Assessing the progressive decontamination of farrowing crate floors by measuring the decrease in aerobic bacteria

Objective: To measure the progressive decontamination of three farrowing crate floor types and evaluate the efficacy of a surfactant and two disinfectants, povidone iodine (polyvinylpyrrolidone-iodine) and cresylic acid, used in the process. Method: Using a randomized incomplete block split-plot design, four treatments (two disinfectants, each with or without a surfactant) were applied to three floor types, including concrete slats, triangular metal bar, and plastic-coated expanded wire. Two areas were swabbed with a sterile sponge after low-pressure washing, power washing, and disinfecting. Material collected on the sponge was suspended in sterile saline, and tenfold dilutions were plated in duplicate onto tryptic soy agar. Plates were incubated aerobically at 37°C (98.6°F) for 24 h, and colonies were counted using a counting grid. Results: After the last step in decontamination, mean log aerobic bacterial counts were similar on all three floor types, regard-less of treatment. Low-pressure washing, power washing, and disinfection each contributed to the decrease in contamination, and use of surfactant had no effect on aerobic bacterial counts. Implications: Sequential low-pressure washing, power washing, and disinfection of farrowing house floors results in a major reduction of aerobic bacteria in the presence of residual organic matter, with each step contributing to decontamination. After power washing, povidone iodine and cresylic acid were equally effective disinfectants, and use of surfactant was not advantageous.