ARS | Publication request: Salmonella prevalence in bovine lymph nodes differs among feedyards

Submitted to: Journal of Food Safety
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: February 1, 2012
Publication Date: June 1, 2012
Citation: Haneklaus, A.N., Harris, K.B., Griffin, D.B., Edrington, T.S., Lucia, L.M., Savell, J.W. 2012. Salmonella prevalence in bovine lymph nodes differs among feedyards. Journal of Food Safety. 75:1131-1133.

Interpretive Summary: Cattle may contain the bacteria Salmonella that can make people sick. Generally, feces is most often implicated as the source of Salmonella contamination of meat and food products. However, recent research indicates that muscle bound lymph nodes may be a route of Salmonella contamination of ground beef. This research examined differences in Salmonella lymph node prevalence due to feedlot origin. Lymph nodes were collected from cattle representing several different feedlots at a commercial slaughter plant and cultured for Salmonella. Lymph node prevalence was found to be either very high or very low, suggesting that management factors at the feedlot may affect prevalence. Further research is underway in an attempt to identify the reasons for these differences.

Technical Abstract: Lymphatic tissue, specifically lymph nodes, is commonly incorporated into ground beef products as a component of lean trimmings. Salmonella and other pathogenic bacteria have been identified in bovine lymph nodes. Although Salmonella prevalence has been examined among lymph nodes within an animal, no research is currently available regarding cattle origin and Salmonella prevalence. Bovine lymph nodes (n = 307) were collected from beef carcasses at a commercial beef processing plant. The superficial cervical (n = 279) and iliofemoral (n = 28) lymph nodes were utilized for this study. Most notably, Salmonella prevalence was found to be exceptionally low (0% positive samples) in cattle sourced from feedyard A and high (88.2%) in cattle from feedyard B. Subsequent research has been initiated to investigate the reasons such distinct differences in Salmonella prevalence were seen among feedyards. The ultimate goal of the present study and subsequent studies is to identify and implement measures that can bring all feedyards to a Salmonella prevalence rate of zero in lymph tissue, as demonstrated by feedyard A.