Foot and Skeletal Disorders in Laying Hens: Effects of Perch Design, Hybrid, Housing System and Stocking Density

Abstract
In four experiments a total of 3660 SCWL laying hens kept in conventional cages at low and high stocking densities with and without a perch, Get-away (GA) cages and aviaries with litter (AL), were used for studies on the presence of bumble foot (BF), distal toe pad hyperkeratosis (TPH), keel bone lesions (KBL) and of the breaking strength of tibia and humerus. Commercial hybrids were used: LSL (Expts. 1, 2 and 4); LSL and Shaver (Expt. 3). Only clearly observed in systems with perches, the incidence of BF and KBL was mostly affected by perch design, while BF was also strongly affected by strain and housing system. LSL showed significantly higher incidence of BF, especially in GA and AL. TPH, only found in conventional cages, was affected both by strain and stocking density, LSL hens and lower stocking density showing significantly lower incidence. Apart from welded wire net platforms, a European beech hardwood circular prototype perch with a flattened upper and lower surface seemed to combine in the best way until now low incidences of BF and KBL. Bone breaking strength was positively influenced by lower stocking density and the presence of a roost.