ASSOCIATION OF LIVER ABSCESS PRESENCE AND EPITHELIAL INTEGRITY OF THE HINDGUT IN FEEDLOT CATTLE TO SALMONELLA CARRIAGE IN SUBILIAC LYMPH NODES

Salmonellosis is the leading cause of bacteria foodborne illness in the United States with over 1 million illnesses annually (Scallan et al., 2015). Salmonella colonizes in the intestines and stress can cause disruptions of the tight junctions (Boyle et al., 2006) allowing for infection of other tissues such as the lymph nodes and liver (Ring, 1985). The objective of this study was to quantify the prevalence and concentration of Salmonella in liver, colon, and subiliac lymph nodes (SLN). Feedlots (n=6) were surveyed, from the Texas Panhandle, quarterly across one year for differences in management. Liver (n=8), colon (n=8), and SLN (n=16) were sampled from cattle from each feedlot, quarterly. Liver samples were organized into severely abscessed (n=4) and edible (n=4). Colon samples were organized into #1 score (n=4) and #2 score (n=4) colons; categorization was based on the integrity of the epithelial cell layer, #1 colon layers resembled a very ridged surface and #2 colon surfaces were free of ridges and smooth. Weather data was collected from the Texas Tech University Mesonet. Salmonella was uncommon in the winter months of quarter 1 (1.70% prevalence) and quarter 2 (0% prevalence). In the warmer months, Salmonella prevalence increased dramatically with quarter 3 having 90.63% prevalence and quarter 4 having 20.45% prevalence. Overall, the greatest prevalence of Salmonella was in SLN from carcasses with a #2 colon (27.59%); the lowest prevalence of Salmonella was in the tissue from edible livers (18.75%). The greatest concentration of Salmonella was detected in #2
colons (2.16 logCFU/g); the lowest prevalence of Salmonella was detected in edible liver tissue (0.1logCFU/g). Feedlot B had the highest average prevalence of Salmonella (29.35%) whereas Feedlot A had the lowest average prevalence (17.19%) among all quarters and sample types. Of the liver and colon samples, roughly 19% of samples were positive for Salmonella whereas 25% of the SLN samples were positive for Salmonella. The relative risk of a SLN being positive for Salmonella when associated with a #1 colon or #2 colon was 0.77 (P = 0.37) and 0.71 (P = 0.22), respectively. The relative risk of a SLN being positive for Salmonella when associated with an edible or abscessed liver was 0.75 (P = 0.30) and 0.83 (P = 0.49), respectively. We hypothesize, samples taken during quarter 3 demonstrated the greatest prevalence of Salmonella likely due to an increase in precipitation and temperature. These data suggest that Salmonella proliferation is strongly associated to local climatic conditions. This would suggest that as temperature and precipitation increase during warmer months strategies need to be developed to minimize Salmonella. Though Salmonella is of notable risk in lymph nodes, these data illustrate other edible products such as the liver are also of concern.