Department of Pathobiology, University of Guelph, Guelph, Canada.
Poult Sci. 2012 Jul;91(7):1558-68. doi: 10.3382/ps.2012-02139.
Appropriate emergency disaster preparedness is a key priority for agricultural agencies to allow effective response to serious avian disease outbreaks. There is a need to develop rapid, humane, and safe depopulation techniques for poultry that are widely applicable across a range of farm settings. Whole barn depopulation with carbon dioxide (CO(2)) has been investigated as a humane and efficient means of killing large numbers of birds in the event of a reportable disease outbreak. It has also been considered as a method for depopulating barns containing end-of-lay hens, particularly when there is limited local slaughter and rendering capacity. Determining the best method of humanely killing large flocks of birds remains problematic and is being investigated by a coordinated international effort. While whole barn depopulation using CO(2) inhalation has been explored, physiologic responses of chickens have not been characterized in field settings and assessment of animal welfare is hampered without this information. In this study, 12 cull laying hens were surgically instrumented with telemetry transmitters to record electroencephalographs, electrocardiographs, body temperature, and activity during 2 large-scale field CO(2) euthanasia trials of end-of-lay hens. The day following surgery, instrumented hens were placed in barns with other birds, barns were sealed, and animals were killed by CO(2) inhalation delivered via a specially designed liquid CO(2) manifold. Instrumented birds were monitored by infrared thermography, and ambient temperature, CO(2), and O(2) concentrations were recorded. Results from these studies indicate that instrumented hens lost consciousness within 2 min of CO(2) levels reaching 18 to 20%. Mild to moderate head shaking, gasping, and 1 to 2 clonic muscle contractions were noted in hens before unconsciousness; however, brain death followed rapidly (<5 min). Evaluation of welfare costs and benefits suggest clear advantages over catching and transporting cull hens for slaughter. The financial costs with this method are greater, however, than those estimated for traditional slaughter techniques. Results of these studies are being used to develop national protocols for whole barn depopulation of hens by CO(2) inhalation.
适当的应急准备是农业机构的一个关键优先事项，以便能够对严重的禽病暴发做出有效应对。需要开发广泛适用于各种农场环境的快速、人道且安全的家禽扑杀技术。在发生报告疾病暴发时，二氧化碳（CO2）全舍扑杀已被研究作为一种人道且高效的大量扑杀禽类的方法。当当地屠宰和加工能力有限时，这种方法也被认为是扑杀即将淘汰母鸡鸡舍的一种方法。确定人道扑杀大批禽类的最佳方法仍然存在问题，目前正在由协调的国际努力进行研究。虽然已经探索了使用 CO2 吸入进行全舍扑杀，但在野外环境中尚未对鸡的生理反应进行特征描述，如果没有这些信息，对动物福利的评估也会受到阻碍。在这项研究中，对 12 只淘汰产蛋母鸡进行了手术，植入了遥测传输器，以记录脑电图、心电图、体温和活动，这是 2 次大型野外 CO2 淘汰母鸡安乐死试验的一部分。手术后的第二天，将仪器化母鸡放入与其他鸟类一起的鸡舍中，鸡舍密封，然后通过专门设计的液态 CO2 歧管将动物用 CO2 吸入杀死。通过红外热成像监测仪器化鸟类，并记录环境温度、CO2 和 O2 浓度。这些研究的结果表明，仪器化母鸡在 CO2 水平达到 18%至 20%后 2 分钟内失去意识。在母鸡失去意识之前，会出现轻度至中度的摇头、喘气和 1 至 2 次阵挛性肌肉收缩；然而，大脑死亡很快（<5 分钟）发生。对福利成本和收益的评估表明，与捕捉和运输淘汰母鸡进行屠宰相比，这种方法具有明显的优势。但是，这种方法的财务成本高于传统屠宰技术的估计成本。这些研究的结果正在用于制定通过 CO2 吸入对母鸡进行全舍扑杀的国家方案。
