Social Network Analysis of Agonistic Behaviour and Its Association with Economically Important Traits in Pigs.

Saif Agha,Raquel Quintanilla,Juan Pablo Sánchez,Emma Fàbrega

doi:10.3390/ani10112123

Abstract

Simple SummaryAggression behaviour has several negative consequences on the performance and welfare of pigs. Here, a Social Network Analysis (SNA) approach was employed to (1) identify individual traits that describe the role of each animal in the aggression; (2) investigate the association of these traits with performance and feeding behaviour traits. The study was conducted on 326 Duroc pigs reared in 29 pens. Several individual centrality traits were identified and used to calculate the Social Rank Index. The Dominant, Subordinate, and Isolated animals represented 21.1%, 57.5% and 21.4%, respectively. No significant correlations were observed between out-degree (number of initiated agonistic behaviours) and growth traits, indicating the similarity of growth patterns for dominant and non-dominant animals. Furthermore, out-degree was correlated positively with average daily occupation time (time at the feeder/day) and average daily feeding frequency (number of visits to the feeder/day), but negatively with average daily feeding rate (gr/min). This may indicate the ability of non-dominant pigs to modify their behaviour to obtain their requirements. The Hamming distances between networks showed that there is no common behaviour pattern between pens. In conclusion, SNA showed potential for extracting behaviour traits that could be used to improve pig performance and welfare.Aggression behaviour has several negative consequences on the performance and welfare of pigs. Here, the Social Network Analysis (SNA) approach was employed to (1) identify individual traits that describe the role of each animal in the aggression; (2) investigate the association of these traits with performance and feeding behaviour traits. The study was conducted on 326 Duroc pigs reared in 29 pens. Several individual centrality traits were identified and used to calculate the Social Rank Index. The Dominant, Subordinate, and Isolated animals represented 21.1%, 57.5% and 21.4%, respectively. No significant correlations were observed between out-degree (number of initiated agonistic behaviours) and growth traits, indicating the similarity of growth patterns for dominant and non-dominant animals. Furthermore, out-degree was correlated positively with average daily occupation time (time at the feeder/day) and average daily feeding frequency (number of visits to the feeder/day) but negatively with average daily feeding rate (gr/min). This may indicate the ability of non-dominant pigs to modify their behaviour to obtain their requirements. The Hamming distances between networks showed that there is no common behaviour pattern between pens. In conclusion, SNA showed the potential for extracting behaviour traits that could be used to improve pig performance and welfare.

Highlights

Mixing unacquainted pigs is a common process in commercial farms
Head-knocking behaviour is considered as a fast, agonistic action that pigs head-knocking was the most observed agonistic behaviour (74%), followed by bite behaviour
Controlling the agonistic behaviour is challenging in pig commercial farms

Summary

Introduction

Mixing unacquainted pigs is a common process in commercial farms. This process usually leads to an increase in agonistic behaviour among pigs, who attempt to establish a dominance hierarchy within the group [1]. Such behaviour has several negative consequences on the performance, health and welfare of pigs, e.g., growth, skin lesions [2]. Getting insights into pig behaviour post-mixing would help in controlling aggression, improve welfare and subsequently increase production efficiency. Traditional experimental dyadic approaches to studying aggression in pigs have an important limitation as they ignore the social structure of the group [4].

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Conclusion