Effect of a characterized continuous-flow culture of cecal bacteria on Salmonella typhimurium crop colonization in broiler chicks

Broiler chicks were inoculated orally at 1 day of age with a continuous-flow (CF) culture of anaerobic cecal bacteria and challenged with 10(4) Salmonella typhimurium 48 hr (at 3 days old) after inoculation to determine the effect of the CF culture (CF3) on Salmonella crop colonization. Chicks were assigned to four groups: 1) untreated control chicks, 2) challenged at 3 days old with Salmonella, 3) inoculated at 1 day old (day-of-hatch) with CF3, and 4) inoculated at 1 day old with CF3 and challenged at 3 days old with Salmonella. Crop pH decreased significantly (P < 0.05) 24 hr after inoculation in chicks provided with CF3. The pH of crops at 24 hr from control chicks (group 1) was 5.4 and the pH of crops from inoculated chicks (group 3) was 4.7. Decreased pH was accompanied by a significant increase (P < 0.05) in crop lactic acid from approximately 0.1 mmol/ml in control chicks to about 0.2 mmol/ml in chicks given the culture. Salmonella crop colonization decreased (P < 0.05) 4 hr after challenge from a 2.6 log(10) colony-forming units (cfu) in Salmonella-control (group 2) chicks to 0.6 log(10) cfu in CF3-inoculated (group 4) chicks. Although at 4 and 8 hr after challenge, there were decreased (P < 0.05) numbers of crops resting culture-positive for Salmonella regardless of treatment, Salmonella colonization decreased (P < 0.05) in chicks inoculated with CF3 as compared with controls. The results indicated that CF3 can effectively reduce Salmonella crop colonization.