Assessment of three large-scale depopulation methods for swine

Area of Science:

• Veterinary Science
• Animal Welfare
• Agricultural Engineering

Background:

• Foreign animal disease outbreaks pose a significant threat to U.S. swine populations.
• Current depopulation methods recommended by the American Veterinary Medical Association (AVMA) are not suitable for large commercial swine herds.
• There is a critical need for effective and accessible large-scale depopulation strategies for swine.

Purpose of the Study:

• To assess and compare the efficacy and performance of three potential large-scale swine depopulation methods.
• To evaluate medium-expansion water-based foam, prototype high-expansion nitrogen foam, and carbon dioxide gas.
• To determine suitability as candidates for AVMA depopulation guidelines.

Main Methods:

• Field study involving 793 finisher pigs, with 84 pigs monitored using bio-loggers for electrocardiogram and movement data.
• Manual collection of aversive pig behaviors and assessment of pig movement intensity.
• Post-mortem examination for lesions, focusing on respiratory effects and cardiac arrest indicators.

Main Results:

• All three methods (water-based foam, nitrogen foam, carbon dioxide) demonstrated 100% mortality.
• Foam methods resulted in significantly shorter times to cessation of movement and fewer aversive behaviors compared to carbon dioxide.
• Water-based foam showed a higher incidence of distal trachea occlusions; no differences in cardiac activity were observed across methods.

Conclusions:

• Large-scale water-based foam, nitrogen foam, and carbon dioxide are effective depopulation methods for swine.
• Foam-based methods appear to offer advantages in terms of animal welfare due to reduced aversive behaviors and faster incapacitation.
• These methods are supported as viable candidates for inclusion in AVMA depopulation guidelines for swine.