Submitted to: Poultry Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: September 30, 1999
Publication Date: N/A
Interpretive Summary: Experiments were conducted to determine changes that occur in the digestive tract of broiler chickens after feed is taken away from them. In the present study changes in the ceca of the lower digestive tract of adult broilers were examined. Broilers were placed in pens and provided feed and water for 1 week. Feed was then taken away from the animals for times ranging from 0 to 24 h. After the appropriate feed withdrawal time, the broilers were processed by electrical stunning, bleeding, hot water scalding, and picking. One cecum was removed from each broiler and weighed. The cecum was then blended in water, and a pH meter was used to measure the acidity of the suspension. The number of bacteria in the cecal suspension were also determined. Results indicated that after 24 h without feed, there was no change in the weights of the ceca and there was very little change in the acidity in the ceca. In 2 of 3 trials the number of E. coli-like bacteria in the ceca increased during feed withdrawal. The number of bacteria in the ceca that produce lactic acid decreased during feed withdrawal, and the number of Salmonella bacteria remained the same. Findings indicate that feed withdrawal does not always effectively remove the contents of the ceca and that the ceca can remain a source of harmful bacteria after feed withdrawal.
Technical Abstract: Trials were conducted to determine the effect of feed withdrawal on the weight, pH, native bacterial flora, and the persistence of Salmonella typhimurium in the ceca of market-age broilers. Broilers were provided medicated or unmedicated feed then 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 broiler was aseptically removed and weighed. The cecum was then blended in 20 mL of distilled water, and the pH of the blended suspension was measured. The number of total aerobes, Enterobacteriaceae, S. typhimurium, and lactic acid bacteria in the suspension were enumerated on bacteriological media. Results indicated that up to 24 h of feed withdrawal produced no significant change in the cecal weights and that cecal pH varied by up to 0.3 units during feed withdrawal. There were significant increases in the population of cecal Enterobacteriaceae during feed withdrawal in Trials 2 and 3, and there was a significant increase in the population of cecal aerobes in Trial 3. Feed withdrawal produced significant decreases in the population of cecal lactic acid bacteria in all trials, but no significant change in the size of the S. typhimurium population occurred during feed withdrawal. There were no significant differences in the cecal weight, pH, native bacterial populations, or S. typhimurium population between broilers to subjected to feed withdrawal on litter or in crates. Findings indicate that feed withdrawal does not always effectively evacuate the contents of the ceca and that the ceca can remain a source of foodborne bacterial pathogens after feed withdrawal.