FOOT AND SKELETAL DISORDERS IN LAYING HENS - EFFECTS OF PERCH DESIGN,HYBRID, HOUSING SYSTEM AND STOCKING DENSITY

In four experiments a total of 3660 SCWL laying hens kept in conventio nal cages at low and high stocking densities with and without a perch, Get-away (GA) cages and aviaries with litter (AL), were used for stud ies 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); LS L and Shaver (Expt. 3). Only clearly observed in systems with perches, the incidence of BF and KBL was mostly affected by perch design, whil e BF was also strongly affected by strain and housing system. LSL show ed significantly higher incidence of BF, especially in GA and AL. TPH, only found in conventional cages, was affected both by strain and sto cking density, LSL hens and lower stocking density showing significant ly lower incidence. Apart from welded wire net platforms, a European b eech hardwood circular prototype perch with a flattened upper and lowe r surface seemed to combine in the best way until now low incidences o f BF and KBL. Bone breaking strength was positively influenced by lowe r stocking density and the presence of a roost.