Salmonella in the intestinal tract and associated lymph nodes of sheep and cattle.

The distribution of salmonellas along the gastrointestinal tract and in associated lymph nodes were studied in 100 sheep and 100 cattle at slaughter. Animals were chosen from those slaughtered on the first day of the week, since this meant that they were likely to have been held at the abattoir for several days and thus to be at high risk of salmonella infection. The contents of the rumen, abomasum, ileum, caecum and rectum were sampled, together with the lymph nodes draining each of these sites. Of the cattle, 77 were carrying salmonellas, including 61 with infected lymph nodes, whereas only 43 sheep were infected, 14 of them with infections in the nodes. The lower prevalence in sheep than in cattle might be explained by a shorter time between leaving the property and slaughter. In both species, within the gastrointestinal tract salmonellas were most frequently found in the caecum and rectum and least frequently in the abomasum. In cattle salmonellas were frequently present, usually in large numbers, in the lymph nodes draining the ileum, caecum and colon, but rarely in the ruminal and abomasal nodes; however this difference was not apparent in sheep. Over 70% of infected animals yielded more than one serotype, the maximum number isolated from any one animal being ten.