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Animals 2018, 8(4), 52;

A Two-Step Process of Nitrous Oxide before Carbon Dioxide for Humanely Euthanizing Piglets: On-Farm Trials

Department of Animal Sciences, Purdue University, West Lafayette, IN 47907, USA
Institute of Animal Husbandry and Animal Welfare, University of Veterinary Medicine, A-1210 Vienna, Austria
Department of Agriculture and Biological Engineering, University of Illinois, Urbana, IL 61801, USA
USDA-ARS, Livestock Behavior Research Unit, West Lafayette, IN 47907, USA
Author to whom correspondence should be addressed.
Received: 27 February 2018 / Revised: 29 March 2018 / Accepted: 30 March 2018 / Published: 4 April 2018
(This article belongs to the Special Issue Humane Killing and Euthanasia of Animals on Farms)
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Current methods of euthanizing piglets are raising animal welfare concerns. Our experiment used a novel two-step euthanasia method, using nitrous oxide (N2O) for six minutes and then carbon dioxide (CO2) on compromised 0- to 7-day-old piglets. A commercial euthanasia chamber was modified to deliver two euthanasia treatments: the two-step method using N2O then CO2 (N2O treatment) or only CO2 (CO2 treatment). In Experiment 1, 18 piglets were individually euthanized. In Experiment 2, 18 groups of four to six piglets were euthanized. In the N2O treatment, piglets lost posture, indicating the onset of losing consciousness, before going into CO2 where they showed heavy breathing and open-mouth breathing; whereas piglets in the CO2 treatment did not lose posture until after exhibiting these behaviors (p ≤ 0.004). However, piglets in the N2O treatment took longer to lose posture compared to the CO2 treatment (p < 0.001). Piglets in the N2O treatment displayed more behavioral signs of stress and aversion: squeals/minute (p = 0.004), escape attempts per pig (p = 0.021), and righting responses per pig (p = 0.084) in a group setting. In these regards, it cannot be concluded that euthanizing piglets for 6 min with N2O and then CO2 is more humane than euthanizing with CO2 alone. View Full-Text
Keywords: on-farm killing; euthanasia; neonatal piglet; carbon dioxide; nitrous oxide on-farm killing; euthanasia; neonatal piglet; carbon dioxide; nitrous oxide

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Smith, R.K.; Rault, J.-L.; Gates, R.S.; Lay, D.C., Jr. A Two-Step Process of Nitrous Oxide before Carbon Dioxide for Humanely Euthanizing Piglets: On-Farm Trials. Animals 2018, 8, 52.

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