An experimental field trial investigating the use of bacteriophage and manure slurry applications in beef cattle feedlot pens for Salmonella mitigation

Authors: NICKODEM, COLETTE - Texas A&M University; ARNOLD, ASHLEY - Texas A&M University; Beck, Matthew; BUSH, JACK - Texas A&M Agrilife; GEHRING, KERRI - Texas A&M University; GILL, JASON - Texas A&M University; LE, TRAM - Texas A&M University; PROCTOR, JARRET - Texas A&M University; RICHESON, JOHN - West Texas A & M University; SCOTT, H - Texas A&M University; SMITH, JASON - Texas A&M Agrilife; TAYLOR, T - Texas A&M University; VINASCO, JAVIER - Texas A&M University; NORMAN, KERI - Texas A&M University

Submitted to: Animals
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/4/2023
Publication Date: 10/11/2023
Citation: Nickodem, C.A., Arnold, A.N., Beck, M.R., Bush, J.J., Gehring, K.B., Gill, J.J., Le, T., Proctor, J.A., Richeson, J.T., Scott, H.M., Smith, J.K., Taylor, T.M., Vinasco, J., Norman, K.N. 2023. An experimental field trial investigating the use of bacteriophage and manure slurry applications in beef cattle feedlot pens for Salmonella mitigation. Animals. 13(20). Article 3170. https://doi.org/10.3390/ani13203170.
DOI: https://doi.org/10.3390/ani13203170

Interpretive Summary: Salmonella contamination of meat is an important food safety concern. Most processes to sanitize beef products are applied directly to the carcass surface and are ineffective at reducing or eliminating Salmonella that are harbored in cattle lymph nodes. Lymph nodes may become incorporated into ground beef products, which can contribute to foodborne illness. Bacteriophages are common viruses, harmless to humans, that infect and destroy bacteria such as Salmonella. The efficacy of applying bacteriophages to pen surfaces to reduce Salmonella prevalence is largely unknown. Scientists from the USDA ARS Conservation & Production Research Laboratory, Bushland, Texas, Texas A&M University, Texas A&M AgriLife Research and Extension, and West Texas A&M University conducted an experiment to determine whether application of natural bacteriophages could reduce Salmonella prevalence on feedlot pen surfaces and on cattle hides. The reduction on cattle hides suggests that bacteriophage treatments applied to the feedlot pen surface may reduce Salmonella populations in cattle during the pre-harvest period resulting in less sources of contamination during slaughter and processing.

Technical Abstract: Post-harvest Salmonella mitigation techniques are insufficient at addressing Salmonella harbored in cattle lymph nodes, necessitating the exploration of pre-harvest alternatives that reduce Salmonella prior to dissemination to the lymph nodes. A 2×2, unbalanced experiment was conducted to determine the effectiveness of treatments applied to the pen surface for Salmonella mitigation in feedlot pens and beef cattle. Treatments included a manure slurry (n = 4 pens), a bacteriophage cocktail (n = 4), a combination of both treatments (n = 5), and a control group (n = 5) that received no treatment. Environment samples from 18 feedlot pens and fecal grabs, hide swabs, and subiliac lymph nodes from 178 cattle were collected. All samples were selectively enriched to determine Salmonella prevalence and isolates were sequenced to identify serovars. The combination treatment was most effective at reducing Salmonella, and prevalence was significantly lower compared with the control group in rump swabs on Days 14 and 21. Treatment impact on Salmonella in lymph nodes could not be determined, due to low prevalence. The reduction on cattle hides suggests that bacteriophage treatments applied to the feedlot pen surface may reduce Salmonella populations in cattle during the pre-harvest period resulting in less sources of contamination during slaughter and processing.