Euthanasia of day-old chicks with carbon dioxide and argon

Abstract

The efficacy for the euthanasia of day-old chicks of mixtures of carbon dioxide and air, or carbon dioxide and argon containing 1, 2 or 5 per cent residual oxygen, or argon containing 1 or 2 per cent residual oxygen was tested in three experiments. The time to the onset of unconsciousness of individual chicks, determined from the time to loss of posture, was similar during their exposure to 2 per cent oxygen in argon, 20, 30 or 40 per cent carbon dioxide in argon with 2 per cent residual oxygen, or 90 per cent carbon dioxide in air. The exposure of chicks in batches of 20 to a mixture of 20, 30 or 40 per cent carbon dioxide in argon resulted in the death of all the chicks within two minutes. However, a residual oxygen level of 5 per cent in these mixtures resulted in the survival of some chicks for longer than two minutes. With argon alone the level of residual oxygen was critical; less than 2 per cent was essential to achieve 100 per cent mortality within three minutes, and a rise from 2 to about 3 per cent resulted in up to 20 per cent of the chicks surviving for seven minutes.

Evaluation of Alternative Euthanasia Methods of Neonatal Chickens

“…Continued exposure to the gas leads to hypercapnic hypoxia, respiratory depression, and ultimately death [ 8 ]. Raj and Whittington [ 9 ] studied the efficacy of either a 90% CO 2 treatment or mixture of 20, 30, 40% CO 2 in argon. Their study [ 9 ] reported that day-old chicks subjected to 90% CO 2 in the air died within two minutes of exposure.…”

“…Raj and Whittington [ 9 ] studied the efficacy of either a 90% CO 2 treatment or mixture of 20, 30, 40% CO 2 in argon. Their study [ 9 ] reported that day-old chicks subjected to 90% CO 2 in the air died within two minutes of exposure. European Union guidelines of Council Directive 93/119/EC on animal protection at the time of slaughter or killing, requires chicks to be exposed to the highest possible concentration of CO 2 dispensed from a 100% source and requires that the gas concentration be maintained until the death of the chicks [ 10 ].…”

“…Nitrogen (N 2 ) and argon (Ar) are tasteless, odorless gases that displace oxygen from breathing air, resulting in a loss of consciousness from anoxia, which finally leads to bird death [ 11 ]. Residual oxygen concentration should be maintained below 2% while using these anoxic gases for euthanasia [ 9 , 12 ]. Raj and Whittington [ 9 ] reported that the recovery rates of chicks exposed to mixtures of 20 to 40% CO 2 in Ar, with a 5% residual oxygen concentration, ranged from 15 to 100%.…”

“…Residual oxygen concentration should be maintained below 2% while using these anoxic gases for euthanasia [ 9 , 12 ]. Raj and Whittington [ 9 ] reported that the recovery rates of chicks exposed to mixtures of 20 to 40% CO 2 in Ar, with a 5% residual oxygen concentration, ranged from 15 to 100%.…”

Gas mixtures for anaesthesia and euthanasia in broiler chickens

“…Raj (1996) found that either 90% argon in air or a mixture of 30% carbon dioxide and 60% argon in air is preferable to a high concentration of carbon dioxide for stunning and killing of turkeys. Raj and Whittington (1995) reported that chickens could also be killed in argon without inducing any apparent respiratory discomfort before the loss of consciousness, although behavioural signs of agitation were obvious. We have previously developed a mixture of carbon dioxide and oxygen for the induction of an acceptable euthanasia in rats (Coenen et al, 1995).…”