Abstract
The transition from conventional cages to cage-free aviary systems in egg production presents unique challenges for performance, welfare, and skeletal health of laying hens. While extensive data exists for conventional systems, aviary systems require comprehensive investigation due to larger colony sizes and increased opportunities for vertical and lateral movement. This study evaluated the production, welfare, and skeletal characteristics of four commercial laying hen hybrids, two brown egg (brown) and two white egg (white) strains, in an aviary housing system under common management. Brown strains were consistently heavier with larger tibia volume, surface area, and mineral content compared to white strains. All 4 strains achieved at least 91 % hen day egg production, with white strain C having 8 percentage point higher production rates throughout the majority of lay. Feather coverage deteriorated as all hens aged, but white strains, especially strain C, had more frequent feather damage during assessments. Brown strains had more incidence of keel damage based on manual palpation. However, visual inspection of excised keel bones revealed brown strain B had fewer fractures than all other strains, though 90 % of the keel bones had fractures, frequently in the tip. These findings reveal significant strain-specific differences in production, skeletal health, and welfare in aviary systems. Our use of common management may have hindered hens from achieving their full genetic potential; thus, tailoring management and housing practices to accommodate these differences is crucial for successful cage-free egg production and hen welfare.