CONTROL OF SALMONELLA-TYPHIMURIUM COLONIZATION IN BROILER CHICKS WITHA CONTINUOUS-FLOW CHARACTERIZED MIXED CULTURE OF CECAL BACTERIA

A continuous-flow culture system was used to isolate and maintain a mi xed culture of cecal bacteria from adult broilers composed of 29 bacte rial strains representing 10 genera. Broiler chicks were treated with the mixed culture in the drinking water on the day of hatch and challe nged orally with 10(4) Salmonella typhimurium 2 d after treatment. The experiment was repeated in four separate trials using newly hatched c hicks. The concentration of propionic acid and total volatile fatty ac id (VFA) in the cecal contents was determined 2 d after treatment and at 10 d of age. Compared with controls, the number of treated chicks t hat were cecal culture-positive for Salmonella decreased (P < .01) in each of the trials. Additionally, the number of Salmonella in the ceca l contents of the treated chicks at 10 d of age was decreased (P <.005 ) compared with controls in each trial. The decreased number of Salmon ella in the cecal contents of the 10-d-old treated chicks was correlat ed with elevated concentrations of propionic acid (P < .05) and total VFA (P < .1) in the cecal contents of the treated chicks 2 d after tre atment. The results indicated that VFA-producing bacteria present in t he mixed culture became rapidly established in the ceca of the treated chicks and effectively increased resistance to S. typhimurium challen ge.