Lookup NU author(s): Elena Armstrong,
Dr Jonathan Guy,
Dr Timothy Boswell,
Dr Tom Smulders
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.
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
Online publication date: 20/02/2020
Acceptance date: 03/02/2020
Date deposited: 27/02/2020
ISSN (electronic): 2045-2322
Publisher: Nature Publishing Group
Altmetrics provided by Altmetric