The effect of keel fractures on egg-production parameters, mobility and behaviour in individual laying hens

Abstract

A majority of laying hens fracture their keel bones during the laying cycle. It is not easy for a farmer to identify hens with fractures and hen survival rate seems high. Thus, the effect of both recent and healed fractures on bird welfare is unclear. We aimed to investigate the impact of these keel-bone fractures on hens' production and behaviour. The egg production, mobility and behaviour of Lohmann Brown hens without keel fractures were compared with that of hens with old healed fractures of varying severity. In addition, the keelbone strength and body temperature around the fracture site was measured for each group. Hens with no fractures laid more eggs and had a higher egg-quality score (derived from measures of egg weight, egg surface area, shell weight, shell percentage and shell density). These hens had the highest keel area temperature, strongest keel bones, accessed perches more frequently and took a shorter time to negotiate a walkway obstacle test and to fly down from a raised perch. Hens without keel fractures were better in all investigated parameters than hens with keel fractures, indicating a detrimental effect of fractures on both welfare and economic return.

Causes of keel bone damage and their solutions in laying hens

“…calcium) and energy, normally directed towards egg production, must consequently be reallocated to the process of healing bone (Thiruvenkadan et al, 2010). Similar results for altered egg production in individual birds were found by Nasr et al (2012b;, although this was assessed in non-commercial conditions (i.e., individual hens isolated in separate cages) in order to link the egg and hen. More critically, work by Nasr et al (2012b;, as well as that by Toscano (in press), did not control for natural variation in bird laying capacity.…”

Modification of aviary design reduces incidence of falls, collisions and keel bone damage in laying hens

“…Prevalence of keel bone damage (fractures and deviations) is greater in aviaries compared with furnished cage systems: reported prevalence in aviaries varies between 56 and 96% (Käppeli et al, 2011;Rodenburg et al, 2008), whereas the prevalence in furnished cages varies between 23 and 30% (Habig and Distl, 2013;Sandilands et al, 2009). Given that keel bone fractures are believed to be painful (Nasr et al, 2012a) and associated with reduced egg production (Nasr et al, 2012b) and increased mortality (McCoy et al, 1996), keel bone damage is one of the major welfare problems associated with laying hens in aviaries. Falls and high energy collisions with internal structures that occur as birds move between tiers or perches are likely to be one of the major sources for the high prevalence of keel bone damage in aviaries (Gregory and Wilkins, 1996;Moinard et al, 2004).…”

Detection of jumping and landing force in laying hens using wireless wearable sensors

“…Perches have been shown to improve bone strength (Fleming et al, 1994), facilitate symmetrical growth (Campo and Prieto, 2009), and allow hens a safe refuge from perceived dangers (Newberry et al, 2001). However, hens with access to perches and other elevated structures can experience keel bone breakage (Wilkins et al, 2011;Nasr et al, 2012a), which has been associated with reduced productivity and ensuing economic loss (Nasr et al, 2012a) as well as causing pain and discomfort to the hen (Nasr et al, 2012b).…”