An individual-based model for Salmonella transmission along the pig production chain

Abstract. The aim was to develop an individual-based model for the transmission of Salmonella from farrowing farm to slaughterhouse. The present study concentrated on farrowing sows as the initial source of Salmonella transmission. The model was evaluated with a sensitivity analysis using a Plackett-Burman design. Three levels (minimum, default, maximum values) for all input factors were considered. The deviations from the default prevalences caused by the extreme values did not balance each other for several significant input factors. For these factors, the relation between input factor and regarded health states was not linear.

Results showed that the probability of effective contact, to restart shedding, the shedding duration and the sow herd prevalences as well as their distribution across farrowing farms determined the Salmonella prevalence at slaughter. The study emphasised the importance of vertical and horizontal transmission. Low Salmonella prevalences obtained after nursing caused prevalences at slaughterhouse up to 12 %.