Salmonella shedding often increases in pigs after transportation and/or lairage. In a paper to be published soon in the journal, Foodborne Pathogens and Disease, Anthea C. Saez of Purdue University and co-authors there and at USDA Agricultural Research Service in West Lafayette report they have previously showed that administering anti-Salmonella bacteriophages to pigs by gavage significantly reduced Salmonella colonisation when the pigs were exposed to a Salmonella-contaminated holding pen.

In their latest paper, they tested whether a microencapsulated phage cocktail would remain effective if the treatment was administered to pigs in the feed.

Pigs (n=21) were randomly placed into three groups: feed, gavage, and control. The feed group was direct-fed a microencapsulated phage cocktail daily for five days. On the fifth day, the gavage group received the same phage cocktail by gavage, whereas control pigs received a mock treatment containing no phage. All pigs were then orally challenged with Salmonella enterica serovar Typhimurium. Faecal swab samples were collected every two hours.

Six hours post-challenge, all pigs were euthanised, and ileal and caecal contents and mesenteric lymph nodes were collected and analyzed for the challenge organism.

Pigs in the feed group were less likely to shed Salmonella Typhimurium after two hours (38.1 per cent) and 4?h (42.9 per cent) post-challenge than pigs in both the gavage (two hours: 71.4 per cent; four hours: 81.1 per cent) and control (two hours: 71.4 per cent; four hours: 85.7 per cent) groups (p<0.05).

Likewise, concentrations of Salmonella Typhimurium in ileal (2.0 log₁₀ colony forming units [CFU]/mL [contents]) and caecal (2.7 log₁₀ CFU/mL) contents from feed pigs were lower than ileal (3.0 log₁₀ CFU/mL) and caecal (3.7 log₁₀ CFU/mL) contents from control pigs.

High concentrations of anti-Salmonella phages were detected in ileal and caecal contents from both feed and gavage pigs (feed ileal: 1.4×10⁶; feed caecal 8.5×10⁶; gavage ileal 2.0×104; gavage caecal: 2.2×10³).

Direct feeding of microencapsulated phages is a practical and effective means of reducing Salmonella colonisation and shedding in pigs, concluded Saez and co-authors.

Reference

Saez A.C., J. Zhang, M.H. Rostagno and P.D. Ebner. 2011. Direct feeding of microencapsulated bacteriophages to reduce Salmonella colonisation in pigs. Foodborne Pathogens and Disease. ahead of print. doi:10.1089/fpd.2011.0905

Further Reading

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