Dominance hierarchy in groups of pregnant sows: characteristics and identification of related indicators

Pig groups are known to be organised along dominance hierarchies. Little is known about the characteristics of the hierarchy in groups of sows and there are various methods to calculate dominance ranks within the hierarchy. Assessing dominance through recording agonistic interactions requires time-c...

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Bibliographic Details
Published in:Applied animal behaviour science 2022-09, Vol.254, p.105683, Article 105683
Main Authors: Lanthony, Mathilde, Danglot, Margot, Špinka, Marek, Tallet, Céline
Format: Article
Language:English
Subjects:
Agonistic behaviour
automatic feeder
Life Sciences
sociometric variables
sows
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Summary:Pig groups are known to be organised along dominance hierarchies. Little is known about the characteristics of the hierarchy in groups of sows and there are various methods to calculate dominance ranks within the hierarchy. Assessing dominance through recording agonistic interactions requires time-consuming observations. In order to compare the ranking methods, to investigate the sociometric characteristics of pig hierarchy such as stability, linearity and steepness, and to identify easy-to-record proxy indicators of hierarchy, four groups of 18 (+/-2) gestating sows were studied. The sows were followed from 71 to 106 days of gestation. Starting from day 79, the access to the self-locking automatic feeders was limited to 6hours a day from to stimulate agonistic interactions. Each week, agonistic interactions were recorded during six continuous hours allowing the calculation of several dominance scores and sociometric variables. The restriction of feeding time increased the number of agonistic interactions but did not impact the proportion of agonistic behaviours with physical contact. The Dominance index, the David score and the Elo-score, used to rank the sow according to their dominance position, were highly inter-correlated (R >0.92). The hierarchy was stable (stability index Stab = 0.996 ± 0.081), transitive (proportion of transitive triads Pt= 0.967 ± 0.035), quasi linear (Improved Landau index of linearity h’ = 0.701 ± 0.068) and moderately steep (real steepness Steep=0.545 ± 0.085). The rankings obtained through Elo-score were highly correlated with the mean order feeding order (RS = 0.76), weakly correlated with the total number of feeder visits (RS =-0.21, P
ISSN:0168-1591
1872-9045
DOI:10.1016/j.applanim.2022.105683