Wageningen UR Livestock Research, PO Box 65, 8200 AB Lelystad, the Netherlands.
Poult Sci. 2013 Jan;92(1):41-50. doi: 10.3382/ps.2012-02551.
The stunning quality of animals for slaughter remains under constant scrutiny. In response to previous research showing low stunning efficiency in poultry, the conventional water bath will be phased out in the Netherlands. Presently, the main practical alternative to water bath stunning of poultry is a 2-phased gas stunning method. Gas stunning methods are recognized by governments and animal welfare organizations across Europe. In this study, 3 sets of experiments were conducted on gas stunning methods using CO(2) in 2 phases. Two methods were examined to identify potential effects on bird behavior and investigate their practical implications: a 5-stage incremental CO(2) scheme lasting 6 min (treatment 1) and a 4-stage incremental CO(2) scheme lasting 4 min (treatment 2). The onset and duration of unconsciousness were specifically tested in experiment 2 by using 25 birds equipped with electrodes monitoring brain and heart activity. Behavioral responses were observed on 15 non-instrument-monitored birds kept in the same cages at that time. Results in all 3 sets of the experiments showed that multistage gas stunning was stable and consistent, and increases in CO(2) concentrations were rapid and reliable. Ambient temperatures and RH of the air remained within acceptable levels at all times. Induction of unconsciousness occurred below 40% CO(2) and did not significantly differ between treatments. Conscious birds were never exposed to high CO(2) concentrations (>40% CO(2)), yet some birds showed signs of distress (e.g., head shaking, wing flapping) before losing consciousness. Discomfort experienced during exposure to low (<40%) CO(2) concentrations compares favorably with the experiences of handling, tilting, and or shackling of conscious birds when using alternative stunning methods, implying that multistage gas stunning has distinct advantages for bird welfare. Compared with the multibird water bath system, this method provides an opportunity to guarantee that all birds are properly stunned. The risk of convulsions, which was higher with treatment 2, leading to possible injuries, indicates a preference for the 5-stage treatment.
动物在被屠宰前的状态仍在持续受到严格的审查。针对之前研究表明家禽致昏效果不佳的问题，荷兰将逐步淘汰传统的水浴式致昏。目前，取代家禽水浴式致昏的主要实用方法是两阶段气体致昏方法。气体致昏方法得到了整个欧洲政府和动物福利组织的认可。在这项研究中，针对两阶段 CO₂气体致昏方法进行了 3 组实验。检查了 2 种方法，以确定其对鸟类行为的潜在影响，并研究其实际意义：一种是持续 6 分钟的 5 阶段递增 CO₂方案（处理 1），另一种是持续 4 分钟的 4 阶段递增 CO₂方案（处理 2）。在实验 2 中，通过使用 25 只装有监测大脑和心脏活动电极的鸟类，专门测试了无意识的开始和持续时间。同时，在同一笼中观察了 15 只未进行仪器监测的鸟类的行为反应。所有 3 组实验的结果均表明，多阶段气体致昏稳定且一致，CO₂浓度的增加快速且可靠。环境温度和空气相对湿度始终保持在可接受的水平。在 40% CO₂以下诱导无意识，并且在处理之间没有显著差异。有意识的鸟类从未暴露在高 CO₂浓度（>40% CO₂）下，但有些鸟类在失去意识之前表现出不适的迹象（例如，摇头，拍打翅膀）。暴露在低浓度（<40% CO₂） CO₂下的不适感与使用替代致昏方法处理、倾斜和/或束缚有意识鸟类的经验相比具有优势，这意味着多阶段气体致昏对鸟类福利具有明显的优势。与多只禽用水浴系统相比，这种方法为确保所有鸟类都被适当致昏提供了机会。处理 2 中更高的惊厥风险，可能导致受伤，表明对 5 阶段处理的偏好。
