Pigs housed in a group.

2016-17 Rapid Ag: Using a novel approach, Social Network Analysis, to remedy animal welfare concerns raised by consumers

July 15, 2016

Principle Leader

Yuzhi Li


Department of Animal Science

Funding Awarded

  • 2016 Fiscal Year: $26,163
  • 2017 Fiscal Year: $49,643

The Problem

Animal agriculture has been shaped by the general public’s concerns about animal welfare. Currently, production procedures that cause pain in animals are coming under scrutiny. One such procedure is tail docking in pigs. The European Union (Directive 91/630/EEC) recommended that tail docking on a routine basis be prohibited. As a result, some countries, such as Finland, Lithuania, Sweden, Norway, and the U.K. have regulated tail-docking. In the U.S., more than 95% of pigs are docked. Tail docking is on the radar of animal activists. In fact, some market supply chains have prohibited tail docking of pigs. If other market channels follow this prohibition, pork producers need to know how to protect the welfare and performance of pigs that have not been tail docked. To prepare U.S. pork producers for future regulations on tail docking, development of alternatives to tail docking is urgent. Tail docking is a routine management practice that prevents tail biting among pigs. Tail biting not only causes economic losses to pork producers, but also compromises welfare of pigs. While tail docking reduces incidence of tail biting, it does not eliminate the problem. Research results and on-farm observations have suggested that tail biting occurs more commonly in conventional production systems where pigs are housed indoors on fully slatted floors. However, tail biting also occurs among pigs raised outdoors suggesting that indoor housing, high stocking density, and lack of bedding in conventional systems are not the root causes of tail biting. Although many researchers have committed much effort to identify contributing factors and seek solutions, the problem of tail biting remains. One aspect of this problem that has been overlooked in past research is the social dynamics of pigs in a group. Pigs are social animals that form social structures to maintain group stability. However, in commercial production, pigs are grouped without much consideration of their social preferences and social rules. Possibly, mismatch of pigs in a group results in unbalanced social structure which induces abnormal behaviors such as tail biting. We hypothesize that tail biting is an abnormal social behavior caused by unbalanced or disturbed social structure. In this proposed project, we will investigate tail biting through a novel approach called Social Network Analysis.


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. A particular strength of SNA is to examine and quantify social structure through interactions at the individual level. Social Network Analysis provides standardized methods for calculating measures of social structure across groups, and from the group level to the individual level. These quantitative measures can be used 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. For social animals, including swine, the behavior of individuals affects and is affected by the behavior of others within their social network. 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 poultry, are new behaviors that emerge through social interactions under conventional production conditions. However, these speculations have not been tested using SNA.

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 intend to use all these features of SNA to investigate tail biting in pigs. Using this tool, we can 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. So, SNA will provide us new insights into development of tail biting that traditional approaches have been unable to uncover.     

While SNA is a powerful tool to reveal social structure and the roles of individuals within the group, it has yet to be used in projects that study farm animal welfare. Social network analysis requires capability to mine large datasets. Just recently, computing power and appropriate software has become available commercially to accomplish SNA (R Development Core Team, 2011). The proposed project will be the first one to use SNA to study tail biting in pigs. Completion of this proposed study will pave a path to utilizing SNA to solve other tough problems in animal welfare that emerge in modern animal production systems. For instance, SNA may help us understand and solve the problem of feather pecking in poultry or aggression amongst group-housed cows or sows. We believe that this project will empower us broadly to remedy animal welfare concerns raised by consumers.      


  1. Investigate social structures of groups of pigs housed in production conditions
  2. Compare differences in social structure of pigs between pens with tail biting and pens without tail biting
  3. Identify social characteristics of potential tail biters and victimized pigs.
  4. Evaluate efficacy of social network measures (statistical descriptors) for predicting outbreaks and development of tail biting. 
Morris ROC pig.

At the West Central ROC in Morris, U of M researchers group-house swine and taste various techniques to increase their well-being and overall health.