Keel bone damage in laying hens is associated with reduced access to elevated resourcesHen behavior changes show links to keel bone damage

Frontiers in Medicine Published October 6, 2026 Study authors: Serge Alindekon, Stefanie Petow, Helen Louton DOI ↗ Editorial oversight: Dr. Sofia Müller, MD · Lifespan & Whole-Person Care

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Key Takeaway

Note that hens with keel bone damage often show reduced frequency and slower movement when accessing elevated resources.

This systematic review synthesized 34 studies to evaluate the association between keel bone damage (KBD) and the use of functional resources and housing areas in laying hens. The review focused on several outcomes, including the frequency of access to elevated resources, speed of descent, frequency of vertical transitions, and resource occupancy.

Findings indicate that hens with keel fractures often accessed elevated resources less frequently, descended more slowly, or performed fewer vertical transitions. Notably, reduced access did not always correlate with reduced occupancy, as some hens with KBD remained on perches or in nests longer once reached. Evidence regarding the use of feeders, drinkers, outdoor areas, and ground-level resources was reported as sparse and inconsistent.

The authors note several limitations, including a limited and unevenly distributed evidence base and substantial variation in housing systems, KBD assessment methods, and study designs. Furthermore, few studies established whether changes in resource use preceded or followed the onset of KBD, which limits causal interpretation. Clinically, resource occupancy should not be interpreted as unrestricted access, as affected hens may remain on a resource longer despite less frequent access.

When a laying hen suffers from keel bone damage, it can change how she moves and interacts with her environment. A review of 34 studies looked at how these injuries affect the way hens use their housing, such as perches, nests, and feeding areas. The findings suggest that hens with fractures often have a harder time reaching elevated spots, move more slowly when coming down, and make fewer transitions between different levels.

While these birds might move less often to high spots, they might still spend a long time there once they reach them. This means that simply watching how long a bird stays in a nest or on a perch doesn't tell the whole story about her physical health. The study also looked at ground-level resources like feeders and drinkers, but the evidence there was inconsistent and sparse.

It is important to note that the data is currently limited and uneven. Because of differences in how different farms are set up, it is hard to say for certain if the change in behavior caused the bone damage or if the damage caused the change in behavior. For now, the clearest link is between the injury and the difficulty of using physically demanding, elevated resources.

What this means for you:

Hens with keel bone damage often struggle to reach elevated resources and move between different areas more slowly.

Common questions

How does keel bone damage affect how a hen moves?

Hens with keel fractures often access elevated resources less frequently. They also tend to descend more slowly and make fewer vertical transitions between different areas. This suggests that the injury makes it physically harder for them to navigate their environment.

Does staying in a nest mean a hen is healthy?

Not necessarily. While a hen might stay on a perch or in a nest for a long time, this does not mean she has easy access to it. A hen with a fracture might reach a resource less often but stay there longer once she finally gets there.

Is there evidence for how hens use feeders or drinkers?

The evidence for how hens use ground-level resources, such as feeders, drinkers, and outdoor areas, is currently sparse and inconsistent. The strongest evidence links the injury specifically to the use of physically demanding, elevated resources.

Study Details

Study typeSystematic review

EvidenceLevel 1

PublishedOct 2026

View Original Abstract ↓

Keel bone damage (KBD) is a major welfare concern in laying hens; however, evidence on its relationship with access to and use of functional resources and housing areas has not been systematically synthesised. This review examined associations between KBD and perches, resting locations, nests, feeders, drinkers, litter and floor areas, outdoor ranges, popholes, wintergardens, and other defined housing areas. PubMed and Web of Science were searched for empirical studies published between 2006 and 2026 involving laying hens, assessing KBD, and reporting relevant resource- or area-related outcomes. Of 345 records identified, 233 remained after deduplication. Following title and abstract screening, 50 reports underwent full-text assessment, of which 17 were excluded; one additional study was identified manually, yielding 34 included studies. Owing to substantial variation among housing systems, KBD assessment methods, outcome measures, and temporal designs, the findings were synthesised narratively by resource category and direction of association. The evidence base was limited and unevenly distributed, with most studies focusing on perches, elevated structures, and resting locations. Hens with keel fractures often accessed elevated resources less frequently, descended more slowly, or made fewer vertical transitions. However, reduced access did not always correspond to reduced occupancy, as some affected hens remained longer on perches or in nests once these locations had been reached. Evidence for feeders, drinkers, outdoor areas, and ground-level resources was sparse and inconsistent. Few studies established whether changes in resource use preceded or followed KBD, limiting causal interpretation. Overall, KBD was most consistently associated with the use of physically demanding elevated resources, while evidence for other functional areas remained uncertain. Resource occupancy should not be interpreted as unrestricted access because affected hens may reach a resource less often yet remain there longer. Future studies should use longitudinal individual-level designs, distinguish access from occupancy and departure, and combine automated tracking with direct behavioural observation.

Keel bone damage in laying hens is associated with reduced access to elevated resourcesHen behavior changes show links to keel bone damage

Common questions

Study Details

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Keel bone damage in laying hens is associated with reduced access to elevated resourcesHen behavior changes show links to keel bone damage

Common questions

Study Details

Health warnings on social media perceived as more effective than neutral messages in teens

Social Media Warnings May Discourage Use in Teens

Clinical research that matters. Delivered to your inbox.

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