Development of defined cultures of indigenous cecal bacteria to control salmonellosis in broiler chicks.

An in vitro continuous-flow (CF) culture system was utilized to isolate and maintain a defined mixed culture of indigenous cecal bacteria from adult broilers. The protective effects of the defined CF culture and dietary lactose on Salmonella typhimurium colonization were evaluated in broiler chicks. The CF culture was administered to chicks by crop gavage on the day of hatch. Lactose was provided as 5% (wt/wt) of the feed ration. The chicks were challenged orally with 10(4) S. typhimurium at 3 days of age and evaluated for Salmonella colonization 7 days after challenge. The experiment was repeated in six separate trials using newly hatched chicks and CF culture that was maintained in continuous steady-state conditions from 42 to 190 days. Compared with controls, the mean number of S. typhimurium in the cecal contents of the chicks given CF culture and dietary lactose decreased significantly (P < .01) by 4.2 log10 units. Similarly, the numbers of Salmonella cecal culture-positive chicks was significantly decreased (P < .01) by 55% in the chicks given CF culture and lactose. The results indicated that a defined culture of indigenous cecal bacteria isolated and maintained in CF culture, together with dietary lactose, effectively controlled S. typhimurium cecal colonization in newly hatched broiler chicks.