Development of a method to assess the efficiency of on-farm cleaning and disinfection

Six rapid control methods to assess the efficiency of on-farm cleaning and disinfection were compared at the ITP experimental farm and in commercial pig farms. The methods used were : visual appreciation of cleanness, measurement of residual ATP levels and four bacteria counting methods in Petri dishes (total aerobic count, coliforms, faecal coliforms, faecal streptococcus).The total aerobic count appears to be the best indicator of the efficiency of disinfection however, in some situations, ATP measurement provided a better assessment of the effectiveness of the cleaning phase. The other methods could not discriminate between the different cleaning and disinfection systems used.The residual bacterial contamination level was higher in fattening rooms than in farrowing and post-weaning units.Moreover, in each type of room, differences were observed between the various sampling sites : the accessibility of the site to cleaning and the material used for flooring, walls and equipment, affected the global efficiency of the cleaning and disinfection process.In order to obtain a reliable measurement of the residual contamination level in a room it is necessary to collect at least ten samples. A practical sampling plan is proposed together with a scale to interpret the results. This allows an estimate of the efficiency of the cleaning and disinfection process to be calculated for each site sampled and for the whole room.