Submitted to: Poultry Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/23/2003
Publication Date: 1/31/2004
Citation: Northcutt, J.K., Berrang, M.E., Dickens, J.A., Fletcher, D.L., Cox Jr, N.A. 2004. Effect of broiler age, feed withdrawal and transportation on levels of coliforms, campylobacter, e. coli and salmonella on carcasses before and after immersion chilling. Poultry Science. 82(1):169-173. Interpretive Summary: A study was conducted to determine the effects of bird age at slaughter, time without feed, and transportation on carcass bacterial levels. Broilers were processed at 42, 49 and 56 days of age. Prior to processing, broilers were held without feed for either 0 h or 12 h. Carcasses were rinsed, and the rinses were analyzed for bacteria. Length of time without feed (0 or 12 h) had a significant effect on carcass bacteria. Immersion chilling with chlorine reduced carcass bacterial levels. These findings suggest that level of bacteria on the exterior of birds entering the processing plant is critical to carcass bacterial counts. Additionally, length of time without feed may increase pre-chill carcass counts, but appears to have no effect on post-chill carcass counts when chlorine is used.
Technical Abstract: A study was conducted to determine the effects of bird age at slaughter, feed withdrawal and transportation on levels of coliforms, Campylobacter, Escherichia coli and Salmonella on carcasses before and after immersion chilling. Broilers were processed at 42, 49 and 56 d-of-age after either a 12 h feed withdrawal period, or a 0 h feed withdrawal period (full fed). At each age, broilers were processed from two commercial farms previously identified as Campylobacter positive. One week before slaughter, broilers were gavaged with nalidixic acid-resistant Salmonella. Whole carcass rinses (WCR) were performed before and after immersion chilling with 20 ppm sodium hypochlorite, and rinses were analyzed for coliforms, Campylobacter, E. coli and Salmonella. Log counts for coliforms, Campylobacter, and E. coli were significantly (P < 0.05) affected by bird age at slaughter (Age). Feed withdrawal (FW) affected only Campylobacter on carcasses of older broilers (56-d-of age). Immersion chilling with sodium hypochlorite resulted in a log reduction of 1.2, 1.3 , 1.4, and 0.5 for coliforms, Campylobacter, E. coli and Salmonella, respectively. These findings suggest that level of contamination on the exterior of birds entering the processing plant is critical to carcass bacterial counts. Moreover, carcass bacterial counts do not vary when microbial counts of broilers are comparable. FW may increase pre-chill carcass counts for E. coli and Campylobacter, but it appears to have no effect on post-chill carcass counts when sodium hypochlorite is used in the chilling operation.