The rapid transition from caged housing to alternative systems including aviaries and barns has revealed defects in production and behavior among current strains of laying hens.  Dr. Sijne Van der Beek, Chief Technology Officer for Lohmann Breeders in the Netherlands recently discussed changes in selection programs for cage-free strains.

Lohmann now uses manual-trap nests to measure individual hen performance in cage-free housing.  The company is also using electronic sensors to monitor movement that will be incorporated into selection programs.  Cage-free production has also highlighted individual hen behavior.  Dr. Van der Beek noted that the highest-producing hen is not necessarily the most optimal since she may express superior production at the expense of aggression. Because it is difficult to measure and to select for positive social interaction, social behavior is evaluated using confinement.  Other traits under evaluation include livability and skeletal integrity.

Dr. Van der Beek noted that keel palpation is a routine procedure to evaluate injury in aviaries.    Independent researchers have demonstrated that manual evaluation is an unreliable indicator of damage to the sternum especially in aviaries.  Radiographic examination is definitive and has disclosed injuries and defects undetected by palpation.

Given current experience with transition from conventional cages to aviaries, it will require many generations of selection to produce strains adapted to alternative systems that offer optimization of commercial production parameters. In the interim producers concentrate on rearing of pullets, training after transfer, appropriate lighting and other management procedures.