Are the layer performances, bone strength and eggshell characteristics affected by the housing system?

Layer performances, eggshell characteristics and bone strength of laying hens reared in three different housing systems (cages, barn and organic) were evaluated. Laying hens of the same strain (Hyline Brown) were housed in each system and fed on the same level of nutrition (2800 ME). The study was carried out from the 18th to the 70th weeks of layer age, weekly recording the number of eggs collected and laid on the floor, as well as the mortality and the feed consumption. The weight and the shell characteristics of the eggs were analyzed for each system at 27, 30, 35, 43, 53 and 68 weeks of hen age. At 70 weeks of age, twenty hens per housing system were slaughtered and bone breaking strength and stiffness were determined by three point bending test. After the steady phase of egg production, the percentage of deposition was generally higher in comparison to the standard production of Hyline hens, especially in the organic and barn systems. The percentage of cracked eggs was clearly related to the shell strength characteristics, with organic eggs showing the highest shell thickness, the most resistant shell and consistently the less cracked eggs. Shell strength and thickness in non-cage eggs were highly affected by hen age, while they were much stable in cage eggs. Organic hens also showed the strongest humeri, while their tibiotarsi were as robust as those of cage hens.