Large numbers of decapod crustacea are farmed and harvested globally for human consumption. Growing evidence for the capacity of these animals to feel pain, and therefore to suffer, has led to increased concern for their welfare, including at slaughter. In New Zealand, decapod crustacea are protected by animal welfare legislation. There is a requirement that all farmed or commercially caught animals of these species killed for commercial purposes are first rendered insensible. The aim of this study was to evaluate the efficacy of the Crustastun™, a commercially available bench-top electrical stunner, in two commercially important New Zealand crustacean species; the rock lobster (Jasus edwardsii) and kōura (freshwater crayfish [Paranephrops zealandicus]). Animals were anaesthetised via intramuscular injection of lidocaine and instrumented to record the electrical activity of the nervous system, prior to being stunned according to the manufacturer’s instructions. Stunning efficacy was determined by analysing neural activity and observing behaviour post stunning. All ten P. zealandicus and three J. edwardsii appeared to be killed outright by the stun. Of the remaining J. edwardsii, six exhibited some degree of muscle tone and/or slow unco-ordinated movements of the limbs or mouthparts after stunning, although there was no recovery of spontaneous or evoked movements. One J. edwardsii was unable to be stunned successfully, likely due to its very large size (1.76 kg). None of the successfully stunned animals showed any evidence of return of awareness in the five minutes following stunning. It was concluded that the Crustastun™ is an acceptable method for killing P. zealandicus and for stunning all but the largest J. edwardsii.

Studies on the transport of deer (Cervidae), in the UK, were published > 15 years ago. A more recent study of deer transport is required to allow for assessments and improvements to the transport of farmed deer. Sixteen deer farmers participated in a survey describing their management practices related to transport. Their responses showed that most vehicles used to transport deer were designed for other livestock. Participating farmers estimated journey times to slaughter as 1–8 h, with an arithmetic mean of 4.8 (± 2.38) h. Specific concerns raised by the respondents, relating to the transport of deer, included a need for deer-specific vehicles, stop-off areas for long journeys, market locations and haulier experience. Furthermore, data were collected from two abattoirs between July 2019 and June 2020 comprising journey times, slaughter times, bruising, location of origin, vehicle type and the number of animals. In total, 4,922 deer were transported across 133 journeys (from farm to abattoir) from 61 farms. Median and range for journey length were 3.2 (0.4–9.8) h and 154.2 (7.1–462.2) km, whereas group size and time spent in the lairage were 24 (1–121) and 17.8 (10.2–68.9) h, respectively. Group size was found to be significantly associated with both the presence of bruising in a group and the amount of bruising per deer. This study provides a much-needed update on the transport of farmed deer in the UK and highlights key areas for future research including the welfare impact of transport in larger groups and for longer durations.

Controlled atmosphere (gas) stunning (CAS) has the potential to improve the welfare of poultry at slaughter but there is a lack of consensus about which gas mixtures are most humane. The aim of this study was to evaluate the welfare consequences of different gas stunning approaches. Individual broilers were exposed to gas mixtures capable of inducing unconsciousness and euthanasia while their behavioural, cardiac, respiratory and neurophysiological responses were measured simultaneously. The approaches investigated included anoxia (N2 or Ar with < 2% residual O2), hypercapnic anoxia (30% CO2 in Ar, 40% CO2 in N2) and a biphasic method (40% CO2, 30% O2, 30% N2 for 60 s followed by 80% CO2 in air). Evaluation of the welfare implications of each approach centred on the likelihood of them inducing negative states or experiences during the conscious phase. Hypercapnic mixtures were associated with strong respiratory responses, while anoxic mixtures induced vigorous wing flapping. Electroencephalogram analysis using the correlation dimension (a non-linear measure of complexity) suggested that anoxic wing flapping occurred during periods in which a form of consciousness could not be excluded. Hypercapnic hyperoxygenation (biphasic approach) exacerbated respiratory responses but eliminated the possibility of vigorous behavioural responses occurring during a conscious phase. The relative importance of respiratory discomfort versus the potential to induce significant distress due to convulsive wing flapping and associated trauma is a matter for debate. We argue that respiratory discomfort is unpleasant but may be preferable to the risk of vigorous wing flapping and associated injury while conscious in poultry during CAS.

The effectiveness of electrical water bath stunning of broilers (n = 96) for 1 s with a constant average current of 100, 150 or 200 mA delivered using a variable voltage/constant current stunner with 200, 800 or 1400 Hz pulsed direct current (DC), with a mark:space ratio of 1:1, followed by slaughter using a unilateral or ventral neck cutting procedure, was evaluated. The results of a binary logistic model showed that both the electrical frequency and average current had significant effects on the probability of inducing epileptiform electroencephalogram (EEG) and therefore, of effective stunning. The results of univariate analysis showed that only slaughter method had highly significant effects on the power contents in the 13–30 Hz and 2–30 Hz EEG frequency bands. Based on these results, it is recommended that a minimum of 200 mA average (400 mA peak) current per bird should be delivered using 200 Hz pulsed DC, with a mark:space ratio of 1:1, to achieve effective water bath stunning in 80% of broilers. Frequencies of above 200 Hz pulsed DC would presumably require average currents of greater than 200 mA. Electrical water bath stunning of broilers with 200 mA average current of 200 Hz resulted in cardiac arrest in six out of eight broilers that showed epileptiform activity. Two other broilers that had cardiac arrest showed no epileptiform EEGs indicative of effective stunning. Owing to the prevalence of cardiac arrest in conscious broilers, the use of pulsed DC for water bath stunning of broilers could be questioned on ethical and bird welfare grounds.

The return to consciousness of 24 electrically stunned lambs was assessed by measurement of physiological reflexes and electroencephalography (EEG) recordings. The physical activity of the lambs after head-only electrical stunning included one tonic phase and two clonic phases. The tonic phase began immediately after the stun and ended 10 s after the stun; the first clonic phase started immediately after the tonic phase and ended 36 s after the stun, and the second clonic phase started immediately after the first clonic phase and ended 70 s after the stun. During the tonic phase and the first clonic phase, electrical activity recordings of the brain showed a dramatic increase in the relative power spectra of alpha and beta frequencies. Both frequencies returned to pre-stun levels with the end of the first clonic phase. During the second clonic phase, the relative power spectrum of theta frequency was higher than that before stunning. These results suggest that during the tonic phase and the first clonic phase, the animal was unconscious, whereas during the second clonic phase the return of some conscious function began. Spontaneous breathing returned at about 29 s post-stun, whereas the corneal reflex returned at about 38 s. It is therefore suggested that the return of spontaneous breathing is the safest indicator that the animal is close to recovering consciousness.

The effect of the pulse width of a direct current (DC) on the effectiveness of electrical water bath stunning, and slaughter, was evaluated in broilers (n = 29). Broilers were individually stunned in a water bath for 1 s with a constant peak current of 400 mA of 200 Hz DC delivered using a variable voltage/constant current stunner. The pulse width of the 200 Hz DC was set at 0.5, 1.5 or 2.5 ms (10, 30 or 50% of 5 ms current cycle). The results showed that pulse width had a significant effect on the incidence of epileptiform activity in the electroencephalograms (EEGs). A pulse width of 10% of the current cycle was less effective than pulse widths of 30 and 50% of the current cycle; there was no significant difference between a pulse width of 30 and 50%. The results of a univariate analysis showed that ventral neck-cutting resulted in a significantly shorter time to the onset of less than 10% of the pre-stun power contents in the 13–30 Hz and 2–30 Hz EEG frequency bands when compared with unilateral neck-cutting. It is concluded that a pulse width of 30 or 50% of the current cycle of 200 Hz DC, delivering 400 mA peak current, was better than using a pulse width of 10% of the current cycle.

This paper reviews the impact on fish welfare of a wide range of slaughter methods used commercially around the world. Because the end result of the slaughter is a food product, and because of the well-known relationship between an animal's welfare and subsequent meat quality, the effects of the slaughter methods on the quality of the flesh are also reviewed where possible. Fish slaughter methods are incredibly diverse, but fall into two broad categories: those that induce loss of sensibility slowly, and those that achieve this rapidly. This paper shows that, in general, the methods that induce loss of sensibility over a long period of time tend to impinge more on the welfare of the animal and are detrimental to the overall quality of the carcass. Methods that cause a rapid loss of sensibility result in the best welfare, providing that they are carried out correctly. They may also produce the highest quality product from the stock offish.

The effectiveness of head-only electrical stunning of broilers, with a root mean square (RMS) current of 100 or 150mA delivered using either 50, 400 or 1500Hz sine wave alternating current (AC), was investigated. The changes occurring in the spontaneous electroencephalogram (EEG) were evaluated using Fast Fourier Transformations (FFT) to determine the impact of the amount and frequency of stunning current on total (2-30 Hz) and relative (13-30 Hz) power contents in the EEG. Induction of epileptiform activity and reduction in the EEG power contents to less than 10% of pre-stun levels from the end of epileptiform activity were used as indicators of effective stunning. The duration of unconsciousness and insensibility was determined on the basis of the return of EEG power contents. In addition, the changes occurring in somatosensory evoked potentials (SEPs) were subjectively evaluated to determine the impact of stunning treatments. The results of ANOVA (repeated measures) showed statistically significant effects of interactions between the current frequencies, amount of current and repeated measures on changes in EEG power contents (P < 0.001). Stunning broilers with 150 mA delivered using 50 Hz resulted in EEG changes that were indicative of more pronounced neuronal inhibition following epileptiform activity and also lasted longer than was the case when broilers were stunned with 150 mA delivered using 400 Hz. Stunning broilers with 100 mA delivered using 50 Hz resulted in changes very similar to those observed after stunning with 150 mA of 50 Hz, but which lasted for a relatively shorter time. However, these changes were more pronounced and lasted longer than did stunning with 100 mA delivered using 400 Hz. The effects of stunning broilers with 150 mA of 400 Hz were similar to those found after stunning with 100 mA of 50 Hz. By contrast, stunning broilers with 100 mA of 1500 Hz failed to fulfil the criteria set out in this study. Stunning of broilers with 150 mA of 1500 Hz induced epileptiform activity but failed to reduce EEG power contents to less than 10% of pre-stun levels. Therefore, the stunning of broilers with 100 or 150 mA of 1500 Hz may not be adequate to avoid pain and suffering during slaughter. Thus, minimum currents of 100, 150 and 200 mA should be delivered whilst using 50, 400 and 1500 Hz, respectively, to achieve effective electrical stunning in broilers. Severing of the carotid arteries in the neck following head-only electrical stunning, and high frequency (> 125 Hz) electrical water bath stunning of broilers should also become a statutory requirement to prevent the return of consciousness during bleeding.

The effects of witnessing the slaughter of conspecifics on the stress responses of pigs were investigated. Previously catheterized pigs were allowed to see the stunning and sticking (exsanguination) of pigs in a nearby pen. Heart rate was monitored and serial blood samples were taken to assess stress responses. Packed cell volume (PCV), Cortisol and β-endorphin were determined in the samples. In addition, behavioural observations and subjective assessments of animals’ responses were made. Although the levels of hormones, PCV and heart rate tended to be generally high due to handling, there were no specific increases in response to witnessing stunning and slaughter. These results suggest that witnessing the slaughter act does not distress pigs.

Proper design of restraint equipment is essential to prevent stress on animals during handling, stunning and slaughter. A small design mistake which may appear to be insignificant to the engineer can be extremely detrimental to animal welfare. Operators of restraint equipment must be properly trained. Cattle will place their heads into stanchion (yoke) or chin-lift types of head-restrainers if they are gently moved forward by a rear pusher gate. Cattle confined in an upright ASPCA pen for religious slaughter will remain calmer if the apparatus is gently closed around them. The vertical travel of the belly lift should be restricted to 71 cm (28 in) — it should not lift the animals off the floor. The rear pusher gates should be equipped with a separate regulator to prevent excessive pressure from being applied. Stunning or ritual slaughter should be carried out within 10 seconds of the animal's head being restrained. The modified ASPCA pen described in the paper was seemingly humane when operated by people concerned about animal welfare.

The behavioural reactions and blood Cortisol levels of cattle stunned using a penetrating captive-bolt pistol whilst standing free in a stunning box were compared with those obtained from cattle similarly stunned but with their heads held in a hydraulically operated chin-lift type of head restrainer. Few (8 out of 55) animals voluntarily put their heads into the restrainer, most had to be ‘persuaded’ to use the head-restrainer; some (5 out of 24) could not be. The mean time between entry into the stunning pen and the stun for 23 free standing animals was 5.6s and for 19 animals which could be persuaded to use the head restrainer was 34.2s. The Cortisol levels in the blood taken at the stick, from 30 animals stunned while standing free was 67.6 nmoVlitre while that from 30 stunned while head-restrained was 143.1 nmolHitre. The behaviour and Cortisol results suggest that enforced usage of this type of head restrainer could be a cause of distress to the cattle involved.

Meat from low-volume farm animals such as farmed deer and wild boar is currently widely available to the consumer within the UK. Despite a rapid growth in production of these species there is a paucity of research that focuses on their welfare. This paper reviews the current literature and legislation relating to the transport and slaughter of farmed deer, wild boar, ostriches, buffalo and bison in order to identify priorities for future research. Research on low-volume farm animals has focused on red deer and their welfare is safeguarded with comprehensive legislation and guidelines. Studies have indicated the importance of appropriately designed facilities and sympathetic handling of red deer to ensure humane slaughter with minimal stress. However, the impact of transport and slaughter on the welfare of other deer species has not been recorded and this should be recognised. Much research has been conducted on the welfare of ostriches during transport and at slaughter. However, many of the results are discordant and research is required to clarify, in particular, posture during transport and stunning methods. Research on the welfare of wild boar, buffalo and bison is scarce. Best practice for both transport and slaughter of these species needs further research and clarification within legislation. For the low-volume species discussed in this review, priorities for further research include (1) appropriate methods of handling to minimise stress during transport and slaughter; (2) identification/clarification of appropriate slaughter methods and (3) training of transport and abattoir personnel in handling and slaughter methods.

The effectiveness of electrical water bath stunning of 172 individual broilers for 1 s with a constant root mean square (RMS) current of 100, 150 or 200 mA, delivered using a variable voltage/constant current stunner with 200, 400, 600, 800, 1000, 1200 or 1400 Hz sine wave alternating current (AC), followed by slaughter using a unilateral or ventral neck-cutting procedure, was evaluated. A binary logistic regression of broilers showing epileptiform activity or not following stunning showed that both the electrical frequency (Hz) and RMS current (mA) had a significant effect on the probability of the electroencephalogram (EEG) manifestation. The univariate analysis of variance showed that the time to the onset of less than 10% of the pre-stun relative power contents was significantly affected only by the interaction between electrical frequency and slaughter method. A similar analysis of variance of the time to reach less than 10% of the pre-stun total power content showed slaughter method, RMS current, the slaughter method/frequency interaction and the RMS current/frequency interaction to be either significant or approaching significance. Based on these results it is recommended that effective water bath stunning of broilers with a minimum constant current of 100, 150 and 200 mA could be achieved with electrical frequencies of up to 200, 600 and 800 Hz, respectively. In addition, It is likely that electrical frequencies of above 800 Hz would have required a minimum current of greater than 200 mA to induce epileptiform activity in the EEGs of broilers.

The question of whether witnessing slaughter of conspecifics is distressing was investigated in sheep. Previously catheterized sheep were allowed to see the stunning and sticking (exsanguination) of other sheep. Heart rate was monitored and serial blood samples were taken to assess stress responses. Although the measurable parameter levels were generally high due to human contact and handling, there were no specific increases in response to witnessing stunning and slaughter. This work failed to produce any evidence to suggest that sheep are distressed by witnessing the slaughter act.

The objective was to evaluate the welfare implications of electrical stunning prior to gill-cutting of farmed African catfish as an alternative to live chilling in combination with gutting. Electroencephalogram (EEG) and electrocardiogram (ECG) recordings, in combination with observation of behaviour and responses to noxious stimuli, were used to assess brain and cardiac function in African catfish (body-weight 1571 ± 362 g [mean ± standard deviation], 32 males and 26 females). In the first experiment, the minimum electrical current required to induce a general epileptiform insult by head-only stunning was determined. The individual catfish were fixed in a specially designed restrainer, and applied voltages of 150 V, 200 V, 250 V, 300 V or 350 V (50 Hz AC) were delivered via scissor-model stunning tongs for approximately I s. A general epileptiform insult was observed in 31 fish, for which a successful EEG recording was obtained using 362 ± 32 V, 629 ± 180 mA for 1.2 s. The durations of the tonic, the clonic and the exhaustion phases were 8 ± 3 s, 12 ± 7 s and 7 ± 5 s as measured by EEG, respectively; a distinct exhaustion phase was not clear in II fish. The total duration of the insult was 23 ± 8 s. After the insult the fish recovered. The heart rate was 63 ± 29 beats min I prior to stunning. After stunning, the ECG revealed extrasystole and was irregular. By using an average current of 629 ± 180 mA (at approximately 360 V, 50 Hz AC), at least 91% of fish are effectively stunned with a confidence level of 95%. In the second experiment, the behaviour of 10 individual catfish, which were able to move freely in water, was observed following head-only stunning (370 V). The durations of the tonic, clonic and exhaustion phases in free-swimming fish were II ± 8 s, 20 ± 5 s and 23 ± 20 s, respectively. All fish recovered. In the third experiment, a group of seven catfish was head-only stunned followed by gill-cutting to kill them as a second procedure (ie after recovery from head-only stunning). No brain activity was seen on the EEG 12 ± 5 s after stunning. However, two fish showed responses to noxious stimuli after 2 min and 5 min. A second group of seven catfish was gill-cut only. They responded to noxious stimuli for at least 15 min. The blood loss was 1.2% and I.0% of live weight for the first and second group, respectively. It may be concluded from our results that African catfish are effectively stunned for 23 ± 8 s with a current of 629 ± 180 mA for 1.2 s, after which they recover. Since evoked responses may remain for at least 5 min after stunning and gill-cutting, we recommended that the stunning and killing procedure should be optimised.

Annual statistics for transport and lairage mortality were used to investigate factors leading to pre-slaughter mortality in Danish pigs. A subset of material from 2002, amounting to 17.8 million pigs, was used for a more detailed study of the effect of producer, haulier, abattoir and transport distance (< 100, 100–200 and > 200 km) on transport mortality. Total mortality was reduced eight-fold during the period that the halothane gene was being removed from the pig population, from 0.12% in the early 1980s to 0.016% in 2002. Overall, transport mortality increased with higher temperature and lower relative humidity/wind speed but a combination of temperature and humidity that fell into the danger zone, as defined by the Livestock Weather Safety Index, almost doubled transport mortality from a level of about 0.016 to 0.031%. Multiple deaths on the same transport were also more frequent during the hotter months of the year. Transport mortality increased with increasing transport distance, especially during warmer weather. Producers, hauliers and abattoirs had widely varying transport mortality. Eighty-nine percent of producers, 11% of hauliers and 86% of farmer transports had no mortality at all. Producers and farmer transports supplying less than 1,000 pigs had a higher transport mortality than those supplying more pigs, whereas it was independent of supply for hauliers. There were many confounding factors in this work, as producers, hauliers and abattoirs are linked and trends over the years can be affected not only by changes in the genetic makeup of the pig population but also by improvements in handling. Nevertheless, the study shows that internal environment within the vehicle and transport pattern, including the time the vehicle is stationary, are important factors for mortality and that particular efforts should be made if weather forecasts predict dangerous combinations of temperature and humidity. It is suggested that efforts to further reduce transport mortality in Danish pigs should concentrate especially on these factors and include a routine follow-up of all multiple deaths to pinpoint specific factors leading to mortality.

There have been many improvements regarding transport conditions, pre-slaughter handling, and captive-bolt stunning of cattle at commercial abattoirs, but many challenges still exist. Animals unaccustomed to human-animal contact, such as free-range beef cattle, may be especially difficult to handle on the day of slaughter. Shifting of the slaughter process from the abattoir to the animals’ familiar environment could improve animal welfare at slaughter. In 2011, the German government passed an amendment allowing farmers to slaughter free-range cattle, on-farm, using a rifle. A proper stun is vital when employing this method but neither sufficient practical experience nor scientific knowledge are in place to allow this. Thus, this study aimed to examine shot placement and the effect of diverse ammunition by means of shooting at cattle heads, post mortem, with a rifle. Impact was assessed using brain tissue damage observed from skull dissections. Placing the shot frontally at the forehead resulted in severe brain damage significantly more frequently than targeting laterally. A precise frontal shot, utilising both large and small bore calibres, caused severe brain damage that would almost certainly have led to immediate unconsciousness and death. One of the small bore calibres caused minimal brain damage apart from the trajectory. However, this was the only calibre not passing straight through. Due to the fact that the bullet remains within the skull, thus transferring all of its energy to the skull and brain, the impact of this calibre on the brain would also be expected to be rapidly fatal. A projectile that does not exit the skull would also be advantageous as regards safety.

The slaughter of animals for the halal market is both ethically and economically significant. There are animal welfare and spiritual requirements that must be met for meat to be considered fit for Muslim consumption. These requirements are enshrined in Islamic law, known commonly as the Shariah law, derived from commandments in the Holy Quran and the Hadith (teachings or traditions of the Prophet of Islam, Mohammed, Peace Be Upon Him). Islamic jurists widely interpret the Shariah law differently, and this has led to debate as to whether pre-slaughter stunning is acceptable for halal slaughter. This paper reviews how these laws are interpreted and implemented and reviews the methods of stunning accepted by proponents of halal stunning. It also describes why some proponents of halal stunning do not accept irreversible stunning methods for producing halal beef within the EU, a situation which has meant that thousands of halal cattle are slaughtered without any form of stunning.