Effect of Stocking Density during CO₂ Stunning of Pigs on Induction Time and Activity Level Measured Using AI

Area of Science:

• Animal Welfare Science
• Agricultural Engineering
• Applied Ethology

Background:

• Carbon dioxide (CO2) stunning is a common method for pig slaughter.
• Variability in pig reactions and induction periods during CO2 stunning is observed.
• Stocking density in transport gondolas is a potential factor influencing the stunning process.

Purpose of the Study:

• To investigate the effect of stocking density on the CO2 stunning process in pigs under commercial conditions.
• To quantify pig reactions and induction periods at varying stocking densities.
• To assess the utility of activity level measurements for documenting animal welfare during stunning.

Main Methods:

• Utilized an AI solution to measure activity levels of pigs in gondolas under industrial settings.
• Compared observed induction periods with simulated expected induction periods.
• Evaluated stocking densities of three, four, seven, and eight pigs per gondola (3.91 m2).

Main Results:

• Significantly longer induction periods were observed in gondolas with seven and eight pigs compared to simulations (p < 0.001).
• No significant difference in induction period was found for densities of three or four pigs.
• Both high and mean activity levels were significantly higher at increased stocking densities (seven and eight pigs).

Conclusions:

• Increased stocking density negatively affects the CO2 stunning process in pigs.
• Higher densities lead to prolonged induction times and increased pig activity, suggesting compromised welfare.
• AI-measured activity levels show promise as a tool for monitoring animal welfare in commercial stunning operations.