This study was conducted to assess the effects of lactulose on the intestinal lumen by measuring the pH content of the gastrointestinal tract, and couting the colony forming units (CFU) of Escherichia coli and Salmonella Typhimurium in broilers experimentally and orally inoculated with Salmonella Typhimurium, at the dose of 5.0 X 102 CFU / mL 0.5. Birds were allotted in a completely randomized design, with 630 day-old male chicks distributed into six treatments, with seven replications and 15 birds per experimental unit. Treatment 1: group that did not receive microbial inoculum or lactulose (placebo group); treatment 2: group that received only lactulose (lactulose-L control group); treatment 3: group that received only Salmonella Typhimurium (ST-positive control group); treatment 4: group that received lactulose and Salmonella Typhimurium on the first day of life (L (1) + ST (1)); treatment 5: group that received lactulose 48 hours before the Salmonella Typhimurium (L (1) + ST (48h)); and treatment 6: group that received the Salmonella Typhimurium 48h before lactulose (ST (1) + L (48h)). At seven, 14, 21 and 28 days of age, one bird per plot was euthanized and cecum and crop contents were collected for counting of Salmonella Typhimurium and Escherichia coli. Furthermore, pH of crop and cecum were measured on for the same birds at seven, 14, 21 and 28 days of age, and blood was collected for liver enzyme evaluation. Lactulose reduced pH value (P<0.05) of digestive organs at seven days of life, and this reduction remained until 28 days only in the crop, regardless of the pathogen inoculation, whereas the cecal pH at 21 and 28 days, did not differ among the other treatments (P> 0.05). We also verified that lactulose reduced (P <0.05) the CFU of Escherichia coli and Salmonella Typhimurium in the crop at 21 and 28 days of age in the treatments in which lactulose was administered before the pathogen inoculation. Lactulose changed pH, except cecal pH, and reduced the colonization of Salmonella Typhimurium in the cecum and the number of UFCs of Escherichia coli in the crop during all experimental period.
control; Escherichia coli; pH; UFCs