The effect of keel bone damage, housing system, hybrid, and phase of production cycle on the plumage condition of laying hens

The aim of this study was to investigate the effect of keel bone damage, housing system, hybrid, and phase of production cycle on the plumage condition of laying hens. The trials were conducted in five industrial farms using different housing systems: enriched cage system, floor system, free range system and aviary system. The hybrids presented were Isa Brown, Hy-Line Brown, Hy-Line Silver Brown and Lohmann Brown. Fifty laying hens per farm were randomly selected for the assessment of keel bone damage and plumage condition. According to their age during assessment of feather cover and keel bone damage, the birds were categorized as being at the beginning (22-38 weeks of age) or in the middle of the production cycle (43-56 weeks of age). Total plumage score and the individual scores of seven body parts were assessed. Plumage scoring was not significantly affected by keel bone damage. Housing system and hybrid significantly (P<0.05) affected both total plumage score and individual plumage scoring. Hens in aviary and floor systems had significantly (P<0.05) higher total plumage score compared to hens farmed in enriched cage and free range systems, with a significantly (P<0.05) lower total plumage score found in free range compared to enriched caged hens. Hy-Line Silver Brown and Isa Brown had significantly (P<0.05) lower total plumage score compared to Lohmann Brown hens. The phase of production cycle had no significant effect on total plumage score, yet, significant (P<0.05) differences in individual plumage scores were observed between hens of different ages. This study showed that the feather cover of laying hens was affected by housing system, genotype, and phase of production cycle, but not by keel bone damage.