Unravelling variation in feeding, social interaction and growth patterns among pigs using an agent-based model

Abstract

Domesticated pigs, Sus scrofa, vary considerably in feeding, social interaction and growth patterns. This variation originates partly from genetic variation that affects physiological factors and partly from behavioural strategies (avoid or approach) in competitive food resource situations. Currently, it is unknown how variation in physiological factors and in behavioural strategies among animals contributes to variation in feeding, social interaction and growth patterns in animals. The aim of this study was to unravel causation of variation in these patterns among pigs. We used an agent-based model to explore the effects of physiological factors and behavioural strategies in pigs on variation in feeding, social interaction and growth patterns. Model results show that variation in feeding, social interaction and growth patterns are caused partly by chance, such as time effects and coincidence of conflicts. Furthermore, results show that seemingly contradictory empirical findings in literature can be explained by variation in pig characteristics (i.e. growth potential, positive feedback, dominance, and coping style). Growth potential mainly affected feeding and growth patterns, whereas positive feedback, dominance and coping style affected feeding patterns, social interaction patterns, as well as growth patterns. Variation in behavioural strategies among pigs can reduce aggression at group level, but also make some pigs more susceptible to social constraints inhibiting them from feeding when they want to, especially low-ranking pigs and pigs with a passive coping style. Variation in feeding patterns, such as feeding rate or meal frequency, can indicate social constraints. Feeding patterns, however, can say something different about social constraints at group versus individual level. A combination of feeding patterns, such as a decreased feed intake, an increased feeding rate, and an increased meal frequency might, therefore, be needed to measure social constraints at individual level.

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

“…Low estimates of group-betweenness and group-closeness centrality scores were found (<0.20) in our Duroc population. Similar results were previously obtained in purebred and crossbred German Landrace and Large White pigs [ 43 ]. These results indicate a lack of direct connection between animals in the pen, which could be a consequence of the avoidance strategy that some animals execute to prevent aggression [ 44 ].…”

Discrimination learning and judgment bias in low birth weight pigs

“…In pigs, only indirect measures of emotional state have been assessed in correlation with their social status. These studies also suggest that in stable hierarchies, lower ranking pigs may have a more negative emotional state, as they have more injuries, lose competition over food and display more fearful behaviors in a novel object test (O’Connell et al 2004; Boumans et al 2018). It is important to note that in our study, avoiding confounding effects of social rank by separate housing of pigs by treatment group may have resulted in other potential confounds.…”

Indirect genetic effects on the relationships between production and feeding behaviour traits in growing Duroc pigs

“…This variety of results is one of the arguments used by Boumans et al . ( 2018 ) to propose simulation models as a tool to study the relationships between performances, social rank and FBT.…”

“…In addition, variation in certain internal physiological mechanisms, for example, satiety, might play an important role in the relationship between FBT and social rank position (Maselyne et al, 2015). This variety of results is one of the arguments used by Boumans et al (2018) to propose simulation models as a tool to study the relationships between performances, social rank and FBT.…”