Survival of Salmonella in the crop contents of market-age broilers during feed withdrawal

Recent studies have indicated that crop contamination increases during pres laughter feed withdrawal and chat contaminated crop contents may serve as a n important source of Salmonella entry into poultry processing plants. Duri ng the present study, we evaluated the effect of preslaughter feed withdraw al on crop pH and Salmonella crop contamination in broilers from three comm ercial broiler flock;. The effect of experimental feed withdrawal on crop p H, lactic acid concentration, and Salmonella crop contamination was also ev aluated in market-age broilers challenged experimentally with Salmonella ty phimurium. Crop pH increased significantly (P < 0.05) from 3.64 +/- 0.25 be fore feed removal to 5.14 +/- 0.72 after 8 hr of feed withdrawal in broiler s from commercial flocks. The incidence of Salmonella crop contamination in the commercial broilers increased (P < 0.05) from 3.3% before feed removal to 12.6% after 8 hr of feed withdrawal. Similarly, crop pH increased (P < 0.05) by a magnitude of approximately 1 unit in broilers after 8 hr of expe rimental feed withdrawal. The population of S. typhimurium in the crops of the experimentally challenged broilers increased (P < 0.05) by approximatel y I log unit during the 8-hr experimental feed withdrawal. The concentratio n of lactic acid in the crop of the broilers during experimental feed withd rawal decreased (P < 0.01) from a range of 119-135 mu mol/ml before feed re moval to a range of 22-32 mu mol/ml after 8 hr of feed withdrawal. The resu lts indicated that feed withdrawal resulted in a decrease in lactic acid in the crop, accompanied by an increase in crop pH, and an increase in Salmon ella crop contamination.