Effects of keel bone deviation on post-peak egg production in a commercial laying hen flock with different breast condition

This study was made to investigate the effects of breast condition and keel bone deviations on post-peak egg production of a commercial laying hen housed in a multi-tier conventional battery cage. The birds divided into two groups according to presence of keel bone deviation at first. Then the birds further divided into two groups according to breast condition as well developed or relatively well developed. The laying hens were kept under identical management conditions for commercial laying hens during the study. Data about daily egg production, feed intake, mortality and egg weight was collected from 62 to 77 weeks of age in the groups. There were no significant effects of keel bone deviation on body weight and egg weight of the layer hens. The initial and final body weight of the birds are significantly different between the breast condition groups (P<0.001). The birds with well developed breast condition had significantly better hen-housed and hen-day egg production (P<0.001). The significant keel bone deviation x breast condition interaction for egg production revealed that presence of keel bone deviation was effective in birds only had relativelly well developed breast condition (P