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Reference intervals of intraocular pressure (IOP) are poorly described in piscine species as the factors that may influence it. Rebound tonometry was used to measure IOP in 28 adult brook trout (Salvelinus fontinalis) anesthetized in a buffered solution of 60 mg/L tricaine methanesulfonate (n = 16) or restrained with electronarcosis (n = 12) at 16 mA. There was no significant effect of the eye side, sex, fish origin, and body weight, but IOP values were significantly higher with electronarcosis (mean ± SD: 16.4 ± 5.0 mm Hg) than with immersion anesthesia (10.8 ± 3.3 mm Hg; P = 0.0017). The same restraint method should be used for comparison with previously published IOP values or when evaluating individual variations over time.

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The influence of stunning methods on the physicochemical and biochemical parameters of chicken breast meat, as indicators of bird stress, was investigated. A total of 200 Cobb broiler chickens aged from 42 to 48 d were submitted to gas or electrical stunning and slaughtered according to the standard industry practice. Pectoralis major muscles (24 h post-mortem) from broilers stunned by electronarcosis exhibited a higher L* and R-value and lower pH45min than did those from gas stunning, indicating modification of the glycolytic rate. Protease activity, measured as the myofibril fragmentation index, and the sarcoplasmic Ca2+ concentration were highest in samples from broilers stunned by electronarcosis, suggesting the greatest activity of the calpain system. In the fatty acid profile, a higher ratio of polyunsaturated fatty acids was observed in samples from broilers stunned by electronarcosis. These characteristics are related to phospholipase A2 activity, which is higher in animal stress conditions. These results indicated that the gas-stunning method produced less bird stress than electrical stunning.

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Brazil is the world's largest exporter and third largest producer of chicken meat. To maintain competitiveness, the productive sector must always be alert to consumer demands, and concern about animal welfare is a growing tendency. Aspects involving animal welfare are especially critical in the slaughter of broiler chickens. This study evaluated the stunning of chickens in a CO2- enriched atmosphere chamber to reduce bird stress, comparing with electrical water bath stunning, the most usual desensitization method used in chicken slaughter. The reaction of birds when exposed to a high CO2 concentration (30%) and to a 10% initial CO2 level, gradually elevated to 30% was compared. The effect of mixing argon with CO2 was also evaluated, always aiming to reduce the discomfort of birds. In all the gas stunning parameters evaluated, evident discomfort reactions before stunning were observed in about two thirds of the birds, but the blood levels of corticosterone and glucose, used as stress indicators, indicated that gas increased the birds' welfare. Gas exposure time required to stun the birds and time to regain consciousness after exiting the gas chamber presented a wide variation. Controlled atmosphere stunning method facilitated bird handling during slaughter, but more studies will be necessary to develop this technological alternative and make it viable for industrial use.(AU)

O Brasil é o maior exportador e terceiro maior produtor mundial de carne de frango. A fim de manter a competitividade, o setor produtivo deve estar sempre alerta às exigências dos consumidores e a preocupação com o bem-estar animal é uma tendência crescente. Aspectos envolvendo bem-estar animal são particularmente críticos no abate de frangos de corte. Este estudo avaliou a insensibilização de frangos em uma câmara com atmosfera enriquecida deCO2para reduzir o estresse das aves, em comparação com a insensibilização elétrica em cuba d'água, o método de atordoamento mais usual no abate de frangos. Foi comparada a reação das aves quando expostas a uma alta concentração de CO2 (30%) ou a uma concentração inicial de 10% de CO2, elevada gradualmente até 30%. O efeito da mistura de argônio com CO2 também foi avaliado, sempre visando a redução das reações de desconforto das aves. Cerca de dois terços das aves apresentaram reações evidentes de desconforto antes do atordoamento, em todos os parâmetros de insensibilização gasosa utilizados, porém, as concentrações sanguíneas de corticosterona e glicose, usados como indicadores de estresse, indicaram que a insensibilização com CO2 promoveu o bem-estar das aves. O tempo de exposição ao CO2 necessário para o atordoamento das aves e o tempo de recuperação da consciência após a saída da câmara de gás apresentou ampla variação. A insensibilização por atmosfera controlada de CO2 facilitou o manejo das aves durante o abate, mas serão necessários mais estudos para desenvolver essa alternativa tecnológica, de forma a torná-la viável para aplicação industrial.(AU)

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The aim of this study was to compare the effects of stunning methods [electrical stunning (ES) vs. gas stunning (GS)] on lipid oxidation in broiler meat and to investigate possible mechanisms of lipid oxidation by measuring plasma variables, muscle reactive oxygen species (ROS), and TBA reactive substance (TBARS) concentrations, muscle fiber ratios, and mRNA levels of avian uncoupling protein (avUCP), avian adenine nucleotide translocator, and avian peroxisome proliferator-activated receptor-γ coactivator-1α (avPGC-1α). Arbor Acres broilers (n = 36) were not stunned (control) or were exposed to the following stunning treatments: 40% CO(2) + 21% O(2) + N(2); 60% CO(2) + 21% O(2) + N(2); 35 V, 47 mA, 400 Hz; 50 V, 67 mA, 160 Hz; and 65 V, 86 mA, 1,000 Hz. The ROS level in tibialis anterior (TA; P < 0.05) and the TBARS concentration in pectoralis major (PM; P < 0.01) were decreased in the GS groups compared with the ES groups at 45 min postmortem. However, the TBARS concentrations at 24 h postmortem in the PM and TA groups were not affected by stunning method (ES or GS). Compared with ES, GS caused greater expression of avUCP mRNA (1.47-fold in PM, and 2.41-fold in TA) and avPGC-1α mRNA (1.42-fold in PM, and 2.08-fold in TA). In conclusion, the upregulation of avUCP and avPGC-1α reduced ROS accumulation and lipid oxidation at 45 min postmortem in the skeletal muscles of broilers stunned with hypercapnic moderate oxygenation GS. However, these changes were not sufficient to cause a difference in meat lipid oxidation at 24 h postmortem between broilers stunned with hypercapnic moderate oxygenation GS and those stunned with low-current, high-frequency ES.

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This study was designed to determine the effect of electrical stunning variables (low currents and high frequencies) on meat quality, glycolytic potential, and blood parameters in broilers. A total of 54 broilers were stunned with 9 electrical stunning methods for 18 s using sinusoidal alternating currents combining 3 current levels (35 V, 47 mA; 50 V, 67 mA; and 65 V, 86 mA) with 3 frequencies (160, 400, and 1,000 Hz). Samples for meat quality were obtained from the pectoralis major (PM) and musculus iliofibularis (MI), and samples for glycogen metabolism were taken from the PM and tibialis anterior muscle at 45 min postmortem. The use of high frequency reduced the shear value in PM (400 and 1,000 Hz vs. 160 Hz; P < 0.01) and cooking loss in MI (1,000 Hz vs. 160 and 400 Hz; P < 0.01). The shear value of PM decreased at high frequency (400 and 1,000 Hz) when current was high (50 V, 67 mA and 65 V, 86 mA; P < 0.01) but increased at high frequency (1,000 Hz) when current was low (35 V, 47 mA). Stunning with 1,000 Hz (vs. 160 Hz) caused low glycogen and glycolytic potential in PM (P < 0.05). Plasma corticosterone decreased (P < 0.05) at high currents (≥50 V, 67 mA) but was not affected by changes in frequency. Electrical current interacted with frequency in plasma glucose, redness 24 h postmortem, shear value (PM), pH 24 h postmortem (MI), and glycolytic potential (tibialis anterior; P < 0.05). This study indicated that high stunning frequencies (400 and 1,000 Hz) may improve meat quality without aggregating stress when the current was not too low (>50 V, 67 mA).

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The aim of this study was to compare the effects of gas stunning (GS) and electrical stunning (ES) on energy metabolism in Arbor Acres broilers. Thirty-six birds were slaughtered without stunning (control) or after stunning with the following treatments: 40% CO(2) + 21% O(2) + N(2) (G40%); 60% CO(2) + 21% O(2) + N(2) (G60%); 35 V, 47 mA, 400 Hz (E35V); 50 V, 67 mA, 160 Hz (E50V); and 65 V, 86 mA, 1,000 Hz (E65V). Muscle samples were obtained from the pectoralis major (breast) and tibialis anterior (leg) muscles in ambient temperature within 45 min postmortem and stored at -80°C. Blood pH decreased consistently with GS (G40% and G60%) compared with ES and the control (P < 0.01). No consistent differences were observed between GS and ES in the plasma variables, glycolytic potential, adenosine phosphates, or fiber intensities. Plasma lactate increased with G40% and E35V (P < 0.05), whereas plasma uric acid and urea nitrogen increased with E35V (P < 0.05) compared with the control. Compared with the control, the intensity of type IIB fibers decreased in broilers stunned with E35V and E50V (P < 0.05) and glycolytic potential increased (P < 0.01) with G60% in the breast muscle and decreased (P < 0.01) in the leg muscle with all the stunning treatments except for E50V. Energy decreased (lower adenosine triphosphate, higher adenosine monophosphate, and adenosine monophosphate:adenosine triphosphate ratio, P < 0.05) in breast muscle with G40% compared with ES at high currents (E50V and E65V). However, the adenosine phosphates with GS were not significantly different (P > 0.05) from ES at low current (E35V) in either breast or leg muscle. In conclusion, no essential difference in energy metabolism was found in broilers stunned with ES and GS when ES was based on low current and high frequency and GS was based on hypercapnic moderate oxygenation. This study indicated that G40% was potentially a superior stunning variable.

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Four groups of Manchega breed suckling lambs, stunned with different CO(2) concentrations and exposure times (G1: 80% CO(2) 90s; G2: 90% CO(2) 90s; G3: 90% CO(2) 60s; G4: 80% CO(2) 60s) plus an electrically stunned control group (G5), were used to determine (1) the physiological responses (hormonal, haematological and biochemical blood parameters) of animals after stunning and (2) the stunning effectiveness in each group. No significant differences were found among groups for hormonal levels. Within haematological parameters, significant differences among groups were only found for haemoglobin (P<0.05) and leucocytes (P<0.01), with lowest values in both groups stunned with 90% CO(2). There were significant differences between groups (P<0.01) for urea and total protein, creatinine and LDH (P<0.05; lowest and highest, respectively, for G1) and for sodium (P<0.001; lowest in G3). Stunning effectiveness was highest in G5, G3 and G1 groups and lowest in G2 and G4 (100%, 90%, 89%, 50% and 43%, respectively). According to discriminant analysis, sodium, leucocytes and creatinine marked the differences among stunning groups.

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The study hypothesis was that pre-slaughter handling is not conducted in such a way that pigs can be considered humanely slaughtered, nor is it conducive to promoting those properties of fresh meat that could enhance pork quality. The 1st phase of the investigation was aimed at confirming the present compliance level within the prescribed norms. To this end the importance of stunning induction requirements for effective electrical stunning, the welfare implications relating to the pre-slaughter handling of pigs and the stunning and sticking techniques were investigated. Pre-slaughter welfare of the pigs at the abattoir was found to be influenced at the outset by the origin and type of pig slaughtered, the daily throughput range of pigs and the type of abattoir involved. A disappointing pre-arrival aspect was that deficiencies in road motor vehicles were observed while off-loading pigs. Through poor design or lack of maintenance, another factor that hampered free movement of pigs was the off-loading facilities. The nature of animal behaviour in the pens, in the passages and when going into the stunning area was directly related to the pig handling efficiency and to the nature and extent of design and maintenance problems with equipment. None of the abattoirs had a well designed in-feed to a well planned stunning area/facility, and a very high level of pig pre-slaughter stress prevailed. The optimum position of the electrodes is virtually impossible to attain under practical conditions and the practice of repeat application of electrical stunning is common. Of the total sample size (n = 1175), 34% were difficult to shackle, 90% of these being from the abattoirs tending to slaughter more routinely a wide range of different sized pigs. In this survey 149 pigs (13%) required more than a single sticking attempt to bleed out properly, considerably higher than in other published reports.

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The first experiment was conducted to determine the effects of varying voltage, 20, 40, 80, and 100 V at 60 Hz, on stunning efficiency, blood loss, and carcass defects. In the second experiment, the same parameters were evaluated to determine the effects of varying frequency, 60, 200, 350, 500, and 1,000 Hz at 40 V. A control group for both experiments was not stunned. At 40V, 30 to 50 mA, 90% of the birds were unconscious, as shown by no response to comb piercing, and blood loss was maximized (55.3%). When varying the stunning frequency, maximum blood loss (73.1%), 90% of the birds were unconscious, and minimum carcass defects were observed at 1,000 Hz, 40 V. In the third experiment, birds were stunned at 40 V, 1,000 Hz and deboned immediately after defeathering (hot boning) and chilled or deboned after passing through all stages of a commercial abattoir operation (conventional boning). Control lots were unstunned and followed normal abattoir stages. Average shear value was significantly lower for stunned compared to unstunned birds (6.0 vs. 7.1 kg/g), although tenderness scores, as measured by a trained panel, were not significantly different (6.6 for stunned birds vs. 6.1 for unstunned). Scores for juiciness were also not significantly different (5.5 for stunned vs. 5.8 for unstunned). Average shear value was also significantly lower for conventionally boned birds (5.2 kg/g) than for hot boned birds (7.9 kg/g). Sensory analysis confirmed the shear value results. Conventionally boned breasts had an average tenderness score of 7.4 vs. an average of 5.3 for hot boned breast. No statistical differences were observed with respect to juiciness, although a score of 6.2 was observed for conventionally boned breast meat vs. a score of 5.1 for hot boned breast meat.

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The purpose of this research was to compare the effectiveness of ring block anesthesia (LA) and electroanesthesia (A) for antler removal in elk given a long-acting tranquilizer to remove stress from restraint. Thirty-two male wapiti were given 1 mg/kg body weight of zuclopenthixol acetate; the next day, they were restrained in a hydraulic chute, provided with electroanesthesia or a lidocaine ring block, and had their antlers removed. Behavioral response to antler removal was scored. Significantly more (P = 0.032) animals responded to antler removal in the EA group. Heart rates and arterial pressures were measured by a catheter connected to a physiological monitor. Heart rate increased significantly over time with EA, but not with LA. Heart rate increased from baseline significantly more in the EA group immediately prior to antler removal (P = 0.017), immediately post antler removal (P = 0.001), and at 1 min post antler removal (P = 0.037). It was concluded that EA is not as effective a method of anesthesia as is LA for antler removal.

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Pigs from four farms (two producing 'easy' and two 'difficult to handle' pigs) were slaughtered at two abattoirs, each with two slaughter handling systems, so that 25 pigs of each behavioural type were slaughtered by all four handling systems on each day; there were 16 replicates (3200 pigs) in total. The pigs at abattoir X were electrically stunned, either in a floor pen holding five pigs or in a race-restrainer. At abattoir Y the pigs were stunned either in a floor pen holding five pigs or in a dip-lift carbon dioxide stunner. The following measurements were made: hot carcase weight and backfat thickness at P2, degree of rigor mortis 35 minutes post mortem, skin blemish, pH and muscle reflectance in the m longissimus dorsi at 60 minutes and 18 hours post mortem, and pH and muscle reflectance in the m adductor at 18 hours post mortem. At abattoir X, the pigs slaughtered in the race-restrainer had heavier carcases (74.0 kg vs 73.0 kg, P < 0.05), developed rigor mortis more rapidly (8.1 mm vs 7.3 mm, P < 0.01), had more skin blemish (2.8 vs 2.7, P < 0.01), paler m longissimus dorsi muscles after one hour (15.7 vs 13.9, P < 0.01) and 18 hours (27.8 vs 26.6, P < 0.05), and paler m adductor muscles (24.5 vs 22.7, P < 0.001) after 18 hours. At abattoir Y, the pigs handled through the floor pen system had more skin blemish (2.7 vs 2.6, P < 0.05) and a tendency to develop rigor mortis more quickly (6.11 vs 5.32, P = 0.089).(ABSTRACT TRUNCATED AT 250 WORDS)

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Recent changes in the Inspection Regulations have made it possible for practising veterinarians to stun and bleed animals on the farm. The Health and Welfare Law stipulates, amongst other things, that it is not permissible to put the welfare of the animal to disadvantage. Mechanical methods are the most suitable for use on farms, and of these methods the humane (cattle) killer is clearly to be preferred. The humane killer should be placed frontally, where the imaginary lines between the eyes and ears cross, or occipitally above the brain. A firearms license is needed. As many practising veterinarians are not experienced in the stunning and bleeding of animals, it is advised that these actions be left to emergency butchers.

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

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Some effects of alternating current electronarcosis and of rectified current electronarcosis on C. carpio were investigated. In all instances recovery from narcosis was accompanied by convulsive spasms. Haemorrhaging of the gills was also observed to occur. Carp do not appear to be suitable candidates for electronarcosis.

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The narcotizing potential of various rectified current configurations on Oreochromis mossambicus was investigated. A 50 Hz, 200 Vp. half-wave rectified current, applied for 30 s, was found to be a suitable configuration for electronarcosis.

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Ten adult Holstein cows were used in an experiment to determine whether the induction of electroimmobilization was a noxious event. The cows were halter trained and accustomed to being led into a set of stocks. The time taken for the cattle to walk the last ten metres into the stocks was recorded. The heart rate of the cow was recorded for a three minute period prior to a ten second exposure to a high pitched sound (the conditioning stimulus). Measurements were collected for three repetitions and then the cows were assigned to two groups of five. One group was immobilized for 30 seconds using a commercial electroimmobilizer, the other group was not treated. This procedure was repeated ten times over a period of eight days. The cows were then exposed to the conditioning stimulus and their response observed. The treated group took significantly (P less than 0.05) longer to get into the stocks and the regression slopes for heart rate were significantly different from the control group. The treated cows responded to the conditioning stimulus at five and nine months after the end of the conditioning period. Adult Holstein cows regarded electroimmobilization as a noxious event and were very strongly conditioned to this stimulus.

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The studies were carried out on 24 healthy young bulls divided into 2 groups. 12 calves, in group I were injected intravenously with 10% solution of gwajamar, dissolved in 10% glucose. Then the electric current of 700 Hz, 90-100 mA and 20 V was switched on. In group II, the mixture of 10% gwajamar, 0.6% thiopental dissolved in 10% glucose was administered intravenously. The studies performed showed that sinusoidal current of 90-110 mA, 700 Hz and about 20 V applied in calves, using needle electrodes on both temples after the administration of gvajamar causes general electric anesthesia during the time of current flow. The narcosis lasted 15 min. when the mixture of 10% gwajamar and 0.6% thiopental was used. During electric anesthesia the reduction in the number of breaths and pulse rate was statistically significant. The content of hemoglobin and lymphocytes in leukograph was decreased as well while metameric neutrophils were raised. In thiopental anesthesia, the pulse rate and the number of breaths were increased (statistically significant) but the number of erythrocytes decreased. The changes in leukograph were observed which were similar to those in the electric anesthesia group. In both kinds of anesthesia hypocalcemia, hypomagnesemia and hypophosphatemia were revealed. More advanced changes (hypocalcemia and hypophosphatemia) were found in electronarcosis. In the above mentioned kinds of anesthesia, the changes and shifts in spite of their statistical significance were temporary and with an exception of hypomagnesemia they reached the values close to the standard by the end of 7th day.

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Since the end of the last century many investigations with electroanaesthesia have been performed in animals and man. The interest in this method of anaesthesia has emerged because anaesthesia is achieved immediately after the onset of the current and the recovery is very rapid after cutting off of the current. Recently a battery operated apparatus became available (Feenix Stockstill) for application of electroanaesthesia and electroimmobilisation under field conditions, and an experiment was conducted with 10 calves, 10 sheep, and 9 pigs, which were equipped with EEG and ECG electrodes, to check the analgesic and other practical effects of the apparatus. The duration of current administration was 20 minutes. Three animals of each species were used as control animals. In all animals, during administration of the current, the breathing movements appeared to be somewhat impaired. The rectal body temperature, the plasma cortisol level, and the pulse rate were raised during the current administration. Moreover, the pulse rate was irregular. The corneal reflex remained positive in all animals, and the reaction to painful stimuli was positive in 15 out of 29 experimental animals. The rectal body temperature, pulse rate, and plasma cortisol level remained constant in the control animals. Before and after administration of the current the electroencephalogram recordings were similar, except in one calf and one sheep, both of which showed patterns suggesting a decreased consciousness. The electrocardiogram recordings showed pronounced changes in cardiac activity. In one pig the heart activity stopped some minutes after the onset of the current. Changes in the electroencephalogram and electrocardiogram were not observed in the control animals during their treatment.(ABSTRACT TRUNCATED AT 250 WORDS)

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