Journal article
Possible risk factors for keel bone damage in organic laying hens

Publication Details
Jung, L.; Niehbuhr, K.; Hinrichsen, L.; Gunnarsson, S.; Brenninkmeyer, C.; Bestmann, M.; Heerkens, J.; Ferrari, P.; Knierim, U.
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Animal: An International Journal of Animal Bioscience
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Keel bone damage (KBD) in laying hens is an important welfare problem in
both conventional and organic egg production systems. We aimed to
identify possible risk factors for KBD in organic hens by analysing
cross-sectional data of 107 flocks assessed in eight European countries.
Due to partly missing data, the final multiple regression model was
based on data from 50 flocks. Keel bone damage included fractures and/or
deviations, and was recorded, alongside with other animal based
measures, by palpation and visual inspection of at least 50 randomly
collected hens per flock between 52 and 73 weeks of age. Management and
housing data were obtained by interviews, inspection and by feed
analysis. Keel bone damage flock prevalences ranged from 3% to 88%.
Compiled on the basis of literature and practical experience, 26
potential associative factors of KBD went into an univariable selection
by Spearman correlation analysis or Mann–Whitney U test (with P<0.1 level). The resulting nine factors were presented to stepwise forward linear regression modelling. Aviary v.
floor systems, absence of natural daylight in the hen house, a higher
proportion of underweight birds, as well as a higher laying performance
were found to be significantly associated with a higher percentage of
hens with KBD. The final model explained 32% of the variation in KBD
between farms. The moderate explanatory value of the model underlines
the multifactorial nature of KBD. Based on the results increased
attention should be paid to an adequate housing design and lighting that
allows the birds easy orientation and safe manoeuvring in the system.
Furthermore, feeding management should aim at sufficient bird live
weights that fulfil breeder weight standards. In order to achieve a
better understanding of the relationships between laying performance,
feed management and KBD further investigations are needed.

Last updated on 2021-06-09 at 16:14