Preventive activities of Scutellariae Radix, Gardeniae Fructus, and probiotics in Salmonella enterica serovar Typhimurium infection in chickens

• Effects of dietary supplements with SR, GF, and LAB in infected chickens.
• Herbs and LAB decreased Salmonella load in feces and intestinal tissues.
• Levels of IFN-γ and IL-1β in intestinal tissues were reduced in all treated groups.
• SR and GF with LAB suppressed the levels of IL-8 in serum and intestines.
• Herbs and LAB could be a natural way to replace antibiotics in feed additives.

In this study, Scutellariae radix (SR), Gardeniae fructus (GF), and probiotic-lactic acid bacteria (LAB) were evaluated to determine their efficiency in preventing an infection from Salmonella enterica serovar Typhimurium in chickens. Chickens were fed with a diet supplied with either LAB (0.5% of diet), SR (0.5% of diet), SR with LAB (0.5% of diet each), GF (0.5% of diet), GF with probiotics (0.5% of diet each), or a basal diet as a control for 10 days before being exposed to a 1010 CFU dose of ST315. Clinical signs were monitored for 6 days post-challenge. The minimal dosage of S. Typhimurium strain ST315 used to infect chickens without causing serious sickness is 1010 CFU/ml. The maximum amount of bacteria that was shed in feces was achieved 3 days after the initial infection. Herbs and LAB supplements reduced Salmonella fecal shedding and the bacterial load in intestinal tissues (P < 0.05). In all treatment groups, the mRNA levels of IFN-γ and IL-1β in intestinal tissues were decreased (P < 0.05). Furthermore, the SR group and GF with LAB group also saw suppression of the serum and intestinal levels of IL-8 (P < 0.05). Our findings suggest that herbs and probiotic-LAB can clear the bacterial infection as well as suppress the inflammation response. The combination of herbs and LAB also has potential in the prevention of an infection when supplied as feed additives.