In the slaughterhouse, how can the first carcasses be more contaminated with Enterobacteriaceae and E. coli than the last ones?
Pork carcasses’ direct or indirect contamination by Enterobacteriaceae and E. coli (hygiene criterions), mainly by bacteria present in intestinal or skin faecal material, can occur at different stages of the slaughter line. In this study it was determined the level of Enterobacteriaceae and E. coli contamination on the skin of 100 pigs and in the corresponding carcasses. It also was analysed, for each pig, the skin visible level of faecal contamination (VLFC), recorded the holding time in lairage and the slaughter order (beginning or ending). In each animal, sponge swabs were performed on the skin and in the respective carcasses (approximate 1000 cm2). A total of 200 samples were microbiologically analyzed according to ISO 21528-2:2004 (Enterobacteriaceae) and ISO 16649-2:2001 (E. coli).
The achieved results showed that there was no significant correlation (p-value >0,05) between VLFC in the skin´s pig and its level of bacteria contamination which could be due to the shower, used before stunning, that maybe had a different effect on the removal of VLFC and bacteria from the skin (that could still adhered to the skin after shower). Increasing holding time in lairage leaded to a highly significant increasing level of Enterobacteriaceae and E. coli (p-value <0.001), both on swines’ skin and in the respective carcasses. Achieved results also showed that pigs mean time in lairage was significantly higher for pigs slaughtered at the beginning than for those ones slaughtered at the end of the session (p<0.001), which could help to explain why the average level of Enterobacteriaceae and E. coli on pigs skin´s and in carcasses was significantly higher for pigs slaughtered at the beginning than for those slaughtered at the end.
The results allows to underline lairage logistic and showers efficiency before slaughter as important processes that should be efficiently controlled in order to improve hygiene level of pork carcasses.