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 3 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 3 emerging commercial turkey-sourced Salmonella serotypes (S. Reading, S. Saintpaul, and S. Agona) in 6-wk-old growing turkeys. Two experiments were conducted. In each experiment, 42, one-day-old turkey poults were randomly distributed into 2 control groups [Negative control (NC) and Positive control (PC) groups], LS group, PF group, VC group, and 2 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 6 wk of age. Poults in the vaccination groups (VC, LSVC, PFVC) received the Salmonella vaccine on day 1 and 2 boosters. At week 5, all birds except the NC group were inoculated with 6 log₁₀ CFU/bird Salmonella (3-serotype mixture) by crop gavage. Salmonella was recovered from the cecum, liver, spleen, and crop 7 d 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 to 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.