Proximity Interactions in a Permanently Housed Dairy Herd: Network Structure, Consistency, and Individual Differences.

Kareemah Chopra,Holly R Hodges,Nick J Bell,Darren P Croft,Jonathan R Amory,Zoe E Barker,Jorge A Vázquez Diosdado,Edward A Codling,Tom C Cameron

doi:10.3389/fvets.2020.583715

Abstract

Understanding the herd structure of housed dairy cows has the potential to reveal preferential interactions, detect changes in behavior indicative of illness, and optimize farm management regimes. This study investigated the structure and consistency of the proximity interaction network of a permanently housed commercial dairy herd throughout October 2014, using data collected from a wireless local positioning system. Herd-level networks were determined from sustained proximity interactions (pairs of cows continuously within three meters for 60 s or longer), and assessed for social differentiation, temporal stability, and the influence of individual-level characteristics such as lameness, parity, and days in milk. We determined the level of inter-individual variation in proximity interactions across the full barn housing, and for specific functional zones within it (feeding, non-feeding). The observed networks were highly connected and temporally varied, with significant preferential assortment, and inter-individual variation in daily interactions in the non-feeding zone. We found no clear social assortment by lameness, parity, or days in milk. Our study demonstrates the potential benefits of automated tracking technology to monitor the proximity interactions of individual animals within large, commercially relevant groups of livestock.

Highlights

The herd social structure of cows on most commercial dairy farms differs significantly from their wild counterparts [1]
Within this study we found that the interaction network of the housed dairy herd was highly connected with significant social differentiation, interactions between cows were more heterogenous than expected by chance [18], but the network structure was temporally unstable
There was no evidence of preferential social assortment, showing cows did not associate more than expected by chance according to lameness state, parity, or days in milk (DIM)

Summary

Introduction

The herd social structure of cows on most commercial dairy farms differs significantly from their wild counterparts [1]. The social structure of animal groups, including how associations and interactions between individuals change over time, can be assessed using social network analysis (SNA) [8]. Proximity Interactions in Dairy Cows is well established; SNA is used across multiple disciplines including sociology [9], computer science [10], and transport [10, 11], and has been developed to study animal social networks, over the last decade [12, 13]. Inter-individual variation in sociality has been found in dairy cattle, potentially driven by personality, established as consistent from calf to adulthood (except during puberty) [17], or dominance, as studied in [18] who found that some individuals are more influential than others within the social network. Dairy cows may groom conspecifics based on familiarity and dominance [21], affiliative and agonistic interaction networks may not be correlated [22]

Methods

Results

Discussion

Conclusion