Water line biofilm regrowth dynamics in six wean-to-finish farms post peracetic acid water line cleaning and disinfection.

Water quality and water line management play a critical role in swine health; however, they are often overlooked aspects of swine production. Best practices for water line cleaning and disinfection in pig barns are limited, and a one-time (terminal) water line cleaning with peracetic acid (PAA) may reduce mineral scale and biofilm presence. The objective of this study was to evaluate swine water line biofilm regrowth dynamics in six commercial wean-to-finish farms on well water following application of 0.78% PAA. Water line samples were collected aseptically pre-treatment (0), after water lines had been flushed 24 h after PAA had been applied (1), and 3, 5, 7, 14, 21, 42, 56, and 77 days post-treatment. Biofilm was quantified via aerobic and anaerobic standard plate counts. Results demonstrate a significant reduction in biofilm quantities pre- (0) and post-treatment (1), with over a three-log reduction in log 10 colony forming units (CFU) per mL (adjusted p-value = 0.0000). Biofilms regrew within three days and were not significantly different than pre-treatment (0) biofilm quantities. This demonstrates that administration of 0.78% PAA is effective at reducing biofilm quantities, however, long-term impacts are limited. Following labeled dosages and continuous water disinfectants should be considered for long term management.