Do ramps between perches reduce keel bone injuries and foot health problems in two laying hen hybrids in non-cage systems?

Increased space allowance and access to litter provide laying hens kept in non-cage systems with more opportunities for natural behaviors. These beneficial characteristics of non-cage systems, however, also increase the risk of sustaining keel bone injuries and foot pad ailments. The aim of this study was to investigate if providing ramps reduces keel bone injuries and foot pad ailments in 2 different hybrids of laying hens. In a 2 × 2 design 16 pens were equipped either with or without ramps between perches and nestboxes (8 pens/treatment), and housed with either 25 ISA Brown birds/pen or 25 Dekalb White birds/pen (in total 200 birds/hybrid). Keel bone injuries and foot health were measured repeatedly between 17 and 52 weeks of age. Fearfulness and Human-Animal relationship were tested using, respectively, the Tonic Immobility (TI) and Voluntary Approach (VAT). ISA Brown birds sustained fewer keel bone fractures (F1,713 = 5.06, P = 0.025) and fewer keel deviations (F1,1195 =15.24, P <0.001) over time, fewer foot pad lesions, less bumble foot, and laid fewer floor eggs over time (all P <0.001), but had more foot pad hyperkeratosis (P <0.001) compared with Dekalb White birds. Ramps reduced keel bone fractures (F1,1003 = 17.47, P <0.001) and foot pad hyperkeratosis (F1,610 = 4.69, P = 0.031) over time and birds had fewer foot pad lesions (P <0.001) and bumble foot (P = 0.003) compared with birds in pens without ramps. White hybrids without ramps developed most foot pad lesions and bumble foot compared with all other treatments (all P <0.001). ISA Brown birds were less fearful (P<0.001) and displayed a better human-animal relationship (P <0.001) than Dekalb White birds. Sustaining fewer keel bone injuries may be related to a hybrid having a lower degree of fearfulness and a better human-animal relationship. Providing ramps appears to be effective in both reducing keel bone and foot health problems in non-cage systems.