Fecal shedding of Salmonella by a cohort of finishing pigs in North Carolina

This longitudinal case study investigated patterns of Salmonella shedding in a cohort of 41 finishing pigs in a finishing barn managed all-in-all-out. Drag swab samples of the finishing barn floor were collected 1 day before placement of pigs (day 0). Individual fecal samples, pooled pen fecal samples, and feed samples were collected on study days 2, 37, and 78. All samples were cultured for Salmonella using selective enrichment. Serotypes isolated were Salmonella serotype Derby, Salmonella serotype Typhimurium (Copenhagen), Salmonella serotype Heidelberg, Salmonella serotype Typhimurium, and Salmonella serotype Mbandaka. Salmonella Mbandaka and Salmonella Typhimurium (Copenhagen) were isolated from floor swabs prior to pig placement. The serotype profiles determined in both individual pig samples and pooled pen fecal samples were similar and changed markedly from day 2 postplacement, when Salmonella Derby comprised 63% of isolates from pigs, to day 78 post placement, when Salmonella Typhimurium comprised 87% of isolates from pigs. The Salmonella status of finishing pigs is dynamic and our observations support previous studies that indicate that infection during the finishing phase may be the major source of Salmonella found in market-age hogs.