Institute of Animal Science, University of Hohenheim, Garbenstr. 17, 70599 Stuttgart, Germany.
Department of Animal Sciences, Georg-August-University, Burckhardtweg 2, 37077, Göttingen, Germany.
Poult Sci. 2023 May;102(5):102548. doi: 10.1016/j.psj.2023.102548. Epub 2023 Feb 4.
Various aspects of activity, such as spontaneous activity, explorative activity, activity in open-field tests, and hyperactivity syndrome have been explored as causal factors of feather pecking in laying hens, with no clear results. In all previous studies, mean values of activity over different time intervals were used as criteria. Incidental observation of alternated oviposition time in lines selected for high (HFP) and low feather pecking (LFP), supported by a recent study which showed differentially expressed genes related to the circadian clock in the same lines, led to the hypothesis that feather pecking may be related to a disturbed diurnal activity rhythm. Hence activity recordings of a previous generation of these lines have been reanalyzed. Data sets of a total of 682 pullets of 3 subsequent hatches of HFP, LFP, and an unselected control line (CONTR) were used. Locomotor activity was recorded in pullets housed in groups of mixed lines in a deep litter pen on 7 consecutive 13-h light phases, using a radio-frequency identification antenna system. The number of approaches to the antenna system was recorded as a measure of locomotor activity and analyzed using a generalized linear mixed model including hatch, line, time of day and the interactions of hatch × time of day and line × time of day as fixed effects. Significant effects were found for time and the interaction line × time of day but not for line. All lines showed a bimodal pattern of diurnal activity. The peak activity of the HFP in the morning was lower than that of the LFP and CONTR. In the afternoon peak all lines differed with the highest mean in the LFP followed by CONTR and HFP. The present results provide support for the hypothesis that a disturbed circadian clock plays a role in the development of feather pecking.
各种活动方面，如自发性活动、探索性活动、开放场测试中的活动和多动综合征，都被探索为导致产蛋母鸡啄羽的原因因素，但没有明确的结果。在所有以前的研究中，使用不同时间间隔的活动平均值作为标准。对高啄羽率（HFP）和低啄羽率（LFP）品系进行交替产卵时间的偶然观察，以及最近一项研究表明，同一品系中与昼夜节律钟相关的差异表达基因，支持了啄羽可能与昼夜活动节律紊乱有关的假设。因此，对这些品系前一代的活动记录进行了重新分析。使用了 3 个后续批次的共 682 只母鸡的数据，这些母鸡来自 HFP、LFP 和未选择的对照系（CONTR）。在一个深垫料鸡舍中，将混合品系的母鸡分组饲养，使用射频识别天线系统连续记录 7 个 13 小时的光照周期的母鸡活动。接近天线系统的次数被记录为运动活动的衡量标准，并使用包含批次、品系、一天中的时间以及批次与一天中的时间和品系与一天中的时间的相互作用的广义线性混合模型进行分析。发现时间和品系与时间的相互作用有显著影响，但品系没有显著影响。所有品系都表现出双峰模式的昼夜活动。HFP 的早晨活动高峰低于 LFP 和 CONTR。下午高峰时，LFP 的平均值最高，其次是 CONTR 和 HFP。本研究结果为昼夜节律钟紊乱在啄羽发展中起作用的假设提供了支持。
