Characterising nosing behaviours in pigs after mixing using social network analysis.

Area of Science:

• Animal Behavior
• Ethology
• Animal Social Networks

Background:

• Proximity is typically used to measure affiliation in farm animals.
• Intensive housing may limit the accuracy of proximity as an affiliation measure due to stocking densities.

Purpose of the Study:

• To investigate affiliation patterns in pigs by examining differences in proximity and contact behaviors after regrouping.
• To analyze the influence of familiarity and sex on social interactions and network structures.

Main Methods:

• Observed 117 finishing pigs (61 males, 56 females) in eight mixed-familiarity groups post-regrouping.
• Utilized video analysis to record social nosing behaviors over two days.
• Applied social network analysis and Exponential Random Graph Models to study interaction patterns, reciprocity, and individual attributes.

Main Results:

• Group density was lower for snout-snout proximity compared to snout-head proximity.
• Contact network density was lowest for snout-snout interactions.
• Familiarity was a significant predictor of interaction; familiar pigs were more likely to interact.
• Females received less social behavior than males in specific contact networks.
• Both proximity and contact behaviors demonstrated significant reciprocity.

Conclusions:

• Familiarity is a crucial factor in pig social interactions, impacting both proximity and contact behaviors.
• Snout-snout proximity and contact are the least observed behaviors, suggesting they may not be primary indicators of affiliation in this context.
• Network analysis reveals behavioral nuances and the influence of individual attributes, informing better grouping strategies for farm animals.