Consciousness, unconsciousness and death in the context of slaughter. Part I. Neurobiological mechanisms underlying stunning and killing

The use of a penetrative captive bolt device during the killing of farmed saltwater crocodiles (Crocodylus porosus)

Killing of farmed saltwater crocodiles involve stunning with a penetrative captive bolt device, followed by a cut across the nape of the neck and physical destruction of the brain to ensure death. This study was a welfare-based assessment of the use of a penetrative captive bolt device in saltwater crocodiles, to determine whether it satisfies the criteria of a humane stunning method and can be regarded as a direct killing method without the need for the application of an adjunct method. Methods used were electroencephalogram (EEG), observation of post-stun behavior, and postmortem examination of gross pathology of the cranium and brain. 30 of 30 animals, demonstrated immediate and irreversible loss of consciousness. There was extensive damage to the brain in all animals, deemed to be inconsistent with cortical function and possible recovery. The CASH Special 0.22 penetrative captive bolt pistol (1.25 grain cartridge), applied to the top of the cranial plate, produced immediate and irreversible unconsciousness in all the animals studied. This method satisfies animal welfare expectations, providing crocodile processors with a technique that contributes to a humane killing process.

Movements after Captive Bolt Stunning in Cattle and Possible Animal- and Process-Related Impact Factors-A Field Study

Movements in cattle after captive bolt stunning cause problems in the slaughter process and lead to uncertainties in assessing stunning effectiveness. The objective of this study was to categorize and quantify these movements and determine animal- and process-related impact factors, as well as connections to stunning effectiveness and shooting position. In total 2911 cows, heifers, and bulls (dairy, beef, and crossbreeds) were examined (mean age 3.02 years). Movements from landing until at least four minutes after sticking were recorded by action cams (Apeman® A100). Nine movement categories were defined ("kicking hind limb", "twitching", "bending and stretching hind limb", "lifting and bending forelimb", "body arching laterally", "body arching ventrally", and "arching backwards"). According to the movement severity, a score was assigned to each category. The scores were summed, either for certain process intervals, e.g., LANDING (ejection from the stunning box), HOISTING, or STICKING, or for the total time between LANDING and end of the FOURTH MINUTE OF BLEEDING (sum score). Statistical analysis (ANOVA) was performed on the scores. Only 6.6% of cattle showed no movement. Most movements occurred during STICKING and FIRST MINUTE OF BLEEDING, occurring rarely up to 8 min after sticking. While cows moved most at LANDING, bulls and heifers moved more if all process intervals were considered. The sum score was highest in German Angus, Charolais, and Limousin and lowest in Brown Swiss and Simmental. The score at LANDING was highest in German Angus and Black Holstein. The use of pneumatic stunners and an increase in bolt-exit length significantly reduced movements. No impact of stunning effectiveness on movements was found, but only 19 cattle showed reduced effectiveness.

The significance of shooting angle in seal shooting

The present study aimed to investigate the relationship between shooting angle to the head and animal welfare outcomes in the hunt of young harp seals (Pagophilus groenlandicus). The study population consisted of young harp seals belonging to the Greenland Sea harp seal population. A sample of 171, 2-7 weeks old, weaned harp seals of both sexes were included. The study was conducted as an open, randomised parallel group designed trial during the regular hunt. The animals were allocated into four groups, A-D, according to the observed shooting angle to the head, defined as the angle between the direction of the shot and the longitudinal axis of the animal's head: (A) directly from the front; (B) obliquely from the front; (C) directly from the side; and (D) obliquely or directly from behind. Instantaneous death rate (IDR) and time to death (TTD) were the main variables. The mean IDR differed significantly between groups and was highest in group B (96.8%) and lowest in group C (66.7%). For all groups combined it was 84.2%. The mean TTD for seals not rendered instantaneously unconscious or dead (n = 27) differed significantly between groups and was shortest in group A (16 s) and longest in group C (85 s). However, the number of animals included in the TTD analysis was limited. In conclusion, based on the significantly higher IDR, the shooting angle obliquely from the front is recommended to help achieve the best animal welfare outcomes during the hunt of young harp seals.

Evaluation of the capacity and effective angle of thalamic damage for 2 commercially available captive bolt tool types on cadaver heads from sows >200 kg body weight

This study evaluated the ability of 2 penetrating captive bolt (PCB) types (PISTOL, INLINE) to reach and disrupt the thalamus when applied in 2 placements (FRONTAL, BEHIND EAR) to chilled cadaver heads (N = 60) from sows >200 kg. Heads were randomly distributed across 6 treatments (n = 10): FRONTAL-INLINE, FRONTAL-PISTOL, FRONTAL-NO SHOT, BEHIND EAR-INLINE, BEHIND EAR-PISTOL, and BEHIND EAR-NO SHOT. The FRONTAL shot was placed 3.5 cm superior to the optic orbits at the midline; the BEHIND EAR shot was placed directly caudal to the pinna of the ear on the same plane as the eyes and targeting the middle of the opposite eye. For INLINE treatments, a Jarvis PAS-Type C 0.25R Super Heavy Duty PCB with a Long Bolt and 6.0 GR power loads was used. For PISTOL treatments, a Jarvis PAS-Type P 0.25R Pistol PCB with a Long Stunning Rod Nosepiece Assembly and 3.5 GR power loads was used. Heads were split along the bolt with a band saw. Tissue depth measurements are reported as Mean ± SE followed by 97.5% one-sided upper reference limit (URL). Total tissue thickness was less (P < 0.0001) at the FRONTAL (56.31 ± 1.76 mm; URL: 73.17 mm) than the BEHIND EAR placement (95.52 ± 3.30 mm; URL: 126.53 mm). Thalamic depth was less (P < 0.0001) at the FRONTAL (78.31 ± 1.32 mm; URL: 88.19 mm) than the BEHIND EAR placement (111.86 ± 3.22 mm; URL: 135.99 mm). The effective angle was greater (P < 0.0001) at the FRONTAL (4.72 ± 0.20°) than the BEHIND EAR placement (3.22 ± 0.17°). Potential for bolt-brain contact was not different (P = 1.0000) between FRONTAL-INLINE (10/10, 100% ± 0.01%), FRONTAL-PISTOL (10/10, 100% ± 0.01%), BEHIND EAR-INLINE (9/10, 90% ± 9.49%), and BEHIND EAR-PISTOL (10/10, 100% ± 0.01%); brain damage (P = 0.5577) between FRONTAL-INLINE (9/9, 100% ± 0.02%), FRONTAL-PISTOL (10/10, 100% ± 0.02%), BEHIND EAR-INLINE (4/10, 40% ± 15.49%), and BEHIND EAR-PISTOL (1/10, 10% ± 9.49%); potential for bolt-thalamus contact (P = 0.0683) for FRONTAL-INLINE (2/10, 20% ± 12.65%), FRONTAL-PISTOL (8/10, 80% ± 12.65%), BEHIND EAR-INLINE (7/9, 77.78% ± 13.86%), and BEHIND EAR-PISTOL (9/9, 100% ± 0.02%); or thalamic damage (P = 0.8041) for FRONTAL-INLINE (1/10, 10% ± 9.49%), FRONTAL-PISTOL (1/10, 10% ± 9.49%), BEHIND EAR-INLINE (2/8, 25% ± 15.31%), and BEHIND EAR-PISTOL (0/9, 0% ± 0.00%). The FRONTAL placement with an INLINE PCB may present the least risk of failure for the PCB euthanasia of mature sows >200 kg body weight due to less total tissue thickness and thalamic depth, greater effective angle, and prevalent brain damage.

Relationship of tissue dimensions and three captive bolt application sites on cadaver heads from mature swine (Sus scrofa domesticus) <200 kg body weight

Penetrating captive bolt (PCB) is a common method of euthanasia for swine but has not been evaluated for mature swine < 200 kg body weight (BW). The objectives were to determine tissue depth, brain contact plane, and visible brain tissue damage (brain damage[BD]) for the common FRONTAL (F) and alternative TEMPORAL (T) and BEHIND EAR (BE) placements for PCB use on sows and boars weighing < 200 kg. Cadaver heads were obtained from 30 sows and 30 boars (estimated BW, mean ± SD; sows: 165.8 ± 22.4 kg; boars: 173.6 ± 21.4 kg) from a slaughter establishment after electrical stunning and exsanguination. Heads were cooled at 2 to 4 °C for approximately 64 h. A Jarvis PAS-Type P 0.25R PCB with a Long Stunning Rod Nosepiece Assembly and a 3.5 GR power load was used for all PCB applications at the following placements: F-3.5 cm superior to the optic orbits at midline, T-at the depression posterior to the lateral canthus of the eye within the plane between the lateral canthus and the base of the ear, or BE-directly caudal to the pinna of the ear on the same plane as the eyes and targeting the middle of the opposite eye. For sows, the bolt path was in the brain for 10/10 (100.0%, 95% CI: 69.2% to 100.0%) F, T, and BE heads. In heads that could reliably be assessed for BD, BD was detected in 10/10 (100.0%, 95% CI: 69.2% to 100.0%) F heads, 9/9 (100.0%, 95% CI: 66.4% to 100.0%) T heads, and 0/10 (0.0%, 95% CI: 0.0% to 30.1%) BE heads. For boars, the bolt path was in the plane of the brain for 8/9 (88.9%, 95% CI: 51.8% to 99.7%) F heads, 9/10 (90.0%, 95% CI: 55.5% to 99.7%) T heads, and 11/11 (100.0%, 95% CI: 71.5% to 100.0%) BE heads. In heads that could reliably be assessed for BD, BD was detected in 8/9 (88.9%, 95% CI: 51.7% to 99.7%) F heads, 7/10 (70.0%, 95% CI: 34.8% to 93.3%) T heads, and 4/11 (36.4%, 95% CI: 10.9% to 69.2%) BE heads. Tissue depth was reported as mean ± SE followed by 95% one-sided upper reference limit (URL). For sows, total tissue thickness differed (P < 0.05) between placements (F: 49.41 ± 2.74 mm, URL: 70.0 mm; T: 62.83 ± 1.83 mm, URL: 76.6 mm; BE: 84.63 ± 3.67 mm; URL: 112.3 mm). Total tissue thickness differed (P < 0.05) between placements for boars (F: 54.73 ± 3.23 mm, URL: 77.6 mm; T: 70.72 ± 3.60 mm, URL: 96.3 mm; BE: 92.81 ± 5.50 mm; URL: 135.3 mm). For swine between 120 and 200 kg BW, the F placement may have the greatest likelihood for successful euthanasia due to the least total tissue thickness and may present less risk for failure than the T and BE placements.

Towards the use of on-farm slaughterhouse

Slaughter on the farm can address the concerns of farmers by meeting the needs of short distribution channels while better preserving animal welfare and meat quality. It can support conventional slaughter, by compensating for the significant decrease in the number of slaughterhouses in recent decades. The review describes first the different stages of slaughter and their possible impacts on animals' stress, welfare and consequences on their meat quality. The second part takes stock of recent thinking on the subject of slaughter and the regulation and technological advances that have led to the development of mobile slaughter units. A non-exhaustive list of mobile slaughter units currently in use in different countries is presented. Although these units can only absorb a small percentage of the total amounts of animals slaughtered, they are a welcome alternative to current slaughter practices for certain types of production and distribution, provided that the animal welfare and all aspects of meat quality are garanteed.

Farmed fish welfare during slaughter in Italy: survey on stunning and killing methods and indicators of unconsciousness

Information on slaughter procedures for farmed fish in aquaculture is limited, both in Europe and in Italy, due to a general lack of field data. The aim of this study was to gather information on the procedures used to slaughter fish in Italy and to discuss them considering the WOAH and EFSA recommendations on fish welfare. Using a questionnaire survey, data were collected by official veterinarians in 64 slaughtering facilities where 20 different species of fish were slaughtered. The main species slaughtered were rainbow trout (Oncorhynchus mykiss; 29/64), followed by European sea bass (Dicentrarchus labrax; 21/64), sea bream (Sparus aurata; 21/64), Arctic char (Salvelinus alpinus; 14/64), European eel (Anguilla anguilla; 11/64), sturgeon (Acipenser spp; 11/64), common carp (Cyprinus carpio; 6/64), and brown trout (Salmo trutta fario L.; 5/64). The most applied stunning/killing methods were "asphyxia in ice/thermal shock" and "electric in water bath," followed by "percussion," "asphyxia in air," and "electric dry system." After the application of the method, the assessment of the fish level of unconsciousness was practiced in 72% of the facilities using more than one indicator, with "breathing" and "coordinated movements" the most practiced. The collected data showed a discrepancy between the available recommendations about the welfare of fish at slaughter and what is practiced in many production sites, but for many species precise recommendations are still not available.

Stunning Compliance in Halal Slaughter: A Review of Current Scientific Knowledge

Muslim scholars are not unanimous on the issue of the application of stunning in the halal slaughtering of animals. Appropriate stunning makes animals unconscious instantaneously, thus avoiding unnecessary pain and stress during the slaughtering of animals. The present review comprehensively summarizes the available scientific literature on stunning methods in view of their halal compliance during the slaughter of animals. The issue of maximum blood loss, reversibility of consciousness, and animals remaining alive during the halal cut are the key determinants of approval of stunning in the halal slaughter. Further, missed stuns due to poor maintenance of equipment, improper applications, and poor restraining necessitates additional stunning attempts, which further aggravates pain and stress in animals. Scientific findings suggest that halal-compliant stunning technologies are reversible, do not kill animals prior to the halal cut, and do not obstruct blood loss. There is a need to carry out further research on the refinement of available stunning technologies and their application, proper restraints, proper identification of the death status of animals, and assurance of animal welfare in commercial halal meat production.

Slaughtering of Water Buffalo (Bubalus bubalis) with and without Stunning: A Focus on the Neurobiology of Pain, Hyperalgesia, and Sensitization

The slaughter process in livestock is considered a stressor where the transport and handling of animals, as well as the selected stunning and bleeding methods, can cause acute pain, distress, and suffering. In water buffaloes, although stunning is known to be performed before bleeding to induce unconsciousness, no emphasis is made on the nociceptive events during this process. Particularly, current mechanical stunning methods applied to cattle are unsuitable for water buffaloes due to anatomical differences in the skull from other large ruminants. Furthermore, although very high-pressure pneumatic (200-220 psi) may be effective in the frontal position for lighter-weight water buffalos, for heavier animals, it is less likely to be effective. The present review aims: (1) to analyze the anatomical particularities of water buffaloes to discuss the importance of selecting a stunning method suitable for buffaloes, and (2) to revise the potential pain-related consequences, such as hyperalgesia and sensitization, and the signs to assess the stun quality and death to comprehend the relevance of a proper technique according to the species.

CO2 Stunning in Pigs: Physiological Deviations at Onset of Excitatory Behaviour

Stunning by carbon dioxide (CO₂) inhalation is controversial because it is associated with vigorous movements and behaviours which may or may not be conscious reactions. Furthermore, it is unknown whether some behaviours might indicate the transition into unconsciousness. Our study objective was to investigate the loss of consciousness during CO₂ stunning by linking physiological variables (in particular pH, PaO₂ and PaCO₂) to the onset of observed behaviours. A total of 11 cross-bred pigs were studied. A tracheostomy tube, venous and arterial cannulae were placed under sevoflurane anaesthesia. After recovery from this, and a "wash out" period of at least 30 min, arterial blood samples were taken (and baseline values established) before 90-95% CO₂ in medical air was administered through the tracheostomy tube. Subsequent behaviours were video-recorded and key physiological variables were evaluated using an anaesthetic monitor and the frequent sampling of arterial blood (albeit with inconsistent inter-sample intervals). After the study, behaviours were classified in an ethogram. At the onset of behaviours categorised as "vigorous movement extremities", "opisthotonos" and "agonal gasping" pH values (range) were: 6.74-7.34; 6.66-6.96 and 6.65-6.87, while PaCO₂ (kPa) was 4.6-42.2, 24.4-51.4 and 29.1-47.6. Based upon these values, we conclude that the pigs were probably unconscious at the onset of "opisthotonos" and "agonal gasping", but some were probably conscious at the onset of "vigorous movements".

The Feasibility of Animal-Based Indicators of Consciousness and Unconsciousness for Stunning in Sheep: A Systematic Review

BACKGROUND

According to EU legislation, animal-based indicators (ABMs) are used to evaluate the efficacy of stunning methods to ensure that animals do not regain consciousness. EFSA has provided a list of ABMs for electrical and mechanical stunning in sheep; however, there is still a lack of information on their feasibility. We aimed to identify and evaluate the feasibility constraints of ABMs commonly applied in slaughterhouses to assess proper stunning in sheep.

METHOD

For this systematic review, we searched the Scopus and Web of Science databases from 2000 to 8 August 2022, including full peer-reviewed papers written in English on the welfare of sheep at the stunning and restraint phases. We excluded studies using a gas stunning method or without prior stunning, as well as manuscripts in which indicators were applied after sticking.

RESULTS

Of 1289 records identified, only 8 papers were eligible for the critical evaluation of physical aspects that affect the feasibility of ABMs. These aspects were defined as a given definition of the feasibility of ABMs, and information was summarized and critically evaluated. The results highlighted a lack of information on the feasibility of ABMs which should be considered in the various conditions of commercial slaughterhouses.

Highly Effective Frontal Stunning Procedure Using a Pneumatic Penetrating Captive Bolt in Water Buffaloes

An effective frontal stunning procedure in water buffaloes was assessed using a pneumatic penetrating captive bolt (PPCB) with high air pressure. The study contemplated two phases; first, 352 buffaloes and 168 post-mortem heads were evaluated to determine the most effective anatomical site for stunning. Then, the second phase (n = 182) was used to validate the stunning procedure at the discovered anatomical site in the first phase, which was located 8 cm dorsal above the middle of the forehead on an "X" formed between the eyes and the base of the contralateral horns, and 2 cm lateral, avoiding the midline, where the skull tended to narrow. A total of 95.1% of buffaloes received effective stunning at the first shot with evidence of the presence of collapse, absence of rhythmic breathing, and absence of ocular reflexes (corneal and palpebral). There were no differences in the stunning efficacy by sex, breed, or skull thickness. These findings demonstrated that stunning with a PPCB at pressures of 1379-1516.8 KPa (200-220 pounds per square inch (psi)) in the site reported here produces a highly effective stunning at the first shot in water buffaloes.

Animal Welfare Compromises Associated with Causes of Death in Neonatal Piglets

Simple Summary

The pre-weaning piglet mortality percentage is a commonly reported metric on commercial pig farms. The mortality percentage tells us how many piglets died, but not what their welfare status was as it relates to their cause of death. This pilot study aimed to evaluate the likely experience of piglets that died, following confirmation of the cause of death via postmortem investigation. The Five Domains Model was then used to collate scientific evidence of the likely experience of these piglets before death from acute disease, starvation, crushing, savaging and euthanasia, to understand the impact of different causes on their welfare. The resulting findings raised the question of differentiating ‘smothering’ as a cause of death from ‘crushing,’, and that co-morbidities (such as hypothermia) may alter the welfare experience due to their influence on consciousness before death.

Abstract

This pilot study aimed to assess the welfare impacts of different causes of pre-weaning deaths in piglets. Piglets that died between 0–7 days after birth (n = 106) were collected from two commercial pig farms and subject to post-mortem examination to confirm their cause of death as well as any contributing factors. Using the Five Domains Model, the most likely affective experiences associated with the pathological findings were carefully inferred to better understand affective experience as it related to known causes of liveborn piglet mortality. The most common causes of liveborn piglet mortality were starvation (23%), crushing (23%) and non-viable (21%). Thirty one piglets had evidence of starvation, but it was only considered the primary cause of death in 15 piglets, as cofactors such as poor viability (n = 13) were also present in many piglets with evidence of starvation. All 15 piglets that were crushed died within 24 h after birth and most had evidence of thoracic and/or abdominal internal bleeding. This study found that common causes of liveborn piglet death were associated with compromises in Domains 1 (Nutrition/hydration), 3 (Health/function), and4 (Behavioural interactions), with the most likely resulting affective states described in Domain 5 (Mental state). This highlights the interaction between physical/functional and situation-related (behavioural) aspects that influence an animals’ welfare status.

Application of Electroencephalography in Preslaughter Management: A Review

Electroencephalography (EEG) can be reliable for assessing the brain's electrical activity of preslaughter stress and pain. The duration between the ventral neck cut and induction of a state of unconsciousness/insensibility is crucial in the slaughtering of animals, reducing pain, fear, and distress. Various EEG variables, such as median frequency (F50), the total power of EEG spectrum (Ptot), waves patterns (amplitude and frequencies), epileptiform EEG, index of consciousness, and isoelectric EEG, are used to identify a valid indicator of the state of unconsciousness. Association among various behavioral, physiological, and hematological parameters with EEG variables could provide an overall assessment and deep insights into the animal stress levels or welfare status during various managemental and preslaughter operations, such as transport, stunning, and slaughtering operations. The application of EEG could help in further refining the stunning technologies and slaughter protocols in livestock, poultry, and fish. The present review analyzed the application of EEG as a neurophysiological tool for assessing animal welfare during the critical state of preslaughter handling and slaughter, thus ensuring proper compliance with animal welfare principles.

The Welfare of Fighting Dogs: Wounds, Neurobiology of Pain, Legal Aspects and the Potential Role of the Veterinary Profession

Simple Summary

Dog fights are cruel and harmful events which have a clear impact on animal welfare. For this reason, many countries have banned these events via statute. However, in some regions of the world they are still legal. Moreover, the enforcement of legal bans can be problematic in countries where they are illegal, and they may still occur. This article provides background information on dog fighting and the welfare implications of it. This includes consideration for the pain inflicted, and its mechanisms of perception and recognition. It also analyzes the injuries and emotions experienced by the animals and considers the profile of the breeders and handlers involved in the activity. Since welfare concerns often extend beyond the animals’ fighting lives, a discussion around the possibilities of reintroduction into suitable environments for these animals is also made. Finally, attention is turned to the role that veterinarians can and should play in dealing with these issues of welfare.

Abstract

Throughout history it has been common to practice activities which significantly impact on animal welfare. Animal fighting, including dogfighting, is a prime example where animals often require veterinary care, either to treat wounds and fractures or to manage pain associated with tissue and where death may even result. Amongst the detrimental health effects arising are the sensory alterations that these injuries cause, which not only include acute or chronic pain but can also trigger a greater sensitivity to other harmful (hyperalgesia) or even innocuous stimuli (allodynia). These neurobiological aspects are often ignored and the erroneous assumption made that the breeds engaged in organized fighting have a high pain threshold or, at least, they present reduced or delayed responses to painful stimuli. However, it is now widely recognized that the damage these dogs suffer is not only physical but psychological, emotional, and sensory. Due to the impact fighting has on canine welfare, it is necessary to propose solution strategies, especially educational ones, i.e., educating people and training veterinarians, the latter potentially playing a key role in alerting people to all dog welfare issues. Therefore, the aim of this review is to describe the risk factors associated with dogfighting generally (dog temperament, age, sex, nutrition, testosterone levels, environment, isolation conditions, socialization, education, or training). A neurobiological approach to this topic is taken to discuss the impact on dog pain and emotion. Finally, a general discussion of the format of guidelines and laws that seek to sanction them is presented. The role that veterinarians can play in advancing dog welfare, rehabilitating dogs, and educating the public is also considered.

Quantification of the Effects of Electrical and CO2 Stunning on Selected Quality Attributes of Fresh Pork: A Meta-Analysis

Stunning is a statutory pre-slaughter process that may affect the quality of pork. The objective of this study was quantification of the effects of stunning (ES vs. CO2 stunning) on selected quality attributes of pork, using a meta-analytical approach. Data from 18 publications with 46 individual experiments were combined using a random-effect model to estimate the effect size of stunning on the initial and ultimate pH (pH1, pHu); drip loss (DL); colour (lightness—L*, redness—a*, yellowness—b*); and tenderness (expressed as Warner–Bratzler shear force, WBSF) of pork. In overall, loins from ES showed significantly lower pH1 (by 0.08 units); greater DL (by 0.68 p.p.); higher L* (by 1.29 units); and a* (by 0.80 units) as they compared to those from CO2 stunning. In subgroups, a greater-than-overall negative change in pH1, pHu, DL, L* and a* was detected with the application of the head-to-back (HB) stunning method. Additionally, alterations in DL and L* may be magnified with the application of conventional chilling (Conv.) to ES pigs. There was no effect of stunning on WBSF but, due to a low number of research in the database, the reliability of these results may be misleading. These results provide evidence that the differences between these two stunning methods in DL and L* may be diminished by the application of the head-only (HO) or head-to-body (HBO) method, followed by the fast chilling of carcasses.

Inter-Observer Repeatability of Indicators of Consciousness after Waterbath Stunning in Broiler Chickens

Simple Summary

Waterbath stunning is intended to induce unconsciousness until death occurs due to bleeding in poultry. However, it is not always effective. For this reason, in order to protect their welfare, it is mandatory in the European Union that the state of consciousness of broiler chickens is monitored at the exit of the waterbath, and that they do not regain consciousness before death. Ineffectively stunned birds can be re-stunned using back-up methods to avoid unnecessary pain, stress and suffering. One of the main challenges in monitoring the state of consciousness in broiler chickens after waterbath stunning is the selection of animal-based indicators ensuring consistency among assessments. The indicators should be valid, feasible and repeatable. However, only the validity and feasibility have been reported. Thus, the main goal of this research was to assess the repeatability of the most valid and feasible indicators of the state of consciousness after waterbath stunning in broilers both before bleeding (tonic seizure, breathing, spontaneous blinking and vocalization) and during bleeding (wing flapping, breathing, spontaneous swallowing and head shaking). This study proposes a refined list of indicators that could be used to assess the consciousness of broiler chickens in commercial slaughterhouses.

Abstract

This study evaluated the prevalence and tested the inter-observer repeatability of the most valid and feasible animal-based indicators of the state of consciousness after waterbath stunning in broilers before bleeding (tonic seizure, breathing, spontaneous blinking and vocalization) and during bleeding (wing flapping, breathing, spontaneous swallowing and head shaking). In addition, correlations among them were computed to better understand their relationship and offer insights into the reliability of such indicators. This was aimed at proposing a refined list of indicators that could be used in commercial slaughterhouses to ensure consistent assessments. This study compared the assessments of three observers of 5241 broilers from 19 batches in six different slaughterhouses. Inter-observer repeatability was assessed through the combination of the crude percentage of agreement and the Fleiss’ kappa coefficient and interpretation. Before bleeding, the results led us to recommend assessing breathing over spontaneous blinking and vocalizations and to neglect tonic seizure in commercial conditions. During bleeding, the recommended indicators are breathing, wing flapping and head shaking while spontaneous swallowing can be neglected.

Evaluation of mechanical cervical dislocation, captive bolt, carbon dioxide, and electrical methods for individual on-farm euthanasia of broiler breeders

Efficacious euthanasia by applying manual cervical dislocation can be difficult on large and mature poultry. The challenge with using manual cervical dislocation is that the strength required to hold heavy poultry and swiftly apply cervical dislocation can be physically impossible for most people. Therefore, alternative methods of euthanasia are needed for mature and large poultry. Mechanical cervical dislocation using the Koechner Euthanizing Device (KED), captive bolt using the Turkey Euthanasia Device (TED), carbon dioxide (CO₂), and electrical euthanasia were evaluated for use on 65-wk-old broiler breeders at flock termination. Following application of each method, physiological reflexes including the eye nictitating membrane reflex, mouth gaping, and body movement, broken skin, blood loss, kill success, time to cessation of heartbeat, and blood plasma corticosterone levels were assessed. Birds euthanized using the KED had longer response durations for eye nictitating membrane (91 s) and reflexive mouth gaping (161 s) compared to TED, CO₂, and electrical euthanasia (0–7 s). Body movement durations were also longer for KED (214 s) and TED (209 s) than for CO₂ and electrical euthanasia (0–8 s). The highest percentages of broken skin (93%) and blood loss (96%) were observed for TED, followed by KED (71%, 68%), then CO₂ (0%, 6%) and electrical euthanasia (0%, 3%). No significant differences (P = 0.1781) were observed for kill success rates with 98% for KED, 100% for TED, 97% for CO₂, and 100% for electrical euthanasia at 4-min. Time to heartbeat cessation did not differ between KED (659 s), TED (427 s), or CO₂ (583 s) euthanasia methods. No heartbeat was detected following electrical euthanasia. Blood plasma corticosterone levels did not differ between preeuthanasia or posteuthanasia from any of the methods applied. Based on these results each euthanasia method is acceptable for use with broiler breeders.

Reduction of the occurrence of incorrect stunning and the occurrence of reflexes and reactions in cattle after pneumatically powered captive-bolt stunning in comparison with cartridge-fired captive-bolt stunning

In this study, the occurrence of repeat stunning, deviations in placement and direction of stun shots, and the occurrence of reflexes/reactions following stunning with a pneumatically powered captive-bolt stunner in comparison with a cartridge-fired captive-bolt stunner in cattle were assessed. Repeat stunning and deviations in placement and direction of the stun shots were less frequent (p < 0.01) with the use of a pneumatic stunner in all cattle. The rate of repeat stunning and deviation from the ideal place and direction of stun shots were lower (5.81%, 24.75%, and 9.60% of all animals, respectively) when a pneumatic stunner was used in comparison with cartridge-fired captive bolt (18.32%, 34.03%, and 47.38% of all animals, respectively). The stunning quality was assessed on the basis of evaluation of signs observed following the stun shot. A pneumatic stunning resulted in a significant reduction of occurrence of signs particularly in bulls in comparison to cows, for which a cartridge-fired stunner already provides an adequate stunning. Our study provides evidence that pneumatic stunning has the potential to be a more effective method than cartridge-fired stunning from the viewpoint of the welfare of slaughtered animals. Pneumatic stunning ensures a high quality of stunning in both bulls and cows.

ELECTRONARCOSIS PROTOCOLS IN BROILER CHICKENS FOR THE HALAL MARKET

This study considered the parameters of the Halal market to evaluate different protocols for broiler electronarcosis regarding time to return of consciousness, bleeding efficiency, and carcass and meat quality. Was performed an experiment in a broiler slaughterhouse. One hundred and eighty-four 43 days old male broilers of the Cobb® strain were used. The experimental design used was completely randomized with 46 broilers for each protocol. The protocols used: 80 v and 600 Hz; 50 v and 1,000 Hz; 60 v and 1,000 Hz; 70 v and 1,000 Hz. Time to return of consciousness, bleeding efficiency, bruising, presence of broken bones in pectoral muscle, and meat quality were evaluated. Birds subjected to stunning by the 50 v / 1,000 Hz protocol showed the shortest time to return of consciousness after electronarcosis, and high incidence of breast hemorrhage. Birds subjected to the 60 v / 1,000 Hz protocol had a higher percentage of broken bones in the Pectoralis minor. The 50 v and 1,000 Hz electronarcosis protocol fits better to the halal market due to the shorter time to return of consciousness and improved bleeding efficiency. This study suggests new proposals for stunning protocols to serve the halal market.

Quality of Death in Fighting Bulls during Bullfights: Neurobiology and Physiological Responses

During bullfights, bulls undergo physiometabolic responses such as glycolysis, anaerobic reactions, cellular oedema, splenic contraction, and hypovolemic shock. The objective of this review article is to present the current knowledge on the factors that cause stress in fighting bulls during bullfights, including their dying process, by discussing the neurobiology and their physiological responses. The literature shows that biochemical imbalances occur during bullfights, including hypercalcaemia, hypermagnesaemia, hyperphosphataemia, hyperlactataemia, and hyperglycaemia, associated with increased endogenous cortisol and catecholamine levels. Creatine kinase, citrate synthase, and lactate dehydrogenase levels also increase, coupled with decreases in pH, blood bicarbonate levels, excess base, partial oxygen pressure, and oxygen saturation. The intense exercise also causes a marked decrease of glycogen in type I and II muscle fibres that can produce myoglobinuria and muscular necrosis. Other observations suggest the presence of osteochondrosis. The existing information allows us to conclude that during bullfights, bulls face energy and metabolic demands due to the high intensity and duration of the exercise performed, together with muscular injuries, physiological changes, and high enzyme concentrations. In addition, the final stage of the bullfight causes a slow dying process for an animal that is sentient and conscious of its surroundings.

Vertebrobasilar Contribution to Cerebral Arterial System of Dromedary Camels (Camelus dromedarius)

It is hypothesized that in the “more highly evolved” mammals, including the domesticated mammals, that the brainstem and the cerebellum receive arterial blood through the vertebrobasilar system whilst the internal carotid arteries primarily supply the forebrain. In camels, the arterial blood supply to the brain differs from that of ruminants since the internal carotid artery and the rostral epidural rete mirabile (RERM) are both present and the basilar artery contributes a significant proportion of cerebral afferent blood. In this study, we described the anatomical distribution of the vertebrobasilar system arterial supply in the dromedary. Secondly, we determined the direction of blood flow within the vertebral and basilar arteries using transcranial color doppler ultrasonography. Thirdly, we quantified the percentage arterial contributions of the carotid and vertebrobasilar systems to the dromedary brain. Fifty-five heads of freshly slaughtered male Omani dromedaries aged 2–6 years were dissected to determine the distribution and topography of the arterial distribution to the brain. Their anatomical orientation was assessed by casting techniques using epoxy resin, polyurethane resin and latex neoprene. The epoxy resin and polyurethane resin casts of the head and neck arteries were used to measure the diameter of vertebrobasilar arterial system and carotid arterial system at pre-determined locations. These arterial diameters were used to calculate the percentage of blood supplied by each arterial system. The vertebrobasilar system in dromedary camels consists of paired vertebral arteries that contribute to the ventral spinal artery and basilar artery at multiple locations. In most specimens the vertebral artery was the primary contributor to the basilar artery compared to that of the ventral spinal artery. In four specimens the ventral spinal arteries appear to be the dominant contributor to the basilar artery. Transcranial color doppler ultrasonography confirmed that the direction of blood flow within the vertebral and basilar arteries was toward the brain in animals examined in ventral recumbency and when standing. The vertebrobasilar system contributes 34% of the blood supply to the brain. The vertebrobasilar system is the exclusive supply to the medulla oblongata, pons and cerebellum.

The efficacy of three on-farm euthanasia methods for broiler chickens throughout the production cycle

1. There is a need to humanely kill moribund or injured broiler birds on-farm with no reasonable chance of recovery. Two experiments evaluated the efficacy of three commercially applicable killing methods; manual cervical dislocation (CD), mechanical cervical dislocation with the Koechner Euthanising Device (KED) and a non-penetrative captive bolt device (Zephyr-EXL; ZEXL), at 7, 21 or 35 d of age, on their ability to induce insensibility (unconsciousness and loss of brain stem reflexes) and death.2. Experiment one assessed the damage to the cranial-cervical region resulting from the methods applied to cadavers of cull birds (n = 180) by radiography and gross pathology observation.3. Experiment two evaluated the latency to insensibility and death when cull broiler birds (n = 240) were killed by CD, KED or ZEXL, using behavioural and reflexive indicators. Insensibility and death were measured by the absence of pupillary light, palpebral blink and nictitating membrane reflexes and cessation of rhythmic breathing, cloacal winking and convulsions. Analysis of variance for the main effect of the method was performed to determine the differences.4. In experiment one, only the Zephyr resulted in skull fractures. A higher number of vertebral fractures occurred with KED application compared to CD, at 21 and 35 d.5. In experiment two, indicators of sensibility were absent earliest with the ZEXL (μ < 2 s); then,CD (μ = 28 s) and were longest with KED (μ = 47 s), at 21 and 35 d. Cloacal winking and convulsions ceased earlier after CD (88 s), compared to either KED (124 s) or Zephyr (118 s). Death after a single application occurred 100%, 100% and 98% of time for CD, KED and ZEXL, respectively.6. Overall, all methods were efficacious at inducing insensibility and death. Insensibility occurred earliest with ZEXL, whilst death occurred earliest with CD. KED resulted in the longest time to insensibility and death.

Pain at the Slaughterhouse in Ruminants with a Focus on the Neurobiology of Sensitisation

Simple Summary

We pose based on a fundamental science examination that events that occur around the time of slaughter have the potential to intensify the pain response, through a process called sensitisation, or an exaggerated response to painful stimuli. Health conditions which result in inflammation, injuries arising from transport and handling and exaggerated fear responses may all be present at the slaughterhouse. Whilst there is limited evidence of a direct effect of these on the processes of sensitisation in animals at slaughter, by analogy with the human neurobiology literature the connection seems plausible. In this review we outline the biology of such a response, and the rationale for suggestion of a possible linkage between events at slaughter and a heightened animal pain response.

Abstract

We pose, based on a neurobiological examination, that events that occur around the time of slaughter have the potential to intensify the pain response, through the processes of sensitisation and enhanced transmission. Sensitisation, or an enhanced response to painful stimuli, is a well-discussed phenomenon in the human medical literature, which can arise from previous injury to an area, inflammatory reactions, or previous overstimulation of the stress axes. A number of events that occur prior to arrival at, or in the slaughterhouse, may lead to presence of these factors. This includes previous on-farm pathology, injuries arising from transport and handling and lack of habituation to humans. Whilst there is limited evidence of a direct effect of these on the processes of sensitisation in animals at slaughter, by analogy with the human neurobiology literature the connection seems plausible. In this review a neurobiological approach is taken to discuss this hypothesis in the light of basic science, and extrapolations from existing literature on the slaughter of ruminants. To confirm the postulated link between events at slaughter, and processes of hypersensitisation, further dedicated study is required.

Comparing Gas and Electrical Stunning: Effects on Meat Quality of Pigs when Pre-Stunning Physical Activity is Minimal

A total of thirty pigs were experimentally slaughtered using gas (80% CO2 in air, 90 s; 30% CO2/70% N2O; 90 s) or electrical stunning (1.3 A, 10 s). Stunning may accelerate post-mortem muscle metabolism, due to psychological stress and/or muscle contractions. The specific effects of the stunning method were studied by limiting pre-stunning physical activity and stress: pigs were driven in a trolley from the rearing to the stunning site (6.5 m) and immediately slaughtered. Bleeding efficiency and carcass characteristics were similar and satisfactory for all stunning methods. Early post-mortem pH decline in the Longissimus lumborum was faster following gas compared to electrical stunning. The pH of other muscles was not influenced; color and drip loss showed minor effects. Hence, results are in contrast to current beliefs: compared to electrical stunning, following gas stunning, the stress and muscle contractions during the induction of unconsciousness have a slightly greater impact on Longissimus lumborum muscle metabolism; differences are minor and limited to certain muscles only.

A Case of Multiple Stun Attempts in a Bovine Due to Chronic Disease Process Causing Cranial Abnormalities

Simple Summary

Cattle that are to be processed for human consumption are routinely and legally rendered unconscious, to ensure that they cannot feel any pain, before the process of bleeding to cause brain death. The main method used in abattoirs is pneumatic or cartridge-powered captive bolt devices, which deliver a high velocity impact to the skull creating a severe concussion (stun). The penetrating captive bolts then continue travelling into the brain to prevent recovery from the stunned state by damaging the structures in the brain that are required for normal brain function. If this method does not work there is an obvious potential for the welfare of the animal to be compromised, so investigations are undertaken to establish the cause of any failures to reduce the risk of reoccurrence. This paper presents the results of such an investigation, where the cause of the failure of the device to stun was found to be due to the anatomy of the individual animal’s head. This unfortunate occurrence is rare but must be considered in any investigation of multiple stun attempts.

Abstract

The preslaughter stunning of bovine animals is a legal requirement in the European Union, unless the animal is being slaughtered according to religious rite. The legislation also requires the investigation and review of stunning methods in cases of failure to stun. This paper presents the results of one investigation into the possible reasons for multiple stun attempts on an animal that received five shot applications. The head was hard frozen to prevent the deformation of brain structures during splitting along the sagittal plane, and then underwent macroscopic examination to assess the likely causes of the repeated stun attempts. In this case, a pre-existing chronic disease process produced anatomical variations of the cranial cavity, increasing the thickness of the sinuses of the frontal bone to a depth of 9 cm and filling the sinuses with a fibrinous pus deposit. It was therefore concluded that the anatomical variation produced by the chronic disease process, in addition to the energy absorption provided by the thicker hide and fibrinous pus, led to the failure of the stunning equipment to achieve the desired stunned state in the animal. As the animal displayed cranial variation before slaughter, a review of the stunning systems should include a requirement that animals displaying any abnormalities should be stunned with the highest-powered cartridge available or a free bullet.

Understanding the Determination of Meat Quality Using Biochemical Characteristics of the Muscle: Stress at Slaughter and Other Missing Keys

Despite increasingly detailed knowledge of the biochemical processes involved in the determination of meat quality traits, robust models, using biochemical characteristics of the muscle to predict future meat quality, lack. The neglecting of various aspects of the model paradigm may explain this. First, preslaughter stress has a major impact on meat quality and varies according to slaughter context and individuals. Yet, it is rarely taken into account in meat quality models. Second, phenotypic similarity does not imply similarity in the underlying biological causes, and several models may be needed to explain a given phenotype. Finally, the implications of the complexity of biological systems are discussed: a homeostatic equilibrium can be reached in countless ways, involving thousands of interacting processes and molecules at different levels of the organism, changing over time and differing between animals. Consequently, even a robust model may explain a significant part, but not all of the variability between individuals.

Euthanasia of laying hens: an overview

Euthanasia of an animal requires that its death occurs in as humane a manner as possible. There are three key scenarios for euthanasia in the egg industry: the humane destruction of day-old male chicks, euthanasia of individual birds, and the depopulation of flocks for disease control or because conventional transport and slaughter is uneconomic. For day-old chicks, instant mechanical maceration, although conditionally humane, presents a public perception problem. Submerging in CO2 gas is less confronting but is thought to be aversive to animals unless more expensive and harder to manage inert gases are incorporated. Future technologies involving pre-hatching sex determination or sex selection may largely solve the problem when fully developed. For the euthanasia of individual birds within the flock, manual cervical dislocation has been shown to be humane when performed by trained personnel who are willing to perform the procedure. Penetrating and non-penetrating mechanical devices that cause irreversible brain trauma are becoming more available and represent a humane alternative to cervical dislocation when properly placed and maintained. These devices may be less confronting for some staff to use than is cervical dislocation. For whole-flock euthanasia, the overwhelming requirements of disease control and public safety may override considerations of euthanasia. Whole-shed CO2 (or other gas combinations) and foam-based alternatives can be used, but have challenges in commercial settings. Modified atmosphere killing units or low atmospheric stunning systems are alternatives that overcome some of these practical problems, but do require birds to be handled.

Animal Welfare and Meat Quality Assessment in Gas Stunning during Commercial Slaughter of Pigs Using Hypercapnic-Hypoxia (20% CO2 2% O2) Compared to Acute Hypercapnia (90% CO2 in Air)

This study assessed aversion, stunning effectiveness, and product quality of nitrogen and carbon dioxide (CO₂) mixtures used for stunning pigs. A total of 1852 slaughter pigs divided into two similar batches was assessed during routine slaughter in a Swedish commercial abattoir using either hypercapnic-hypoxia (20% CO₂ and less than 2% O₂; 20C2O) or hypercapnia (90% CO₂; 90C) gas mixtures. Behavioral indicators of aversion and discomfort were recorded. After exposure, the stunning quality was assessed through brainstem reflexes. After slaughter, the pH and electric conductivity of carcasses were assessed to estimate the incidence of pale, soft, and exudative (PSE) pork, and the presence of ecchymosis were inspected. Compared to 90C, pigs exposed to 20C2O showed a later (p < 0.05) onset of behaviors indicative of aversion, and a lower (p < 0.01) incidence of breathlessness. However, unconsciousness (i.e., losing posture) appeared earlier (p < 0.01) in 90C compared to 20C2O. In 90C, all (100%) pigs were adequately stunned, whereas in 20C2O a 7.4% of pigs showed signs of poor stunning, especially when oxygen concentrations were >2% (p < 0.001). The percentage of PSE carcasses was higher (p < 0.01) in 20C2O than 90C. In conclusion, compared to 90C, 20C2O reduced aversion and discomfort but showed lower stun effectiveness, especially when O₂ was above 2%, and a slightly poorer pork quality.

Responses of Pigs to Stunning with Nitrogen Filled High-Expansion Foam

Nitrogen gas (N2) delivered in high expansion foam in a closed container could be a feasible method for humanely stunning pigs. This study aimed to evaluate potential aversion in pigs to the N2 foam method and its effect on stun quality. Furthermore, the study aimed to assess potential aversion to the foam itself. Sixty pigs (27.8 ± 4.4 kg) were divided into three treatments and were exposed to either N2-filled foam, air-filled foam, or no foam air. The N2 foam was effective at purging the air from the container and quickly created stable anoxic conditions. The pigs did not show any strong aversive behaviours when exposed to foam. However, they seemed to avoid putting their heads and snouts into the foam when foam levels became high. Escape attempts through the lid also increased when the foam started covering their heads. The mean time to loss of posture was 57.9 s. Based on the results, stunning with the N2 foam technique could be a viable alternative to high concentration CO2 stunning and potentially lead to improved animal welfare at slaughter.

A Systematic Literature Review on Depopulation Methods for Swine

Swine mass depopulation refers to the destruction of large numbers of pigs and may include not only animals affected with a disease but also healthy pigs in a facility or surrounding areas. Emerging applications of mass depopulation include reducing welfare issues associated with slaughter delays, which was observed in the United States in 2020 as a result of the Coronavirus disease (COVID-19) pandemic. The objectives of this review were to summarize the available literature on swine depopulation methods and to highlight critical gaps in knowledge. Peer-reviewed articles were identified through a systematic search in electronic databases including Web of Science, MEDLINE, and PubMed. A total of 68 publications were assessed. Gaseous carbon dioxide inhalation was the most commonly reported depopulation method for both small- and large-scale trials. Measurements of consciousness state, which serves to assess suffering and humaneness, appeared to be lacking in a high proportion of the studies. None of the published studies demonstrated an ideally reliable and safe way to induce rapid unconsciousness in large groups of pigs. Development of rapid mass depopulation methods applicable to large groups of pigs is necessary to provide industry partners with suitable and low-cost emergency preparedness procedures while adhering to personnel safety and animal welfare standards. Lastly, there is an urgent need to standardize comprehensive reporting guidelines for depopulation studies.

Further Examination of the Performance of Blank Cartridges Used in Captive Bolt Devices for the Pre-Slaughter Stunning of Animals

Blank cartridges produce gas through deflagration and are used as the main power source in captive bolt devices used within abattoirs and on farms in Europe. The European legislation recognises this and requires users to follow manufacturers' recommendations in terms of which power cartridge to use. Variation in cartridge performance of Eley (E) cartridges was found in previous research, which was published before Accles and Shelvoke (AS) started full production of their own cartridges. This work examined cartridge performance, structural integrity and dimensional tolerances, and found that the new AS cartridges that varied more greatly in performance in terms of velocity, kinetic energy and mechanical stability of casing than the more established E cartridges. In this study, 15% of the cartridges split at the primer flange on firing, resulting in less kinetic energy, which could impact the ability of the captive bolt to produce a successful stun. This, combined with the variation in performance in a primary component of a device that should have a uniform performance, could lead to animal welfare issues as this variation cannot be predetermined by examination of the cartridge pre firing.

Humane Euthanasia of Guinea Pigs (Cavia porcellus) with a Penetrating Spring-Loaded Captive Bolt

Simple Summary

Various euthanasia methods are currently employed for guinea pigs at their experimental or humane endpoint; however, many have significant limitations or negative animal welfare implications. Captive bolt euthanasia has been used in the guinea pig meat industry but has not been explored in a research setting. This work aimed to investigate the use of a penetrating spring-loaded captive bolt gun as a refinement to guinea pig euthanasia in research. The study found that when compared to blunt force trauma, the captive bolt procedure performed well against all parameters of humane slaughter of production animals and appears to be a feasible refinement for animal welfare.

Abstract

Guinea pigs (Cavia porcellus) have been used in research since the 19th century to collect data due to their physiological similarities to humans. Today, animals perform a vital role in experiments and concerns for laboratory animal welfare are enshrined in the 3R framework of reduction, refinement and replacement. This case study explores a refinement in humane euthanasia of guinea pigs via the use of an irreversible penetrating spring-loaded captive bolt (CB). Penetrating spring-loaded CB stunning for euthanasia (CBE) was performed on 12 guinea pigs with the parameters for humane slaughter of production animals in order to assess the suitability of this method of euthanasia in contrast to blunt force trauma (BFT). All 12 of the guinea pigs were rendered immediately unconscious with excellent experimental tissue quality collection, high repeatability of results and operator (n = 8) preference over BFT. Overall, CBE in guinea pigs appears to be a feasible refinement for animal welfare, human preference and improved tissue quality for experimental collection in settings where uncontaminated tissues are required.

Effects of penetrating captive bolt gun model and number of stuns on stunning-related variables of cattle in a commercial slaughter facility

The objective of this study was to assess two different penetrating captive bolt gun models (Jarvis USSS-1 and USSS-21) and two stunning methods (1KNOCK and 2KNOCK, applying one and two knocks, respectively) on stunning-related variables in cattle. Heads were collected at a commercial slaughter facility and knocking efficiency, knock hole diameter, brain damage, knock hole placement and hemorrhage were assessed. Knocking efficiency was not impacted by gun model or number of knocks (P = .39 and .12, respectively). Knock number influenced knock hole diameter, brain damage and hemorrhage in the cavity (P ≤ .01). Presence of brainstem damage was greater (P < .01) when using the USSS-21 gun. Results suggested similar performance between the USSS-1 and USSS-21 gun models. Potential benefits of using the newest model could be related to damaging vital brain areas like the brainstem.

Defining characteristics of immersion carbon dioxide gas for successful euthanasia of neonatal and young broilers

This study investigated how the carbon dioxide (CO₂) concentration within a chamber affects the efficacy of CO₂ euthanasia and how the efficacy of CO₂ induction methods changes as birds age. In experiment 1, pairs of broiler chicks (n = 192; 0, 3, and 6 D of age) were immersed into a chamber prefilled with 70, 80, 90, or 100% CO_2. For experiment 2, 3- and 6-day-old broiler chicks (n = 88) were immersed in pairs into 100% CO₂ or exposed to CO₂ gradual fill in a chamber with a displacement rate of 28% chamber volume per minute. Latency to performance of headshaking (HS) and gasping (GS) as potential indicators of distress, loss of posture indicative of insensibility, and the cessation of rhythmic breathing (CRB) and cessation of movement (COM) as the indicators of death were monitored (live focal sampling/video recordings). The duration and frequency of HS and GS were assessed. For both experiments, behavior data were analyzed for CO₂ method and age (4 × 3 factorial). Age and CO₂ concentration interacted for latency to CRB and COM, with longer latencies for 0-day-old chicks immersed into 70% CO₂ than other concentrations and ages. CO₂ concentration did not affect latency to HS, GS, or loss of posture but affected CRB and COM, with latencies longest for 70% and shortest for 90 and 100% CO₂. Newly hatched chicks had a longer latency to CRB and COM and longer duration and frequency of distress behaviors than older chicks. At all ages, initiation of all behaviors occurred later with gradual fill compared to immersion. There was an increased duration and frequency of distress behaviors with gradual induction compared with immersion. Overall, immersion into 90 to 100% CO₂ resulted in the shortest time to insensibility and death, with a decreased duration and frequency of distress behaviors. Chicks immersed into 70% CO₂ had the longest duration of GS and time to death. Age affects the efficacy of CO₂ euthanasia, with increasing age decreasing time to death and the duration and frequency of distress behaviors.

The Impact of Deviation of the Stun Shot from the Ideal Point on Motor Paralysis in Cattle

The effect on motor paralysis of a deviation in the stun shot placement from the ideal point on cattle skulls was monitored in 627 bovine animals (271 bulls and 356 cows) stunned with a captive bolt during slaughter in a slaughterhouse. The number of animals that experienced motor paralysis and the necessary fall of the animal in the stunning box were recorded after the stun shot. Subsequently, the position of the stun shot was measured on the skull of the slaughtered cattle in relation to the ideal point on the skull, and at a deviation from the ideal point, the quadrant on the skull in which the bullet was located was determined. The results show that with the increasing distance of the placement of the stun shot from the ideal point on the skull, the incidence of failure to induce motor paralysis in cattle increases significantly (p < 0.01) from 2.4% (within 3 cm of deviation) to 72.2% (at deviations ˃ 7 cm). There was a significant increase in the failure to induce motor paralysis in bulls as well as in cows, but this was more frequent in bulls regardless of the magnitude of the deviation from the ideal point (with the exception of a distance greater than 7 cm where the chances of inducing motor paralysis in bulls and cows are equally low). The incidence of failure to induce motor paralysis in cattle was not dependent on the placement of a stun shot in various quadrants on the skull. With the increasing deviation in any direction from the ideal point, the likelihood of effective stunning of cattle decreases. The results are important from the animal welfare point of view of the slaughter of cattle, and demonstrate the necessity of optimum placement of the stunning shot on the bovine skull in order to achieve the successful motor paralysis of cattle during their stunning at the slaughterhouse.

Effect of Indigenous Slaughter Methods on the Behavioural Response, Bleeding Efficiency and Cardiac Arrest of Nguni Goats

Simple Summary

Resource-limited farmers under communal farming environments slaughter goats for cultural beliefs and meat consumption using indigenous slaughter methods. These methods include transverse neck incision (TNI), piercing with a short spear on the suprasternal notch targeting the heart (SNP), and piercing with a short spear under-shoulder-blade chest-floor point-of-elbow (CFP) targeting the heart to induce insensibility and death. Unsatisfied animal welfare institutes consider these slaughter methods as cruel because goats are slaughtered while sensible; therefore, experiencing pain and suffering before death. In this study, we slaughtered castrates using the above-mentioned methods and collected behavioural responses before slaughter and while bleeding, the total blood expelled during bleeding, the time it took for the blood to be expelled, the time it took the goats to lose sensibility, and time to lose heartbeat. We found that goats slaughtered using CFP lost sensibility faster. We concluded that goats slaughtered using the CFP method experienced less pain and suffering during slaughter and died faster.

Abstract

Resource-limited farmers slaughter goats without stunning. The objective of the current study was to assess the influence of indigenous slaughter methods used by resource-limited households on slaughter stress-related behaviour, bleeding efficiency, and time to post-slaughter trauma of goats. Thirty clinically healthy castrated Nguni goats aged between 15 to 18 months old with body condition score of three were randomly assigned to three non-stunning informal slaughter methods, (1) transverse neck incision (TNI); (2) suprasternal notch piercing in the direction of the heart (SNP); and (3) under-shoulder-blade chest-floor point-of-elbow (CFP) sticking in the direction of the heart. Ten goats were slaughtered using each method. Slaughter method had no effect (p < 0.05) on stress-related behaviour. Rate of bleeding efficiency was highest (p < 0.05) for SNP slaughtered goats. Time to lose sensibility was lowest (p < 0.05) for goats slaughtered using the CFP (55 s) when compared to SNP (68 s) and TNI (75 s) slaughter methods. Time to post-slaughter trauma was highest (p < 0.05) for SNP (247 s) and lowest for TNI (195 s). These findings suggest that goats slaughtered with SNP experienced rapid death when compared to TNI and SNP slaughter methods. It was concluded that the SNP slaughter method is the most effective slaughter technique because it is associated with higher bleeding efficiency and lower time to lose sensibility before death.

The Physiological Aspects, Technique and Monitoring of Slaughter Procedures and their Effects on Meat Quality – A Review

The aim of the paper was a review of the scientific achievements in physiological stunning and slaughtering mechanisms, control methods of consciousness and their effect on meat quality. Special attention was paid to neurophysiological phenomena that accompany the process of depriving consciousness before animal deaths using mechanical, electrical and gas stunning methods. These mechanisms are associated with cerebral hypoxia or ischemia or depolarization, acidification and the destruction of cerebral neurons. Such effects can be caused by shock waves, bleeding, electric fields, reduction or arrest of the circulation of blood in the brain, high CO2 level or low O2 level in inhaled air or by the mechanical damage of neurons. Some of the stunning methods cause immediate and some gradual consciousness loss. An important factor in the animals’ slaughtering process is the estimation of their consciousness level before bleeding. The indicators of consciousness during mechanical, electrical and gas stunning are discussed within this paper. It is pointed out that at least 2 indicators should be used when estimating animals’ consciousness after stunning, e.g. phonic and clonic limb movements and lack of breathing. Ten indicators to control the consciousness were described. The effect of stunning on meat quality is also discussed. It was found that the impact of this process on the quality is not clear. However, the prevailing view is that electric stunning causes effusions and blood haemorrhages in meat. Whereas gas stunning with a CO2 mixture diminishes the risk of PSE meat. Despite numerous scientific research on the slaughter process there is still deficiency in knowledge on losing consciousness mechanisms and feeling pain. It might be useful to extend the knowledge concerning neurotransmitters and use of magnetic resonance in future studies.

An Examination of the Performance of Blank Cartridges Used in Captive Bolt Devices for the Pre-Slaughter Stunning and Euthanasia of Animals

Blank cartridges provide the power source for the majority of captive bolt devices used for rendering animals unconscious prior to slaughter within the United Kingdom or euthanasia worldwide. This paper presents the results of the examination of cartridges as one of the variables that can contribute to an unsuccessful application of this method in practice. Variation was found in cartridge weight, propellant fill volume and velocity within boxes of 1000 cartridges. The variation found was greater in lower charge (1.00 grain) cartridges than in 3.00 grain cartridges, however velocity was found to be variable in both sets. For example, in vivo velocity measurements with 0.25″ calibre 3.00 grain cartridges demonstrated an average velocity of 50.8 m/s over 200 shots with a range of 35.7 to 62.9 m/s when used in the same device. This work demonstrates that variation in cartridge performance does occur and can be due to various factors such as fill volume and propellant function, and simply weighing cartridges cannot be used to determine function, therefore cartridge performance must be a factor that is considered in the event of a miss-stun.

Alternatives to Carbon Dioxide-Taking Responsibility for Humanely Ending the Life of Animals

Simple Summary

Carbon dioxide has long been considered one of the better methods for euthanizing laboratory rodents because it allows termination of several animals at one time, does not require handling of the animal, is easy to use, is inexpensive, and is environmentally friendly. Research, though, has shown that this gas is aversive to rodents and that it may be inhumane to expose them to this gas while they are conscious. Therefore, the Swiss Federal Food Safety and Veterinary Office has set out to find a suitable replacement and organized a meeting that included representatives and experts of the different stakeholders involved in this process in order to find a solution. The conclusion of this meeting was that a replacement is required, and the next step would be to draft a research strategy to find a suitable replacement.

Abstract

Carbon dioxide (CO₂) is commonly used to kill rodents. However, a large body of research has now established that CO₂ is aversive to them. A multidisciplinary symposium organized by the Swiss Federal Food Safety and Veterinary Office discussed the drawbacks and alternatives to CO₂ in euthanasia protocols for laboratory animals. Dialogue was facilitated by brainstorming sessions in small groups and a “World Café”. A conclusion from this process was that alternatives to CO₂ were urgently required, including a program of research and extension to meet the needs for humane killing of these animals. The next step will involve gathering a group of international experts to formulate, draft, and publish a research strategy on alternatives to CO₂.

Descriptive Analysis of Cerebral Arterial Vascular Architecture in Dromedary Camel (Camelus dromedarius)

The artiodactyl brain has multiple levels of vascular pooling and the rostral epidural rete mirabile (RERM) at its base. The current study is the first of its kind to precisely demonstrate the arterial vasculature of the dromedary brain, utilizing a new casting method with colored latex and epoxy paint. In total, 35 freshly slaughtered dromedary heads were injected with colored latex or colored epoxy paint prior to dissection in order to reveal cerebral vasculature; Ten processed heads were chemically digested with 5% potassium hydroxide to obtain hard casts of cerebral arteries and anastomosing structures. The outcomes of this study ascertain the distinct vascular features of dromedaries that set them apart from other artiodactyls. In addition to the RERM, the dromedary possesses a well-developed ophthalmic and chiasmatic rete. The dromedary is similar to giraffe, goat, cat and pig in the contribution of middle meningeal artery to the rete mirabile; however, dromedaries have several arteries emerging directly from the cerebral arterial circle that supply the choroid plexus and pineal gland. Additionally, dromedaries exhibit a dominant basilar system that dominates the blood supply to the medulla oblongata, pons, and cerebellum. In our study, we were able to graphically prove the lack of connection between the areas supplied by vertebrobasilar system and carotid system in the dromedary. Furthermore, the vertebral artery does not branch into the basilar artery; instead, it acts as a contributing vessel to the ventral spinal artery that later fuse to form the basilar artery. This study employed the new casting method to illustrate a new arterial source to RERM and the various anastomoses among arterial sources supplying the brain in the dromedary. These anastomoses play an important role in maintaining an uninterrupted cerebral blood supply, decreasing the vulnerability of the fragile brain against ischemia and stroke, as well as, play an important role in maintaining blood pressure and flow in long-necked dromedaries when they raise or lower their heads.

Macroscopic Examination of Multiple-Shot Cattle Heads-An Animal Welfare Due Diligence Tool for Abattoirs Using Penetrating Captive Bolt Devices?

Ideally, the application of a penetrating captive bolt device to render cattle immediately unconscious prior to slaughter would be 100% effective. Unfortunately, due to various factors this is not always the case. This paper examined, as an initial proof of concept, 12 bovine heads which had received more than one shot from a penetrating captive bolt, collected from various abattoirs within the United Kingdom. The heads were frozen to facilitate splitting on the medial plane to prevent distortion of soft tissue and each sagittal section was examined macroscopically to ascertain if this method could be used to determine the reasons for repeated stun attempts. In 10 out of 12 heads, shot placement was the determining factor, in one other head it was felt that anatomical variation was the reason and the twelfth head demonstrated signs of gun malfunction as the likely cause. This work provides evidence for a larger trial to facilitate the production of guidance for the abattoir industry, the Animal Welfare Officer and regulators on the examination of heads as part of an investigation of failures of a mechanical stunning system and to provide training material for slaughter staff tasked with effectively stunning cattle.

The effects of bolt length on penetration hole characteristics, brain damage and specified-risk material dispersal in finished cattle stunned with a penetrating captive bolt stunner

The purpose of this study was to determine the effect of captive bolt lengths on penetration hole characteristics, brain damage, and specified risk material (SRM) dispersal. Cattle were stunned with a pneumatic captive bolt stunner using: standard (15.2 cm; STRD), medium (16.5 cm; MED), or long (17.8 cm; LON) bolts. Heads (N = 293) and exsanguination blood (N = 103) were collected for analyses. Penetration hole diameter and depth differed by treatment (P ≤ 0.004); both parameters were greatest for LON (P < 0.05). Presence of damage in frontal, parietal, and occipital lobes, olfactory bulb, and collective area including the corpus callosum, fornix and thalamus were impacted by treatment (P < 0.003). Treatment did not impact SRM dispersal (P = 0.33), determined by presence of glial acidic fibrillary protein. Data suggest that bolt length affects both the extent of brain damage and the specific structures damaged but all bolt lengths are successful in causing substantial brain damage and subsequent insensibility.

Effect of captive bolt gun length on brain trauma and post-stunning hind limb activity in finished cattle Bos taurus

Hind limb post stunning kicking in properly stunned unconscious cattle is a safety hazard for employees. Three different captive bolt lengths of 15.2 cm (STRD), 16.5 cm (MED), and 17.8 cm (LON) were evaluated for amount of tissue damage and hind limb kicking in a Jarvis USSS-1 pneumatic stunner. The air pressure setting was 1378.95 to 1447.90 pKa for all captive bolts. All 45 test cattle were rendered unconscious with a single shot. There was a trend (P = .06) for less kicking to occur when the 16.5 cm length bolt was used in the stunner. Visual appraisal of the brains on the split heads indicated that the shortest bolt caused the least amount of brain damage. The brainstems were intact for all cattle regardless of captive bolt treatment. Young fed English, Continental European, and Holstein steers and heifers can be effectively stunned without visible brainstem disruption.

Evaluation of carbon dioxide induction methods for the euthanasia of day-old cull broiler chicks

This study was conducted to evaluate the efficacy of 5 different CO2 euthanasia induction techniques for day-old cull chicks in minimizing distress and inducing a rapid loss of sensibility and death. Each induction treatment was characterized for concentration change over time, maximum concentration, and time to reach maximum. Sixteen chicks were euthanized with the gradual treatments to establish validity of treatment. Then, all 5 treatments were evaluated for effect on distress, insensibility, and death. Day-of-hatch cull chicks (n = 110) were euthanized in pairs by either immersion into 100% CO2 or gradual induction to 100% CO2 at displacement rates of 7, 14, 21, or 28% of chamber volume added per min (% vol/min). CO2 concentration was measured at chick level. Live focal observations and video recordings were used to assess latency to behavioral responses: head shaking (HS) and gasping (GS) as indicators of distress; loss of posture (LOP) as an indicator of insensibility; and cessation of rhythmic breathing (CRB) and movement (COM), indicating death. All behaviors occurred at the earliest with immersion compared to gradual treatments, and time between first signs of distress and LOP was shorter for immersion than gradual treatments. Gradual treatments showed a linear decrease in latency to HS, GS, and LOP as displacement rate increased. Latency to CRB decreased quadratically with increasing displacement rate, while COM decreased linearly. Within gradual treatments, HS and GS occurred at CO2 concentrations between 0.43 and 1.14%, LOP between 11.1 and 17.5%, while CRB and COM occurred between 61.8 and 78.4%. Overall, immersion induced distress, insensibility, and death significantly faster and with the shortest interval between distress and insensibility. For gradual treatment, insensibility and death occurred faster with increasing displacement rates. Behavioral signs of distress were observed with all treatments, and occurred at concentrations lower than those causing insensibility. In conclusion, immersion into 100% CO2 environment resulted in the shortest time of distress and fastest time to death compared to gradual displacement rates of any speed measured.

An evaluation of environmental, intrinsic and pre- and post-slaughter risk factors associated to dark-cutting beef in a Federal Inspected Type slaughter plant

The objective was to determine the risk factors associated to dark-cutting in bovine carcasses. The study was conducted at a Federal Inspection abattoir located in northeastern Mexico. A random sample of 394 animals at slaughter was used. A total of 26 explanatory variables were evaluated; the analysis included environmental, animal-specific, and management factors both at pre- and post- slaughter periods. Only four variables were statistically significant within the final logistic regression model (P < .001). The frequency of dark-cutting carcasses was 13.45%. Lairage time was directly proportional to the percentage of risk for dark-cutting beef. Improper desensitization also increased the frequency of carcasses with this anomaly. Backfat thickness and the 24-h pH differential of the carcasses were inversely proportional to the risk for dark-cutting beef. An interesting finding was that risk factors for DFD meat are present in all stages of the slaughter process and thus to effectively address this problem an integral evaluation is needed throughout the slaughter process.