Armstrong Elena A, Voelkl Bernhard, Voegeli Sabine, Gebhardt-Henrich Sabine G, Guy Jonathan H, Sandilands Victoria, Boswell Tim, Toscano Michael J, Smulders Tom V
Centre for Behaviour and Evolution, Newcastle University, Newcastle upon Tyne, United Kingdom.
Biosciences Institute, Newcastle University, Newcastle upon Tyne, United Kingdom.
Front Vet Sci. 2020 Aug 26;7:587. doi: 10.3389/fvets.2020.00587. eCollection 2020.
Access to outdoor areas is provided as a means of enhancing welfare in commercial systems for laying hens (), but substantial individual differences exist in their proportional use. Baseline cell proliferation levels of Adult Hippocampal Neurogenesis (AHN) have been associated with individual differences in reactive vs. proactive coping style, and in both mammals and birds, AHN is upregulated by positive experiences including environmental enrichment and exercise. We thus sought to explore whether individual differences in use of outdoor areas and in tonic immobility responses (indicative of fearfulness) were associated with hippocampal cell proliferation and neuronal differentiation. Radio frequency identification technology was used to track the ranging behavior of 440 individual focal hens within a commercially-relevant system over a 72-days period, after which tonic immobility durations were measured. Following hippocampal tissue collection from 58 focal hens, proliferation and neuronal differentiation were measured through quantitative PCR for proliferating cell nuclear antigen (PCNA) and doublecortin mRNA, respectively. Individual differences in tonic immobility duration positively correlated with PCNA expression over the whole hippocampal formation, while greater time spent in outdoor areas (the grassy range and stone yard) was associated with higher proliferation in the rostral subregion. Basal proliferation in the chicken hippocampal formation may thus relate to reactivity, while levels in the rostral region may be stimulated by ranging experience. Doublecortin expression in the caudal hippocampus negatively co-varied with time on the grassy range, but was not associated with tonic immobility duration. This suggests that ranging outside may be associated with stress. Within laying hen flocks, individual differences in hippocampal plasticity thus relate to coping style and use of external areas.
在蛋鸡商业养殖系统中，提供户外区域是提高蛋鸡福利的一种方式，但蛋鸡对户外区域的使用比例存在显著个体差异。成年海马神经发生（AHN）的基线细胞增殖水平与反应性应对方式和主动性应对方式的个体差异有关，在哺乳动物和鸟类中，包括环境丰富化和运动在内的积极体验都会上调AHN。因此，我们试图探究户外区域使用情况的个体差异以及强直性静止反应（指示恐惧程度）是否与海马体细胞增殖和神经元分化有关。利用射频识别技术在一个与商业养殖相关的系统中，对440只个体焦点蛋鸡的活动范围行为进行了72天的跟踪，之后测量了它们的强直性静止持续时间。从58只焦点蛋鸡收集海马组织后，分别通过定量PCR检测增殖细胞核抗原（PCNA）和双皮质素mRNA，来测量细胞增殖和神经元分化情况。强直性静止持续时间的个体差异与整个海马结构中的PCNA表达呈正相关，而在户外区域（草地和石院）花费的时间越长，与吻侧亚区更高的细胞增殖有关。因此，鸡海马结构中的基础增殖可能与反应性有关，而吻侧区域的增殖水平可能受到活动范围体验的刺激。尾侧海马中的双皮质素表达与在草地上的时间呈负相关，但与强直性静止持续时间无关。这表明在户外活动可能与压力有关。在蛋鸡群中，海马可塑性的个体差异因此与应对方式和外部区域的使用有关。
