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Abstract

Centrality parameters in animal trade networks typically have right-skewed distributions, implying that these networks are
highly resistant against the random removal of holdings, but vulnerable to the targeted removal of the most central
holdings. In the present study, we analysed the structural changes of an animal trade network topology based on the
targeted removal of holdings using specific centrality parameters in comparison to the random removal of holdings. Three
different time periods were analysed: the three-year network, the yearly and the monthly networks. The aim of this study
was to identify appropriate measures for the targeted removal, which lead to a rapid fragmentation of the network.
Furthermore, the optimal combination of the removal of three holdings regardless of their centrality was identified. The
results showed that centrality parameters based on ingoing trade contacts, e.g. in-degree, ingoing infection chain and
ingoing closeness, were not suitable for a rapid fragmentation in all three time periods. More efficient was the removal
based on parameters considering the outgoing trade contacts. In all networks, a maximum percentage of 7.0% (on average
5.2%) of the holdings had to be removed to reduce the size of the largest component by more than 75%. The smallest
difference from the optimal combination for all three time periods was obtained by the removal based on out-degree with
on average 1.4% removed holdings, followed by outgoing infection chain and outgoing closeness. The targeted removal
using the betweenness centrality differed the most from the optimal combination in comparison to the other parameters
which consider the outgoing trade contacts. Due to the pyramidal structure and the directed nature of the pork supply
chain the most efficient interru