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Pathological consequences of low atmospheric pressure stunning in broiler chickens

Published online by Cambridge University Press:  26 June 2019

J. E. Martin*
Affiliation:
The Royal (Dick) School of Veterinary Studies and The Roslin Institute, The College of Medicine and Veterinary Medicine, Easter Bush Campus, The University of Edinburgh, Edinburgh EH25 9RG, UK
D. E. F. McKeegan
Affiliation:
Institute of Biodiversity, Animal Health and Comparative Medicine, College of Medical, Veterinary & Life Sciences, University of Glasgow, Glasgow G61 1QH, UK
D. L. Magee
Affiliation:
Department of Pathobiology and Population Medicine, Poultry Research and Diagnostic Laboratory, Mississippi State University, P. O. Box 97813, Pearl, MS 39288-7813, USA
N. Armour
Affiliation:
Department of Pathobiology and Population Medicine, Poultry Research and Diagnostic Laboratory, Mississippi State University, P. O. Box 97813, Pearl, MS 39288-7813, USA
D. G. Pritchard
Affiliation:
Consultant Animal Welfare Science and Practice, Tulip House, 70 Borough High Street London Bridge, London SE1 1XF, UK
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Abstract

Low atmospheric pressure stunning (LAPS) is a novel approach to pre-slaughter stunning of chickens using progressive hypobaric hypoxia by the application of gradual decompression (280s cycle) according to a set of prescribed pressure curves. Low atmospheric pressure stunning produces a non-recovery state. Concerns have been raised relating to the possible pathological and welfare consequences of expansion of air in the body during LAPS. In a randomised trial, we compared the gross pathology of broilers exposed to LAPS with a control group euthanised by intravenous injection of pentobarbital sodium (60 mixed sex broilers per treatment). The birds were exposed to each treatment in triplets and all birds were subject to necropsy examination to detect and score (1 to 5, minimal to severe) haemorrhagic lesions or congestion for all major organs and cavities (e.g. air sacs, joints, ears and heart) as well as external assessment for product quality (e.g. wing tips). Behavioural data (latency to loss of posture and motionless) and chamber cycle data (temperature, humidity, pressure and oxygen availability) confirmed that LAPS had been applied in a manner representative of the commercial process. All of the organs observed were structurally intact for both treatment groups. No lesions were observed in the external ears, oral cavity, tracheal lumen, crop and air sacs of birds from either treatment group. There was no difference between treatments in the wingtips, nasal turbinates, thymus, biceps femoralis and colon. Haemorrhagic lesions were observed in the calvaria, brains, hearts and lungs of both treatment groups, but lesions in these areas were more severe in the LAPS treatment group. It was not possible to distinguish between pathological changes induced by decompression or recompression. In the barbiturate group, more severe haemorrhagic lesions were observed in the superficial pectoral muscles as well as greater congestion of the infraorbital sinuses, liver, spleens, duodenum, kidneys and gonads. These findings provide evidence that LAPS did not result in distension of the intestines and air sacs sufficient to cause changes, which were grossly visible on postmortem examination. There was also no evidence of barotrauma in the ears and sinuses. The pathological changes observed in the barbiturate treatment were as expected based on barbiturate toxicity. Low atmospheric pressure stunning appears to produce pathological changes by a variety of well-established mechanisms, and while these pathological data have limited value as welfare indicators, the results confirm that organ integrity was not compromised by the process.

Type
Research Article
Copyright
© The Animal Consortium 2019 

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