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Lookup NU author(s): Dr Helen GrayORCiD, Dr Jack O'Sullivan, Professor Lucy AsherORCiD
This work is licensed under a Creative Commons Attribution 4.0 International License (CC BY 4.0).
© 2024Piling, a high density of chickens choosing to gather, is increasingly being recognized as a major problem behavior in the laying hen industry with both economic and welfare impacts. Groups of animals in close proximity generate heat, and observations of piling have noted instances of over 1200 hens in direct contact. Here, we investigate the impact of piling behavior on the temperature of the chicken shed. Since heat stress causes panting in chickens, piling also has potential to increase the CO2 concentration and as such, we also investigated the impact of piling on CO2. We used annotations of piling behavior from video footage of approximately 21 days for each of 12 flocks. The Birdbox system for flock management was used to obtain matched logged temperature (°C) and CO2 (ppm) from two sensor stations every minute, resulting in 17,396 datapoints. Bayesian multilevel modelling was used to estimate the effects of pile number and duration on temperature and CO2, including an effect to control for time of day. Since baseline daily fluctuations in temperature and CO2 could not be obtained, time of day effects were modelled in different ways, as autoregressive, random intercept, sinusoidal and polynomial terms. As autoregressive and non-autoregressive models could not be directly compared, we present the results of the autoregressive and best fit non-autoregressive models. We found no association between piling and temperature or CO2 for the autoregressive models but did find an association between pile number, pile duration and temperature in the random effects model. Higher temperature was associated with an interaction between increasing pile numbers and increasing pile duration. Since the effect size was very small and this result was not replicated in the autoregression model it should be interpreted with caution but does provide interesting rationale for future work investigating behavior-environment interactions.
Author(s): Gray HE, O'Sullivan J, Asher L
Publication type: Article
Publication status: Published
Journal: Poultry Science
Year: 2025
Volume: 104
Issue: 4
Print publication date: 01/04/2025
Online publication date: 17/12/2024
Acceptance date: 13/12/2024
Date deposited: 17/03/2025
ISSN (print): 0032-5791
ISSN (electronic): 1525-3171
Publisher: Elsevier Inc.
URL: https://doi.org/10.1016/j.psj.2024.104672
DOI: 10.1016/j.psj.2024.104672
