Qualitative und quantitative Risikofaktoren für die Einschleppung und Verbreitung von Salmonellen in unterschiedlichen Produktionsverfahren beim Schwein

Subject of this examination was the detection of Salmonella seroprevalence in different pig housing systems as well as detecting of specific risk factors and analyzing them in consideration of their qualitative and quantitative importance. Furthermore consideration of the linkage between stages of production was intended to get information on the importance of vertical infection chains. Additionally in all farms with at least one positive ELISA finding samples of the surrounding (feed stuff, water, dust, soil) were taken to detect possible entry-sources of salmonella. Alltogether 4343 blood samples were taken from 78 conventional, 17 ecological and 13 outdoor farms and serologically examined by SALMOTYPEâ meat juice ELISA (Cut-off at 40%). 1498 sows from farrowing and farrow-to-finish farms showed a seroprevalence of 17.1%. 12.3 % of sows from 39 conventional farms, 7.6 % of sows from nine ecological farms and 35.1 % of sows from 13 free range farms were serological positive. In fattening farms altogether 301 (11.4 %) of 2642 samples showed positive findings. 13 % of animals from 43 conventional and 1.9 % of animals from twelve ecological farms reacted positively to ELISA. The low Salmonella seroprevalence at ecological housing systems is to be interpreted cautiously due to the small number of samples and limited choice of farms. Whether specific conditions of production play a major role has to be clarified in further examinations. Specific housing and mangement data was collected by a questionnaire to determine risk factors in conventional and free range farms and statistically evaluated in conjunction with the results of the serological examination. The following factors were determined to be of significant influence on an increase of seroprevalence of sows from conventional farms: integration of gilts without preceding quarantine, less than three persons caring for the herd, pasture housing systems and the presence of a hygienic sluice. Furthermore the risk of infection is increased at combined farms, by not using acids, leaving ill animals with the herd and not cleaning the feed storage. A significant rise of seroprevalence for fattening pigs from conventional housing systems was observed in pigs, when regular or occasional antibiotic treatment in the beginning of the fattening period, keeping of animals on partially slatted floors, feeding of granulate, not cleaning the feeding facilities as well as a location in regions with high pig density. Additionally an all-in/all-out management, the presence of cats on the farms and missing acid in feed or water can raise the detection rate in fattening farms. On outdoor farms, especially an increasing occurence of rodents and birds as well as declining frequency of change of area lead to a rise of seroprevalence. This result supports the suggestion that frequent contact with the environment provides a higher risk of infection and is responsible for higher seroprevalence at free range farms. Based on the serological examination there was no relation between the seroprevalence of rearing or breeding farms with that of farrowing farms. The detection of Salmonella from fecal samples of weaner pigs from those herds as well showed no dependencies from the seroprevalences of the sows. Fattening pigs on the other hand showed higher seroprevalences, if more than 2 % of the sows from the original farms were seropositiv. A comparison of serotype from sows and fattening pigs was not possible, because bacteriological examination of pooled fecal samples from the herds only showed negative results. The importance of vertical infection chains for salmonella-status in fattening farms stays uncertain. For the detection of possible sources of salmonella 136 samples of the surrounding from seropositiv farms have been bacteriologically examined. Altogether, one feed, one water and two dust samples were positive. In none of these farms positive pooled fecal samples were found so that it is not possible to definitely determine the entry-source of infection by a comparison of serovar.