Physical, chemical, and microbiological changes in the ceca of broiler chickens subjected to incremental feed withdrawal

Trials were conducted to determine the effect of feed withdrawal on the wei ght, pH, native bacterial flora, and the persistence of Salmonella typhimur ium in the ceca of market-age broilers. Broilers were provided medicated or unmedicated feed and then were subjected to feed withdrawal for 0 to 24 h in transportation crates or on litter. After feed withdrawal, broilers were stunned, bled, scalded, and picked. One cecum from each bird was aseptical ly removed and weighed. The cecum was then blended in 20 mt of distilled wa ter, and the pH of the blended suspension was measured. The number of total aerobes, Enterobacteriaceae, S. typhimurium, and lactic acid bacteria in t he suspension were enumerated on the appropriate bacteriological media. Res ults indicated that up to 24 h of feed withdrawal produced no significant c hange in cecal weight and that cecal pH varied by up to 0.3 units during fe ed withdrawal. There were significant increases in the population of Entero bacteriaceae during feed withdrawal in Trials 2 and 3, and there was a sign ificant increase in the population of cecal aerobes in Trial 3. Feed withdr awal produced significant decreases in the population of lactic acid bacter ia in all trials, but no significant change in the population of S. typhimu rium occurred during feed withdrawal. There were no significant differences in cecal weight, pH, native bacteria populations, or S. typhimurium popula tions between broilers that were subjected to feed withdrawal on litter or in crates. Findings indicate that feed withdrawal does not always effective ly evacuate the contents of the ceca and that the ceca of broilers subjecte d to feed withdrawal can remain a source of foodborne bacterial pathogens.