Breathless Birds: Does air hunger impact the welfare of poultry at slaughter?

喘不过气来的鸟：空气饥饿会影响屠宰时家禽的福利吗？

• 批准号: BB/X000680/1
• 负责人: Jessica Martin
• 金额: $ 72.55万
• 依托单位: Newcastle University
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2023
• 资助国家: 英国
• 起止时间: 2023 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=BB%2FX000680%2F1
• 关键词: Breathless; Birds; Does; air; hunger

Globally, 72 billion chickens are slaughtered each year. Controlled atmosphere stunning (CAS) is increasingly used, involving exposure to gas mixtures causing gradual loss of consciousness, with welfare advantages compared to electrical stunning. Commercial CAS systems most commonly expose conscious birds to increasing concentrations of carbon dioxide (CO2). Although painful levels of CO2 are avoided, these gases cause a hyperventilation (deep breathing) response which is obvious behaviourally. It unknown whether this reaction corresponds to the breathlessness and 'air hunger' reported by humans when inhaling CO2. Air hunger is a potent and deeply unpleasant experience, consisting of an uncomfortable urge to breathe which is associated with profound anxiety, frustration and fear. If the gas mixtures used in gas stunning cause air hunger in chickens, this constitutes a very significant welfare issue, calling into question whether CAS is a humane method of pre-slaughter stunning. Given the anatomical and physiological differences between mammals and birds, the susceptibility of birds to air hunger is difficult to predict, and no previous studies have specifically examined animal perceptions of this sensation. Although some earlier studies have demonstrated that chickens avoid CO2 in certain situations, the available research has never specifically addressed the contribution of air hunger to this avoidance and is confounded by the fact that CO2 is painful to inhale above certain concentrations. Simple behavioural approaches (such as allowing birds to leave a space containing CO2) are flawed since CO2 is an anaesthetic that is likely to reduce the ability to express appropriate responses. More sophisticated behavioural approaches such as those allowing birds to display any learned aversion after, not during, exposure to CO2, and a focus on non-painful concentrations are needed to understand whether air hunger is a welfare issue. The aim of this project is to determine whether birds experience air hunger during exposure to gas mixtures relevant to commercial slaughter. Initially, we will expose chickens to a range of relevant gas mixtures which represent different CAS methods, untangling their responses to CO2 and low oxygen levels, both of which cause respiratory changes. We will record detailed behavioural and physiological outcomes to determine the conditions under which hyperventilation occurs and how its apparent character and severity relates to gas types and concentrations. We will then investigate whether hyperventilation occurring during CAS represents a welfare issue by evaluating whether chickens avoid and/or escape areas associated with exposure to relevant gas mixtures. We will also deteremine if any spontaneous behaviour corresponds with learned avoidance behaviour to help us understand which apparent signs of breathlessness may indicate unpleasant respiratory experiences. Finally, we will image parts of the brain to examine whether key regions associated with fear, stress and anxiety are activated by exposure to relevant gas mixtures. Collectively, we expect these experiments to allow a corroborative and robust assessment of the welfare implications of hyperventilation.Tackling the question of whether air hunger is experienced by billions of poultry undergoing CAS is extremely important. The work we propose is ground-breaking and will enable the development of novel methodology to detect air hunger in animals. Whatever the findings, the work will provide valuable information to inform future policy globally. If our studies show that air hunger is not an issue relevant to poultry slaughter, CAS will be proven to be a high welfare method and its uptake will be enhanced. If air hunger is apparent, the results will underpin the development of more humane stunning approaches, ensuring that the current transition away from electrical stunning systems represents genuine welfare improvement.

全球每年屠宰720亿只鸡。受控气氛致晕（CAS）越来越多地被使用，涉及暴露于气体混合物导致逐渐丧失意识，与电致晕相比具有福利优势。商业CAS系统最常见的是将有意识的鸟类暴露在浓度不断增加的二氧化碳（CO2）中。虽然避免了令人痛苦的二氧化碳水平，但这些气体会引起过度换气（深呼吸）反应，这在行为上是明显的。目前尚不清楚这种反应是否与人类吸入二氧化碳时报告的呼吸困难和“空气饥饿”相对应。空气饥饿是一种强烈的、令人非常不愉快的体验，包括一种不舒服的呼吸冲动，这种冲动与深刻的焦虑、沮丧和恐惧有关。如果在气体致晕中使用的气体混合物导致鸡的空气饥饿，这构成了一个非常重要的福利问题，质疑CAS是否是一种人道的屠宰前致晕方法。鉴于哺乳动物和鸟类在解剖学和生理学上的差异，鸟类对空气饥饿的敏感性很难预测，以前的研究也没有专门研究过动物对这种感觉的感知。尽管一些早期的研究已经证明鸡在某些情况下会避免二氧化碳，但现有的研究从未专门讨论过空气饥饿对这种避免的贡献，并且令人困惑的是，吸入超过一定浓度的二氧化碳会感到痛苦。简单的行为方法（例如允许鸟类离开含有二氧化碳的空间）是有缺陷的，因为二氧化碳是一种麻醉剂，可能会降低表达适当反应的能力。需要更复杂的行为方法，例如允许鸟类在暴露于CO2之后而不是暴露于CO2期间表现出任何习得的厌恶，以及关注非痛苦的浓度，以了解空气饥饿是否是一个福利问题。该项目的目的是确定鸟类在暴露于与商业屠宰相关的气体混合物期间是否经历空气饥饿。最初，我们将鸡暴露于一系列代表不同CAS方法的相关气体混合物中，解开它们对CO2和低氧水平的反应，这两种反应都会引起呼吸变化。我们将记录详细的行为和生理结果，以确定过度换气发生的条件以及其明显特征和严重程度与气体类型和浓度的关系。然后，我们将调查是否过度换气发生在CAS代表一个福利问题，通过评估鸡是否避免和/或逃避与暴露于相关气体混合物相关的领域。我们还将确定是否有任何自发行为与习得性回避行为相对应，以帮助我们了解哪些明显的呼吸困难体征可能表明不愉快的呼吸体验。最后，我们将对大脑的某些部分进行成像，以检查与恐惧，压力和焦虑相关的关键区域是否会因暴露于相关气体混合物而被激活。总的来说，我们希望这些实验能够对过度换气的福利影响进行确证和可靠的评估。解决数十亿接受CAS的家禽是否经历空气饥饿的问题是非常重要的。我们提出的工作是开创性的，将使新的方法来检测动物的空气饥饿的发展。无论结果如何，这项工作都将为全球未来的政策提供有价值的信息。如果我们的研究表明空气饥饿不是家禽屠宰的相关问题，CAS将被证明是一种高福利方法，其使用将得到加强。如果空气饥饿是明显的，结果将支持更人道的击昏方法的发展，确保目前从电击昏系统的过渡代表真正的福利改善。