Behavioral responses of broilers to different gaseous atmospheres

Area of Science:

• Animal Science
• Agricultural Engineering
• Veterinary Medicine

Background:

• Effective stunning methods are crucial for broiler welfare.
• Understanding broiler behavior in response to different stunning gas mixtures is essential for optimizing protocols.
• Previous research has not fully elucidated the initial behavioral responses of broilers to novel gas stunning environments.

Purpose of the Study:

• To investigate the behavioral responses of broilers upon first exposure to various gas mixtures used for stunning.
• To compare the efficacy and behavioral impact of different gas compositions, including argon (Ar) and carbon dioxide (CO2).
• To determine if broilers can detect and avoid atmospheres with elevated CO2 or reduced O2.

Main Methods:

• Broilers were divided into six groups: four experimental (exposed to gas mixtures) and two control (exposed to air).
• Gas mixtures tested included >90% Ar, 60% CO2, 40% CO2 + 30% O2, and 70% Ar + 30% CO2.
• Behavioral responses, including entry into the gas tunnel, attempts to return, headshaking, gasping, convulsions, and loss of posture, were video-recorded and analyzed.

Main Results:

• No significant differences were observed in broilers entering the gas tunnel or attempting to return to the cage across groups.
• The 70% Ar and 30% CO2 mixture induced the most rapid loss of posture.
• The >90% Ar mixture resulted in the least headshaking and gasping, while the 40% CO2 + 30% O2 mixture showed minimal convulsions compared to other gas mixtures.

Conclusions:

• Broilers do not appear to detect or avoid novel gas mixtures containing elevated CO2 or reduced O2 levels upon first exposure.
• The 70% Ar and 30% CO2 mixture offers rapid incapacitation, while the >90% Ar mixture may reduce signs of distress.
• Further research is needed to balance stunning efficiency with minimized adverse behavioral responses in broilers.