Insensibility during slaughter of pigs in comparison to other domestic stock

The onset of insensibility during slaughter was studied in five, 31-day-old pigs. The state of sensibility was determined from the study of electroencephalograms (EEC) which were of a bipolar transhemispheric derivation. In 3 pigs slaughtered by bilateral severance of both common carotid arteries and jugular veins, it was judged that insensibility occurred within 25s and there was no resurgence of cerebrocortical activity following subsequent respiratory gasps. The EEGs became isoelectric within 115s. These results are compared with previous findings by the authors that adult sheep and lambs slaughtered by similar techniques became insensible within 7s whereas, in calves, the onset of insensibility was delayed for up to 85s and there were resurgences of cerebrocortical activity, following a respiratory gasp, for more than 300s.

These differences in the apparent onset of insensibility in the 3 species of animal are discussed in relation to the anatomical features and possible dynamics of the blood supply to the brain during slaughter.

It is concluded that for humane reasons, “head-to-back” electrical stunning of pigs is preferable to a “head-only” method.     

Insensibility during slaughter of pigs in comparison to other domestic stock

The onset of insensibility during slaughter was studied in five, 31-day-old pigs. The state of sensibility was determined from the study of electroencephalograms (EEC) which were of a bipolar transhemispheric derivation. In 3 pigs slaughtered by bilateral severance of both common carotid arteries and jugular veins, it was judged that insensibility occurred within 25 s and there was no resurgence of cerebrocortical activity following subsequent respiratory gasps. The EEGs became isoelectric within 115 s. These results are compared with previous findings by the authors that adult sheep and lambs slaughtered by similar techniques became insensible within 7 s whereas, in calves, the onset of insensibility was delayed for up to 85 s and there were resurgences of cerebrocortical activity, following a respiratory gasp, for more than 300 s. These differences in the apparent onset of insensibility in the 3 species of animal are discussed in relation to the anatomical features and possible dynamics of the blood supply to the brain during slaughter. It is concluded that for humane reasons, head-to-back electrical stunning of pigs is preferable to a head-only method.     

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.     

Head-only followed by cardiac arrest electrical stunning is an effective alternative to head-only electrical stunning in pigs

Many small slaughter facilities use head-only electrical stunning to render swine unconscious and insensible to pain before slaughter. Head-only electrical stunning is a reversible procedure that is optimally effective for approximately 15 s after stun completion. In many small North American slaughter plants, the authors have observed hoist speeds that are too slow to achieve a short enough stun-to-bleed interval to maintain insensibility through exsanguination. Unlike many European plants, there is no separate high-speed hoist for pigs and exsanguination on the floor is not condoned. As a result, a 2-stage stunning method was proposed where head-only stunning for 3 s was immediately followed by application of the same stunning wand to the cardiac region of the animal for 3 s while lying in lateral recumbancy. A paired-comparison study was conducted on 89 pigs in a small slaughter facility to compare the head-only method applied for 6 s with the head/heart method. The objective was to evaluate signs of return to sensibility, stun-to-bleed time, blood lactate concentration, muscle pH, drip loss, and fresh meat color to validate the head/heart electrical stunning method for small slaughter plants. Incidence of corneal reflex was not different (P > 0.05) between head/heart (93.8%) and head only (85%) stunning. Nose twitching was more common (P < 0.05) in head only (26.5%) than head/heart (5%) stunning. Head/heart stunning eliminated rhythmic breathing, natural blinking, eye tracking to moving objects, and righting reflex, which were all observed in head-only stunned pigs. Eye tracking to moving objects was observed in 40.8% of head-only stunned pigs. Blood lactate was not different (P > 0.05) between stunning methods (head only: 8.8 ± 0.7 mmol/L, head/heart: 7.8 ± 0.7 mmol/L). Stun-to-bleed time did not differ (P > 0.05; head only: 32 ± 1 s, head/heart: 33 ± 1 s). Mean time to loss of heartbeat with the head-only method was 121 ± 5 s. No heartbeat was observed with the head/heart method. Longissimus thoracis pH, color, and drip loss were not different (P > 0.05) between stunning methods. This study determined that the head/heart electrical stunning method reduces the incidence of signs of return to sensibility without significant effects on meat quality, plant operation speed, or blood lactate concentration. In addition, the head/heart method requires no capital investment for plants that are currently using the head-only method.     

Animal welfare and workers' protection during electric stunning of poultry for slaughter

Every slaughter process involves problems as to animal welfare as well as safety aspects and the protection of workers. With poultry these are basically concentrated on electrical stunning. Electrical currents and voltages suitable for stunning slaughter animals are principally also hazardous for man in what respect body resistance is of crucial importance. Potential hazards have to be looked upon as present in spite of existing safety regulations. Comparatively high stunning voltages for poultry recently proposed because of animal welfare considerations have met objections not only from the viewpoint of meat hygienic but workers' safety regulations as well. While the former meanwhile could be overcome the latter still has to be investigated, especially as a regulation on the electrical stunning of poultry is currently being prepared. In this respect the question whether adequate stunning efficiency can be obtained by reducing the voltage and prolonging the time of exposure is of special interest. First preliminary results of such investigations are presented. To ensure workers' safety other related aspects should also be taken into account and examined for improvements.     

Electrical stunning of cattle--experiences in New Zealand

Ever since the middle of the nineteen-eighties electrical stunning of cattle is used in industrial slaughter plants in New Zealand. Today electrical stun boxes operate in export slaughter plants throughout New Zealand. The reversible stun is utilised on the vast majority of slaughtered cattle. The electrical stunning (head only) immediately followed by bleeding is an alternative to ritual slaughter without prior stunning. Throughout the world's islamic community this alternative is widely accepted as Halal.     

Killing of cattle via electrical stunning

For disease control in the case of epidemics killing of cattle via electrical stunning is a method of choice. The official veterinarian is responsible for monitoring the adhesion to animal welfare principles during electrical stunning and killing.This requires specialised knowledge and experience as the symptoms of effective stunning are quite variable in cattle. Signs of effective and ineffective stunning are described below. In addition to suitable technical equipment, restraint of the animals and correct use of the equipment, neurophysiological processes have to be considered. Calm handling of the animals avoiding stress is a prerequisite for ensuring animal welfare and minimising pain especially when killing cattle using electrical methods.     

Physiologic reactions during the slaughter of cattle and sheep with and without stunning

In a first trial the cortical activity of cattle and sheep was tested using only an electrocorticogram (ECoG). The results showed a shorter phase after sticking or the ritual slaughter cut respectively, until the ECoG disappears in stunned animals. However, considering the time between stunning and the cervical state, the interval until disappearance of the ECoG was prolonged in the stunned animals. The observed time differences, however, are only a tendency and not statistically confirmed. Insofar, concerning animal protection, the different slaughter methods could be regarded equivalent. A second trial was designed in a manner to allow a more exact interpretation of the ECoGs and was completed by measuring visually and somatosensorically evoked potentials. Additionally, in contrast to the first trial, only adult cattle were used here. The results revealed shorter intervals until disappearance of cortical activities when using captive-bolt stunning. Also the variance was much lower in this trial than after ritual slaughter. The mean of the time differences was relatively low (5.5 seconds). It was especially remarkable that after captivebolt stunning absolutely no evoked potentials could be registrated, whereas these potentials lasted for 77 seconds (somatosensorically evoked potentials) and 55 seconds respectively (visually evoked potentials) after the ritual slaughter cut. Thus, after ritual slaughter a nervous conduction was measured up to 126 seconds in the extreme cases. However, from the results obtained it can not be concluded whether or not pain sensitivity occurred in the animals.     

The effect of different slaughter methods on the post mortem glycolysis of muscle in lambs

Differences in muscular activity and rates of decline in the pH of the M. longissimus dorsi of lambs subjected to different methods of stunning and slaughter were observed. Lambs electrically stunned by a “head-to-leg” method had significantly lower initial pH values as compared to animals stunned by an electrical “head-only” method, or by captive bolt, or without any form of stunning prior to slaughter. When electrical stunning by a “head-to-leg” method was combined with low voltage (24V) electrical stimulation during slaughter and bleeding, mean pH values declined at the highest rate and fell to approximately 6.0 within two hours of slaughter. This last procedure, therefore, has the potential to greatly reduce times between slaughter and freezing without increasing the risk of cold shortening and the associated toughness of meat.     

Religious slaughter in Italy

This research aims to understand the prevalence of religious slaughter practices in Italy. Two different ways of slaughtering animals are identified. Conventional slaughter is performed with prior stunning; kosher slaughter is practiced without stunning. Halal slaughter is performed for most animals without stunning. Halal slaughter with prior stunning is acceptable for 5.90% of small ruminants. For Halal slaughter in Italy, the terms “religious slaughter with stunning” and “religious slaughter without stunning” should be used to differentiate religious slaughter practices, keeping animal welfare in perspective.

     

Slaughter methods: electroencephalographic (EEG) studies on spinal cord section, decapitation and gross trauma of the brain in lambs

By means of electroencephalograms (EEG), attempts were made to determine when insensibility could be presumed in five lambs, two subjected to immobilisation by the punctilla method, two decapitated and one shot by a captive bolt in the poll region. Section of approximately 80% of the spinal cord by the punctilla method had no apparent effect on sensibility and the technique was considered to be inhumane. The EEG obtained from a decapitated bead showed no obvious change in pattern for eight seconds and subsequent changes were similar to those associated with exsanguination only. Thus no evidence was obtained to indicate that decapitation causes immediate insensibility, neither was the belief substantiated that severance of the spinal cord, during the slaughter of sheep, hastens the onset of insensibility. These results also provide additional evidence on the inhumane nature of punctilla slaughter of cattle. The animal shot with a captive bolt in the poll region, as opposed to the frontal region, showed EEG activity for 78 seconds.     

Effect of electrical stunning current on the duration of insensibility in hens

1. Hens were subjected to electrical stunning at 85, 105 or 125 mA per bird. The time to recovery of physical behaviour was measured in those birds which did not experience a cardiac arrest at stunning.

2. On average the duration of apparent insensibility lasted between 53 and 59 s, and at 105 mA per bird it was as short as 22 s in the bird which showed the quickest recovery.

3. Increasing the stunning current had no effect on the duration of insensibility.     

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 PO2, PCO2, 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.     

Effects of electrical water bath stunning current frequencies on the spontaneous electroencephalogram and somatosensory evoked potentials in hens

1. The effectiveness of water bath electrical stunning of chickens with a constant root mean square (rms) current of 100 mA per bird delivered for 3 s using 100, 200, 400, 800 and 1500 Hz sine wave alternating current (AC) was investigated in layer hens. The quantitative changes occurring in the electroencephalogram (EEG) and somatosensory evoked potentials (SEPs) were used to determine the effectiveness of stunning. The changes occurring in the EEG were evaluated using Fast Fourier Transformations (FFT) and the SEPs were averaged to determine whether they were present or abolished. 2. The results of FFT indicated that stunning of chickens with a constant rms current of 100 mA per bird using 100 or 200 Hz induced epileptiform activity in all the hens, immediately followed by a reduction in the total (2 to 30 Hz) and relative (13 to 30 Hz) power contents in the EEG frequency bands indicative of unconsciousness and insensibility. The SEPs were abolished in the majority of hens stunned with 100 Hz and all the hens stunned with 200 Hz. 3. By contrast, stunning using 400, 800 or 1500 Hz failed to induce epileptiform activity in all the birds, the total and relative power contents in the EEG frequency bands showed a substantial increase, rather than reduction, and the SEPs were also retained in the majority of chickens. It is therefore suggested that stunning using these frequencies failed to stun them satisfactorily. In these birds, occurrence of a painful arousal, rather than unconsciousness, could not be ruled out. 4. It is therefore suggested that water bath electrical stunning of chickens with a minimum rms current of 100 mA per bird delivered using 100 or 200 Hz would be adequate to ensure bird welfare under commercial conditions, provided both the carotid arteries in the neck are severed at slaughter. On humanitarian and bird welfare grounds, a rms current of greater than 100 mA per bird should be applied whilst using frequencies of 400 Hz or more of sine wave AC for water bath electrical stunning of chickens.     

Cattle stunning with a penetrative captive bolt device: A review

The captive bolt device has been used for stunning cattle at abattoirs for more than 100 years and is now one of the stunning devices used most widely. The aim of this review article was to assess the effects that are decisive during cattle slaughter on the quality of stunning with the use of a captive bolt stunning device. The basis of effective stunning is the use of a suitable type of device, with the speed of the bolt and the kinetic energy corresponding to the anatomical parameters of the slaughtered animal. The importance of the regular cleaning and maintenance of stunning devices and monitoring of the effectiveness of stunning goes without saying. The immediate loss of sensibility in the animal must occur after the first shot. The effectiveness of the stunning process can be quantified by regular monitoring of the behavior of animals after stunning with an emphasis on the loss of reflexes (corneal reflex, regular breathing, attempts to regain physiological posture) and checks on the shot location on the skulls of slaughtered animals.     

Electroencephalographic studies of adult cattle associated with electrical stunning, throat cutting and carcass electro-immobilization

Twelve adult cattle were electrically stunned head-only (400 V, 2.5 A, 50 Hz) behind the ears for four seconds. Within ten seconds of stun initiation, the carotid arteries, jugular veins, trachea and oesophagus were severed. Twenty seconds after the stun initiation, ten animals received an electro-immobilization current (80 V peak, 14.3 Hz, 5 ms square wave, 300 mA) nose to anus for periods ranging from 30-37 seconds. Electroencephalographic (EEG) traces were recorded before and after the stun up until electroimmobilization and at cessation of electro-immobilization by means of implanted electrodes, and animal movement was recorded on videotape. Before the stun, the EEG trace was within a window of sensibility (10-40 microV amplitude). During the stun, the amplitude increased and sometimes exceeded 500 microV. At the end of electro-immobilization, EEG amplitude was less than 10 microV, indicating insensibility. This amplitude was reached in the two non-immobilized animals 57 seconds and 63 seconds after stun initiation. During stunning, the forelegs and hindlegs usually tucked under the animals. Various degrees of foreleg extension then occurred. From about ten seconds post-stun, paddling movements occurred, at which time the EEG trace showed large-amplitude waves characteristic of a stunned animal. During immobilization, the animals stiffened and breathing stopped. After immobilization weak muscle spasms occurred that did not interfere with dressing operations. Non-immobilized animals moved excessively, inhibiting dressing. It is concluded that adult cattle rendered insensible by stunning do not recover sensibility during the stun/throat-cut/immobilization operation and therefore this procedure is humane.     

Occurrences of thermophilic <Emphasis Type="Italic">Campylobacter</Emphasis> in cattle slaughtered at Morogoro municipal abattoir,Tanzania

An investigation was conducted in Morogoro municipality to assess the likelihood of slaughter cattle posing public health risk of contaminating carcasses with thermophilic Campylobacter. Butchers and meat shopkeepers were interviewed on source of slaughter cattle, method of animal and carcass transportation, carcass dressing, meat storage facilities, access to clean water and availability of food hygiene practices. Faecal samples were collected from 107 slaughter cattle and after slaughter; four different parts of dressed carcasses (i.e. from ham, neck, pelvis and thigh muscles) were also sampled. In addition 107 cattle meat samples for Campylobacter culture were collected in different meat shops. The samples were subjected to standard bacteriological examination using Skirrows protocol. It was found that cattle slaughter, dressing and meat handling in meatshops was done under unhygienic condition. Thermophilic Campylobacter prevalence in slaughter cattle was 5.6% while contamination rate of dressed carcasses and cattle meat at shops was 9.3% and 1.9%, respectively. The majority of thermophilic Campylobacter isolated were C. jejuni (88.9%) while C. coli was isolated at 11.1%. Findings of this study suggest possibility of humans acquiring zoonotic Campylobacter infections from cattle meat particularly when meat preparation and processing is not done properly. More work is required to establish the magnitude of zoonotic enteric Campylobacteriosis in humans and epidemiological role of cattle and other animals in the study area.     

A review of the criteria used to assess insensibility and death in hunted whales compared to other species

This review addresses the diagnosis of insensibility and death in various species so as to evaluate the validity of the current criteria used to judge death in hunted whales by the International Whaling Commission (IWC). The only other species in which official criteria of death have been formulated is humans and these are controversial with the kernel of the debate being the definition of brain death. In slaughter animals, the moment of insensibility is regarded as the most important criterion and the issue has received scientific interest related to the pre-slaughter stunning. During hunting of terrestrial wildlife, the moment of death is usually regarded as the moment the animal falls and does not move. Based on the data presented in the present paper, it is concluded that when death in whales is solely determined on the basis of the IWC criteria, which in practice are based on immobility, a significant proportion of animals will be recorded as being sensible and alive when they are actually unconscious and the time to death (TTD) will be overestimated. If the criteria are used in conjunction with a postmortem examination, the recorded TTD will be closer to the real TTD and can be used for comparison of methods and performance.     

Return-to-sensibility problems after penetrating captive bolt stunning of cattle in commercial beef slaughter plants

OBJECTIVE: To evaluate efficacy of penetrating captive bolt stunning of cattle in commercial beef slaughter plants and identify potential causes of a return to sensibility among stunned cattle. DESIGN: Observational study. SAMPLE POPULATION: 21 federally inspected commercial beef slaughter plants. PROCEDURE: In each plant, stunning of at least 100 cattle (19 large plants) or a minimum of 1 hour of production (2 small plants) was observed, and cattle were evaluated for signs of returning to sensibility on the bleed rail. Cattle with a limp, flaccid head, a lack of spontaneous blinking, and an absence of a righting reflex were considered insensible. RESULTS: In 17 of the 21 (81%) plants, all cattle were rendered insensible before they were hoisted onto the bleed rail. The remaining 4 plants had cattle that had signs of returning to sensibility; these cattle were restunned prior to skinning or leg removal. Of 1,826 fed steers and heifers, 3 (0.16%) had signs of returning to sensibility, whereas 8 of 692 (1.2%) bulls and cows did. Return-to-sensibility problems were attributed to storage of stunner cartridges in damp locations, poor maintenance of firing pins, inexperience of the stunner operator (ie, shooting cattle too high on the forehead), misfiring of the stunner because of a dirty trigger, and stunning of cattle with thick, heavy skulls. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that efficiency of captive bolt stunning of cattle in commercial slaughter plants can be safely and objectively assessed. Care should be taken to maintain stunners correctly, particularly when stunning bulls and cows with heavy skulls.     

Assessment of cattle welfare at a commercial slaughter plant in the northwest of Mexico

Slaughter plants have been undergoing radical transformations in recent years due to the need to increase efficiency and incorporate new technologies for the improvement of the infrastructure, animal welfare, and product quality. The aim of this study was to assess the cattle welfare status during the unloading, lairage, stunning, bleeding and quantify bruising incidence at a commercial slaughter plant in the northwest of Mexico. We monitored 8,118 cattle during the unloading, lairage, stunning, bleeding, and carcass bruise incidence. Our results showed that in the unloading stage, 2% of the cattle vocalized, 5% were prodded with an electric goad, and 4% either slipped or fell. In the lairage stage, 12% of the animals vocalized, 80% prodded with an electric goad, and 8% of the animals slipped or fell. In the stunning stage, 10% of the animals vocalized, 67% prodded with an electric goad, and 15% of the animals slipped or fell. Ninety-five percent of the animals were stunned with a single shot, and 51% of the animals were effectively desensitized. Ninety-two percent of the carcasses had some type of bruise. Although the slaughter plant had adequate infrastructure and stringent operational standards, in all of the stages except unloading handling had an impact on the welfare of the animals being slaughtered.