School of Natural and Environmental Sciences, Newcastle University, Newcastle upon Tyne NE1 7RU, United Kingdom.
School of Natural and Environmental Sciences, Newcastle University, Newcastle upon Tyne NE1 7RU, United Kingdom.
Poult Sci. 2023 Oct;102(10):102989. doi: 10.1016/j.psj.2023.102989. Epub 2023 Aug 5.
Piling, a dense cluster of hens, is a behavior of major concern to the cage-free egg industry. It can cause large numbers of mortalities at which point it is considered smothering. The aim of this study was to quantify whether piling can also have consequences on production and non-smothering mortalities, which have not previously been described. Additionally, we aimed to describe characteristics of piling behavior relevant to for management. Video footage from 12 flocks of laying hens was analyzed for piling behavior across 3 wks. Production and mortality data were accessed using an integrated online management system. Bayesian linear mixed-effect models were used for formal statistical testing of the relationships between piling and production. Accounting for some missing data, a total of 252 d amounting to approximately 15,624 h were analyzed for the presence or absence of piling behavior, which we believe constitutes the largest analysis of piling behavior in the scientific literature to date. All flocks observed exhibited piling behavior even if they had no history of smothering. On average, flocks piled more than 4 times per day for around 44 min per event and the peak piling time occurred between 1300 and 1359. We found that the number of piling events was associated with a reduction in the number of eggs produced the next day; based on the average of 4 piles per day this amounted to 7.35 fewer eggs per 1,000 birds per day. Contrary to our hypothesis, we found total piling duration per day was positively associated with fewer Grade B eggs, with a decrease of 0.74 Grade B eggs for every hour of piling per day. No relationship was observed between piling and mortality not attributed to smothering. We discuss possible causes and explanations for these results including birds' response to stress, crowd dynamics, and daily rhythms. Here we show the potential for piling behavior to have sublethal consequences on production even in the absence of smothering-related deaths.
叠堆，即密集的母鸡群集，是无笼养蛋鸡产业主要关注的行为。它会导致大量死亡，此时可被视为窒息死亡。本研究的目的是量化叠堆行为是否也会对生产和非窒息性死亡产生影响，而这些影响此前并未被描述过。此外，我们旨在描述与管理相关的叠堆行为特征。对 12 个产蛋鸡群的视频片段进行了 3 周的叠堆行为分析。使用集成的在线管理系统获取生产和死亡率数据。使用贝叶斯线性混合效应模型对叠堆行为与生产之间的关系进行正式的统计检验。考虑到一些缺失数据，总共分析了 252 天，共计约 15624 小时，以确定是否存在叠堆行为，我们认为这是迄今为止科学界对叠堆行为进行的最大分析。即使没有窒息死亡的历史，所有观察到的鸡群都表现出了叠堆行为。平均而言，鸡群每天叠堆超过 4 次，每次事件持续约 44 分钟，高峰叠堆时间发生在 1300 至 1359 之间。我们发现，叠堆事件的数量与次日产蛋量的减少有关；基于每天 4 堆的平均值，这相当于每 1000 只鸡每天减少 7.35 个鸡蛋。与我们的假设相反，我们发现每天的总叠堆时间与 B 级蛋的数量呈正相关，每天每小时的叠堆时间会导致 B 级蛋减少 0.74 个。未观察到与窒息无关的死亡率与叠堆之间存在关系。我们讨论了这些结果的可能原因和解释，包括鸟类对压力的反应、群体动态和日常节律。在这里，我们展示了即使没有与窒息相关的死亡，叠堆行为也可能对生产产生亚致死影响的潜力。
