This study aims to improve laying hen welfare in multi-tier systems, particularly with respect to keel bone fractures, by understanding how hens move around the system, identifying impact hazards, and investigating modifications directed at mitigating identified hazards. A variety of techniques were used to investigate housing hazards, including the use of accelerometers, behavioural observation, keel bone palpation and foot pad scoring. Although the overriding aim of this thesis was to identify hazardous areas in a multi-tier system and modify these areas to reduce keel bone fractures, the effect of modifications on the overall health of the hens was also investigated. The main findings of this study indicated, through accelerometry data, that falls resulted in higher loads at the keel compared to non-falls, and that collisions had higher loads compared to non-collisions. Movements around the nest box and top tier region resulted in a higher percentage of falls compared to other regions in the system. Dusk and dawn were more hazardous compared with day and night times, considering both the number of movements within the time point and the percentage of falls. Changes made to a multi-tier system aimed at reducing keel bone fracture prevalence either showed no clear benefit or increased prevalence. The only modification that made an improvement in health was the provision of ramps reducing the prevalence of foot pad dermatitis. On-farm studies showed a reduced keel bone fracture prevalence and bumblefoot prevalence with ramp access compared to those with no ramp access. This work has shown that it is possible to identify hazards associated with certain types of hen movement, specific regions within the system, and times of the day. Modifications to housing systems can influence hazards, though not necessarily as expected, with the provision of ramps showing the most promise at improving welfare.
|Date of Award||28 Nov 2019|
- The University of Bristol
|Supervisor||John F Tarlton (Supervisor), Stephanie Buijs (Supervisor) & Michael Toscano (Supervisor)|