Poultry water systems can be a vector for both avian and human pathogenic bacteria. To sanitize, producers often use bleach -- an economical, chlorine-based, solution of sodium hypochlorite (8.25% NaOCl). New research evaluates current water sanitation practices and their effect on Salmonella, Escherichia coli, Campylobacter, Listeria, and Staphylococcus in broiler production. While the chlorine in bleach is a useful sanitizing agent, its effectiveness depends on the bacterial load and application technique. Rapid formation of biofilms in water lines can limit treatment efficacy, thus requiring more consistent and robust poultry drinking water sanitation practices.
Researchers call water "the most critical nutrient for poultry." Water availability and quality impact the overall health and productivity of birds. Despite water's importance, "the role of providing safe and quality water for optimal poultry performance is generally neglected," says a team of researchers from Tennessee State University and the University of Arkansas.
They acknowledge that a variety of factors affecting water quality can hinder optimal performance, but state that microbial contamination often tops the list: "The water line system in a poultry house can be an appropriate habitat where bacteria can thrive and pose health risks to birds. Several factors such as warm water temperature (27–30°C or 81-86°F)..., reduced flow of water in poultry water lines, and supplementation of water additives like vitamins and organic acids favor the growth of bacteria. These factors can likely predispose chicks to infections during their early grow-out phase."
Contaminated water also can impact litter quality, increase ammonia, and decrease effectiveness of vaccines and medications supplied through the waterlines. Moreover, waterborne bacteria in the poultry water supply may become foodborne pathogens -- Salmonella, Campylobacter, E. coli, and Listeria, for example. To complicate matters, biofilms -- sticky organic matter in water lines -- can harbor bacteria, rendering disease-causing organisms less susceptible to bleach and other biocides and antimicrobials.
In this study, the research team conducted two separate on-farm evaluations of water sanitation practices. They first evaluated two commercial broiler farms that used well water sources and "performed inconsistent, or no water sanitation practices... during the flock grow-out period."
Their second evaluation involved a broiler farm that "treated water supplies consistently" during grow-out with bleach (free chlorine of about 1 ppm) and flushed waterlines with concentrated chlorine solution (greater than 1,000 ppm) between flocks immediately before placing chicks.
In addition, the team conducted benchtop studies to assess the efficacy of bleach against Salmonella Enteritidis (strain 35664), E. coli (ATCC 25922), and Listeria monocytogenes (strain 7644), mimicking typical industry application rates.
Interestingly, both the farms using well water had water lines contaminated with Listeria and Staphylococcus, but neither had contamination with Salmonella, E. coli, or Campylobacter.
The research team noted how Listeria species typically appear in all the stages of poultry production and are common in soil, sewage, feces from birds, and surface water. Factors such as chlorine concentration, contact time, and environmental conditions -- including temperature and biofilms -- can reduce efficacy of bleach against Listeria.
The researchers point out how Staphylococcus species colonize the skin and upper respiratory passage of both healthy and infected chickens and often show resistance to disinfectants used in commercial operations. Moreover, biofilms of these bacteria increase the risk of transferring antimicrobial and biocide resistant genes to other microbes. Staphylococcus thrives under typical broiler growing conditions and tolerates NaOCl concentrations up to 10%.
Warmer water and slower flow rates can accelerate formation of pathogenic biofilms, the researchers noted: "Flushing the water system with sanitized water loosens the substances thus removing the developed biofilms."
Their benchtop work revealed that the standard bleach treatment (experimentally 1 mL of 8.25% NaOCl in 32 mL of distilled water with free chlorine about 1 ppm) was effective against a low Salmonella Enteritidis load but not effective against the tested loads of E. coli or Listeria.
Nonetheless, the researchers also cited other studies in which such chlorine concentrations (1 mg/L) effectively inactivated E. coli in drinking water, while even lower concentrations (above 0.5 mg/L) controlled waterborne aerobic bacteria.
"Product efficacy," the team cautioned, "could be dictated by the strain of E. coli or Listeria... or their load in water...."
The Tennessee-Arkansas research team specifically focused how chlorine-based sanitizer (bleach, sodium hypochlorite, 8.25% NaOCl) impacts bacterial pathogens and the biofilms that can protect these microorganisms in poultry water systems. Also, they sought to assess the efficacy of such sanitation against the foodborne pathogens Salmonella, E. coli, and Listeria.
What does this study mean for producers?
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Recognize that poultry drinking water lines are at risk of contamination with avian and human disease-causing bacteria -- including Salmonella, E. coli, Campylobacter, Listeria, and Staphylococcus -- no matter the water source.
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Test water supplies for specific pathogenic bacteria and apply sanitation treatment for those species.
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Clean water lines between flocks because the lines can harbor pathogenic biofilms that reduce the efficacy of water treatment.
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Keep in mind that bleach (sodium hypochlorite) may be effective against Salmonella but ineffective against E. coli and Listeria.
The full paper, titled "Impacts of on-farm water sanitation practices on microbial hygiene in poultry waterlines and efficacy of sodium hypochlorite-based product on foodborne pathogens," can be found in Applied Poultry Research and online here.
DOI: 10.1016/j.japr.2024.100425
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