[Investigations on the identification of risk factors for seroprevalences of Salmonella infections in breeding gilt rearing herds].

The aim of this study in breeding gilt rearing herds was to identify production-specific risk factors for an increased Salmonella seroprevalence. The statistical analysis for determining risk factors based on 10,429 animals from 40 herds. Blood samples were taken regularly between 2001 and 2003 from gilts five and six months of age. Only those herds from which at least 60 samples per year and 10 per quarter were available were included in the statistical analysis of risk factors. For this, the results of the serological examinations were combined with data obtained from a questionnaire and subsequent visual examination of the herds and their environment. Different kinds of categories were validated using sensitivity analysis. Finally, all herds with a Salmonella seroprevalence < 0.15 were classified as "Salmonella low risk", and those with a Salmonella seroprevalence > or = 0.15 were classified as "Salmonella high risk". Four of the sixteen variables could be ascertained as risk factors for enhanced Salmonella seroprevalences: the use of pelleted or granulated feed, the use of purchased feed, partially or not slatted floors in the pens, a floor space of 0.85m2/pig and the freedom of PRRSV-infection in a herd. Some of these variables were identified as risk factors in earlier studies, too. The identification of these risk factors in pig herds of a breeding company with a low Salmonella seroprevalence, emphasises the importance of these factors for controlling Salmonella infections in pig herds.