False aneurysms in carotid arteries of cattle and water buffalo during shechita and halal slaughter

It has previously been shown that the cattle brain is supplied with blood via a basi-occipital plexus, in addition to branches from the carotid and basilar arteries. In addition it has been shown during conventional stunning and slaughter that the carotid arteries in cattle can develop false aneurysms at their severed ends and this can curtail exsanguination. This investigation examined whether false aneurysms can occur during religious slaughter, and during bleeding following electrical stunning that simultaneously induced a cardiac arrest. The prevalence of large (>3 cm outer diameter) false aneurysms in cattle carotid arteries was 10% for both shechita and halal slaughter. The prevalence of animals with bilateral false aneurysms (at least 2 cm in one artery and at least 3 cm diameter in the opposite artery) was 7% and 8% for shechita and halal slaughter, respectively. No false aneurysms occurred during bleeding in cattle that were electrically stunned and simultaneously developed a cardiac arrest. The combination of false aneurysms and collateral routes to the brain present a risk of sustained consciousness during religious slaughter in cattle.     

Arrested blood flow during false aneurysm formation in the carotid arteries of cattle slaughtered with and without stunning

The time to onset of arrested blood flow and the size of false aneurysms in the severed carotid arteries were assessed in 126 cattle during halal slaughter without stunning. Thirty six cattle (29%) showed early arrest of blood flow. In 6%, both the left and right carotid arteries in the same animal stopped bleeding before 60 s had elapsed following the neck cut. The time to early arrested blood flow was on average 21 s, and this was accompanied by enlargement with false aneurysms which occluded the arteries. In the arteries which were still bleeding at 60 s after the neck was cut the artery size was normal. Based on comparative data from different slaughter premises it appeared that making the cut in the neck at the first cervical vertebra instead of the second to fourth cervical vertebrae reduced the frequency of false aneurysm formation and early arrested blood flow. This was confirmed in a separate controlled trial where 100 cattle were stunned with a captive bolt and the arteries were examined following neck cutting at either the C1 or C3 positions.     

A comparison of the effects of electrical, captive bolt or percussion stunning on the incidence of blood splash in lambs

Three-hundred-and-three lambs were divided into three equal groups. Half the lambs in each group were not weaned before slaughter and the weaned half were slaughtered a week later. Lambs in one group were head stunned electrically before slaughter; in the second group lambs were stunned with a captive bolt pistol and in the third group they were percussion stunned before slaughter. Carcasses, gall-bladders, hearts and duodenums were inspected for blood splash after slaughter. A few small haemorrhages were detected in 57% of the electrically stunned lambs, in 30% of the captive bolt stunned lambs and in only 16% of the percussion stunned animals. Although no splash of commercial significance was found in any carcass, 25% of the electrically stunned lambs had detectably splashed carcasses, whilst only 1% of percussion-stunned lambs had splashed carcasses with captive bolt stunned lambs being intermediate in carcass splash incidence. These results show that stunning method affects the incidence of blood splash.     

Animal welfare at markets and during transport and slaughter

This review highlights some recent developments in our understanding of stress and physical injuries that occur before and during transport to slaughter, during handling at livestock markets, and at the time animals are put-up for slaughter within abattoirs. Stress in pigs during transfer to the stunning point within the abattoir has important effects on meat quality, and there is growing evidence that strenuous exercise or CO(2) stunning can contribute to oxidative rancidity in pigs, poultry and fish. In the EU, putting cattle through a crush in order to check that their eartag numbers correspond to their passport numbers is imposing additional stress, and there are reports that it is leading to greater hide contamination with Escherichia coli O157. Recent developments in stunning and slaughter include a better understanding of the causes of variation in captive bolt gun performance, the effectiveness of poll instead of frontal shooting in water buffalo, the prevalence of false aneurysms in carotid arteries during shechita and halal slaughter, and the stress effects of CO(2) stunning in fish. Stunning pigs with 90% CO(2) leads to less PSE meat than 80% CO(2). There have been concerns about the physical activity that cattle show following electrical stunning with an electrically induced cardiac arrest, and with electrical stunning using DC waveforms in broiler chickens. There is also growing concern about the hygiene problems that exist in wet markets, where animals are slaughtered alongside meat that is on display to customers.     

Stunning and animal welfare from Islamic and scientific perspectives

The transformation of an animal into pieces fit for human consumption is a very important operation. Rather than argue about halal slaughter without stunning being inhumane or stunning being controversial from the Islamic point of view, we discuss slaughter, stunning and animal welfare considering both Islamic and animal welfare legislation requirements. With the world Muslim population close to two billion, the provision of halal meat for the Muslim community is important both ethically and economically. However, from the animal welfare standard point of view, a number of issues have been raised about halal slaughter without stunning, particularly, about stressful methods of restraint and the latency of the onset of unconsciousness. This paper sets out to, discuss the methods of stunning that are acceptable by Islamic authorities, highlight the requirements for stunning to be acceptable in Islam and suggest practical ways to improve the humanness of slaughter.     

Influence of gas stunning and halal slaughter (no stunning) on rabbits welfare indicators and meat quality

This study assessed the effect of gas stunning which has not been conducted until now in comparison with slaughter without stunning on the welfare and meat quality of rabbits. Eighty male New Zealand White rabbits were divided into two groups of 40 animals and subjected to either halal slaughter without stunning (HS) or gas stunning using 61.4% CO₂, 20.3% oxygen and 18.3 % nitrogen (GS). Analysis of the sticking blood revealed that both slaughter procedures caused a substantial increase in the levels of catecholamines, hypercalcemia, hyperglycemia, lactic acidemia and an increase in enzyme activities. The ultimate pH of the Longissimus lumborum muscle did not differ between treatments. GS exhibited higher lightness and cooking loss, and lower glycogen and MFI than HS. This indicates that both GS and HS can be significant stressors although the amount of stress may be below the threshold to negatively affect rabbit meat quality.     

致昏电压对兔肉品质的影响研究

采用100、75、65、55V和人工致昏(对照组)的宰杀方式,研究其对兔肉品质的影响,结果表明:不同致昏电压对兔肉pH值的影响差异不显著(p>0.05),只有75V致昏组与100V致昏组间宰后1h的背最长肌pH值差异显著(p<0.05);宰后1h,不同致昏电压对兔背最长肌的肉色亮度L*值、红度a*值、黄度b*值和后腿肉的L*值、a*值的影响差异不显著(p>0.05);宰后24h,75V致昏组的肌肉颜色鲜红,而人工致昏组和100V致昏组的肌肉颜色较苍白;100V致昏组的滴水损失最大,为3.738%,而75V致昏组的最小,为2.420%;蒸煮损失最大的为100V致昏组,最小的为55V致昏组,其次是75V组;肌肉嫩度最好的是75V致昏组,最差的是人工致昏组。     

Behavioural and physiological reactions of cattle in a commercial abattoir: relationships with organisational aspects of the abattoir and animal characteristics

Behavioural, physiological and metabolic reactions of cattle to handling and slaughter procedures were evaluated in a commercial abattoir, from arrival until slaughter. Different genders or breeds were not subjected to the same procedures due to abattoir equipment or organisational aspects of the abattoir. Reactions to similar slaughter procedures varied according to animal characteristics and could have consequences for subsequent handling procedures. Factors that appeared to cause handling problems and vocalisation were excessive pressure during restraint, and distractions in the corridor such as noise, darkness, seeing people and activity. Post-mortem muscle metabolism depended on slaughter procedures. Following stunning or halal slaughter, some animals showed head rising movements despite the abolition of the corneal reflex, suggesting that head rising is not always indicative of consciousness. Overall, this study presents concrete data on how different types of cattle may react to slaughter procedures with a direct interest for the abattoir itself but also for scientific purposes.     

The effects of electrical stunning and percussive captive bolt stunning on meat quality of cattle processed by Turkish slaughter procedures

The effects of electrical and percussive captive bolt stunning both on initial and up to 14 days post mortem meat quality of Friesian young bulls were studied. The first group (NS; n=10) were slaughtered without stunning under Turkish slaughter procedure (these animals were slaughtered under conditions acceptable to the appropriate ethics committee) in a modern abattoir. In the second group (ES; n=10) animals were electrically stunned. In the third group (PS; n=10) animals were stunned with percussive captive bolt. Meat quality was assessed by examining muscle glycogen concentration, pH and WHC. Also cooking loss, texture parameters and consumer sensory properties were assessed at 24 h, 4, 7 and 14 days post mortem. Meat colour as L^*, a^*, b^*, C^*, h^* values were evaluated at 0, 48 h, 3, 5, 7, 9 and 14 days post mortem. Pre-slaughter handling affected muscle glycogen concentration (P<0.05). Animals in electrical and percussive captive bolt stunned groups had higher muscle glycogen concentrations compared to animals in the non-stunned group (P<0.05). Although pre-slaughter handling did not affect significantly pH_{24 h} and WHC, differences were significant for cooking loss, colour coordinates and texture parameters at some storage times. For all sensory attributes (odour, flavour, tenderness and overall acceptability) at all ageing periods (24 h, 4, 7 and 14 days) the percussive stunned (PS) group was significantly superior to the non-stunned (NS) group. The electrically-stunned (ES) group also tended to be superior to the NS group although not all differences were statistically significant. These results indicate that percussive captive bolt stunning of cattle improved meat quality compared with cattle electrically stunned using head only tongs and those non stunned under approved Turkish slaughter procedure.     

Effect of electrical stunning method and cardiac arrest on bleeding efficiency, residual blood and blood splash in lambs

Five hundred and fifty-nine Southdown-Romney cross lambs were used in a comparison of the efficiency of bleeding animals slaughtered by one of three different methods. The main comparison was between spear stuck lambs that had been electrically stunned by either head application or a head-back method. In addition, some unstunned lambs were slaughtered by the traditional New Zealand gash cutting method, no longer used by industry but known to produce well bled carcasses. There was no difference in blood obtained during a 120-s bleeding time between the unstunned and head stunned lambs. For the head-back stunned lambs little, if any, of the blood not collected at bleeding remained in the carcass after dressing despite the fact that these animals released only 46% of the weight of blood recorded from the head stunned lambs during the bleeding time. The head-back stunning method markedly decreased the incidence of carcass blood splash in comparison with the splash observed in lambs stunned by the head application method.     

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

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

Advances in the industrial production of halal and kosher red meat

The worldwide volume and value of trade in halal and kosher meat and co-products are huge. Muslim countries alone consumed meat estimated to be worth USD 57.2 billion in 2008. The halal and kosher principles that govern the production of red meat have many similarities, as well as some fundamental differences. Perhaps the most significant difference is that at the time of slaughter, the animal needs only to be alive to meet the minimum halal requirement, but must be both alive and conscious for kosher. It is for this reason that reversible pre-slaughter stunning is acceptable only for halal meat, although a compromise form of post-slaughter stunning is now considered kosher in some countries. Extensive research on animal physiology and welfare has characterised and optimised the methods for stunning livestock, and enabled advancement in associated technologies. This forms the basis for harmonising the religious and secular requirements for the protection of animal welfare at slaughter. These technologies and the associated processing practices for the industrial production of halal and kosher meat are reviewed in this paper.     

Relationships between time of stunning and time of throat cutting and their effect on blood pressure and blood splash in lambs

A study based on 84 electrically stunned lambs showed that those gash stuck (transverse incision of the extended neck which almost simultaneously severs the trachea, oesophagus, common carotid arteries and jugular veins and the spinal cord at the occipito-atlantal junction; Blackmore & Newhook, 1976) immediately after removal of the electrical applicator had a lower incidence of blood splash than lambs gash stuck 5-8 sec r stunning. Lambs whose throats were cut immediately before the application of the electrical current had the lowest incidence of blood splash. None of the splash observed was of commercial significance. Systolic blood pressure recordings were made on a further 12 lambs of a similar age, 10 of which were electrically stunned and two shot with a captive bolt pistol. Blood pressure changes observed were related to the blood splash results obtained in the first trial. Electrical stunning raised blood pressures to an average of 3·5 times normal in lambs allowed to recover from stunning. A further seven young unweaned lambs which were electrically or percussion stunned showed a similar pattern of blood pressure change to that reported for older lambs following stunning, except that lower maximum pressures were reached. The authors interpret the results of the present trials as indicating that the application of electrical current to the heads of lambs results in damage to small vessels prior to the elevation of blood pressure. This damage may become apparent in the dressed carcass and organs as small haemorrhages. The subsequent rise in blood pressure following stunning then exacerbates the leakage of blood into tissues and it becomes more apparent in the form of discrete haemorrhages or blood splash.     

屠宰应激对宰后猪肉保水性的影响

本文研究了电击晕和二氧化碳致晕对杜大长三元杂交猪和三门峡黑猪的应激效应及宰后肌肉保水性的影响。结果表明:与电击晕相比,二氧化碳致晕使得杜长大三元杂交猪和三门峡黑猪血液中的乳酸(LAC)、乳酸脱氢酶(LDH)、肌酸激酶(CK)、肌酐(CRE)、皮质醇(COR)含量显著降低(P0.05);且杜长大三元杂交猪和三门峡黑猪宰后p H45min值较高,差异显著(P0.05),宰后24 h汁液损失率(降低1.17%和0.59%)、蒸煮损失率(降低3.09%和3.56%)及解冻损失率(降低0.55%和0.29%)显著降低(P0.05);剪切力显著降低0.71 kg及0.66 kg(P0.05)。此外,杜长大三元杂交猪的抗应激能力较差,其宰后肌肉保水性显著低于三门峡黑猪(P0.05)。LF-NMR研究表明,二氧化碳致晕能够显著降低解冻后肌肉中的自由水含量(降低32.24%和28.92%),抑制了不易流动水向自由水的"态变"。因此,在实际生产中采用二氧化碳致晕能降低生猪屠宰应激,提高肌肉保水性。     

Prevalence of ballooning of the severed carotid arteries at slaughter in cattle, calves and sheep

Previous work in calves indicated that ballooning of the severed arteries is a potential concern in animals receiving a reversible stun before slaughter, and in animals not stunned before slaughter, as it could extend the duration of brain function before the animals die. This study determined the prevalence of ballooning of the carotid arteries in a total of 987 cattle, calves and lambs at slaughter. The severed ends of the carotid arteries were examined by palpation. The prevalence of ballooning that was 3 cm or more in diameter, was 16%, 25% and 0% for cattle, calves and lambs, respectively. Artery sections were taken from a sample of large cattle and examined histologically. In ballooned arteries there was coagulated blood between the outer surface of the artery and the inner aspect of the connective tissue sheath surrounding the artery, suggesting the formation of a false aneurysm in the ballooning phenomenon.     

Prevalence of ballooning of the severed carotid arteries at slaughter in cattle,calves and sheep

Previous work in calves indicated that ballooning of the severed arteries is a potential concern in animals receiving a reversible stun before slaughter, and in animals not stunned before slaughter, as it could extend the duration of brain function before the animals die. This study determined the prevalence of ballooning of the carotid arteries in a total of 987 cattle, calves and lambs at slaughter. The severed ends of the carotid arteries were examined by palpation. The prevalence of ballooning that was 3 cm or more in diameter, was 16%, 25% and 0% for cattle, calves and lambs, respectively. Artery sections were taken from a sample of large cattle and examined histologically. In ballooned arteries there was coagulated blood between the outer surface of the artery and the inner aspect of the connective tissue sheath surrounding the artery, suggesting the formation of a false aneurysm in the ballooning phenomenon.     

Effects of normal, light/normal or double stunning on the incidence and severity of blood splash in lambs

One-hundred-and-twenty lambs were divided into three equal groups which were subjected to head electrical anaesthesia before bleeding. The normal group was stunned and bleeding was initiated within 5 to 8 s. The light/normal group was partially stunned and then treated as the normal group after a delay of 10s. The double stunned group was electrically anaesthetised, allowed to recover and then restunned and bleeding was initiated within 5 to 8 s. The light/normal and double stunning procedures increased the incidence and severity of carcass blood splash compared with normal stunning but the increase was less than that sometimes seen in normal mobs of head-stunned sheep and which occurs for unknown reasons.     

The influence of slaughter method on the residual blood content of meat

The effect of slaughter method on the residual haemoglobin content of the M. longissimus dorsi and the amount of blood lost at exsanguination of sheep was investigated. The influence of stunning method (electrical, 90 V, or captive bolt pistol), pithing and bleeding-out position were examined. Sheep bled lying lost more blood than those bled hanging and electrically-stunned animals lost more blood than those stunned with a captive bolt pistol; pithing had no effect. The residual haemoglobin content of the muscle did not vary significantly between methods and there was no relationship between it and the amount of blood lost at slaughter.     

The effect of electrical stunning and slaughter on the electroencephalogram of sheep and calves

To study the application of electroencephalography (EEG) for the assessment of insensibility during stunning and slaughter, recordings were made on sheep that were slaughtered by throat cutting, electrically stunned head-only and allowed to recover, electrically stunned head-only followed by throat cutting or electrically stunned head-to-back. The same experiments were repeated on calves (1–6 weeks old) except some calves were stunned and allowed to recover before final stunning and throat cutting.

After the throat cut, sheep became insensible (i.e. EEG < 10 μV) at 8–22 s but the calf EEG did not fall below 10 μV until 79 s after the cut. With head-only stunning/recovery, high-amplitude EEG waves (electroplectic fit) continued for 47 s (sheep) and 33 s (calves) post stun. A quiescent period followed, which then developed into a period of moderate-amplitude EEG signals, so that, at 50 s post stun, the EEG usually exceeded 50 μV and often had bursts of 150 μV activity. After head-only stunning/throat cutting, the electroplectic fit was shortened (39 s in sheep, 23 s in calves) and the EEG took at least 50 s to fall below 10 μV. With sheep stunned head-to-back, which stops the heart, and thus should cause immediate, permanent insensibility, the EEG took longer to fall below 10 μV (52 s) than after throat cutting. These results suggest that electrical stunning of sheep and calves causes a prolonged increase in the post-stun EEG amplitude. Therefore, during slaughter, stunned animals have larger amplitude EEG signals than unstunned animals, and EEG criteria developed for judging the sensibility of unstunned animals cannot be used for those that are electrically stunned.     

Electrical stunning by direct brain stimulation in pigs

The effects of electrical stunning of slaughter pigs by electrodes shot into the brain, on sensibility and on the incidence of haemorrhages in the shoulder postmortem, were studied.

To determine the efficiency of this method 37 slaughter pigs were equipped with EEG (electroencephalograph) and ECG (electrocardiograph) electrodes and stunned twice via the EEG electrodes. In the first experiment the pigs were stunned with 25 V and in the second with 25 V followed by a relaxation current. The day after slaughter the shoulders were scored for haemorrhages. Under more practical conditions three groups of 10 pigs each were electrically stunned via electrodes shot into the brain using 25, 50 or 75 V, followed by a relaxation current. The day after stunning the shoulders were scored for haemorrhages.

The pigs did not react to shooting electrodes frontally into the head. After stunning all animals showed a general epileptiform seizure. However, after the second stun the tonic and clonic muscle cramps were impaired. The heart rate increased significantly (P < 0·01) after stunning, and extra systolae and irregular heart rates were observed. In the shoulders of 27% of the carcasses no haemorrhages were found and in the remainder only minor haemorrhages were seen. Under practical conditions a voltage of 87(± 2) V and a current of 511(±20) mA seemed to be necessary for an effective stun. When lower voltages were applied fewer carcasses with shoulder haemorrhages were found.

It may be concluded from these experiments that 25 V (134 mA; 150 Hz) is sufficient for effective stunning of slaughter pigs when electrodes are in direct contact with the brain. But as the optimum position of the electrodes may not be reached under practical conditions a voltage of approximately 90 V (550 mA; 150 Hz) is recommended. After this stunning method only a few haemorrhages were observed in the shoulders.