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Keel bone fractures induce a depressive-like state in laying hens

Lookup NU author(s): Elena Armstrong, Jane Eastham, Dr Jonathan Guy, Dr Timothy Boswell, Dr Tom SmuldersORCiD



This work is licensed under a Creative Commons Attribution 4.0 International License (CC BY 4.0).


In commercial flocks of laying hens, keel bone fractures (KBFs) are prevalent and associated with behavioural indicators of pain. However, whether their impact is severe enough to induce a depressive-like state of chronic stress is unknown. As chronic stress downregulates adult hippocampal neurogenesis (AHN) in mammals and birds, we employ this measure as a neural biomarker of subjective welfare state. Radiographs obtained longitudinally from Lohmann Brown laying hens housed in a commercial multi-tier aviary were used to score the severity of naturally-occurring KBFs between the ages of 21-62 weeks. Individual birds’ transitions between aviary zones were also recorded. Focal hens with severe KBFs at 3-4 weeks prior to sampling (n=15) had lower densities of immature doublecortin-positive (DCX+) multipolar and bipolar neurons in the hippocampal formation than focal hens with minimal fractures (n=9). KBF severity scores at this time also negatively predicted DCX+ cell numbers on an individual level, while hens that acquired fractures earlier in their lives had fewer DCX+ neurons in the caudal hippocampal formation. Activity levels 3-4 weeks prior to sampling were not associated with AHN. KBFs thus lead to a negative affective state lasting at least 3-4 weeks, and management steps to reduce their occurrence are likely to have significant welfare benefits.

Publication metadata

Author(s): Armstrong EA, Rufener C, Toscano MJ, Eastham JE, Guy JH, Sandilands V, Boswell T, Smulders TV

Publication type: Article

Publication status: Published

Journal: Scientific Reports

Year: 2020

Volume: 10

Online publication date: 20/02/2020

Acceptance date: 03/02/2020

Date deposited: 27/02/2020

ISSN (electronic): 2045-2322

Publisher: Nature Publishing Group


DOI: 10.1038/s41598-020-59940-1


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