Do male mice prefer to live on their own?

老鼠是最常用的实验动物。它们为研究人员提供了一种哺乳动物生理学的模式生物，它概括了人类生物学中许多正常和病理的过程。在过去的几十年里，最重要的科学进步之一是能够操纵老鼠的基因来产生新的突变，这些突变可以用来回答重要的科学问题。基因改造的老鼠现在在用于研究的动物中占很大比例，老鼠群体的管理是一个可以在动物福利方面取得巨大利益的领域，但同样，如果不是最理想的，可能会造成巨大的福利成本和累积的痛苦。这些动物的居住环境是对动物一生影响最大的一个领域。虽然动物通常不会表现出与它们的居住环境有关的明显的痛苦迹象，但在雄性老鼠身上却不是这样。性成熟的雄性之间的争斗会导致严重的伤害甚至死亡。即使动物没有表现出身体受伤的迹象，在这些群体饲养的动物中，也有可能出现长期的社会压力。在科学界，人们普遍关注雄性老鼠的战斗以及如何最好地控制这种情况。目前的看法是，老鼠是高度社会化的，因此需要群体的社会住房来达到最高的福利标准。然而，这方面的证据相当多样，而且令人惊讶地有限。事实上，一些对野生老鼠的研究表明，雄性老鼠可能不喜欢与其他雄性老鼠生活在一起。我们认为，虽然老鼠可以从社会互动中受益，但这可能不会被限制（实验室笼子）环境中的群体住房所产生的社会压力所抵消。也有可能集体居住的社会压力比失去与其他老鼠身体接触的后果带来更高的福利成本。与这一领域先前的研究相关的一个主要限制是缺乏客观的方法来衡量长期、低水平的社会压力和累积痛苦的影响。事实上，直到最近才开发出能够可靠地测量直接反映动物情感状态的行为的方法，从而可以提供福利结果的衡量标准。我们的研究小组是率先测量啮齿动物情感状态方法的研究小组之一。我们是研究抑郁症啮齿动物模型领域的领先团队之一，现在我们想运用这一专业知识来解决我们的关键问题，“雄性老鼠是否更喜欢独自生活？”我们制定了一项研究方案，将着眼于不同的住房条件和社会结构。我们希望为雄性老鼠的饲养和饲养提供客观证据，以最大限度地减少累积的痛苦，并通过减少压力及其对数据可变性的影响，从而提高科学成果，从而减少特定实验所需动物的数量。虽然我们的主要目的是了解群体与个体住房的影响，但我们也设计了实验来测试仔细管理笼子环境是否可以使老鼠在更小的笼子环境中实现更自然的社会结构。我们期望这些研究能就不同房屋状况对福利的影响，提供清晰和客观的衡量标准。动物技术人员、研究人员、兽医、伦理审查机构、内政部和政策制定者可以利用这些知识，根据对不同选择对福利的影响的了解，以及在提供社会接触（感官和/或身体接触）与避免社会压力、战斗、伤害和死亡之间的平衡，对畜牧业程序做出明智的决定。

Mice are the most commonly used laboratory animal species. They provide researchers with a model organism of mammalian physiology which recapitulates many of the normal and pathological processes seen in human biology. One of the most important scientific advances in the last few decades has been the ability to manipulate the genetics of the mouse to create novel mutations which can be used to answer important scientific questions. Genetically altered mice now represent a large proportion of the animals being used in research and the management of mouse colonies is an area where huge benefits in animal welfare could be made but equally, if not optimal, can create significant welfare costs and cumulative suffering. The housing environment of these animals is an area where the greatest impact over the duration of an animal's lifetime can be made. Whilst animals often do not show overt signs of distress associated with their housing environment, in male mice this is not the case. Fighting among males as they become sexually mature can lead to serious injury and even death. Even where animals do not show evidence of physical injury, there is the potential for chronic social stress within these group housed animals. Amongst the scientific community there is widespread concern about fighting in male mice and how best to manage this. Current beliefs are that mice are highly social and therefore require social housing in groups to achieve the highest standards of welfare. However, the evidence for this is quite varied and surprisingly limited. In fact, some studies in wild mice suggest that males may prefer not to live with other males. We propose that whilst mice may benefit from social interaction, this may not be offset by the social pressures which arise from group housing in a restricted (laboratory cage) environment. It is also possible that the social stress of group housing has higher welfare costs than the consequences of loss of physical contact with other mice. A major limitation associated with previous research in this area has been a lack of objective methods to measure the impact of long term, low level social stress and cumulative suffering. In fact, it is only very recently that methods have been developed which can reliably measure behaviours which directly reflect the animals affective state and hence can provide a measure of welfare outcomes. Our research group is one of those which has pioneered methods to measure affective state in rodents. We are one of the leading groups working in the field of rodent models for depression research and we now want to apply this expertise to address our key question, 'Do male mice prefer to live on their own?' We have developed a programme of research which will look at different housing conditions and social structures. We want to provide objective evidence of the best approaches to male mouse housing and husbandry to minimise cumulative suffering and improve scientific outcomes through reduced stress and its impact on the variability of the data and therefore the numbers of animals needed for a particular experiment. Whilst our primary aim is to understand the impact of group versus individual housing, we also have designed experiments to test whether careful management of the cage environment could enable mice to achieve a more natural social structure even within the much smaller cage environment.We anticipate that these studies will provide clear and objective measures of the welfare implications of different housing conditions. This knowledge can be used by animal technicians, researchers, vets, ethical review bodies, the Home Office and policy makers to make informed decisions about husbandry procedures based on knowledge of the welfare implications of the different options and the balance between providing social contact (sensory and/or physical) but avoiding social stress, fighting, injury and death.