigate the causes of inadequate sticking encountered during a survey of pig abattoirs. The results of the investigation identified the length of the sticking (exsanguination) wound as a major contributor to the problem. Experimental abattoir trials conducted on slaughter pigs comparing two sticking lengths indicated that the rate of bleed out was delayed with short sticking wounds. In addition, information about the identity of blood vessels severed following sticking was obtained. The results indicate that following head-only electrical stunning, a relatively long sticking wound should provide better welfare in slaughter pigs. The study has also highlighted the health and safety problems for the operatives as well as the welfare concerns associated with manual application of electrical stunning.

Changes in the release of amino acid neurotransmitters in the brains of calves and sheep after head-only electrical stunning and throat cutting

In calves aged two to five months, throat cutting resulted in an increase in the concentration of the amino acid neurotransmitters glutamate and aspartate in the brain. Electrical head-only stunning by itself also increased the concentrations of these two neurotransmitters. The levels induced by stunning resulted in a seizure state characterised by epileptiform-like activity in the electroencephalograph. Combing head-only stunning with throat cutting within 10 seconds of the stun had a synergistic effect upon glutamate and aspartate, increasing their concentration by a greater amount and more quickly than either procedure on its own. An irreversible loss of brain function also occurred more quickly than after throat cutting alone. The administration of glutamate and aspartate receptor antagonists before the throat cutting lengthened the time to the loss of brain function in a dose dependent manner. Similar changes were observed in sheep but they occurred much more quickly than in cattle.

Electrical head-only stunning of fallow deer (Dama dama)

Abstract We recently published a paper(1) documenting the success of head-only electrical stunning in red deer (Cervus elaphus). This work has now been extended to fallow deer (Dama dama) to determine whether there are differences between this species and red deer in terms of behavioural responses and effectiveness of electrical stunning.

Minimum duration of effective head-only electrical stunning of fallow deer (Dama dama) and time to loss of consciousness following a throat-cut

Abstract Extract Recent work(1) (2) has demonstrated the success of headonly electrical stunning in both red (Cervus eluphus) and fallow (Dama dama) deer. This work has been extended to investigate the export market and welfare requirements of the minimum duration needed for successful stun and the time to loss of consciousness following a throat-cut (severance of both carotid arteries and jugular veins) alone in fallow deer.

Electrical stunning of red deer (Cervus elaphus)

Eighteen of 23 red deer (Cervus elaphus) at a deer slaughtering premises were successfully stunned with an apparatus modified from that normally used to stun sheep. The five unsuccessful electrical stuns were associated with poor head restraint and poor head contact by the electrodes. The median stunning current was 0.9 A, and in the majority of cases the duration of stunning was less than 1 second. The signs of the electrically induced epileptiform seizures in the deer were dissimilar to those seen in sheep, cattle and pigs, in that the initial tonic phase was less marked, and of shorter duration. A similar shorter and less obvious tonic phase was noted in four deer shot with a captive bolt pistol. Two animals which were electrically stunned, and bled within 10 seconds, showed no signs of recovery while bleeding. The electroencephalograms of four deer stunned with currents of 1.3 A for a duration of either 0.5 or 1.0 seconds were recorded under more controlled conditions. All four animals developed electroencephalograms typical of an epileptiform seizure. The animals exhibited behavioural reactions similar to the other 18 animals in the trial at the deer slaughtering premises and were rendered unconscious for between 54 and 122 seconds. The electroencephalogram activity amplitude was greater than that recorded immediately before stunning and took between 6 and 9 seconds to build up to maximum value. It is concluded that, providing the heads of deer are adequately restrained, head-only electrical stunning can be incorporated into a humane method of slaughter for deer.

Onset of insensibility at slaughter in calves: effects of electroplectic seizure and exsanguination on spontaneous electrocortical activity and indices of cerebral metabolism

Cerebral venous and femoral arterial blood samples were collected from 21 young calves either during electrical stunning and recovery or electrical stunning and slaughter by carotid severance or slaughter without stunning. The blood samples were analysed for P O 2 , P C0 2 , pH, glucose and lactate. The results were compared with simultaneous recordings of spontaneous electrocortical ( ECOG) activity. Calves subjected to head-only electrical stunning and slaughter became permanently insensible at the time of the stun. The six calves slaughtered without stunning lost sensibility within 10 seconds. One calf, in which a clot formed in the carotid arteries inhibiting bleeding, maintained some evidence of cortical activity beyond 52 seconds; this was high amplitude low frequency activity and analysis by Fast Fourier Transform showed sensibility was not regained. In the remaining calves the ECOG activity was lost on average within 49±3·5 ( SEM) seconds after slaughter. The cerebral extraction of metabolites increased after carotid severance, indicating inadequacy of cerebral bloodflow after slaughter. No correlations were found between indices of cerebral metabolism and the time of loss of cortical function.

Electrocardiograms as an aid in assessing the stunning of cattle and pigs

Electrocardiograms (ECG's) were made from cattle and pigs after slaughter using only the left arm and right arm recording electrodes of a portable electrocardiogram with 12 recording electrodes. Functional heart activity was demonstrated in cattle after stunning with a captive bolt, nonpenetrative percussive methods and a head-only electrical technique. Recordings compatible with ventricular fibrillation were made in the majority of cattle and pigs subjected to a head-to-chest form of electrical stunning. In cases where the placement of stunning electrodes was defective, functional cardiac activity could be detected. Movement artefact on the ECG trace associated with epileptiform seizures following head-only electrical stunning was a technical problem. This was reduced by restunning the animal with a captive bolt before taking an ECG. The examination of ECG's made subsequent to slaughter could form an important component of the quality control of Halal slaughter or a slaughter process using the head-to-body electrical stunning techniques. Adoption of this would be facilitated by the development of a more simple and less sensitive electrocardiograph than that used in the present investigation.

Jugular blood flow in calves after head-only electrical stunning and throat-cutting

Jugular flow was measured after head-only electrical stunning and gash cutting in 12 calves less than a week old. Jugular flow was assumed to provide a crude measure of cerebral perfusion during exsanguination. In 10 animals the average amount of jugular blood collected within 1–2 min of throat-cutting was the equivalent of a total cerebral blood flow of 3·6 ml/min/100 g ± 1·4 SD or 4·8% of normal. In two animals the jugular flow was increased to 39% and 22% of normal cerebral flow. All animals had strong retrograde flow from the head ends of the cut carotid arteries. The dynamics of cerebral blood perfusion are discussed with reference to systemic arterial blood pressure and spontaneous cortical electrical activity, and some potentially fruitful areas of research on the humaneness of halal slaughter of cattle are proposed.

The use of electrical stunning followed by electro-immobilization for the humane slaughter of cattle

Abstract Sir;- In New Zealand, calves are often electrically stunned before slaughter. However, electrical stunning is not usually used for adult cattle, primarily because the large size of the adult animal makes restraint more difficult, resulting in less reproducible stunning, with potential danger to personnel from animal movement. In addition, the slaughter of cattle may be inhumane if the stunning process does not ensure immediate and permanent insensibility (Newhook and Blackmore 1982b). The use and humaneness of electrical stunning of sheep and cattle have been the subject of our recent research, in which we have addressed and resolved many of these problems. We wish to relate our observations in the context of head-only electrical stunning of cattle followed by electro-immobilization to maintain insensibility and ensure carcass stillness.