3 results
A pilot study to assess whether high expansion CO2-enriched foam is acceptable for on-farm emergency killing of poultry
- MA Gerritzen, J Sparrey
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- Journal:
- Animal Welfare / Volume 17 / Issue 3 / August 2008
- Published online by Cambridge University Press:
- 11 January 2023, pp. 285-288
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This pilot experiment was conducted to ascertain whether CO2-enriched high expansion foam could be an acceptable and efficient alternative in emergency killing of poultry. This method could have wide-ranging applications but with particular emphasis on small (backyard) flocks, free-range sheds or open (naturally-ventilated) housings. The objectives of the study were as follows: 1) to determine whether the injection of foam and being covered with foam leads to fear or panic reactions in birds; 2) to determine the time taken to render birds unconscious and dead and 3) to determine whether any pathological abnormalities are observed post mortem. Six laying hens were individually exposed to increasing levels of CO2 foam with an expansion rate of 300:1. The test box containing individual birds filled with foam within 30 s. During foaming, two out of six birds tried to escape from the test box (1–2 attempts per bird). Apart from displaying greater alertness, birds showed no aversive reactions to the CO2 foam. Twenty-to-thirty seconds after being covered with foam, five of the six birds demonstrated one or two forcable or convulsive movements. Movement patterns and muscle jerks immediately following this convulsive movement led us to believe that birds lost consciousness at this moment and, within approximately three minutes, all birds had ceased to have a heartbeat. Macroscopic post mortem examination of the birds revealed no abnormalities and microscopic examination showed moderate bronchiolar bleeding and a small amount of alveolar bleeding. After assessing behavioural parameters, measurements of heart rate and pathological data, it is our conclusion that CO2 foam has the potential to be an acceptable method of killing poultry. It is advisable for this method to be examined on a larger scale in order to assess the implications of physiological (EEG and ECG) measurements on welfare.
Head-only electrical stunning and bleeding of African catfish (Clarias gariepinus): assessment of loss of consciousness
- E Lambooij, RJ Kloosterboer, MA Gerritzen, JW van de Vis
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- Journal:
- Animal Welfare / Volume 13 / Issue 1 / February 2004
- Published online by Cambridge University Press:
- 11 January 2023, pp. 71-76
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The objective was to evaluate the welfare implications of electrical stunning prior to gill-cutting of farmed African catfish as an alternative to live chilling in combination with gutting. Electroencephalogram (EEG) and electrocardiogram (ECG) recordings, in combination with observation of behaviour and responses to noxious stimuli, were used to assess brain and cardiac function in African catfish (body-weight 1571 ± 362 g [mean ± standard deviation], 32 males and 26 females). In the first experiment, the minimum electrical current required to induce a general epileptiform insult by head-only stunning was determined. The individual catfish were fixed in a specially designed restrainer, and applied voltages of 150 V, 200 V, 250 V, 300 V or 350 V (50 Hz AC) were delivered via scissor-model stunning tongs for approximately I s. A general epileptiform insult was observed in 31 fish, for which a successful EEG recording was obtained using 362 ± 32 V, 629 ± 180 mA for 1.2 s. The durations of the tonic, the clonic and the exhaustion phases were 8 ± 3 s, 12 ± 7 s and 7 ± 5 s as measured by EEG, respectively; a distinct exhaustion phase was not clear in II fish. The total duration of the insult was 23 ± 8 s. After the insult the fish recovered. The heart rate was 63 ± 29 beats min I prior to stunning. After stunning, the ECG revealed extrasystole and was irregular. By using an average current of 629 ± 180 mA (at approximately 360 V, 50 Hz AC), at least 91% of fish are effectively stunned with a confidence level of 95%. In the second experiment, the behaviour of 10 individual catfish, which were able to move freely in water, was observed following head-only stunning (370 V). The durations of the tonic, clonic and exhaustion phases in free-swimming fish were II ± 8 s, 20 ± 5 s and 23 ± 20 s, respectively. All fish recovered. In the third experiment, a group of seven catfish was head-only stunned followed by gill-cutting to kill them as a second procedure (ie after recovery from head-only stunning). No brain activity was seen on the EEG 12 ± 5 s after stunning. However, two fish showed responses to noxious stimuli after 2 min and 5 min. A second group of seven catfish was gill-cut only. They responded to noxious stimuli for at least 15 min. The blood loss was 1.2% and I.0% of live weight for the first and second group, respectively. It may be concluded from our results that African catfish are effectively stunned for 23 ± 8 s with a current of 629 ± 180 mA for 1.2 s, after which they recover. Since evoked responses may remain for at least 5 min after stunning and gill-cutting, we recommended that the stunning and killing procedure should be optimised.
Killing wild geese with carbon dioxide or a mixture of carbon dioxide and argon
- MA Gerritzen, HGM Reimert, A Lourens, MBM Bracke, MTW Verhoeven
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- Journal:
- Animal Welfare / Volume 22 / Issue 1 / February 2013
- Published online by Cambridge University Press:
- 01 January 2023, pp. 5-12
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The killing of animals is the subject of societal and political debate. Wild geese are caught and killed on a regular basis for fauna conservation and damage control. Killing geese with carbon dioxide (CO2) is commonly practiced, but not listed in legislation on the protection of flora and fauna, and societal concerns have been raised against this method. In this study, an experiment was carried out killing 30 wild-caught geese using either CO2 or a mixture of CO2 and argon (Ar). Brain function (EEG) and heart function (ECG) were measured to determine loss of consciousness and onset of death. The stage of unconsciousness was reached on average within one minute in both treatments (56 s for CO2 and 50 s for CO2 and Ar). States of minimal brain activity and ineffective heart beat were reached more quickly using CO2 compared to CO2 and Ar (112 versus 178 s for minimal brain activity and 312 versus 394 s for ineffective heart beat for CO2 and the mixture of CO2 and Ar, respectively). The mixture of carbon dioxide and argon did not significantly reduce time to loss of consciousness or death. Further studies on behaviour and stress physiology are needed to determine conclusively whether CO2 alone is a satisfactory agent to kill wild-caught geese as the lower CO2 concentration in the CO2-Ar treatment may act as a sedative and reduce the aversiveness of the animals during exposure to lethal gas concentrations.