Effect of familiarity, group size, and floor space availability on agonistic behaviour in fattening turkeys (Meleagris gallopavo) and effect of an analgesic on their activity behaviour

Aggressive encounters and injuries due to head pecking seriously threaten the welfare of domestic turkeys and also result in economic waste within the turkey industry. The aim of this study was to investigate whether domestic turkey toms distinguish group members from non group members and if they preferably attack the latter. Two unfamiliar groups of four domestic turkey toms were brought into an experimental pen and the subsequent incidence of aggressive interactions and the spatial distribution of the birds were recorded for the duration of one hour. There were significantly more fights towards non group members than towards group members. The average duration of fights between group members and non group members was the same, but showed large variances. Aggressive pecking was significantly more frequent between non group members than between group members and turkey toms tended to leap more frequently at non group members than at group members. The distance between the birds tended to be greater amongst non group members than amongst group members. From our study it may be concluded, that not only wild turkeys but also domesticated broad-breasted fattening turkeys do distinguish between conspecifics of the own group and conspecifics of an other group, and that they antagonise non group members markedly more than group members. The results are discussed with respect to animal welfare and economic problems caused by the aggressive behaviour of domestic turkeys in commercial husbandry.