Understanding Tail-Biting in Pigs through Social Network Analysis

Pigs are social animals that form social structures to maintain group stability. Grouping pigs without consideration of their social preferences may result in the development of abnormal behaviors such as tail-biting. This study was conducted to evaluate the association between social structure and incidence of tail-biting in pigs. Pigs were grouped according to their relatedness: (1) all pigs in a pen were related (born and raised by the same mother pig and called littermates); (2) all pigs in a pen were not related (born and raised by different mother pigs—non-littermates); and (3) half of the pigs in a pen were related (all pigs in a pen were born and raised by two mother pigs with equal number of pigs from each mother—half-group of littermates). Results indicate that littermates were less socially connected among themselves within a pen by spending less time lying together with their pen-mates than non-littermates. Littermates had a higher incidence of tail-biting compared to non-littermates. These results suggest that less social connection with pen-mates might predispose littermate pigs to the development of tail-biting. This pilot study demonstrates that social network analysis may provide us new insights into development of tail-biting