Carbon dioxide for euthanasia of laboratory animals.
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Administration, Inhalation↗
Biomedical subjects
A B Mohan Raj
Publications and source records attributed to A B Mohan Raj.
Efficiency of bleeding of broilers after gaseous or electrical stunning.
The efficiency of bleeding of broilers (g blood/kg liveweight) was measured after stunning them with either 45 per cent carbon dioxide in air for two minutes or with 2 per cent oxygen (achieved by displacing air with argon) for two minutes or with an electric current (77 or 104 mA at 50 Hz for four seconds). The results indicated that the initial rate of bleeding was higher in the electrically stunned broilers with non-fibrillated hearts than in the gas stunned broilers and electrically stunned broilers with fibrillated hearts. This difference was significant up to 60 seconds after neck cutting (P less than 0.05) but after 140 seconds all the broilers had bled out to a similar extent (30 to 33 g/kg liveweight). It is concluded that after gas stunning the time interval between neck cutting and scalding should be 60 to 140 seconds.
Abattoirs↗
Preferential feeding behaviour of hens in different gaseous atmospheres.
1. The object of this study was to identify the concentrations of carbon dioxide (CO2) and hypoxia (induced by argon) which hens could detect and by preference avoid. 2. Hens were housed in an apparatus consisting of an upper roosting chamber connected to two descending passages which led to separate identical feeding chambers. The gas concentration in both these feeding chambers could be regulated. 3. The hens were allowed to feed in either a normal air atmosphere or an altered atmosphere containing a sub-stunning concentration of CO2 or argon. The birds' preference for feeding in the two chambers was used as an indicator of the concentration which they chose to avoid. 4. The study involved two experiments. In the first it was found that when the concentration of CO2 was raised above 5%, or the concentration of oxygen was reduced to 10% or below, the occupancy of that chamber was significantly reduced. 5. The results of the second experiment confirmed that a concentration of above 7.5% CO2 or oxygen levels of 10% or below can be detectable to hens and, given a free choice, the hens learnt to avoid such atmospheres. 6. The presence of a dominant bird in the roosting chamber or in the feeding chamber containing air caused the subordinate birds to enter the treatment chamber containing gas. This would imply that the unpleasantness of the stunning gases at the concentrations used in this study was less severe than the social pressure.(ABSTRACT TRUNCATED AT 250 WORDS)
Animals↗
Prevalence of broken bones in broilers killed by different stunning methods.
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Abattoirs↗
Effect of carbon dioxide stunning on somatosensory evoked potentials in hens.
The spontaneous electroencephalogram (EEG) and somatosensory evoked potentials (SEPs) were examined in 17 hens before and during stunning in 45 per cent carbon dioxide. The results indicated that EEG suppression and loss of SEPs occurred in 21 +/- 4 s and 30 +/- 2 s, respectively, after exposure to carbon dioxide, eventually leading to EEG silence in 101 +/- 18 s. Convulsions occurred 15 seconds after the loss of SEPs, suggesting that the hens convulsed while they were unconscious. It is concluded that the induction of anaesthesia can be rapid in carbon dioxide stunning and in this respect carbon dioxide is potentially suitable for stunning poultry under commercial conditions.
Abattoirs↗
Effect of rate of induction of carbon dioxide anaesthesia on the time of onset of unconsciousness and convulsions.
The effect of different rates of induction of carbon dioxide anaesthesia on the time to loss of consciousness was investigated in broilers and hens. In experiment 1, 24 and 17 broilers, respectively, were exposed to 45 per cent carbon dioxide within 8 or 18 seconds (accession time). In experiment 2, 18 to 20 broilers and hens were exposed to either 35, 45, 55 or 65 per cent carbon dioxide within 8 seconds. The results indicated that, in general, the rate of accession is more critical than the final concentration of carbon dioxide; however, in 35 per cent carbon dioxide an exposure time of longer than 5 minutes is required to kill the birds. The time to sustained eye closure, time to onset of clonic and tonic convulsions and the duration of convulsive episodes were shorter in broilers than in hens. It is suggested that under commercial situations a final concentration of 55 per cent carbon dioxide would be suitable for killing broilers and hens.
Abattoirs↗
Investigation into the batch stunning/killing of chickens using carbon dioxide or argon-induced hypoxia.
Three hundred and twenty broilers were stunned for 2 minutes in batches of 10 per crate in four treatments: 45 per cent carbon dioxide; 55 per cent carbon dioxide; 2 per cent oxygen, or 5 per cent oxygen presented as air diluted by argon. The number of survivors and the time to resumption of consciousness were recorded using the time to eye opening and response to comb pinching as indicators of consciousness. In 45 per cent and 55 per cent carbon dioxide and 2 per cent oxygen, 28, none and eight birds, respectively, survived out of 100 in each group. In 5 per cent oxygen the birds were still fully conscious after a 2 minute exposure period, and the test was discontinued. The time to recovery could be rapid after stunning in both the gases. It is suggested that a concentration of 55 per cent carbon dioxide or less than 1 per cent oxygen are required to kill broilers within a 2 minute exposure period, and that care should be taken to ensure that there is sufficient turbulence within the stunning chamber to avoid air pockets being trapped between the birds.
Abattoirs↗
Changes in the somatosensory evoked potentials and spontaneous electroencephalogram of hens during stunning with a carbon dioxide and argon mixture.
A previous investigation indicated that when hens were exposed to 2% oxygen in argon (anoxia) EEG suppression and loss of SEPs occurred at 17 and 29 s after exposure. In this study, hens were exposed to 49% carbon dioxide in air (hypercapnic hypoxia) or 31% carbon dioxide with 2% oxygen in argon (hypercapnic anoxia) and their spontaneous electroencephalogram (EEG) and somatosensory evoked potentials (SEPs) were investigated. The results indicated that EEG suppression and loss of SEPs occurred in 11 and 26 s, respectively, in hypercapnic hypoxia. These events occurred at 11 and 19 s, respectively, after exposure to hypercapnic anoxia. These results indicated that, with regard to preslaughter stunning/killing of chickens, a mixture of 31% carbon dioxide with 2% oxygen in argon resulted in a more rapid loss of evoked responses in the brain when compared with 49% carbon dioxide in air or with 2% oxygen in argon. It is concluded that stunning chickens with low concentrations of carbon dioxide in argon would result in a more rapid loss of consciousness.
Animals↗