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Aversion to nitrogen and carbon dioxide mixtures for stunning pigs

Published online by Cambridge University Press:  01 January 2023

P Llonch ,
A Dalmau ,
P Rodríguez ,
X Manteca  and
A Velarde
P Llonch
Affiliation:
IRTA, Animal Welfare Subprogram, Finca Camps i Armet s/n, E-17121 Monells (Girona), Spain Universitat Autònoma de Barcelona, Facultat de Veterinària, Departament de Ciència Animal i dels Aliments, Campus Bellaterra, edifici V Cerdanyola del Vallès, 08193, Barcelona, Spain
A Dalmau
Affiliation:
IRTA, Animal Welfare Subprogram, Finca Camps i Armet s/n, E-17121 Monells (Girona), Spain
P Rodríguez
Affiliation:
IRTA, Animal Welfare Subprogram, Finca Camps i Armet s/n, E-17121 Monells (Girona), Spain
X Manteca
Affiliation:
Universitat Autònoma de Barcelona, Facultat de Veterinària, Departament de Ciència Animal i dels Aliments, Campus Bellaterra, edifici V Cerdanyola del Vallès, 08193, Barcelona, Spain
A Velarde*
Affiliation:
IRTA, Animal Welfare Subprogram, Finca Camps i Armet s/n, E-17121 Monells (Girona), Spain
*
* Contact for correspondence and requests for reprints: antonio.velarde@irta.cat
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Abstract

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Inhalation of concentrations greater than 30% of carbon dioxide (CO2) by volume in atmospheric air causes aversion in pigs. The objective of this study was to assess, using aversion learning techniques and behavioural studies, the aversion to three alternative gas mixtures of nitrogen (N2) and CO2: 70% N2 and 30% CO2 (70N30C), 80% N2 and 20% CO2 (80N20C) and 85% N2 and 15% CO2 (85N15C). The experiment consisted of two trials of three groups of ten pigs each. Pigs were placed individually at the starting point of the test facility and allowed to enter the crate of a dip-lift stunning system during one control session with atmospheric air and three treatment sessions with one of the gas treatments in each group. When the pit contained any of the three gas mixtures, the time taken to cross the raceway and enter the crate did not increase compared to the control session. However, when exposed to the gas mixtures, the majority (85.80%) of pigs performed attempted retreats in the crate, 22.22% exhibited escape attempts, and 7.91% vocalised, without differences between gas mixtures. The percentage of pigs gasping was higher when exposed to 70N30C compared to 80N20C and 85N15C. The results suggest that pigs show signs of aversion to the inhalation of 15 to 30% CO2 in nitrogen atmosphere compared to atmospheric air but the aversion response did not increase in consecutive sessions.

Keywords

animal welfareaversioncarbon dioxidenitrogenpigsstunning
Type
Research Article
Information
Animal Welfare , Volume 21 , Issue 1 , February 2012 , pp. 33 - 39
Copyright
© 2012 Universities Federation for Animal Welfare

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