Presence of Salmonella in the crop and ceca of broiler chickens before and after preslaughter feed withdrawal

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Abstract
Recent studies have suggested that crop contents may serve as an important source of Salmonella carcass contamination within processing plants. During the present study, we evaluated the effect of preslaughter feed withdrawal on the presence of Salmonella in the crops of broilers from nine commercial broiler flocks reared in individual growout houses. Crops were collected aseptically from 40 randomly selected broilers in each flock before feed removal and at the end of the feed withdrawal period, immediately before capture and transport to the processing plant. Similarly, the ceca were collected before and after feed withdrawal in six of the nine broiler flocks. The presence of Salmonella in the crops and ceca was determined by enrichment culture in tetrathionate broth followed by culture on brilliant green agar. The incidence of Salmonella in crop contents increased significantly (P < 0.05) in five of the nine flocks during feed withdrawal. The total number of Salmonella contaminated crops from all nine flocks increased significantly (P < 0.005) from 7/360 (1.9%) before feed removal to 36/359 (10.0%) at the end of feed withdrawal. The increased incidence of Salmonella in the crop contents was associated with an increased tendency of the broilers to consume contaminated rearing house litter during feed withdrawal. The incidence of Salmonella in the ceca increased nonsignificantly from 14/240 (5.8%) before feed removal to 19/240 (7.9%) at the end of feed withdrawal. The results indicate that the incidence of Salmonella crop contamination may increase as much as fivefold during preslaughter feed withdrawal and represent a critical preharvest control point in reducing Salmonella entry into the processing plant.