Abstract
Assessing unconsciousness in livestock at different stages of the slaughter process is a legal requirement according to EU legislation. The assessment can be based on absence of readily observable indicators (behavioural indicators, physical signs and reflexes) or, under experimental conditions, by recording and subsequent assessment of brain activity as presented in an electroencephalogram (EEG). There is no consensus, however, to what extent different behavioural indicators, physical signs and reflexes accurately reflect unconsciousness. The aim of this thesis was to study the relationships between these readily observable indicators and EEG activity to provide information on 1. the exact point in time at which animals lose consciousness when subjected to different stunning and slaughter methods and 2. the validity of behavioural indicators, physical signs and reflexes used to assess unconsciousness at slaughter under commercial conditions. The results showed a large variation in time to loss of consciousness, based on EEG activity, both between stunning and slaughter procedures and amongst animals. Captive bolt stunned calves lost consciousness instantly following the stun. Loss of consciousness in pigs during CO2 stunning varied from 21 to 61 s after start of the exposure. An increased CO2 concentration decreased the time to loss of consciousness. Times to loss of consciousness in sheep slaughtered without stunning varied from 6 to 24 s. In cattle slaughtered without stunning, times to loss of consciousness varied from 14 s up to over two minutes. Following captive bolt stunning in calves, absence of reflexes indicated unconsciousness. When consciousness was lost gradually (e.g. CO2 stunning and non-stunned slaughter) none of the readily observable indicators could identify the exact point in time at which animals lost consciousness. Absence of rhythmic breathing, corneal reflex- and eyelid reflex were valid indicators of unconsciousness following CO2 stunning and non-stunned slaughter, but these indicators were quite conservative as they were initially absent long after EEG activity indicated unconsciousness. When presence of these indicators would require (re)stunning, many animals will have to be (re)stunned. The results also showed that under full commercial conditions, stunning effectiveness must be closely monitored by slaughter plant employees, since risks for stun failures are higher under commercial conditions compared to experimental conditions.
| Language | English |
|---|---|
| Qualification | Doctor of Philosophy |
| Awarding Institution |
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| Supervisors/Advisors |
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| Award date | 11 Nov 2016 |
| Place of Publication | Wageningen |
| Publisher | |
| Print ISBNs | 9789462579064 |
| DOIs | |
| Publication status | Published - 2016 |
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Keywords
- livestock
- slaughter
- animal welfare
- stunning
- electroencephalograms
- animal behaviour
- consciousness
- animal production
- animal health
- pigs
- cattle
- sheep
Cite this
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Assessing unconsciousness in livestock at slaughter. / Verhoeven, Merel.
Wageningen : Wageningen University, 2016. 187 p.Research output: Thesis › internal PhD, WU › Academic
TY - THES
T1 - Assessing unconsciousness in livestock at slaughter
AU - Verhoeven, Merel
N1 - WU thesis 6500 Author's name on cover: Merel Verhoeven Includes bibliographic references. - With summary in English
PY - 2016
Y1 - 2016
N2 - Assessing unconsciousness in livestock at different stages of the slaughter process is a legal requirement according to EU legislation. The assessment can be based on absence of readily observable indicators (behavioural indicators, physical signs and reflexes) or, under experimental conditions, by recording and subsequent assessment of brain activity as presented in an electroencephalogram (EEG). There is no consensus, however, to what extent different behavioural indicators, physical signs and reflexes accurately reflect unconsciousness. The aim of this thesis was to study the relationships between these readily observable indicators and EEG activity to provide information on 1. the exact point in time at which animals lose consciousness when subjected to different stunning and slaughter methods and 2. the validity of behavioural indicators, physical signs and reflexes used to assess unconsciousness at slaughter under commercial conditions. The results showed a large variation in time to loss of consciousness, based on EEG activity, both between stunning and slaughter procedures and amongst animals. Captive bolt stunned calves lost consciousness instantly following the stun. Loss of consciousness in pigs during CO2 stunning varied from 21 to 61 s after start of the exposure. An increased CO2 concentration decreased the time to loss of consciousness. Times to loss of consciousness in sheep slaughtered without stunning varied from 6 to 24 s. In cattle slaughtered without stunning, times to loss of consciousness varied from 14 s up to over two minutes. Following captive bolt stunning in calves, absence of reflexes indicated unconsciousness. When consciousness was lost gradually (e.g. CO2 stunning and non-stunned slaughter) none of the readily observable indicators could identify the exact point in time at which animals lost consciousness. Absence of rhythmic breathing, corneal reflex- and eyelid reflex were valid indicators of unconsciousness following CO2 stunning and non-stunned slaughter, but these indicators were quite conservative as they were initially absent long after EEG activity indicated unconsciousness. When presence of these indicators would require (re)stunning, many animals will have to be (re)stunned. The results also showed that under full commercial conditions, stunning effectiveness must be closely monitored by slaughter plant employees, since risks for stun failures are higher under commercial conditions compared to experimental conditions.
AB - Assessing unconsciousness in livestock at different stages of the slaughter process is a legal requirement according to EU legislation. The assessment can be based on absence of readily observable indicators (behavioural indicators, physical signs and reflexes) or, under experimental conditions, by recording and subsequent assessment of brain activity as presented in an electroencephalogram (EEG). There is no consensus, however, to what extent different behavioural indicators, physical signs and reflexes accurately reflect unconsciousness. The aim of this thesis was to study the relationships between these readily observable indicators and EEG activity to provide information on 1. the exact point in time at which animals lose consciousness when subjected to different stunning and slaughter methods and 2. the validity of behavioural indicators, physical signs and reflexes used to assess unconsciousness at slaughter under commercial conditions. The results showed a large variation in time to loss of consciousness, based on EEG activity, both between stunning and slaughter procedures and amongst animals. Captive bolt stunned calves lost consciousness instantly following the stun. Loss of consciousness in pigs during CO2 stunning varied from 21 to 61 s after start of the exposure. An increased CO2 concentration decreased the time to loss of consciousness. Times to loss of consciousness in sheep slaughtered without stunning varied from 6 to 24 s. In cattle slaughtered without stunning, times to loss of consciousness varied from 14 s up to over two minutes. Following captive bolt stunning in calves, absence of reflexes indicated unconsciousness. When consciousness was lost gradually (e.g. CO2 stunning and non-stunned slaughter) none of the readily observable indicators could identify the exact point in time at which animals lost consciousness. Absence of rhythmic breathing, corneal reflex- and eyelid reflex were valid indicators of unconsciousness following CO2 stunning and non-stunned slaughter, but these indicators were quite conservative as they were initially absent long after EEG activity indicated unconsciousness. When presence of these indicators would require (re)stunning, many animals will have to be (re)stunned. The results also showed that under full commercial conditions, stunning effectiveness must be closely monitored by slaughter plant employees, since risks for stun failures are higher under commercial conditions compared to experimental conditions.
KW - livestock
KW - slaughter
KW - animal welfare
KW - stunning
KW - electroencephalograms
KW - animal behaviour
KW - consciousness
KW - animal production
KW - animal health
KW - pigs
KW - cattle
KW - sheep
KW - vee
KW - slacht
KW - dierenwelzijn
KW - bedwelmen
KW - elektro-encefalogrammen
KW - diergedrag
KW - bewustzijn (consciousness)
KW - dierlijke productie
KW - diergezondheid
KW - varkens
KW - rundvee
KW - schapen
U2 - 10.18174/388582
DO - 10.18174/388582
M3 - internal PhD, WU
SN - 9789462579064
PB - Wageningen University
CY - Wageningen
ER -