[Epidemiological studies on salmonella in a certain area ("Walcheren project"). II. Presence of salmonella in the mesenteric lymph nodes and rectal contents of normal pigs slaughtered in Walcheren (author's transl].

During a period of twelve months, all pigs slaughtered on the former Isle of Walcheren were examined for the presence of Salmonella in the mesenteric lymph nodes and rectal contents. Salmonella was detected in 22.3% of 7,756 animals studied. Fifty different serotypes were isolated, two of these (S. menhaden and S. mikawasima) being isolated for the first time in the Netherlands. Data on the farms was collected, a differentiation being made between the type of farm (breeding, breeding and fattening, and fattening farms), the type of feed (pellets, pellets plus meal and meal) and the number of fattening pigs on each farm. The results show that there is a slight difference in the proportion of pigs responding positively to pellet rather than meal feeding, viz. 20.9% against 23.7%. A striking feature consists in the fact that this difference is much larger in favour of pellet feeding on the smaller farms (up to one hundred fattening pigs), viz. 12.9% against 21.0%. Another finding was that the average number of serotypes isolated on farms on which pellets were fed was smaller than that on farms on which meal was fed.