The Relationships Between the Performance of Injurious Pecking and Behavioural and Physical Traits in Domestic Turkeys
This thesis is an investigation of the relationships between the performance of injurious pecking and other behavioural and physical traits in domestic turkeys. Injurious pecking is a serious concern for the welfare and productivity of domestic turkeys, as a large proportion of the mortalities and culls in commercial flocks show injurious pecking damage. There are three distinct types of injurious pecking in turkeys: head pecking, severe feather pecking, and cannibalism; however, the development and causation of this damaging behaviour in turkeys is still poorly understood. The first research study in this thesis investigated the development of injurious pecking damage in relation to physical characteristics, such as body weight, leg health, and the snood length of growing male turkeys. This study showed that male turkeys develop more injurious pecking damage and poorer leg health over time. Yet, head pecking damage showed no correlation with body weight and snood length in domestic male turkeys. The validation study of data accelerometers for detecting turkey steps determined that this technology is best suited to evaluate the relationship between activity levels and injurious pecking in turkeys under small-scale research settings. The next study used temporal pattern analysis and a conventional behavioural assessment to identify differences in the behavioural organization of head pecking, severe feather pecking, and non-damaging gentle feather pecking. Both analyses identified similar differences in the structure of active behaviours and gentle feather pecking among pecking types, yet gave conflicting results on the organization of feeding and foraging behaviour for turkeys engaged in head, severe, or gentle feather pecking. The final study was an initial step for determining if morphological differences in beak shape influence the injurious pecking behaviour of individual turkeys. This research used landmark-based geometric morphometrics to establish that beak shape shows a wide phenotypic variation between male and female domestic turkeys at both 6 and 18.5 weeks of age. This morphological study provides a foundation for future genetics and behavioural research to evaluate the heritability of beak shape in domestic turkeys and to identify differences in potential capacity for injurious pecking damage between the distinct beak shape phenotypes.