Alternatives to Carbon Dioxide in Two Phases for the Improvement of Broiler Chickens’ Welfare during Stunning
Author:
Rucinque Daniel Santiago1ORCID, Velarde Antonio1ORCID, Xercavins Aida1, Varvaró-Porter Aranzazu1, Gibson Troy John2ORCID, Michel Virginie3, Contreras-Jodar Alexandra1
Affiliation:
1. Animal Welfare Program, Institute of Agrifood Research and Technology (IRTA), 17121 Monells, Spain 2. Department of Pathobiology and Population Sciences, Royal Veterinary College, University of London, Hatfield AL9 7TA, UK 3. Direction of Strategy and Programmes, French Agency for Food, Environmental and Occupational Health & Safety (ANSES), 14 Rue Pierre et Marie Curie, 94701 Maisons-Alfort, France
Abstract
This study evaluated the exposure to gas mixtures of carbon dioxide (CO2) associated with nitrogen (N2) as alternatives to CO2 in two phases to improve the welfare of broiler chickens at slaughter. Broilers were exposed to one of three treatments: 40C90C (1st phase: <40% CO2 for 2 min; 2nd phase: >90% CO2 and <2% O2 for 2 min, n = 92), 40C60N (40% CO2, 60% N2, and <2% O2 for 4 min, n = 79), or 20C80N (20% CO2, 80% N2, and <2% O2 for 4 min, n = 72). Brain activity (EEG) was assessed to determine the onset of loss of consciousness (LOC) and death. Behavioural assessment allowed for characterisation of an aversive response to the treatments and confirmed loss of posture (LOP) and motionlessness as behavioural proxies of LOC and brain death in 40C60N and 20N80C. However, the lack of quality of the EEG traces obtained in 40C90C did not allow us to determine the onset of LOC and brain death for this treatment. The onset of LOC in 40C60N was found at 19 s [14–30 s] and in 20C80N at 21 s [16–37 s], whereas a LOP was seen at 53 s [26–156 s] in 40C90C. Birds showed brain death in 40C60N at 64 s [43–108 s] and in 20C80N at 70 s [45–88 s]), while they became motionless in 40C90C at 177 s [89–212 s]. The 40C90C birds not only experienced more events of aversive behaviours related to mucosal irritation, dyspnoea, and breathlessness during induction to unconsciousness but were at risk of remaining conscious when the CO2 concentration was increased in the 2nd phase (known to cause severe pain). From an animal welfare point of view, 40C60N proved to be the least aversive of the three treatments tested, followed by 20C80N and 40C90C.
Funder
European Commission
Subject
General Veterinary,Animal Science and Zoology
Reference51 articles.
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