Effects of analgesic intervention on behavioural responses to Low Atmospheric Pressure Stunning

Worldwide, more than 50 billion chickens are killed annually for food production so their welfare at slaughter is an important concern. Low Atmospheric Pressure Stunning (LAPS) is a novel approach to pre-slaughter stunning of poultry in which birds are rendered unconscious by gradually reducing oxygen tension in the atmosphere to achieve a progressive anoxia (hypobaric hypoxia). Advantages of this approach over electrical stunning are that birds are not shackled while conscious and all birds are reliably and irreversibly stunned. However, concerns remain that birds undergoing LAPS could experience discomfort or pain. Here we investigated whether subjecting birds to LAPS with and without administration of an opioid analgesic (butorphanol) affected behavioural responses. A blocking design was used in which pairs of birds receiving either analgesic or sham treatment were allocated to three types (analgesic/analgesic, analgesic/sham, or sham/sham). In line with previous studies, birds showed a consistent sequence of behaviours during LAPS: ataxia, loss of posture, clonic/tonic convulsions, leg paddling and motionless. Overall, administration of butorphanol had no effect on the range and patterning of behavioural responses during LAPS, but there were some differences in behaviour latencies, counts and durations. For example, latencies to ataxia, mandibulation and deep inhalation were delayed by analgesic treatment, however the duration of ataxia and other behaviours related to loss of consciousness were unaffected. Fewer birds receiving analgesia showed jumping and slow wing flapping behaviour compared to controls, which suggests these may be pain related. These behaviours after the onset of ataxia and the results may reflect a smoother induction to unconsciousness in analgised birds. Collectively, the results do not provide convincing evidence that birds undergoing LAPS are experiencing pain. While there were effects of analgesia on some aspects of behaviour, these could be explained by potential sedative, dysphoric and physiological side effects of butorphanol. The behavioural responses to LAPS appear to be primarily related to exposure to anoxia rather than hypobaric conditions, and thus in terms of welfare, this stunning method may be equivalent to controlled atmosphere stunning with inert gases

Behavioural, brain and cardiac responses to hypobaric hypoxia in broiler chickens

A novel approach to pre-slaughter stunning of chickens has been developed in which birds are rendered unconscious by progressive hypobaric hypoxia. Termed Low Atmospheric Pressure Stunning (LAPS), this approach involves application of gradual decompression lasting 280 s according to a prescribed curve. We examined responses to LAPS by recording behaviour, electroencephalogram (EEG) and electrocardiogram (ECG) in individual male chickens, and interpreted these with regard to the welfare impact of the process. We also examined the effect of two temperature adjusted pressure curves on these responses. Broiler chickens were exposed to LAPS in 30 triplets (16 and 14 triplets assigned to each pressure curve). In each triplet, one bird was instrumented for recording of EEG and ECG while the behaviour of all three birds was observed. Birds showed a consistent sequence of behaviours during LAPS (ataxia, loss of posture, clonic convulsions and motionless) which were observed in all birds. Leg paddling, tonic convulsions, slow wing flapping, mandibulation, head shaking, open bill breathing, deep inhalation, jumping and vocalisation were observed in a proportion of birds. Spectral analysis of EEG responses at 2 s intervals throughout LAPS revealed progressive decreases in median frequency at the same time as corresponding progressive increases in total power, followed later by decreases in total power as all birds exhibited isoelectric EEG and died. There was a very pronounced increase in total power at 50–60 s into the LAPS cycle, which corresponded to dominance of the signal by high amplitude slow waves, indicating loss of consciousness. Slow wave EEG was seen early in the LAPS process, before behavioural evidence of loss of consciousness such as ataxia and loss of posture, almost certainly due to the fact that it was completely dark in the LAPS chamber. ECG recordings showed a pronounced bradycardia (starting on average 49.6 s into LAPS), often associated with arrhythmia, until around 60 s into LAPS when heart rate levelled off. There was a good correlation between behavioural, EEG and cardiac measures in relation to loss of consciousness which collectively provide a loss of consciousness estimate of around 60 s. There were some effects of temperature adjusted pressure curves on behavioural latencies and ECG responses, but in general responses were consistent and very similar to those reported in previous research on controlled atmosphere stunning with inert gases. The results suggest that the process is humane (slaughter without avoidable fear, anxiety, pain, suffering and distress). In particular, the maintenance of slow wave EEG patterns in the early part of LAPS (while birds are still conscious) is strongly suggestive that LAPS is non-aversive, since we would expect this to be interrupted by pain or discomfort

Effects of light on responses to Low Atmospheric Pressure Stunning in Broilers

1. Low atmospheric pressure stunning (LAPS) is a novel approach to poultry stunning invol-ving the application of gradual decompression lasting 280 s according to a prescribed pressure curve.2. The aim of this study was to determine how behavioural, electroencephalogram (EEG) and electro-cardiogram (ECG) responses to LAPS are influenced by illumination of the decompression chamber. Asecondary aim was to examine responses to the decompression chamber without LAPS being applied, assuch a“sham”control has been absent in previous studies.3. A two by two factorial design was employed, with LAPS/light, LAPS/dark, sham/light and sham/darktreatments (N= 20 per treatment). Broilers were exposed to each treatment in pairs, in each of which onebird was instrumented for recording EEG and ECG. Illumination was applied at 500 lx, and in shamtreatments, birds were identically handled but remained undisturbed in the LAPS chamber withoutdecompression for 280 s.4. Birds which underwent the sham treatment exhibited behaviours which were also observed in LAPS(e.g. sitting) while those exposed to LAPS exhibited hypoxia-related behaviours (e.g. ataxia, loss ofposture). Behavioural latencies and durations were increased in the sham treatments, since the wholecycle time was available (in LAPS; birds were motionless by 186 s).5. Within the sham treatments, illumination increased active behaviour and darkness induced sleep, butslow-wave EEG was seen in both. The pattern of EEG response to LAPS (steep reduction in medianfrequency in thefirst 60 s and increased total power) was similar, irrespective of illumination, thoughbirds in darkness had shorter latencies to loss of consciousness and isoelectric EEG. Cardiac responses toLAPS (pronounced bradycardia) closely matched those reported previously and were not affected byillumination.6. The effects of LAPS/sham treatment primarily reflected the presence/absence of hypoxia, whileillumination affected activity/sleep levels in sham-treated birds and slowed time to unconsciousness inbirds undergoing LAPS. Therefore, it is recommended that LAPS be conducted in darkness for poultry

Comparison of Neck Skin Excision and Whole Carcass Rinse Sampling Methods for Microbiological Evaluation of Broiler Carcasses before and after Immersion Chilling

Sampling protocols for detecting Salmonella on poultry differ among various countries. In the United States, the U.S. Department of Agriculture Food Safety and Inspection Service dictates that whole broiler carcasses should be rinsed with 400 ml of 1% buffered peptone water, whereas in the European Union 25-g samples composed of neck skin from three carcasses are evaluated. The purpose of this study was to evaluate a whole carcass rinse (WCR) and a neck skin excision (NS) procedure for Salmonella and Escherichia coli isolation from the same broiler carcass. Carcasses were obtained from three broiler processing plants. The skin around the neck area was aseptically removed and bagged separately from the carcass, and microbiological analysis was performed. The corresponding carcass was bagged and a WCR sample was evaluated. No significant difference (alpha <= 0.05) in Salmonella prevalence was found between the samples processed by the two methods, but both procedures produced many false-negative Salmonella results. Prechill, 37% (66 carcasses), 28% (50 carcasses), and 51% (91 carcasses) of the 180 carcasses examined were positive for Salmonella by WCR, NS, and both procedures combined, respectively. Postchill, 3% (5 carcasses), 7% (12 carcasses), and 10% (17 carcasses) of the 177 carcasses examined were positive for Salmonella by the WCR, NS, and combination of both procedures, respectively. Prechill, E. coli plus coliform counts were 3.0 and 2.6 log CFU/ml by the WCR and NS methods, respectively. Postchill. E. coli plus coliform counts were 1.7 and 1.4 log CFU/ml by the WCR and NS methods, respectively