Cost estimates are based on figures provided by Dutch experts from the Vionfood company.
The cost of monitoring the plant manager’s effort to avoid cross-contamination of carcasses are
included in all three plant control packages and set at zero costs. The costs of plant control packages 2
and 3 are estimated to be €0.10 and €0.40 per hog3.
Bacteriological prevalence distributions for plant control package, γt, are shown in table 2. Each
row of the probability matrix for a given plant control package is associated with a serological
prevalence level, and each column is associated with a bacteriological prevalence level. The matrix
elements are bacteriological prevalence probabilities derived from a Danish study in three Danish
abattoirs (Sorensen et al., 2004). First, a probability matrix was constructed based on odds of 1.4 for
Salmonella positive carcasses for each 10% point increase in herd serology, together with an increasing
dispersion of the probability distribution when serological prevalence levels increase4. It was estimated
that monitoring the plant manager’s effort to reduce Salmonella by the investor owner or cooperative
results for plant control package 1 resulted in a 50% reduction of the values in the probability matrix,
except for the zero bacteriological prevalence level (Urlings, 2007). Acidification of slaughter
equipment in cleaning and disinfecting procedures under plant control package 2 results in an
additional 50% reduction of the probability matrix values, again except for the zero bacteriological
prevalence level, compared to plant control package 1. This results in higher probabilities for a
bacteriological prevalence level of 0%. Adding logistic slaughter of sero-negative pig herds as control
measure results in a probability matrix equal to that for control package 2, except for the zero
serological herd prevalence level, in which the probability for a zero bacteriological probability is 1.
3 Within the “Control of Control program” Dutch slaughter companies seek to qualify for less intensive public control for
food related hazards by inspectors of the government. The reduced costs of less public inspection are assumed to outweigh
the costs of implementing and maintaining own control systems. The costs of logistic slaughter of Salmonella-free herd are
estimated for the Dutch Vionfood company. The company has six plants in the Netherlands. It was considered not feasible
to slaughter Salmonella-free herds at specific plants. Positively tested herds will be slaughtered at the end of the day. Costs
of logistic slaughter include an estimated 10 % increase in transportation costs.
4 The authors wish to express their gratitude to Liz Alban from Danmark for providing the original data of this study.
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