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Baxter EM, McKeegan DEF, Farish M, Thomson JR, Clutton RE, Greenhalgh SN, Gregson R, Martin JE. Characterizing candidate decompression rates for hypobaric hypoxic stunning of pigs. Part 2: Pathological consequences. Front Vet Sci 2022; 9:1027883. [PMID: 36439339 PMCID: PMC9681787 DOI: 10.3389/fvets.2022.1027883] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2022] [Accepted: 10/04/2022] [Indexed: 11/11/2022] Open
Abstract
Pigs are commonly stunned pre-slaughter by exposure to carbon dioxide (CO2), but this approach is associated with significant welfare concerns. Hypobaric hypoxia, achieved with gradual decompression (also known as Low Atmospheric Pressure Stunning or LAPS) may be an alternative, allowing the retention of welfare friendly handling approaches and group stunning. Although validated in poultry, the feasibility and welfare consequences of gradual decompression for pigs are unknown. Here, we characterize pathological changes in 60 pigs resulting from exposure to a range of candidate decompression curves (ranging from 40 to 100 ms−1 ascent equivalent, with two cycle durations 480 and 720 s). To protect welfare, we worked on unconscious, terminally anesthetized pigs which were subject to detailed post-mortem examinations by a specialized porcine veterinary pathologist. All pigs were killed as a result of exposure to decompression, irrespective of cycle rate or length. Pigs showed no external injuries during ante-mortem inspections. Exposing pigs to decompression and the unavoidable subsequent recompression resulted in generalized congestion of the carcass, organs and body cavities including the ears, oral cavity, conjunctivae and sclera, mucosa of other external orifices (anus and vulva), nasal planum, nasal cavities including nasal conchae, frontal sinuses, cranium, meninges, brain, larynx, trachea, lungs, heart, parietal pleura of the thoracic cavity, peritoneum of the abdominal cavity, stomach, small intestine, caecum, colon, liver, spleen and kidneys and representative joint cavities in the limbs (stifles and elbows). Various severities of hemorrhage were observed in the conjunctivae and sclera, mucosa of other external orifices (anus and vulva), nasal cavities including nasal conchae, frontal sinuses, cranium, meninges, brain, larynx, tracheal lumen, lungs, parietal pleura of the thoracic cavity, liver, spleen and kidneys and representative joint cavities in the limbs (stifles and elbows). In general, faster decompression rates produced higher scores, but in the conjunctivae, sclera and kidneys, faster decompression rates were associated with marginally lower congestion scores. There was considerable individual variation in pathological scores across all body regions. The congestion and hemorrhage observed could translate into welfare harms in conscious pigs undergoing this type of stunning, depending when in the cycle the damage is occurring, but no welfare related conclusions can be drawn from the responses of unconscious pigs. Since recompression is always required, its effects cannot be separated from decompression, however cessation of cardiac activity several minutes before recompression should have eliminated any haemodynamic effects relating to cardiac function and blood pressure. This study represents the first systematic attempt to identify candidate rate profiles to underpin future explorations of decompression as a stunning method for pigs. These pathological findings also inform discussions about the likely carcass quality implications of this novel stunning method.
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Affiliation(s)
- Emma M. Baxter
- Animal and Veterinary Sciences Research Group, Scotland's Rural College (SRUC), Edinburgh, United Kingdom
| | - Dorothy E. F. McKeegan
- School of Biodiversity, One Health and Veterinary Medicine, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom
| | - Marianne Farish
- Animal and Veterinary Sciences Research Group, Scotland's Rural College (SRUC), Edinburgh, United Kingdom
| | - Jill R. Thomson
- Animal and Veterinary Sciences Research Group, Scotland's Rural College (SRUC), Edinburgh, United Kingdom
| | - Richard E. Clutton
- The Wellcome Trust Critical Care Laboratory for Large Animals LARIF, The Roslin Institute, The University of Edinburgh, Edinburgh, United Kingdom
| | - Stephen N. Greenhalgh
- The Wellcome Trust Critical Care Laboratory for Large Animals LARIF, The Roslin Institute, The University of Edinburgh, Edinburgh, United Kingdom
| | - Rachael Gregson
- The Wellcome Trust Critical Care Laboratory for Large Animals LARIF, The Roslin Institute, The University of Edinburgh, Edinburgh, United Kingdom
| | - Jessica E. Martin
- The Royal (Dick) School of Veterinary Studies and The Roslin Institute, The University of Edinburgh, Edinburgh, United Kingdom
- School of Natural and Environmental Sciences, Newcastle University, Newcastle upon Tyne, United Kingdom
- *Correspondence: Jessica E. Martin
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Wang X, Zhao D, Milby AC, Archer GS, Peebles ED, Gurung S, Farnell MB. Evaluation of Euthanasia Methods on Behavioral and Physiological Responses of Newly Hatched Male Layer Chicks. Animals (Basel) 2021; 11:ani11061802. [PMID: 34204180 PMCID: PMC8235231 DOI: 10.3390/ani11061802] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2021] [Revised: 06/08/2021] [Accepted: 06/11/2021] [Indexed: 11/16/2022] Open
Abstract
Newly hatched male layer chicks are considered as "by-products" in the egg industry and must be humanely euthanized at the hatchery. Instantaneous mechanical destruction (maceration) is the predominant euthanasia method applied in poultry hatcheries and is approved by the American Veterinary Medical Association (AVMA). However, maceration is not perceived by the public to be a humane means of euthanasia. The effects of alternative euthanasia methods, including carbon dioxide (CO2) or nitrogen (N2) inhalation, and a commercial negative pressure stunning system on behavioral and physiological responses of day-of-hatch male layer chicks, were evaluated in a field trial. Chick behaviors, including ataxia, loss of posture, convulsions, cessation of vocalization, and cessation of movement, were monitored. Serum hormones were assessed at the end of each of the alternative euthanasia treatments, including a control group allowed to breathe normal atmospheric air. The N2 method induced unconsciousness and death later than the CO2 and negative pressure methods, and increased serum corticosterone concentrations of neonatal chicks. Carbon dioxide inhalation increased serotonin concentrations as compared to controls, as well as the N2 and the negative pressure methods. The behavioral and physical responses observed in this study suggest that both CO2 inhalation and negative pressure stunning can be employed to humanely euthanize neonatal male layer chicks.
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Affiliation(s)
- Xi Wang
- Department of Poultry Science, Texas A&M AgriLife Research, College Station, TX 77843, USA; (X.W.); (D.Z.); (A.C.M.); (G.S.A.); (S.G.)
| | - Dan Zhao
- Department of Poultry Science, Texas A&M AgriLife Research, College Station, TX 77843, USA; (X.W.); (D.Z.); (A.C.M.); (G.S.A.); (S.G.)
| | - Allison C. Milby
- Department of Poultry Science, Texas A&M AgriLife Research, College Station, TX 77843, USA; (X.W.); (D.Z.); (A.C.M.); (G.S.A.); (S.G.)
| | - Gregory S. Archer
- Department of Poultry Science, Texas A&M AgriLife Research, College Station, TX 77843, USA; (X.W.); (D.Z.); (A.C.M.); (G.S.A.); (S.G.)
| | - E. David Peebles
- Department of Poultry Science, Mississippi State University, Starkville, MS 39762, USA;
| | - Shailesh Gurung
- Department of Poultry Science, Texas A&M AgriLife Research, College Station, TX 77843, USA; (X.W.); (D.Z.); (A.C.M.); (G.S.A.); (S.G.)
| | - Morgan B. Farnell
- Department of Poultry Science, Texas A&M AgriLife Research, College Station, TX 77843, USA; (X.W.); (D.Z.); (A.C.M.); (G.S.A.); (S.G.)
- Correspondence: ; Tel.: +1-(979)-847-7363
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Gent TC, Gebhardt-Henrich S, Schild SLA, Rahman AA, Toscano MJ. Evaluation of Poultry Stunning with Low Atmospheric Pressure, Carbon Dioxide or Nitrogen Using a Single Aversion Testing Paradigm. Animals (Basel) 2020; 10:ani10081308. [PMID: 32751528 PMCID: PMC7459835 DOI: 10.3390/ani10081308] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2020] [Revised: 07/25/2020] [Accepted: 07/28/2020] [Indexed: 12/14/2022] Open
Abstract
Simple Summary The use of gas stunning for poultry in the abattoir is considered preferable from a welfare and ethical perspective since it reduces the need for stressful handling and birds do not need to be separated from each other. Stunning with low atmospheric pressure is thought to be less stressful than the widely used carbon dioxide; however, there are no published studies directly comparing their aversiveness. Here we trained broiler breeders to indicate aversion to either carbon dioxide, low atmospheric pressure or the inert gas nitrogen, by relinquishing a food reward to seek a preferable environment. We found that exposure to carbon dioxide resulted in the rapid cessation of feeding, whereas with low atmospheric pressure and nitrogen, birds continued to eat for longer. We further found that carbon dioxide exposure resulted in more aversion behaviours, such as headshaking and gasping. These findings suggest that both low atmospheric pressure and nitrogen offer a welfare refinement to gas stunning with carbon dioxide in poultry. Abstract Low atmospheric pressure stunning (LAPS) has been suggested for use in poultry under 4 kg in the abattoir as a more humane alternative to carbon dioxide (CO2). However, there are currently no studies offering a direct comparison of the aversion between methods. Here, we trained adult female broiler breeders to relinquish a food reward by moving to another area of the gas chamber in response to aversive stimuli. They were then stunned and subsequently killed using single exposure to either CO2, N2, LAPS or medical air as a control. Birds exposed to CO2 relinquished the food reward the quickest and exhibited gasping and headshaking more than the other groups. LAPS resulted in the quickest time to loss of posture (LOP) and birds in the N2 group took the longest. Birds exposed to N2 displayed the longest duration of ataxia of any group; however, they did not show any wing-flapping prior to LOP, unlike the LAPS and CO2. Collectively these data demonstrate that both LAPS and N2 are less aversive to poultry than CO2 and may offer a significant welfare refinement for poultry killed for meat production.
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Affiliation(s)
- Thomas C. Gent
- Anaesthesiology Section, Department of Clinical Diagnostics and Services, University of Zurich, 8057 Zurich, Switzerland
- Correspondence:
| | - Sabine Gebhardt-Henrich
- Center of Proper Housing for Poultry and Rabbits, Division of Animal Welfare, University of Bern, 3052 Zollikofen, Switzerland; (S.G.-H.); (A.A.R.); (M.J.T.)
| | - Sarah-Lina Aagaard Schild
- Department of Biosystems and Technology, Swedish University of Agricultural Sciences (SLU), 230 53 Alnarp, Sweden;
| | - Abdulsatar Abdel Rahman
- Center of Proper Housing for Poultry and Rabbits, Division of Animal Welfare, University of Bern, 3052 Zollikofen, Switzerland; (S.G.-H.); (A.A.R.); (M.J.T.)
| | - Michael J. Toscano
- Center of Proper Housing for Poultry and Rabbits, Division of Animal Welfare, University of Bern, 3052 Zollikofen, Switzerland; (S.G.-H.); (A.A.R.); (M.J.T.)
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Nielsen SS, Alvarez J, Bicout DJ, Calistri P, Depner K, Drewe JA, Garin-Bastuji B, Gonzales Rojas JL, Gortázar Schmidt C, Miranda Chueca MÁ, Roberts HC, Sihvonen LH, Spoolder H, Stahl K, Velarde Calvo A, Viltrop A, Winckler C, Candiani D, Fabris C, Van der Stede Y, Michel V. Killing for purposes other than slaughter: poultry. EFSA J 2019; 17:e05850. [PMID: 32626157 PMCID: PMC7008794 DOI: 10.2903/j.efsa.2019.5850] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Poultry of different ages may have to be killed on‐farm for purposes other than slaughter (in which slaughtering is defined as being for human consumption) either individually or on a large scale (e.g. because unproductive, for disease control, etc.). The processes of on‐farm killing that were assessed are handling and stunning and/or killing methods (including restraint). The latter were grouped into four categories: electrical methods, modified atmosphere, mechanical methods and lethal injection. In total, 29 hazards were identified and characterised, most of these regard stunning and/or killing. Staff were identified as origin for 26 hazards and 24 hazards were attributed to lack of appropriate skill sets needed to perform tasks or due to fatigue. Specific hazards were identified for day‐old chicks killed via maceration. Corrective and preventive measures were assessed: measures to correct hazards were identified for 13 hazards, and management showed to have a crucial role in prevention. Eight welfare consequences, the birds can be exposed to during on‐farm killing, were identified: not dead, consciousness, heat stress, cold stress, pain, fear, distress and respiratory distress. Welfare consequences and relevant animal‐based measures were described. Outcome tables linking hazards, welfare consequences, animal‐based measures, origins, preventive and corrective measures were developed for each process. Mitigation measures to minimise welfare consequences were also proposed.
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Nielsen SS, Alvarez J, Bicout DJ, Calistri P, Depner K, Drewe JA, Garin-Bastuji B, Gonzales Rojas JL, Gortázar Schmidt C, Miranda Chueca MÁ, Roberts HC, Sihvonen LH, Spoolder H, Stahl K, Velarde Calvo A, Viltrop A, Winckler C, Candiani D, Fabris C, Van der Stede Y, Michel V. Slaughter of animals: poultry. EFSA J 2019; 17:e05849. [PMID: 32626156 PMCID: PMC7008870 DOI: 10.2903/j.efsa.2019.5849] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
The killing of poultry for human consumption (slaughtering) can take place in a slaughterhouse or during on-farm slaughter. The processes of slaughtering that were assessed, from the arrival of birds in containers until their death, were grouped into three main phases: pre-stunning (including arrival, unloading of containers from the truck, lairage, handling/removing of birds from containers); stunning (including restraint); and bleeding (including bleeding following stunning and bleeding during slaughter without stunning). Stunning methods were grouped into three categories: electrical, controlled modified atmosphere and mechanical. In total, 35 hazards were identified and characterised, most of them related to stunning and bleeding. Staff were identified as the origin of 29 hazards, and 28 hazards were attributed to the lack of appropriate skill sets needed to perform tasks or to fatigue. Corrective and preventive measures were assessed: measures to correct hazards were identified for 11 hazards, with management shown to have a crucial role in prevention. Ten welfare consequences, the birds can be exposed to during slaughter, were identified: consciousness, heat stress, cold stress, prolonged thirst, prolonged hunger, restriction of movements, pain, fear, distress and respiratory distress. Welfare consequences and relevant animal-based measures were described. Outcome tables linking hazards, welfare consequences, animal-based measures, origins, and preventive and corrective measures were developed for each process. Mitigation measures to minimise welfare consequences were also proposed.
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Steiner AR, Flammer SA, Beausoleil NJ, Berg C, Bettschart-Wolfensberger R, Pinillos RG, Golledge HDW, Marahrens M, Meyer R, Schnitzer T, Toscano MJ, Turner PV, Weary DM, Gent TC. Humanely Ending the Life of Animals: Research Priorities to Identify Alternatives to Carbon Dioxide. Animals (Basel) 2019; 9:E911. [PMID: 31684044 PMCID: PMC6912382 DOI: 10.3390/ani9110911] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2019] [Revised: 10/14/2019] [Accepted: 10/25/2019] [Indexed: 02/06/2023] Open
Abstract
: The use of carbon dioxide (CO2) for stunning and killing animals is considered to compromise welfare due to air hunger, anxiety, fear, and pain. Despite decades of research, no alternatives have so far been found that provide a safe and reliable way to induce unconsciousness in groups of animals, and also cause less distress than CO2. Here, we revisit the current and historical literature to identify key research questions that may lead to the identification and implementation of more humane alternatives to induce unconsciousness in mice, rats, poultry, and pigs. In addition to the evaluation of novel methods and agents, we identify the need to standardise the terminology and behavioural assays within the field. We further reason that more accurate measurements of consciousness state are needed and serve as a central component in the assessment of suffering. Therefore, we propose a roadmap toward improving animal welfare during end-of-life procedures.
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Affiliation(s)
- Aline R Steiner
- Department of Clinical and Diagnostic Services, Section of Anaesthesiology, Vetsuisse Faculty, University of Zurich, Winterthurerstrasse 258c, 8057 Zurich, Switzerland.
| | - Shannon Axiak Flammer
- Department of Clinical Veterinary Medicine, Section of Anesthesia and Analgesia, Vetsuisse Faculty, University of Berne, Laenggassstrasse 124, 3012 Bern, Switzerland.
| | - Ngaio J Beausoleil
- Animal Welfare Science and Bioethics Centre, School of Veterinary Science, Massey University, Palmerston North 4410, New Zealand.
| | - Charlotte Berg
- Department of Animal Environment and Health, Swedish University of Agricultural Sciences, Box 234, SE-53223 Skara, Sweden.
| | - Regula Bettschart-Wolfensberger
- Department of Clinical and Diagnostic Services, Section of Anaesthesiology, Vetsuisse Faculty, University of Zurich, Winterthurerstrasse 258c, 8057 Zurich, Switzerland.
| | - Rebeca García Pinillos
- Animal and Plant Health Agency and Department for Environment, Food and Rural Affairs, Nobel House, 17 Smith Square, London SW1P 3JR, UK.
| | - Huw D W Golledge
- Universities Federation for Animal Welfare (UFAW), The Old School, Brewhouse Hill, Wheathampstead, Hertfordshire AL4 8AN, UK.
| | - Michael Marahrens
- Institute of Animal Welfare and Animal Husbandry, Friedrich-Loeffler-Institut, Dörnbergstraße 25/27, 29223 Celle, Germany.
| | - Robert Meyer
- Department of Clinical Sciences, College of Veterinary Medicine, Mississippi State University, Mississippi State, MS 39762, USA.
| | - Tobias Schnitzer
- Roche Pharma Research and Early Development, Pharmaceutical Sciences, Roche Innovation Center Basel, F. Hoffmann-La Roche Ltd., Grenzacherstrasse 124, 4070 Basel, Switzerland.
| | - Michael J Toscano
- Center for Proper Housing: Poultry and Rabbits (ZTHZ), Animal Welfare Division, VPH Institute, University of Bern, 3052 Zollikofen, Switzerland.
| | - Patricia V Turner
- Department of Pathobiology, University of Guelph, Guelph, ON, N1G 2W1, Canada and Charles River, Wilmington, MA 01887, USA.
| | - Daniel M Weary
- Animal Welfare Program, University of British Colombia, 2357 Main Mall, Vancouver, BC V6T 1Z4, Canada.
| | - Thomas C Gent
- Department of Clinical and Diagnostic Services, Section of Anaesthesiology, Vetsuisse Faculty, University of Zurich, Winterthurerstrasse 258c, 8057 Zurich, Switzerland.
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More S, Bicout D, Bøtner A, Butterworth A, Calistri P, Depner K, Edwards S, Garin-Bastuji B, Good M, Gortázar Schmidt C, Miranda MA, Saxmose Nielsen S, Velarde A, Thulke HH, Sihvonen L, Spoolder H, Stegeman JA, Raj M, Willeberg P, Winckler C, Marano R, Verdonck F, Candiani D, Michel V. Guidance on the assessment criteria for applications for new or modified stunning methods regarding animal protection at the time of killing. EFSA J 2018; 16:e05343. [PMID: 32625979 PMCID: PMC7009557 DOI: 10.2903/j.efsa.2018.5343] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
This guidance defines the process for handling applications on new or modified stunning methods and the parameters that will be assessed by the EFSA Animal Health and Welfare (AHAW) Panel. The applications, received through the European Commission, should contain administrative information, a checklist of data to be submitted and a technical dossier. The dossier should include two or more studies (in laboratory and slaughterhouse conditions) reporting all parameters and methodological aspects that are indicated in the guidance. The applications will first be scrutinised by the EFSA's Applications Desk (APDESK) Unit for verification of the completeness of the data submitted for the risk assessment of the stunning method. If the application is considered not valid, additional information may be requested from the applicant. If considered valid, it will be subjected to assessment phase 1 where the data related to parameters for the scientific evaluation of the stunning method will be examined by the AHAW Panel. Such parameters focus on the stunning method and the outcomes of interest, i.e. immediate onset of unconsciousness or the absence of avoidable pain, distress and suffering until the loss of consciousness and duration of the unconsciousness (until death). The applicant should also propose methodologies and results to assess the equivalence with existing stunning methods in terms of welfare outcomes. Applications passing assessment phase 1 will be subjected to the following phase 2 which will be carried out by the AHAW Panel and focuses on the animal welfare risk assessment. In this phase, the Panel will assess the outcomes, conclusions and discussion proposed by the applicant. The results of the assessment will be published in a scientific opinion. This publication is linked to the following EFSA Supporting Publications article: http://onlinelibrary.wiley.com/doi/10.2903/sp.efsa.2018.EN-1436/full This publication is linked to the following EFSA Journal article: http://onlinelibrary.wiley.com/doi/10.2903/j.efsa.2013.3486/full
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Holloway PH, Pritchard DG. Effects of ambient temperature and water vapor on chamber pressure and oxygen level during low atmospheric pressure stunning of poultry. Poult Sci 2018; 96:2528-2539. [PMID: 28521045 PMCID: PMC5850479 DOI: 10.3382/ps/pex066] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2016] [Accepted: 03/03/2017] [Indexed: 12/20/2022] Open
Abstract
The characteristics of the vacuum used in a low atmospheric pressure stunning system to stun (render unconscious) poultry prior to slaughter are described. A vacuum chamber is pumped by a wet screw compressor. The vacuum pressure is reduced from ambient atmospheric pressure to an absolute vacuum pressure of ∼250 Torr (∼33 kPa) in ∼67 sec with the vacuum gate valve fully open. At ∼250 Torr, the sliding gate valve is partially closed to reduce effective pumping speed, resulting in a slower rate of decreasing pressure. Ambient temperature affects air density and water vapor pressure and thereby oxygen levels and the time at the minimum total pressure of ∼160 Torr (∼21 kPa) is varied from ∼120 to ∼220 sec to ensure an effective stun within the 280 seconds of each cycle. The reduction in total pressure results in a gradual reduction of oxygen partial pressure that was measured by a solid-state electrochemical oxygen sensor. The reduced oxygen pressure leads to hypoxia, which is recognized as a humane method of stunning poultry. The system maintains an oxygen concentration of <5% for at least 2 minutes, which ensures that birds are irreversibly stunned. Calculated pump down (pressure versus time) data match experimental data very closely because the programmable logic controller and the human machine interface enable precise and accurate control. The vacuum system operates in the turbulent viscous flow regime, and is best characterized by absolute vacuum pressure rather than gauge pressure. Neither the presence of broiler chickens nor different fore-line pipe designs of four parallel commercial systems affected the pressure-time data. Water in wet air always reduces the oxygen concentrations to a value lower than in dry air. The partial pressure of water and oxygen were found to depend on the pump down parameters due to the formation of fog in the chamber and desorption of water from the birds and the walls of the vacuum chamber.
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Affiliation(s)
- Paul H Holloway
- Department of Materials Science and Engineering, University of Florida Gainesville, FL 32611- 6400
| | - David G Pritchard
- Animal Welfare Science and Practice, Tulip House, 70 Borough High Street, London Bridge, London SE1 1XF, United Kingdom
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