Abstract
Simple SummaryYoung poultry that are malformed, fail to hatch, or are not economically viable must be humanely killed at the hatchery. Maceration is the predominant method used and is instantaneous and humane. However, it is possible that new methods may be developed which could improve animal welfare and reduce suffering. In this study, we used gases and a vacuum system to kill chicks by reducing available oxygen. We found that using carbon dioxide or the vacuum system resulted in better welfare, as compared to the nitrogen treatment.Newly hatched male layer chicks are considered as “by-products” in the egg industry and must be humanely euthanized at the hatchery. Instantaneous mechanical destruction (maceration) is the predominant euthanasia method applied in poultry hatcheries and is approved by the American Veterinary Medical Association (AVMA). However, maceration is not perceived by the public to be a humane means of euthanasia. The effects of alternative euthanasia methods, including carbon dioxide (CO2) or nitrogen (N2) inhalation, and a commercial negative pressure stunning system on behavioral and physiological responses of day-of-hatch male layer chicks, were evaluated in a field trial. Chick behaviors, including ataxia, loss of posture, convulsions, cessation of vocalization, and cessation of movement, were monitored. Serum hormones were assessed at the end of each of the alternative euthanasia treatments, including a control group allowed to breathe normal atmospheric air. The N2 method induced unconsciousness and death later than the CO2 and negative pressure methods, and increased serum corticosterone concentrations of neonatal chicks. Carbon dioxide inhalation increased serotonin concentrations as compared to controls, as well as the N2 and the negative pressure methods. The behavioral and physical responses observed in this study suggest that both CO2 inhalation and negative pressure stunning can be employed to humanely euthanize neonatal male layer chicks.
Highlights
The CO2, N2, and negative pressure methods had the potential to improve the welfare of chicks because the serotonin levels of the chicks in those treatments were higher than those in a control treatment that could breathe normal atmospheric air [14]. The effects of these euthanasia methods on the behavioral and physiological responses of newly hatched male layers were compared in a commercial LAPSTM system
Animals 2021, 11, 1802 experimental design was applied to investigate the potential effects of various euthanasia methods on chick behavioral and physiological responses
The LAPSTM system has been reported to induce early high amplitude slow waves of EGG signaling, indicating a loss of consciousness [12], reduce aversive behavioral responses, decrease acute heart elevation during the conscious period [19], and cause limited pathological changes by the decompression and the recompression process [34]. These current data suggest that the commercial negative pressure method is a humane method for culling male layer chicks
Summary
Male layers, pipped embryos, and hatched chicks with lethal deformities must be humanely euthanized on day-of-hatch. Male chicks can be distinguished via feather, vent, and color sexing techniques on day-of-hatch before they are humanely euthanized. Maceration, with rotating blades or projections, is predominantly applied at hatcheries as a humane killing method of chicks within 72 h post hatch, which causes minimal pain and distress because of its rapid physical disruption of the brain [9]. The current report is the first to evaluate the effects of this commercial stunning system when employed for the euthanasia of newly hatched chicks. The effects of these euthanasia methods on the behavioral and physiological responses of newly hatched male layers were compared in a commercial LAPSTM system
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