Welfare of laying hens in a cage free system: effect of genotype and enrichment on animal based measures

Cage-free systems are known to increase activity and behavioural pattern for laying hens, but effects on overall welfare are controversial depending on several factors. Our study aimed to evaluate welfare of 1,800 laying hens of two genotypes (Hyline Brown vs. Lhomann White) housed in an aviary in 8 pens, enriched or not with additional perches. Live weight, percentage of keel bone and foot lesions, and plumage damage and cleanliness were assessed six times from 25 to 39 weeks of age on a sample of 400 hens (50/pen). No differences between hens were observed until 32 weeks. Then, at 39 weeks, the occurrence of keel bone lesions was higher and that of foot lesions lower in Brown compared to White hens (P<0.01). At all recordings, plumage cleanliness was better in Brown than in White hens (P<0.001), whereas the plumage damage was low (1% of hens) and not different among experimental groups. At 39 weeks, the occurrence of foot lesions was higher in pens enriched with additional perches than not enriched pens (P<0.05). In conclusion, lesions associated with welfare concerns appeared when the age of hens increased, and differed between genotypes, whereas the enrichment with additional perches played a minor role.