Assessing the consequences of behavioural deprivation in laying hens

有关动物福利的一些最困难的问题与测量和解释行为限制的影响有关，当动物被关在圈养环境中，阻止它们表现出物种典型的行为模式时，就会发生这种限制。“行为需求”一词通常用于指对动物的表现可能很重要的特定行为模式，如果加以阻止，则会导致挫折或一些可能导致痛苦和损害福利的负面情绪状态。传统的蛋鸡饲养方式（电笼）受到了强烈的批评，因为缺乏必要的环境资源来容纳对母鸡的福利可能很重要的基本行为活动。特别值得关注的两种行为活动是筑巢和洗灰尘；在没有适当刺激的铁丝笼中观察到这两种行为的要素。产蛋前的母鸡有很高的动力进入窝箱，当没有窝箱时，它们表现出的行为反应被认为是沮丧的迹象。尽管有大量关于筑巢和洗澡动机的工作，但很少有人尝试调查蛋鸡在被剥夺或有机会进行这些活动时所经历的情绪状态。一些负面情绪状态的生理证据将加强在没有窝箱或基质的情况下降低母鸡福利的论点。越来越多的人认为，动物的幸福也包括体验积极情绪状态的潜力。大多数非人类动物的情感概念框架包括认知、神经生理和行为成分，一些用于研究它们的方法可以应用于对蛋鸡的研究。在这个项目中，将进行一系列实验，使用压力反应测量、减少恐惧和痛苦的药理学制剂以及被认为表明动物积极和消极精神状态的行为测试，以调查蛋鸡在被拒绝或被提供机会从事筑巢和打扫灰尘行为时消极或积极情绪状态的证据。

Some of the most difficult issues concerning animal welfare have to do with measuring and interpreting the effects of behavioural restriction that occurs when animals are kept in captive environments that prevent them from performing species-typical behaviour patterns. The term 'behavioural need' is often used to refer to specific behaviour patterns that may be important for animals to perform and that, when prevented, result in frustration or some negative emotional state that can cause suffering and impair welfare. Conventional housing of laying hens (battery cages) is highly criticized because of the lack of environmental resources necessary to accommodate basic behavioural activities that may be important for the welfare of hens. Two behavioural activities of particular concern are nesting and dustbathing; elements of both of these behaviours are observed in wire cages in the absence of appropriate stimuli. Pre-laying hens are highly motivated to access a nest box and show behavioural responses that are considered to be a sign of frustration when a nest box is not available. Despite the substantial body of work on nesting and dustbathing motivation, there have been few attempts at investigating the emotional states experienced by laying hens when deprived of or provided the opportunities to perform them. Corroborating physiological evidence of some negative emotional state would strengthen the arguments for reduced hen welfare in the absence of nest boxes or substrate. Increasingly, it is suggested that animal well-being also includes the potential for experiencing positive emotional states. Most conceptual frameworks for emotions in non-human animals include aspects of cognitive, neurophysiological and behavioural components and several of the approaches used to study them could be applied to the study of laying hens. In this project series of experiments will be conducted using measures of stress response, pharmacological agents that reduce fear and distress and behavioural tests thought to indicate positive and negative mental states in animals in order to investigate evidence for negative or positive emotional states in laying hens that are either denied or provided opportunities to engage in nesting and dustbathing behaviour.