CO2 Stunning Research Articles

Effect of Stocking Density during CO2 Stunning of Pigs on Induction Time and Activity Level Measured Using AI.

During the CO2 stunning of pigs, a variation in their reaction to the gas and the duration of the induction period is observed. The stunning process can be affected by several conditions, such as stressful events and previous experiences, but the stocking density in the gondola may also have an impact. The objective was to investigate the effect of stocking density on the stunning process under commercial conditions. To quantify the pigs' reactions under industrial settings with a stocking density of up to eight pigs pr. Gondola (3.91 m2), the activity level was measured using an AI solution. Compared with a simulation of the expected induction period, a significantly longer induction period was found in gondolas containing seven and eight pigs (p < 0.001) but not when the gondolas contained three or four pigs. Both high and mean activity levels were significantly higher when stocking density was increased from three or four pigs to seven or eight pigs. The stunning process was thus negatively affected when increasing the stocking density. More knowledge is needed to explain this effect and to make statements on optimal stocking density. The measured activity levels may be a useful tool for obtaining information under commercial conditions and for documenting animal welfare.

Are slaughterhouse-obtained livers suitable for use in ex vivo perfusion research?

The success of the ex vivo machine perfusion of pig livers used for preclinical research depends on organ quality and availability. In this study, we investigated whether livers obtained from slaughterhouses are suitable and equivalent to livers obtained from laboratory pigs. Livers were obtained from slaughterhouse pigs stunned by electrocution or CO2 inhalation and from laboratory pigs. For the latter group, 45 minutes of warm ischemia was mimicked for a subgroup, ensuring a valid comparison with slaughterhouse-derived livers. Livers from CO2-stunned pigs showed lower indocyanine green clearance and bile production, higher blood lactate and potassium concentrations, and higher alanine aminotransferase activities than electrically stunned pigs. Furthermore, livers from electrically stunned pigs, and livers from laboratory pigs, subjected or not to warm ischemia, showed similar performance in terms of perfusion and metabolism. For an ex vivo liver model generated using slaughterhouse pigs, electrical stunning is preferable to CO2 stunning. Livers from electrically stunned slaughterhouse pigs performed similarly to laboratory pig livers. These findings support the use of livers from electrically stunned slaughterhouse pigs, which may therefore provide an alternative to livers obtained from laboratory pigs, consistent with the principle of the 3Rs.

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".

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

Simple SummaryStunning is an important and statutory pre-slaughter process that aims to induce a state of unconsciousness and insensibility to pain just before sticking and bleeding out. In Europe, two main stunning methods that are applied at pig slaughter are electrical (ES) and gas stunning with high-concentration carbon dioxide (CO2). Stunning is not only crucial in terms of the welfare of pigs at slaughter, but it may also have effects on meat quality. Various studies have compared these two methods with respect to meat-quality traits. In several studies, stunning with CO2 has been shown to improve meat quality in comparison with ES; however, other research indicated that ES enhanced the meat quality as opposed to CO2 or had no significant effect. The current study analysed the combined results of independent research and experiments to achieve quantitative evidence of the effects of two stunning methods, electrical and gas with a high concentration of carbon dioxide, on selected quality attributes of fresh pork. The results of the meta-analysis revealed that relative to CO2 stunning, overall, ES pigs had a lower pH1, higher drip loss (DL) and lightness (L*). However, the greater alterations in these traits were achieved with the application of the head-to-back (HB) electrical-stunning method and conventional chilling (Conv.) of the carcasses. The results of the meta-analysis provide evidence that 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 the carcasses.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.

73 Commercial Management of Fresh Pork Quality Using Post-Mortem pH and Temperature Declines

Abstract Historically, research involving the pH decline of pork has been conducted under university conditions with the use of electrical stunning and conventional chilling (minimum temperature &amp;gt; -10). Most large commercial slaughter plants in the U.S. currently use CO2 stunning and many have some form of accelerated chilling of the carcass. With ante-mortem stress level of the pig and post-mortem carcass temperature decline being 2 of the major factors affecting post-mortem pH decline rate, it should be expected that the pH decline rate may be different in current commercial conditions when compared with the literature. Our work has focused on developing methods to measure pH and temperature decline in short intervals (5 min, 15 min, 30 min, or 1 h) and determine the critical time periods to manage the chilling process in order to slow pH decline and obtain higher ultimate pH levels (20h). This research indicates the potential to alter the carcass chill curve to make precision adjustments in the quality of pork.

Welfare in Nile Tilapia Production: Dorsal Fin Erection as a Visual Indicator for Insensibility.

Simple SummaryAquaculture has been the fastest-growing production segment in recent years, and as such, it is necessary to have clear guidelines on how fish are reared, stunned and slaughtered, always taking into account their welfare. By aiming for the stunning stage to be efficient, quick and practical before the fish are finally slaughtered in the fish farming process, we propose to verify and validate dorsal fin erection as a painless visual indicator of sensibility in Nile tilapia, ensuring that animals do not suffer during the stunning and slaughtering processes. Our results have validated the method as an effective indicator to assess the state of fish sensibility, and is simple to be carried out in large-scale production systems. The presence/absence of an erect dorsal fin alone does not totally ensure fish insensibility, and must be used together with other well-established visual sensibility indicators, for a better assessment of the state of fish sensibility, such as fish equilibrium, vestibulo-ocular reflex and opercular beats.In aquaculture, to ensure animal welfare in pre-slaughter and slaughter stages, it is fundamental that fish are insensible. A method for evaluating fish insensibility is based on visual sensibility indicators (VSI) assessment (i.e., self-initiated behavior, responses to stimuli and reflexes). However, many stimuli used to assess fish responses are painful. Therefore, this study verifies whether the presence/absence of a dorsal fin erection (DFE) response can be used as a painless VSI in Nile tilapia (Oreochromis niloticus). Three stunning protocols were applied to fish: benzocaine anesthesia (40 mg/L and 80 mg/L), ice water immersion (0–1, 2–3 and 5–6 °C) and CO2 stunning. After these stunning methods were applied in fish, the time of loss and return of DFE was observed, along with the vestibulo-ocular reflex (VOR). All fish stunned using benzocaine and ice water immersion lose both VSIs, while 95% of fish stunned using CO2 lose these VSIs. In all treatments, DFEs return quicker than VOR. Therefore, DFE can be used as a VSI in Nile tilapia, which is simple for producers to assess and does not require a painful stimulus. However, the DFE alone does not totally ensure fish insensibility and must be used together with other well-established VSIs at fish farms.

Pre-slaughter factors linked to variation in responses to carbon dioxide gas stunning in pig abattoirs

The stunning process is an important component of slaughter with implications for animal welfare due to the potential distress and pain in the case of a sub-effective or lengthy stun. This study examined the factors correlated with variation in responses to carbon dioxide (CO2) stunning of pigs in five Australian commercial abattoirs. A total of 1 769 pigs (199–492 focal pigs per abattoir) were individually followed from lairage to post-stunning. A standardised observation protocol was used based on a literature review of the pre-slaughter factors that may influence the reaction to CO2 stunning, such as animal background, lairage conditions, handling, stunning system and conditions. Pigs lost posture 22.5 ± 0.2 s after commencement of descent of the gondola into the CO2 chamber. Latency to loss of posture was associated with farm of origin and time of day, which could be linked to various factors. Pigs that crawled or attempted to escape while in the gondola within the CO2 chamber took longer to lose posture. Crawl and escape attempts differed between abattoirs (0.6–46.2% of the pigs observed) as well as mounting other pigs (1.0–24.3%). Greater amounts of forceful contacts during handling in the race were related to more mounting in the gondola, but to less pigs crawling or attempting to escape. Mounting in the gondola was more frequent for pigs from lairage pens of mixed sexes, followed by pens of entire males and finally pens of females. Males were also twice as likely to show crawl and escape attempts than females. Gasping in the gondola was relatively frequent (63.1–81.8%) and was associated with higher activity in the lairage pen and higher skin injuries. Convulsions (60.1–69.6%) were generally observed after loss of posture. The type of CO2 system (group-wise vs single-file loading) had no significant effect on behaviour in the gondola. Nevertheless, pigs slaughtered in abattoirs with group-wise loading systems and automatic gates had lower cortisol concentrations post-stunning, which may be linked to minimal handling by stockpeople, other factors related to the systems, or differences in timing of when blood samples were taken. In conclusion, substantial variation in the reaction of pigs to CO2 stunning was observed between and within abattoirs using a uniform protocol for data collection. This variation in outcomes between abattoirs and stunning systems and the relationships between handling and behavioural outcomes indicates that improvements can be made to reduce aversive responses to CO2 stunning. In particular, avoiding mixing pigs of different sexes in lairage and aversive handling in the race may reduce aversive response to CO2 stunning.

PSI-21 Relationship of captive bolt stunning location with basic tissue measurements and exposed cross-sectional brain area in cadaver heads from market pigs

Abstract The objective of this study was to contrast the soft tissue thickness, cranial thickness, total tissue thickness, cross-sectional brain area and bolt–brain contact from the common frontal application of captive bolt euthanasia with the alternative location behind the ear in cadaver swine heads. Twenty-three cadaver heads from pigs that were approximately 136 kg and 6 mo of age were collected from a slaughter establishment following CO2 stunning and assigned to either the FRONTAL (n = 11) or CAUDAL TO PINNA (n = 12) application of the captive bolt. The soft tissue thickness was different (P &amp;lt; 0.0001) between the 2 applications (FRONTAL: 8.3±3.4 mm; CAUDAL TO PINNA: 56.5±3.4 mm). The cranial thickness was different (P &amp;lt; 0.0001) between the applications (FRONTAL: 23.4±2.9 mm; CAUDAL TO PINNA: 26.5±2.9 mm). There was a difference (P &amp;lt; 0.0001) in the total tissue thickness between the 2 applications (FRONTAL: 31.7±3.8 mm; CAUDAL TO PINNA: 73.4±3.8 mm). Cross-sectional area was calculated from images collected immediately after the heads were cut along the plane of bolt travel by bandsaw and was different (P = 0.0028) between the 2 applications (FRONTAL: 25.2±1.3 cm2; CAUDAL TO PINNA: 18.9±1.3 cm2). Bolt–brain contact was also assessed from the images, and a difference (P = 0.0360) between the 2 applications (FRONTAL: 100±10.5%; CAUDAL TO PINNA: 66.7±10.5%) was identified. The results of this study suggest that the FRONTAL application may provide a bolt path with less tissue to travel through when compared with the CAUDAL TO PINNA application for pigs of the approximate age and weight of those in this study. Ultimately, the FRONTAL location may present less risk for the captive bolt euthanasia of swine at market weight at this time. Additional refinement of the CAUDAL TO PINNA procedure and modification to the captive bolt device to penetrate to a suitable depth to ensure brain damage is recommended.

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

Simple SummaryStunning pigs with carbon dioxide gas is one of the most common methods for commercial slaughter. Carbon dioxide, however, has been shown to be aversive for pigs and causes a high degree of distress before they lose consciousness. Stunning with nitrogen gas is less aversive than with carbon dioxide, and an innovative method that delivers the nitrogen gas in high-expansion foam in a closed container could potentially improve pig welfare at stunning. Pigs were exposed to either air-filled foam, nitrogen-filled foam, or no foam in air, and the behavioural and physiological responses were assessed. The pigs did not show any strong aversive behaviours when exposed to foam, regardless of whether it was air-filled or nitrogen-filled foam. However, they seemed to avoid putting their heads and snouts into the foam, and the rate of escape attempts through the lid increased when foam levels became high. Five minutes after the nitrogen foam production started, the pigs were assessed to be in deep unconsciousness or dead. Based on the results found, stunning with the nitrogen foam technique may be a viable alternative to carbon dioxide stunning and offer improved animal welfare. Further studies are needed to assess the new method for stunning of slaughter-weight pigs.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.

Evaluation of the reliability of indicators of consciousness during CO2stunning of rainbow trout and the effects of temperature

A two-part experiment was conducted to determine whether visual indicators of consciousness such as equilibrium, eye-roll reflex and ventilation are reliable for evaluating whether CO2 stunning of rainbow trout (Oncorhynchus mykiss) is humane. In part 1, the time taken until the loss of visual indicators in rainbow trout during CO2 stunning was monitored under field conditions at 14, 8 and 2 degrees C. Here, we clearly demonstrate that it takes longer for visual indicators to disappear as temperature decreases, with significant differences in the time taken until the loss of equilibrium between 2 and 14 degrees C, and significant differences between all temperatures in the time taken until the loss of eye-roll reflex and ventilation. In part 2, rainbow trout were equipped with external non-invasive electrodes for recording EEG prior to, and following, CO2 stunning to assess the presence or absence of visually evoked responses (VERs), which are indicative of brain function and sensibility. The resulting EEG recordings during CO2 stunning at 10 degrees C demonstrated a poor relationship between visual indicators of consciousness and loss of sensibility, as VERs were present up to 3.5 min after ventilation was lost and up to 6.5 min after the fish lost equilibrium. Collectively, these results show that cold-water temperatures prolong the time taken until loss of consciousness and that visual indicators are insufficient for determining when sensibility is lost in rainbow trout during CO2 stunning.

Relationship of captive bolt stunning location with basic tissue measurements and exposed cross-sectional brain area in cadaver heads from market pigs.

The objective of this study was to contrast the soft tissue thickness, cranial thickness, total tissue thickness, cross-sectional brain area, and bolt–brain contact from the common frontal application of captive bolt euthanasia with the alternative location behind the ear in cadaver swine heads. Twenty-three cadaver heads from pigs that were approximately 136 kg and 6 mo of age were collected from a regional slaughter establishment following CO2 stunning and assigned to either the FRONTAL (n = 11) or the CAUDAL TO PINNA (n = 12) application of the captive bolt. The soft tissue thickness was different (P < 0.0001) between the 2 applications (FRONTAL: 8.3 ± 3.4 mm; CAUDAL TO PINNA: 56.5 ± 3.4 mm). The cranial thickness was different (P < 0.0001) between the applications (FRONTAL: 23.4 ± 2.9 mm; CAUDAL TO PINNA: 26.5 ± 2.9 mm). There was also a difference (P < 0.0001) in the total tissue thickness between the 2 applications (FRONTAL: 31.7 ± 3.8 mm; CAUDAL TO PINNA: 73.4 ± 3.8 mm). Cross-sectional area was calculated from images collected immediately after the heads were cut along the plane of bolt travel by bandsaw and was different (P = 0.0028) between the 2 applications (FRONTAL: 25.2 ± 1.3 cm2; CAUDAL TO PINNA: 18.9 ± 1.3 cm2). Bolt–brain contact was also assessed from the images, and a difference (P = 0.0360) between the 2 applications (FRONTAL: 100 ± 10.5%; CAUDAL TO PINNA: 66.7 ± 10.5%) was identified. The results of this study suggest that the FRONTAL application may provide a bolt path with less tissue to travel through when compared with the CAUDAL TO PINNA application for pigs of the approximate age and weight of those in this study. Ultimately, the FRONTAL location may present less risk for the captive bolt euthanasia of swine at market weight at this time. Additional refinement of the CAUDAL TO PINNA procedure and modification to the captive bolt device to penetrate to a suitable depth to ensure brain damage is recommended.

Meta‐analysis of the effect of chilling on selected attributes of fresh pork

The objective of this study was to examine the effect of accelerated chilling on ultimate pH (pHu), drip loss, color (L*a*b*), and Warner-Bratzler shear force (WBSF) of fresh pork using a meta-analytical approach. Additionally, two subgroups differentiated by stunning method (electrical vs. CO2) were included. The meta-analysis shown that accelerated chilling has an ability to improve quality of fresh pork, however, not all benefits were obviously evident. The overall effects with no overlapping zero CI provide that accelerated chilling can increase ultimate pH and prevent negative alterations in drip loss and color of pork with the evidence of heterogeneity (except pHu). Moreover, CO2 stunning favors fast chilling in development of fresh pork but undesired changes in lightness, redness, and yellowness may occur as well as relatively low shear force increase (probably not detectable by average consumer). Also, fast chilling followed by CO2 stunning has no effect on drip loss. Practical applications The study demonstrated, that accelerated chilling regime has an ability to improve quality of fresh pork, due to increase in ultimate pH and prevention of negative changes in drip loss and color. Additionally, it has been stated, that use of CO2 stunning favors accelerated chilling, however, undesired changes in lightness, redness, yellowness, and shear force may occur. The abovementioned results could provide possibility of chilling processes optimization, which should benefits development of high quality fresh pork in meat industry.

Pork quality after electrical or carbon dioxide stunning at slaughter

A total of 172 pigs were randomly allocated to two stunning treatments: carbon dioxide (CO2) and electrical stunning at a commercial abattoir. The Longissimus lumborum (LL) muscle was used to evaluate the effects of stunning methods on pork quality and financial losses of carcasses and viscera condemnation was also determined following by sanitary inspection. There was no effect due to stunning method on quality parameters (P > .137) of pH 24, drip or thaw loss, lipid oxidation, myofibrillar fragmentation index, shear force or PSE / DFD meat incidence. The LL muscle of the electrically stunned pigs had a higher L * value (P < .05), higher cooking loss (P < .001) and lower pH 45 (P < .05) compared to those stunned with CO2. CO2 stunned pigs had fewer carcasses condemned due to fractures / lesions (P < .05), hepatic and renal congestion (P < .05). CO2 stunning can be beneficial from an economic point of view because it has reduced losses through condemnation at the slaughterhouse.

Efectividad de Dos Métodos de Aturdimiento de Cerdos: Electronarcosis de Tres Puntos y Narcosis con CO2

Los objetivos de este estudio fueron evaluar y comparar la efectividad de los métodos de aturdimiento eléctrico de tres puntos (MA1) y de narcosis con dióxido de carbono (CO2) (MA2) , así como evaluar la infraestructura y manejo de los cerdos en dos plantas de sacrificio comercial de Colombia. Se realizó un estudio de corte transversal que evaluó 520 cerdos (MA1=185; MA2=335). Se estudiaron indicadores conductuales en el cajón de aturdimiento e indicadores de consciencia antes y después del desangrado. Los movimientos oculares (39%) y el parpadeo espontáneo (36.7%) fueron signos frecuentes para MA1, mientras que en MA2 se evidenció la respiración rítmica (24.1%). La efectividad del aturdimiento fue baja en las dos plantas de sacrificio antes (48.7%, 50.5%) y después del desangrado (79.5%, 37.3%). Se recomienda instaurar indicadores para evaluar de manera rutinaria la efectividad del aturdimiento, así como un programa de mantenimiento preventivo de los equipos y de capacitación continua del personal.

Investigation Into the Humaneness of Slaughter Methods for Guinea Pigs (Cavia porcelus) in the Andean Region

Guinea pigs (Cavia porcelus) are an important source of nonhuman animal protein in the Andean region of South America. Specific guidelines regarding the welfare of guinea pigs before and during slaughter have yet to be developed. This study critically assessed the humaneness of 4 different stunning/slaughter methods for guinea pigs: cervical neck dislocation (n = 60), electrical head-only stunning (n = 83), carbon dioxide (CO2) stunning (n = 21), and penetrating captive bolt (n = 10). Following cervical neck dislocation, 97% of guinea pigs had at least 1 behavioral or cranial/spinal response. Six percent of guinea pigs were classified as mis-stunned after electrical stunning, and 1% were classified as mis-stunned after captive bolt. Increased respiratory effort was observed during CO2 stunning. Apart from this finding, there were no other obvious behavioral responses that could be associated with suffering. Of the methods assessed, captive bolt was deemed the most humane, effective, and practical method of stunning guinea pigs. Cervical neck dislocation should not be recommended as a slaughter method for guinea pigs.

Effects of catching and transportation versus pre-slaughter handling at the abattoir on the prevalence of wing fractures in broilers

AbstractFractures occurring in conscious broiler chickens are painful and severely compromise animal welfare. The aim of this study was to investigate the effects of pre-slaughter handling procedures on the frequency of wing fractures. Wings were examined for fractures in 11,609 broilers, from 12 different flocks, slaughtered in two abattoirs: one using bi-phasic CO2stunning (CS); and one using electric water-bath stunning (ES). The same broilers were examined: i) in lairage, representing fractures attributed to catching and transportation; ii) after evacuation of transport containers and shackling (only ES); and iii) post-stunning. The mean frequencies of wing fractures were: in the lairage; 0.8% (CS 0.73%, ES 0.88%); after shackling prior to stunning; 2.90% (only ES); and after stunning; 2.35% (CS 1.80%, ES 2.90%). Regardless of stunning method, significantly more fractures occurred during pre-slaughter handling at the abattoirs than during catching/transportation. The difference in prevalence between CS and ES was not significant. All fractures observed in the ES occurred in conscious animals, whereas in the CS it was not possible to distinguish between fractures occurring in conscious or stunned broilers. From a welfare perspective, fractures occurring on-farm/transport result in prolonged suffering and are thus considered more serious in risk assessments of broiler welfare, even though more fractures occur at the abattoir. Monitoring of wing fractures at abattoirs should be included as an indicator of broiler welfare.

The effect of stunning methods and season on muscle texture hardness in Atlantic salmon (Salmo salar L.).

Commercially collected records of Atlantic salmon (Salmo salar L.) muscle texture hardness were used to evaluate the effect of slaughter procedures and seasonality on texture quality. A database collected by Marine Harvest® contained flesh hardness records of Atlantic salmon slaughtered at processing plants in Norway from summer 2010 to summer 2011. The fish were slaughtered either by (1) percussion followed by automated bleeding ("Percussive") or (2) live chilling with exposure to carbon dioxide (CO2 ) followed by manual severing gill arches and bleeding ("CO2 ") or (3) live chilling with exposure to CO2 followed by percussive stunning and at the end automated bleeding ("CO2 ·percussive"). Hardness in salmon muscle cutlets was measured in Newtons (N) by Materials Testing Machine Zwick 500N. The hardness in salmon varied significantly over the study period (P < 0.05, mixed effect model) and showed the softest value of 21.2 (± 0.7) Newton (N) in summer 2011 and hardest 24.1 (± 0.2) N in autumn 2010. Slaughter procedures had a significant effect on salmon muscle hardness (P < 0.05, mixed effect model), where percussion followed by automated bleeding resulted in the hardest value (24.0 ± 0.4 N) as compared with CO2 stunning (21.8 ± 0.2 N) and combination of CO2 and percussive stunning (23.1 ± 0.15 N). CO2 is suspected as a causal factor in accelerated postmortem softening of the salmon muscle. Commercial use of CO2 in combination with live chilling results in accelerated postmortem softening of the muscle tissue in salmon and should be avoided.

Identifying reasons for stun failures in slaughterhouses for cattle and pigs: a field study

AbstractChecking the effectiveness of stunning was one of the major tasks when the authors evaluated the stunning process on request of the slaughterhouse managements, retailers or competent authorities in slaughterhouses in Austria, Germany and Switzerland between the years 2000 and 2011. A total of 50 assessments in slaughterhouses for cattle and 116 for pigs were included in this study. For every assessment the technical features of the stunning device, the performance by the personnel and the clinical signs of the animals after stunning were recorded. The assessments of captive-bolt (CB) stunning were made in 1,823 cattle. For pigs, 63 assessments were carried out in electrical stunning (26 in a pen [ESP], 24 in a trap [EST] and 13 in an automatic restrainer [ESR]) and 53 assessments in CO2 stunning, covering a total of 35,220 pigs (6,855 electrically stunned and 28,365 stunned using CO2). The proportions of assessments in which there were no failures were 28% (CB), 12% (ESP), 21% (EST), 31% (ESR) and 13% (CO). The mean percentages of animals showing signs not compatible with sufficient depth of stunning were 13.5 (± 19.0)% (CB), 12.5 (± 16.4)% (ESP), 10.9 (± 11.4)% (EST), 3.2 (± 3.3)% (ESR) and 7.5 (± 13.0)% (CO2) showing a high variability between premises assessed. Stunning effectiveness for cattle was better where a chest stick was performed compared to a neck cut. For pigs, less stunning failures occurred in electrical stunning where the two-cycle method (head/heart current) was applied compared to head-only stunning, and most of the failures in CO2 stunning were due to insufficient dwell time. Reasons for the stunning failures are described and recommendations given to improve the situation.

EFFECTS OF ON‐FARM MAGNESIUM SUPPLEMENTATION THROUGH WATER ON PORK QUALITY UNDER TWO SLAUGHTER CONDITIONS

ABSTRACT The objective of this study was to determine the effects of pre‐harvest Mg supplementation and stunning method on longissimus (LM) and semitendinosus (SM) pork muscle quality. Magnesium was supplemented for 2 days in drinking water (300 ppm) before pigs were harvested at a commercial packing plant using either electrical or CO2 stunning. Magnesium supplementation did not affect (P &gt; 0.10) ultimate pH, initial fluid loss, retail display purge loss or color of the LM and SM. Pork quality was generally improved in LM and SM samples obtained from the plant using CO2 stunning as evidenced by reduced initial fluid loss (P &lt; 0.001), reduced purge loss (P &lt; 0.05) and lower L* (darker), a* (less red) and b* (less yellow) values (P &lt; 0.05) during an 8‐day retail display. Pork quality was improved when using CO2 stunning technology; however, Mg supplementation did not improve pork quality in either plant.PRACTICAL APPLICATIONSPork quality is one of the main issues for the pork industry to consider in order to remain competitive in a global market. We evaluated the supplementation of Mg through the water in collaboration with a swine production company and two large commercial packing plants. Clear differences in pork quality were evident, with the packing plant using CO2 stunning having superior pork quality compared with the plant using electrical stunning. Supplementation of Mg through water can be applied on the farm immediately at a very low cost, but was not effective in improving pork quality in two commercial packing plants under practical conditions.

Species‐specific welfare aspects of the main systems of stunning and killing of farmed Carp

Species‐specific welfare aspects of the main systems of stunning and killing of farmed Carp