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United States Department of Agriculture

Agricultural Research Service

Research Project: HANDLING AND TRANSPORT STRESS INTERACTIONS WITH PATHOGEN BIOLOGY IN SWINE AND CATTLE

Location: Livestock Behavior Research

Title: Direct feeding of microencapsulated bacteriophages to reduce Salmonella colonization in pigs

Authors
item Saez, Anthea -
item Zhang, J -
item Rostagno, Marcos
item Ebner, Paul -

Submitted to: Foodborne Pathogens and Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: July 29, 2011
Publication Date: December 1, 2011
Citation: Saez, A.C., Zhang, J., Rostagno, M.H., Ebner, P.D. 2011. Direct feeding of microencapsulated bacteriophages to reduce Salmonella colonization in pigs. Foodborne Pathogens and Disease. 8(12):1269-1274.

Interpretive Summary: Salmonella shedding often increases in pigs following transportation and/or lairage. We previously showed that oral administration of anti-Salmonella bacteriophages (viruses that infect and destroy bacteria) reduced Salmonella colonization when the pigs were exposed to a Salmonella-contaminated pen. In this study, we tested whether a microencapsulated/protected bacteriophage mix would remain effective if the treatment was administered to pigs in the feed prior to a Salmonella challenge. Pigs were randomly placed into three groups: in-feed, gavage, and control. The in-feed group was fed the bacteriophage mix daily for five days. On the fifth day, the gavage group received the same bacteriophage mix by gavage, while control pigs received a mock treatment containing no bacteriophage. All pigs were then orally challenged with Salmonella Typhimurium. Fecal samples were collected every two hours. At six hours post-challenge, all pigs were euthanized, and intestinal contents, and associated lymph nodes were collected and analyzed for the challenge strain. Pigs in the in-feed group were less likely to shed Salmonella at 2 h and 4 h post-challenge compared to pigs in both the gavage and control groups. Likewise, concentrations of Salmonella in intestinal contents from in-feed pigs were significantly lower than in control pigs. It is concluded that direct feeding of microencapsulated bacteriophages is a practical and effective means of reducing Salmonella colonization and shedding in pigs.

Technical Abstract: Salmonella shedding often increases in pigs following pre-slaughter transportation and/or lairage. We previously showed that administering anti-Salmonella bacteriophages to pigs by gavage significantly reduced Salmonella colonization when the pigs were exposed to a Salmonella-contaminated pen. In this study, we tested whether a microencapsulated phage cocktail would remain effective, if the treatment was administered to pigs in the feed. Twenty-one pigs (in each of three replicates) were randomly placed into three groups: in-feed, gavage, and control. The in-feed group was fed a microencapsulated phage cocktail daily for five days. On the fifth day, the gavage group received the same phage cocktail by gavage, while control pigs received a mock treatment containing no phage. All pigs were then orally challenged with Salmonella Typhimurium. Fecal samples were collected every two hours. At six hours post-challenge, all pigs were euthanized, and ileal and cecal contents, and mesenteric lymph nodes were collected and analyzed for the challenge strain. Pigs in the in-feed group were less likely to shed Salmonella at 2 h (38.1%) and 4 h (42.9%) post-challenge compared to pigs in both the gavage (2 h: 71.4%; 4 h: 81.1%) and control (2 h: 71.4%; 4 h: 85.7%) groups (P < 0.05). Likewise, concentrations of Salmonella in ileal (2.0 log10 CFU/mL) and cecal (2.7 log10 CFU/mL) contents from in-feed pigs were significantly lower (P < 0.05) than ileal (3.0 log10 CFU/mL) and cecal (3.7 log10 CFU/mL) contents from control pigs. High concentrations of the anti-Salmonella phages were detected in ileal and cecal contents from both in-feed and gavage pigs. It is concluded that direct feeding of microencapsulated phages is a practical and effective means of reducing Salmonella colonization and shedding in pigs.

Last Modified: 8/22/2014
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