Release of Escherichia coli from Feathered and Featherless Broiler Carcasses in Warm Wate

Abstract

Release of bacteria from individual broiler carcasses in warm water was measured as a model of bacterial contamination of scald water. Immediately after shackling and electrocution, feathered and genetically featherless broiler carcasses (n = 24 of each) were immersed individually in 42 degrees C, air-agitated tap water for 150 s. Although any visible fecal material expelled as a result of electrocution was removed before sampling, carcass condition was typical for market-age broilers subjected to 12 h of feed withdrawal. Duplicate water samples were taken at 10, 30, 70, 110, and 150 s, and Escherichia coli counts were determined. Samples of initial tap water and contaminated water approximately 2 min after removal of carcasses indicated that E. coli could not be detected in the original water source and that mortality of E. coli in the warm water was negligible. Mean numbers of E. coli released were 6.2 and 5.5 log(10) (cfu/carcass) at 150 s for feathered and featherless carcasses, respectively. For both feathered and featherless carcasses, the rate of release of E. coli was highest in the first 10 s, and the rate declined steadily during the remaining sampling period. This result is compatible with published reports of sampling of operating multiple-tank scalders, indicating that a high proportion of total bacteria in a multiple-tank scalder are in the first scald tank that carcasses enter. Higher numbers of E. coli released from feathered carcasses are probably due to the much greater surface area of contaminated feathers compared with the skin of featherless carcasses.