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ARS Home » Midwest Area » West Lafayette, Indiana » Livestock Behavior Research » Research » Publications at this Location » Publication #312737

Research Project: Safeguarding Well-being of Food Producing Animals

Location: Livestock Behavior Research

Title: Assessment of aversion to different concentrations of CO2 gas by weaned pigs using an approach-avoidance paradigm

item KC, L - Iowa State University
item JOHNSON, AK - Iowa State University
item KARRIKER, LA - Iowa State University
item SHEPHERD, TA - Iowa State University
item STINN, JP - Iowa State University
item XIN, H - Iowa State University
item SUTHERLAND, MA - Agresearch New Zealand
item Lay, Jr, Donald - Don
item MILLMAN, ST - Iowa State University

Submitted to: Humane Slaughter Association Symposium
Publication Type: Proceedings
Publication Acceptance Date: 12/16/2014
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: The objective of this study was to examine the aversiveness of carbon dioxide (CO2) to weaned pigs using approach-avoidance and condition place avoidance paradigms. A preference-testing device was custom designed with two connected chambers maintained at static gas concentrations. The control chamber maintained ambient air conditions (1% CO2); the treatment chamber maintained predetermined CO2 concentrations. Twelve crossbred healthy weaned pigs were individually trained for 5 consecutive days to enter the treatment chamber to access a food reward, with ambient air in both chambers. Pigs were feed deprived for 5-6 hours prior to testing to stimulate foraging motivation. After 2 minutes in the control chamber, a sliding door was opened to provide access to the treatment chamber. Pigs could move freely between chambers for 6 minutes after initial entry to the treatment chamber, after which they were removed and returned to the home pen. During the testing phase, the same procedures were used with the treatment chamber maintained at one of three CO2 levels: 10%, 20% or 30%. Tests concluded when loss of posture occurred or after 6 minutes. Pigs experienced each of the CO2 treatments, followed by one wash out day with ambient air conditions. Behavior collected using live observations and video recordings. During testing at 10% and 20% CO2, 3 pigs failed to enter the treatment chamber. Of the 9 pigs that entered at 10% CO2, none displayed avoidance responses or loss of posture. Of the 9 pigs that entered at 20% CO2, all displayed ataxia and open mouth breathing. Five pigs remained in the treatment chamber until loss of posture occurred (mean +/- SEM = 192 +/- 23 s). Eleven of the pigs tested at 30% CO2 entered the treatment chamber within 6 minutes, and 5 remained in the treatment chamber until loss of posture occurred (mean +/- SEM = 84 +/- 6 s). Pigs that failed to remain in the treatment compartment until loss of posture occurred frequently moved between the control and treatment chambers. During 20% and 30% CO2 tests, pigs displayed violent neuromuscular excitation, at which time the test was terminated for ethical reasons (mean +/- SEM = 212 +/- 24 s at 20% CO2 and 81 +/- 6 s at 30% CO2). No pigs displayed conditioned place avoidance of the treatment chamber on any of the wash out days. Exploratory behavior of pigs posed challenges for interpretation in this approach-avoidance experimental design.