Application of Social Network Analysis to Animal Welfare Research

Yuzhi Li, Associate Professor, Alternative Swine Production

April 2016 

Animal agriculture has been shaped by the general public’s concerns about animal welfare. The emergence of abnormal behaviors in farm animals is an indicator of poor welfare. Some abnormal behaviors, such as tail biting in pigs and feather pecking in chickens, can cause injuries which compromise not only animal welfare, but also health and performance of victimized animals. Stress is generally considered causes for these abnormal behaviors. In order to solve the problems, previous research has focused on identifying and removing physical stressors (such as improper thermal environment, poor air quality, inadequate space, or unbalanced nutrition). However, removing physical stressors does not always eliminate these abnormal behaviors. 

Docked vs undocked tails

A recent study at the WCROC had us compare behaviors of two groups of pigs; one group had docked tails (left) and the other group had undocked tails (right). We specifically were interested in the tail biting behavior exhibited in the undocked tail group.

One piece of the abnormal behavioral puzzle being overlooked is the social dynamics of animals. Pigs and chickens are social animals that form social structures in a group. In commercial production, pigs and chickens are usually grouped without consideration of their social preferences or social rules. Possibly, mismatch of pigs or chickens in a group results in unbalanced social structure which induces abnormal behaviors such as tail biting and feather pecking. On the other hand, the behavior of individual pigs or chickens affects and is affected by the behavior of their penmates. Social interactions can spread (or transmit) certain behaviors within a group through learning. However, social interactions may also create new behaviors, sometimes abnormal behaviors, through adaptation or as a coping strategy. Researchers have speculated that some abnormal behaviors, including tail biting in pigs and feather pecking in chickens, are new behaviors that emerge through social interactions under conventional production conditions. However, these speculations have not been tested.  

Social Network Analysis (SNA) is a method of studying social structure. In other words, SNA tells us who is connected to whom in a group and by what relationship. Social Network Analysis has been used by sociologists and psychologists to predict and explain why an individual is more susceptible to an infectious disease or abnormal behavior as a result of their particular position in a social network. At the group level, SNA can be used to predict how fast a disease or an abnormal behavior will be transmitted within the network. We can apply the same principle to investigate tail biting in pigs. We can utilize SNA to describe and compare social structures, to identify factors that change social structure, and to examine the effect of social structure on behavior of individuals. Using this tool, we may identify potential tail biters and victimized pigs, predict when tail biting will occur, and determine how fast tail biting will be spread within a group of pigs. 

While SNA is a powerful tool to reveal social structure and the roles of individuals within the group, it has yet to be used for farm animal welfare research. Recently, we were granted the Rapid Agricultural Response Funds by the Minnesota Agricultural Experiment Station. To our best knowledge, we will be the first institution to use SNA to study tail biting in pigs. We hope that this project may pave a path to utilizing SNA to solve other tough problems in animal welfare that emerge in modern animal production systems.      

More Info

Animal Welfare research at the WCROC

Tail biting in pigs - what do we know about it?