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Evaluation of Alternative Euthanasia Methods of Neonatal Chickens

Department of Poultry Science, Texas A&M AgriLife Research, College Station, TX 77843, USA
Southern Plains Agricultural Research Center, Agricultural Research Service, US Department of Agriculture, College Station, TX 77843, USA
Department of Poultry Science, Mississippi State University, Mississippi State, MS 39762, USA
Author to whom correspondence should be addressed.
Animals 2018, 8(3), 37;
Received: 13 December 2017 / Revised: 14 February 2018 / Accepted: 6 March 2018 / Published: 9 March 2018
(This article belongs to the Special Issue Humane Killing and Euthanasia of Animals on Farms)
PDF [1078 KB, uploaded 9 March 2018]


Hatched male layer chicks are currently euthanized by maceration in the United States. Public concerns on the use of maceration have led to the search for alternative methods. We hypothesized that gas inhalation and low atmospheric pressure stunning (LAPS) are viable and humane alternatives to instantaneous mechanical destruction. The objective of this study was to evaluate the physiological and behavioral responses of recently hatched male layer chicks when subjected to carbon dioxide, nitrogen inhalation, or LAPS. The study consisted of seven treatments: breathing air (NEG), 25% carbon dioxide (CO2), 50% CO2, 75% CO2, 90% CO2, 100% nitrogen (N2), or LAPS. Ten day-of-hatch, male layer chicks were randomly assigned to each treatment, and each treatment was replicated on ten different days. A custom-made vacuum system was used to reduce air pressure inside the chamber from 100.12 kPa to 15.3 kPa for the LAPS treatment. Serum corticosterone and serotonin levels were measured using commercially available competitive enzyme linked immunosorbent assay (ELISA). Latencies to loss of posture and motionlessness were determined from video recordings. The 25% and 50% CO2 treatments were discontinued after the first replication, as the majority of the chicks recovered. The chicks in the negative (NEG) group had significantly higher levels of corticosterone than the other four euthanasia treatments. On the other hand, the serotonin levels of chicks in the NEG group was significantly lower when compared to the other four euthanasia treatments. The latencies to loss of posture and motionlessness of chicks exposed to 75% and 90% CO2 were significantly shorter than those in the LAPS and N2 inhalation treatments. These data suggest that the stress responses of chicks to the CO2, N2, and LAPS treatments do not differ among each other. However, the CO2 inhalation method was faster in inducing loss of posture and motionlessness in chicks than the LAPS and N2 inhalation treatments. View Full-Text
Keywords: euthanasia; gas inhalation; low atmospheric pressure stunning; male layer chicks euthanasia; gas inhalation; low atmospheric pressure stunning; male layer chicks

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Gurung, S.; White, D.; Archer, G.; Zhao, D.; Farnell, Y.; Byrd, J.A.; Peebles, E.D.; Farnell, M. Evaluation of Alternative Euthanasia Methods of Neonatal Chickens. Animals 2018, 8, 37.

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