Recently there has been growing public concern for the traditional intensive housing of battery caged laying hens. In response to public demand to increase hen welfare on farm, the Canadian Farm Animal Care Council in conjunction with egg producers, is moving toward single-tier or multi-tier aviary systems. Where battery cage systems force hens into very tight, barren quarters, aviaries contain certain basic elements such as perches, nest boxes, feeders, drinkers and even litter. Multi-tier systems meet the behavioural needs of the hens and enable the hens to flap their wings, walk and jump while also facilitating increases in stocking density 3-4 times, increasing profitability of the flock.
While aviaries provide freedom of locomotion, this is associated with an increased risk of bone fractures. Recent evidence indicates that the incidence of keel fractures in non-cage systems ranges from 52% to 80% . The risk of collision during flying or jumping is increased by increased mobility, and it is assumed that bumping of the keel bone when the hens jump up or down or fly incorrectly from litter to raised perches, tiers or nest boxes is responsible for keel fractures. Such fractures are likely to be painful. Furthermore, keel fractures compromise the birds’ mobility.
The newest faculty member of the Animal and Poultry Science department Dr. Alexandra Harlander, her newly recruited graduate students Madison Kozak, Chantal LeBlanc & Stephanie LeBlanc, are working on investigating welfare problems of laying hens in the new aviary systems. The group is working in conjunction with Dr. Tina Widowski’s PhD student, Teresa Casey, who will be studying keel bone fractures specifically. Together, they are looking into the basics of the development of locomotory skills of hens on the ground and in the air, as well as their preferences for walking and flying. All this can inform optimal housing for laying hens and pullet rearing practices in non-cage systems.
Above left: Chicken skeletal anatomy with Keel indicated, Top (ventral) and bottom (dorsal) right: Show a normal keel bone on the left and tow examples of curvature deformations and fractures at the tips of keel bones. Photos by Teresa Casey
The results (intellectual property) of this study will provide significant knowledge to the Canadian egg industry with respect to laying hens locomotion skills in view of improving the design of aviaries/but also single tier systems to avoid welfare problems such as keel injuries.
The keel bone is the straight bone that projects the length of the sternum or breast bone. In the image above there is an example of a normal vs. damaged keel bones from hens. In addition, Harlander’s group is working with breeding stock producers to increase bone strength and health in laying hens.
For more detailed information about the project please watch this video.
Due to the current push toward more welfare conscious housing systems for laying hens this research comes in a timely fashion for hens everywhere. The European Union has already banned battery cage operations and the Canadian Recommended code of practice for the care and handling of pullets, layers and spent fowl has just begun the media and public review process for updating. However, since animal based welfare indicators such as keel fractures are more prevalent in non-cage systems the process of changing housing systems needs to be done with care and careful investigation into the effects on hen health and welfare.
APS News: Sunday, January 12, 2014 - By: Judy Stryker
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