Effects of a Phytogenic Water Supplement on Selected Cultivable Bacterial Populations and Intestinal Histomorphology in Ross 308 Broiler Chickens Challenged with Salmonella Typhimurium

Increasing antimicrobial resistance and restrictions on antibiotic use in poultry have drawn attention to phytogenic products as a complementary approach for controlling enteric bacterial infections. The aim of this study was to evaluate the effects of a phytogenic product (Herba Top Salmonella, HTS) on selected cultivable intestinal bacterial populations, intestinal histomorphology and tissue distribution of Salmonella Typhimurium in experimentally infected broiler chickens. A total of sixty one-day-old Ross 308 broilers were randomly assigned to six experimental groups (10 birds/group; two pens/group, five birds/pen, with the pen considered the experimental unit. Birds in three groups were experimentally challenged with Salmonella enterica subsp. enterica serovar Typhimurium, and HTS was administered in drinking water for 14 consecutive days at two nominal concentrations (3 mL/L and 6 mL/L). Intestinal microbiological parameters, histomorphometric characteristics, and the presence of Salmonella Typhimurium in tissues by immunohistochemistry were evaluated. The effects of infection status, HTS concentration, and their interaction were analyzed using two-way ANOVA. HTS administration was associated with reduced counts of total aerobic bacteria, Escherichia coli and Enterobacteriaceae counts. In experimentally infected broilers, HTS treatment was also associated with reduced Salmonella Typhimurium in intestinal tissue and significant changes in intestinal histomorphometric parameters, including increased crypt depth and mitotic activity. The observed responses were influenced by both infection status and the HTS nominal concentration. Because of the limited number of independent experimental units and the absence of individual HTS intake measurements, these findings should be considered exploratory preliminary findings, and further studies with larger animal groups under commercial production conditions are required.