Possible risk factors for keel bone damage in organic laying hens

Abstract

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.

Dual-purpose production of eggs and meat—part 2: hens of crosses between layer and meat breeds show moderate laying performance but choose feed with less protein than a layer hybrid, indicating the potential to reduce protein in diets

“…Therefore, our observation is within the range reported by Bestman and Wagenaar (2014). However, Jung et al (2019) found that aviary housing and high laying performance are positively correlated with keel bone damage; therefore, the comparatively low laying performance of our floor-housed dual-purpose crosses should have resulted in less damage. With even lower laying performances of 54.5 and 54.2% in Bresse Gauloise and Bresse × NH hens, Lambertz et al (2018) found keel bone damage in only 1.1 and 13.5% of the birds.…”

Keel fracture changed the behavior and reduced the welfare, production performance, and egg quality in laying hens housed individually in furnished cages

“…In modern intensive production systems for laying hens, furnished cages and noncage systems have become common because of the increasing attention given to hen welfare ( Stratmann et al., 2015 , Weeks et al., 2016 ) and the ban imposed by the European Union on the traditional cage-raising system from 2012. Noncage systems allow more space for hens to practise natural behaviors ( Stratmann et al., 2015 ); however, it evidentially increases the production and management cost ( Lay et al., 2011 ) and the incidences of mortality and keel fracture ( Wilkins et al., 2004 , Rodenburg et al., 2008 , Käppeli et al., 2011 , Jung et al., 2019 ).…”

Health and welfare in organic livestock production systems—a systematic mapping of current knowledge

“…In comparison with aviary systems with high stocking density, the increased space allowance and free-range access in organic egg production are meant to improve the welfare of laying hens by providing them possibilities to express their species-specific behaviour. This can result in a lower incidence of maladaptive behaviours like feather pecking and cannibalism, if the hens use the outdoor area, as reported in different studies (Bestman et al 2017;Jung et al 2019). The understanding of injurious pecking, however, still needs to be improved in order to fully prevent the problem.…”

“…However, Wnuk-Gnich et al (2016) found that broiler chickens having access to free ranging systems were characterized by a significantly lower mortality rate compared to the control birds. High levels of freerange use have been associated with a reduced incidence of keel bone fractures in laying hens (Richards et al 2012;Jung et al 2019). The literature search did not result in specific studies of the occurrence of erysipelas infections; thus, this was excluded in this review.…”

“…Moreover, keeping sows in loose housed farrowing systems enhances sow behaviour and allows for improvements in post-weaning piglet feed consumption and growth. Among organic layers, the incidence of harmful behaviours, such as feather pecking and cannibalism, can be reduced when hens are reared in lower stocking densities and are offered free-range areas (Bestman et al 2017;Jung et al 2019). The use of slower-growing breeds in broiler production is a prerequisite for the longer rearing time and adaptation to the production system.…”