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ARS Home » Midwest Area » West Lafayette, Indiana » Livestock Behavior Research » Research » Publications at this Location » Publication #350150

Research Project: Protecting the Welfare of Food Producing Animals

Location: Livestock Behavior Research

Title: A two-step process of nitrous oxide before carbon dioxide for humanely euthanizing piglets: on-farm trials

item SMITH, REBECCA - Purdue University
item RAULT, JEAN-LOUP - University Of Veterinary Medicine
item GATES, RICHARD - University Of Illinois
item Lay Jr, Donald

Submitted to: Animals
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/29/2018
Publication Date: 4/4/2018
Citation: Smith, R.K., Rault, J., Gates, R.S., Lay Jr, D.C. 2018. A two-step process of nitrous oxide before carbon dioxide for humanely euthanizing piglets: on-farm trials. Animals. 8(4):52. doi:10.3390/ani8040052.

Interpretive Summary: The current approved method of using carbon dioxide to euthanize newborn piglets is raising concerns from the public and scientists on whether the method is truly humane. A new form of euthanasia that is humane, practical, and socially acceptable is needed. Nitrous oxide, also known as laughing gas, may be a potential answer. Nitrous oxide acts as an anesthetic and is not aversive to piglets like carbon dioxide, so it does not elicit aversive behaviors. After exposure to nitrous oxide, piglets enter a state of unconsciousness before being exposed to the aversive effects of carbon dioxide. On-farm use of a two-step method using nitrous oxide provides a more humane way to euthanize newborn piglets than the current on-farm method using carbon dioxide.

Technical Abstract: The current methods of euthanizing neonatal piglets are raising concerns from the public and scientists. Our experiment tests the use of a two-step euthanasia method using nitrous oxide (N2O) for six minutes and then carbon dioxide (CO2) as a more humane way to euthanize piglets compared to just using CO2. A euthanasia chamber was modified to test two euthanasia treatments: the two-step delivery of N2O for six minutes and then CO2 or just CO2. There were two different experiments using these two treatments. Experiment 1 euthanized eighteen piglets individually and Experiment 2 euthanized eighteen groups of 4-6 piglets with behavior data collected during the processes. When comparing the data between the two treatments, the sequence of behaviors was different. In the N2O treatment, piglets start to lose consciousness before going into aversive behaviors of heavy breathing and open-mouth breathing compared to the CO2 piglets that do not start to lose consciousness until after these adverse behaviors. In this regard, euthanizing piglets for six minutes with N2O and then CO2 is a more humane way to euthanize neonatal piglets than just CO2.