Understanding biofilms in poultry drinking water lines
Water quality could impact the kind of microbial populations in poultry drinking water lines and lead to the buildup of a biofilm that can produce pathogenic bacteria such as Salmonella, according to a new study.
Biofilm is a thin, slimy layer made up of long-chain carbohydrates, proteins, fats and other substances that serve as a sort of cocoon for microscopic bacteria. These biofilms form regardless of water quality, according to Tomi Obe, an assistant professor of poultry science with the Arkansas Agricultural Experiment Station and the Dale Bumpers College of Agricultural, Food and Life Sciences.
“If you have good water quality, that doesn’t mean you don’t want to understand what’s in your water lines and in the biofilm,” said Obe, who is also a member of the food science department and the Arkansas Centre for Food Safety. “We want to know what’s in the biofilm, and how that can contribute to the persistence of pathogenic bacteria.”
A study on sulphur-iron water
A recent study by Obe, with lead author Tolulope Ogundipe, DVM, who recently completed a master’s degree from the poultry science department under Obe’s advisement, examined 2 groups of poultry houses. One group of 5 houses had historically normal sulphur-iron water, and another group of 5 houses had historically high sulphur-iron water. Between the 2 groups, the researchers found there were no major differences in the quantity of Salmonella incidence. However, there were differences in the microbial makeup of both the poultry litter on the ground and in the biofilms within the poultry water drinking lines.
The study showed that a Bacillus species with probiotic properties was more prevalent in the biofilms of poultry house water lines with a historically normal sulphur-iron content, and a pathogenic Bacillus species was more prevalent in the biofilm of water lines in the historically high sulphur-iron content group.
Additionally, the one farm showing a low level of Salmonella in the biofilm was also the farm with the highest quantity of Salmonella in the litter. Although that farm was in the historically high sulphur-iron water group, another farm in that group had the lowest quantity of Salmonella in its litter.
“It’s hard to say that one group is good compared to the other,” Obe said. “We just observed different microbial populations, and we’re saying the water quality can impact the kind of microbial population that we see in the water line.”
The recently published study is titled ‘Differences in microbial composition of litter and water line biofilm of broiler farms as influenced by water quality history’. Other co-authors of the study include Samantha Beitia, University of Arkansas Ph.D. student in the poultry science department, and Li Zhang and Xue Zhang, assistant professors of poultry science and animal and dairy sciences, respectively, both with the Mississippi Agricultural and Forestry Experiment Station at Mississippi State University.
Effective removal of biofilms is, according to the study, crucial for controlling Salmonella at pre-harvest poultry production.
Pipeline monitoring
Although the microbial load of drinking water is monitored regularly at the source on broiler farms, Obe said not much has been done to assess the inside of drinking water pipelines for the presence and composition of biofilm despite it being a control point for Salmonella.
The study noted that while maximum recommended levels for poultry drinking water are less than 0.3 parts per million for iron and 200 ppm for sulfate, sulfate concentrations of 50 ppm or more in combination with high levels of magnesium and chloride in water could negatively affect bird performance. Water containing high levels of iron and manganese supplied in commercial poultry houses can also serve as nutrients for the survival of some pathogens. This is problematic, the study added, especially for farms in rural areas that use well water and have a history of such water quality issues.
Poultry farmers will often add a water filtration system to help reduce the mineral content; however, routine water line microbial analysis is not a common practice, Obe said.
“We don’t often think of it, but water is a very important nutrient, and routine monitoring of water lines should be important to the poultry industry – not only the quality but the content as well,” Li Zhang said. “We didn’t expect a big difference in quality, but the water source apparently does affect biofilm content.”
Obe and Li Zhang said they are considering the potential for adapting “sight glasses” or small windows that let viewers see inside pipelines, for visual monitoring and access to swab and analyse microbial content.
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