Impact of Significant Dyads on Dominance Indices in Pigs

Abstract

Dominance indices are calculated by considering the differences between the number of won and lost fights. Whether these differences show a significant asymmetric outcome or not is neglected. Thus, two calculation methods for the limits of significant dyads are proposed using a sign test based on the differences in won and lost fights, considering all dyadic interactions in the pen (PEN: pen individual limits), and a sign test focusing on each individual dyad (DYAD: dyad individual limits). These were compared to the data set containing all dyadic interactions (ALL). Agonistic interactions in three mixing events were video recorded for two and a half days (weaned piglets) or one and a half days (fattening pigs, gilts). Dominance indices (DI) were calculated for all data sets. Pen/dyad individual limits revealed a small number of significant dyads (weaned piglets: 12.4%/8.8%; fattening pigs: 4.2%/0.6%; gilts: 3.6%/0.4%). Pen individual limits should be selected as they allow adaption of the limits according to the fighting frequency. Spearman rank correlation coefficients of the dominance indices between the data sets were always above 0.7, implying that the rank order remained relatively stable. Information about the impact of significant dyads on sociometric measures is important to prevent misinterpretations about the social structure in animal groups and should be considered in future studies.

Social Network Analysis in Farm Animals: Sensor-Based Approaches

“…Investigations into the dominance behaviour and group interactions in pigs highlighted the importance of a nuanced understanding of social interactions [31]. Using video recording, Büttner et al [32,33] were able to demonstrate the harmonizing effects of aggressive behaviour and physical conflict on the group of pigs. This effect has been systematically overlooked, with agricultural employees traditionally separating animals who display aggressive behaviour due to safety concerns.…”

“…Combined with social monitoring technology and analysis software, sensor data can be collected in greater amounts, which would lead to an increase in meaningful contributions to enhancing animal welfare [17,23,39]. While the technology is in continuous development and is making breakthroughs in animal husbandry research, analysts acknowledge that the scope of the current sensor-based technological assessment is limited and more research and innovation is needed for continuation and improvement of farm-specific SNA research [31][32][33]40].…”

Network analysis of tail-biting in pigs – the impact of missed biting events on centrality parameters

“…Social network analysis is a method to investigate relations and interactions between actors in groups (Wasserman and Faust, 1994; Newman, 2010). This is not limited to studies on humans and has been increasingly applied to animal behaviour in recent years (Lusseau and Newman, 2004; Croft et al ., 2005; McCowan et al ., 2008; Drewe et al ., 2009; Hinton et al ., 2013; Büttner et al ., 2019), as the behaviour of group-housed animals is affected by the behaviour of other pen mates as well (Makagon et al ., 2012). Thus, the group structure is important for the understanding of the individual's behaviour and social network analysis is a useful method to analyse it (Krause et al ., 2007).…”