Are keel fractures in laying hens related to bone strength or to fearfulness?

T.B. Rodenburg, J.L.T. Heerkens, F.A.M. Tuyttens

Research output: Chapter in Book/Report/Conference proceedingAbstract

Abstract

The relatively high incidence of keel bone fractures in alternative systems for laying hens is cause for concern. It is still unclear what the major causes for these fractures are. One of the dominant hypotheses is that high fracture rates in non-cage systems are related to high levels of accidents, where birds hit the system with their keel bone during flight and suffer fractures. This effect may be stronger in fearful flocks, where birds may respond hysterically to humans entering the house. On the other hand, there are also indications that bone strength plays a key-role, with birds with weaker bones being more at risk. That would also offer an explanation for the relatively high fracture rates seen in furnished cage systems, where the risk of accidents is reduced. The aim of this study was to compare bone strength and fearfulness in laying hens with and without keel bone fractures from both furnished cages and non-cage systems. To meet this aim 13 commercial flocks, 7 non-cage and 6 furnished cage flocks, were visited around 60 weeks of age. Fifteen birds from each flock, caught at different locations in the house, were tested in a tonic immobility test, with a maximum test duration of five minutes. After all birds were tested, they were killed humanely using electrical stunning or the CASH poultry killer and taken to the lab for dissection. After dissection, it was established whether each bird had a keel bone fracture or not (0/1 trait). Further, from each bird the keel bone, leg bones and wing bones were collected for bone strength measurements (N) using a Versatest™ test stand. Effects of housing system, absence or presence of keel fractures and their interaction on bone strength and fearfulness were tested in a mixed model with flock nested within housing system as random effect. Overall, birds from non-cage systems had a higher incidence of keel bone fractures (87 vs. 65%), a shorter duration of tonic immobility (44±4 vs. 130±9 s; P
Original languageEnglish
Title of host publicationProceedings of the 48th Congress of the International Society for Applied Ethology (ISAE2014)
Place of PublicationWageningen, The Netherlands
PublisherWageningen Academic Publishers
Pages161-161
Publication statusPublished - 2014
Event48th Congress of the International Society for Applied Ethology (ISAE2014), Vitoria-Gasteiz, Spain -
Duration: 29 Jul 20142 Aug 2014

Conference

Conference48th Congress of the International Society for Applied Ethology (ISAE2014), Vitoria-Gasteiz, Spain
Period29/07/142/08/14

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    Rodenburg, T. B., Heerkens, J. L. T., & Tuyttens, F. A. M. (2014). Are keel fractures in laying hens related to bone strength or to fearfulness? In Proceedings of the 48th Congress of the International Society for Applied Ethology (ISAE2014) (pp. 161-161). Wageningen Academic Publishers. https://www.applied-ethology.org/res/ISAE%202014.pdf#page=162