A comparison of argon, carbon dioxide, and nitrogen in a broiler killing system

Argon, CO2, and N2 gasses were each evaluated in a broiler chicken gas killing system. Birds were killed by individual exposure to one of the three gasses for 2 min in a flow-through system. The gasses were evaluated by determining the time, in seconds, for the following responses: first reaction to the gas, loss of posture, eye closure, initiation of death struggle, and cessation of respiration. Percentage blood loss over a 3-min bleed time was determined by weight loss. Breast muscle pH values were determined at 15 min and 24 h post-mortem on the Pectoralis major muscle. Carbon dioxide resulted in the earliest first reaction, loss of posture, eye closure, and initiation of struggle. Argon and N2 exhibited a delayed first reaction, a less severe early reaction, but a more severe unconscious death struggle. All birds died in approximately 75 s. Results indicate that the flow-through gas system takes longer to kill broilers than the immersion systems previously reported. Gas killing resulted in lower (P < .05) blood loss. Initial breast muscle pH values were significantly highest for the birds killed with CO2, followed by the control treatment, which was significantly higher than the values for broilers killed with either Ar or N2. After 24 h of chilling, there were no differences in broiler breast muscle pH among the four treatments. These results indicated that a flow-through gassing chamber may be a feasible, although slower, method of performing gas killing as compared to an immersion system.