Texas A&M AgriLife Research
Dr. Morgan Farnell, PhD
Department of Poultry Science
Texas A&M University
101 Kleberg Building; 2472 TAMU
College Station, TX 77843
In the egg industry, the sex of day-old chicks is determined at the hatchery. Male layer chicks, unwanted sexes from breeding lines and broiler chicks with lethal deformities or inability to pip must be euthanized humanely at the day of hatch. Currently, instantaneous mechanical destruction (maceration) is the predominant euthanasia method used in poultry hatcheries and approved by the American Veterinary Medical Association (AVMA). However, it is not always perceived by the public to be a humane means of euthanasia.
The purpose of this study was three-pronged: to determine the most humane and efficacious method of gas asphyxiation of chicks in a customized chamber; to evaluate the use of a vacuum system as a means of day of hatch euthanasia; and to adapt the best of the above treatments for a large-scale hatchery field trial. The welfare of neonatal chicks euthanized by these alternative methods was evaluated through behavioral and physiological responses.
The alternative euthanasia methods evaluated included carbon dioxide (CO2), nitrogen (N2) and a vacuum system to euthanize day-of-hatch male layer chicks. In the laboratory phase, male layer chicks were subjected to breathing air, 25% CO2, 50% CO2, 75% CO2, 90% CO2, 100% N2 and an experimental vacuum system. Chicks recovered from the exposure to the 25% and 50% CO2 treatments. The CO2 treated chicks (either 75% or 90%) spent less time to lose posture and to reach motionlessness than chicks treated by the vacuum system or N2 inhalation. However, there were no statistical differences among 75% CO2, 90% CO2, 100% N2 and vacuum treatments in the level of stress hormones detected in the chicks. In the field study, male layer chicks were subjected to breathing air, CO2, N2 and a low atmospheric pressure stunning (LAPSâ„¢) system in a commercial chamber. The N2 treated chicks spent more time to initiate ataxia, loss of posture, convulsions and motionlessness and demonstrated higher corticosterone levels; whereas the LAPS™ system and the CO2 methods induced unconsciousness of chicks quicker without increasing stress levels. Interestingly, the CO2 treatmentincreased the hormone responsible for eliciting a sense of well-being in chicks compared to the other treatments.
The data collected suggests that both CO2 and vacuum treatments could be considered as alternatives to maceration to euthanize day of hatch chicks humanely and quickly on a commercial scale. The investment of the chamber, gas cost and worker safety/training may be short-term drawbacks for these methods. These methods have been shown to be humane alternatives.
