Dairy-origin Propionibacterium freudenreichii, turkey-origin Lactobacillus salivarius, and a Salmonella typhimurium vaccine elicit comparable colonization resistance on drug-resistant Salmonella serotypes (S. Reading, S. Agona, and S. Saintpaul) in growing turkeys after oral challenge

Abstract

The emergence of uncommon Salmonella serotypes with the potential to cause foodborne outbreaks linked to turkeys demands sustainable broad-spectrum preharvest safety approaches. We investigated the effects of three preharvest interventions [turkey-origin probiotic, Lactobacillus salivarius UMNPBX2 (LS), dairy-origin probiotic, Propionibacterium freudenreichii subsp. freudenreichii (PF), and a live, attenuated S. Typhimurium vaccine (VC)] against a cluster of three emerging commercial turkey-sourced Salmonella serotypes (S. Reading, S. Saintpaul, and S. Agona) in 6-week-old growing turkeys. Two experiments were conducted. In each experiment, 42, one-day-old turkey poults were randomly distributed into two control groups [Negative control (NC) and Positive control (PC) groups], LS group, PF group, VC group, and two combinations (LSVC = LS+VC and PFVC = PF+VC) groups with ad libitum access to feed and water. Poults in the probiotic-supplemented groups (LS, PF, LSVC, PFVC) received 105 CFU/ml through drinking water until six weeks of age. Poults in the vaccination groups (VC, LSVC, PFVC) received the Salmonella vaccine on day one and two boosters. At week 5, all birds except the NC group were inoculated with 6 log10 CFU/bird Salmonella (three-serotype mixture) by crop gavage. Salmonella was recovered from the cecum, liver, spleen, and crop seven days after inoculation. Statistical analysis was performed using ANOVA, and a significant difference was determined at P < 0.05. All treatments significantly reduced Salmonella colonization in the cecum of growing turkeys by 1.4 – 2 log10 CFU/g compared to PC (P < 0.05). Treatments also effectively reduced Salmonella dissemination to the liver and spleen and crop recolonization. No pathological differences between the treatment groups were apparent in histopathology and immunohistochemistry analyses of liver samples. This study indicates the potential of novel preharvest approaches against multiple serotypes of Salmonella colonizing in tandem in commercial growing turkeys.