Cleaning and disinfection of the lairage at the slaughterhouse: a link in the fight against the contamination of pigs by Salmonella

The main risk factor in the contamination of pork by Salmonella is the intestinal carriage of the bacteria by the animals.It is currently recognised that the time spent in the lairage at the slaughterhouse is a significant risk factor for crosscontamination of pigs by Salmonella. Therefore, the present study was designed to investigate the effectiveness of three cleaning-disinfection protocols of the lairage area in several slaughterhouses.The results confirmed that there was a high level of contamination of the sites sampled: 37% of the 0.5 m2 sites sampled were positive for Salmonella. The complete protocol, comprising of 4 phases (preliminary wash, detergency, rinsing with mild pressure and disinfection), was effective in eliminating Salmonella and the aerobic bacteria. However, this protocol can only be implemented at the weekend in large capacity slaughterhouses. Two shorter protocols, which could be used daily, were also tested: the first, based on a detergent with a chlorinated alkaline solution followed by scouring, was not very effective since nearly 50% of the sites initially contaminated by Salmonella were still positive after cleaning. Therefore, cleaning without disinfection is not effective in the control of Salmonella in the lairage. However, the second short protocol, based on a scouring phase followed by disinfection seems to give satisfactory results both in the control of Salmonella (only 2 of the 21 initially contaminated sites remained positive) and aerobic bacteria. The long-term effectiveness of this last procedure needs to be confirmed.