Fig 1.
Pyramidal structure of the Danish pig production chain.
The 24 holding types considered in this study were assigned to generic production steps. Besides the vertical connections, illustrated by the vertical transit sites horizontal connections also exist.
Table 1.
Number of active Danish pig holdings.
Fig 2.
Descriptive statistics of the examined data.
Figure (a) and (c) show the median (solid black line) and average (dashed black line) of holding sizes and of the number of pigs moved per pig movement sizes over time. Grey areas represent the range between 1st and 3rd quantile. Temporal trends of holding sizes for the investigated 24 holding types are shown in S1 File. Figure (b) shows the proportion of registered pig movements out of all possible movements in Denmark between 1st January 2006 and 31st December 2015 on daily base (green) and aggregated for 7 (dark blue), 14 (red), 28 (light blue) and 84 (grey) days.
Fig 3.
Registered pig movements and number of pigs moved.
Heat maps describing (a) the number of registered pig movements and (b) the number of pigs moved between holding types from 1st January 2006 and 31st December 2015 in Denmark. The heat maps show stability over time and for the number of movements (data not shown).
Fig 4.
Fraction of common directed links.
(a) Network loyalty (fraction of common directed links contained in two consecutive snapshots) of the pig movement network in Denmark between 1st January 2006 and 31st December 2015. Asymmetry is caused by varying number of directed links per year. (b) Development of the fraction of common directed links per year time difference. Dark grey areas represent the interval between 1st and 3rd quantile, light grey areas represent the interval between minimum and maximum values for the fraction of common directed links.
Fig 5.
(a) Fraction of holdings with in-loyalty and out-loyalty equal to 0 and 1 for the whole network of pig movements from 1st January 2006 to 31st December 2015 in Denmark. (b) and (c) show the histograms of in- and out-loyalty for the two consecutive years 2006 and 2007. Both histograms refer to the years 2006 and 2007 for visualization purposes, all other distributions show stability over time and are shown in in S2 File.
Table 2.
Levels of loyalty and contact chains for different pig holding types in Denmark, based on data from the CHR, 1st January 2006 – 31st December 2015.
Fig 6.
Pig movement network component sizes (proportion of overall number of active holdings).
Sizes of (a) the giant connected components (GSCC), (b) the giant in components (GIC) and (c) the giant out components (GOC) for the yearly snapshots of the pig movement network in Denmark between 2006 and 2015.
Table 3.
Number of years between 2006 and 2015, in which the holding type is present in the pig movement network components.
Fig 7.
Contact chains for production and breeding and multiplier herds.
Boxplots of (a) in-going and (b) out-going contact chains for production herds and (c) in-going and (d) out-going contact chains for breeding and multiplier herds from 2006 to 2015.