Measurement of the residual contamination of post-weaning facilities for pigs and related risk factors.

A survey was designed in France to assess residual contamination in post-weaning rooms within the 2 h prior to restocking when all the pigs of the previous batch had been removed (all in-all out) and after application of the 'in use' cleaning procedures. The protocol was based on the results of a pilot study and was considered 'a good compromise'. Special agar plates (Rodac plates) with a prominent agar medium surface were prepared and used to collect the bacteria. They were applied by impression onto the floors and the partitions between the pens. In all, 24 plates were applied per room. The culture medium was VRBG which mainly permits the growth of enterobacteria. The plates were incubated for 24 h (37 degrees C) and the Colony-Forming Units (CFU) counted. After sampling, measurements were made and information collected from the farmer to obtain potential explanations for the resulting microbiological data. The same scientist sampled 129 post-weaning rooms with slatted floors. Of the 3045 plates, 18.4% were negative and 12.8% were heavily colonized (> 300 CFU). A score combining six criteria based on the counts was produced, and indicated a wide spread of the rooms. The profile of circumstances associated with the different levels of the score was extracted. The following points should be respected to achieve low residual contamination: removal of the slurry from the pit below the slatted floor; damping to be started soon after pig removal; prolonged damping; thorough washing; disinfecting soon after washing; and attention to the recommended dosage of disinfectant. Smooth surfaces were found to be less contaminated than rough ones. It is concluded that cleaning and disinfecting operations must not be considered as minor tasks and should clearly be integrated into the process of pig production.