Abstract
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.
Data availability
The dataset generated during this study is available in the Iowa State University Open Data repository “DataShare” at the following link: https://doi.org/10.25380/iastate.29175365.v1.
Abbreviations
- PAA:
-
Peracetic acid
- CFU/ mL:
-
Colony forming units per mL
- PVC:
-
Polyvinyl chloride
- WDS:
-
Water distribution system
- EPS:
-
Extracellular polymeric substance
- TOO:
-
Total oxidizing oxygen
- SPC:
-
Standard plate count
- ASPC:
-
Aerobic standard plate count
- ANSPC:
-
Anaerobic standard plate count
- ISU VDL:
-
Iowa State University Veterinary Diagnostic Laboratory
- VBNC:
-
Viable but non-culturable
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Acknowledgements
The authors are grateful for Grace Clark, Grace Nightser, and Rylee Hundley for their tremendous help with sample collection and processing, and Chantz Nittler for his work in creating the illustrations. The authors want to thank the veterinarians and producers involved in the study for facilitating access to their farms.
Funding
This research was supported by funds from CID LINES, an Ecolab Company.
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GD and LK contributed equally to the study design, project execution, data analysis and manuscript preparation. BK, MP, KS, JTB contributed equally to this work through study design review, project execution, and manuscript review. NM contributed to the study design and directed sample processing at the Clinical Microbiology laboratory and aided in preparation of the manuscript. CS contributed significantly to sample collection, sample processing, and editing of the manuscript. JLB contributed to study design and contributed to the preparation of the manuscript. DZ performed statistical analysis. All authors have read, revised, and approved the final version of the manuscript.
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Competing interests
Dr. Gabrielle Doughan’s salary was partially supported by funds from CID LINES, an Ecolab Company. The funding source had no role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript. All other authors declare that they have no competing interests.
Ethics approval and consent to participate
Oral consent to perform the project was obtained from veterinarians representing farm 1–6’s owners to perform the project. No procedures on swine were performed and the study was IACUC exempt.
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Doughan, G.E., Walthart, B.K., Petersen, M.B. et al. Water line biofilm regrowth dynamics in six wean-to-finish farms post peracetic acid water line cleaning and disinfection. Sci Rep (2026). https://doi.org/10.1038/s41598-026-40725-x
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DOI: https://doi.org/10.1038/s41598-026-40725-x
