Maintaining drinking water quality for poultry is an important nutritional aspect as birds consume water at twice the level of feed. One prime factor that determines the wholesomeness of water is its microbial quality. Therefore, it should be of primary concern for production personnel and poultry producers to know the microbial quality of water supplies provided to their birds and confirm if it is within the acceptable range. Various researches indicate that water supplies are much vulnerable to microbial contamination and this is true even with the farms with good management system. Furthermore, water sources such as wells or reservoirs are dynamic with water quality changing as often season to season. Establishing routine testing of supplies and taking corrective action when necessary can have a significant impact on optimizing flock performance.
1- Taking swab sample to examine waterline s sanitation, 2- Taking drip sample to examine drinking water quality.
Microbial Water Quality Standards for Poultry Drinking Water.
Water is presumed safe if it has a zero microbial population, provided that mineral content is at safe levels and undesired contaminants are not present. However, presence of microbes in water is not always correlated with a disease in flocks unless it increases above a certain infectious level. The following table gives the acceptable levels of bacteria in colony forming units (cfu) per milliliter (ml) in drinking water for poultry operation.
Microbial contamination above the acceptable levels in drinking water directly affects health and performance.
Water supplied to birds should be within the acceptable microbial load.
Water Supplies are Vulnerable to Microbial Contamination.
If the source water has an acceptable bacterial level, it does not mean the levels present at the end of drinker line where the birds are drinking is also within safe microbial levels. The following field evaluations is just an illustration that how the microbial levels can significantly change by the time the water supply reaches the end of the drinker system from the source, if the drinker system is unhygienic.
Aerobic Bacteria Levels in Drip Samples (cfu/ml).
A recent study in U of Arkansas in water supplies of commercial broiler farms shows water is much vulnerable to microbial contamination, often to unacceptable levels even in a regular water sanitation program. This explains the need of a consistent monitoring program for disinfectant residuals in water supplied for effective sanitation procedures.
Various lab reports for microbial water quality in U of Arkansas show that the top and bottom producing farms suffer equally from microbial problem in water such as E. coli and Pseudomonas. Some farms experience campylobacteriosis in chickens caused by water borne Campylobacter jejuni as these can easily thrive in poultry drinking water and drinker lines. Reduced broiler performances can be noticed if the water supplied to birds is contaminated with coliforms and Enterobacter. Water supplies including water tanks and drinker lines can act as a source of Salmonella infection in chickens and treating wáter is a good control strategy for salmonellosis at farm level. Similarly, contaminated water can also results in viral diseases like infectious bursal disease and avian encephlomyelitis and protozoal diseases like histomoniasis and coccidiosis. Testing and treating water can help reduce potential microbial contamination issues.
Line Cleaning: A Mandatory Practice to Address Biofilm Problem.
While the introduction of enclosed water systems such as nipple drinkers during the early 1990’s revolutionized the industry by dramatically improving water quality, unfortunately the industry became complacent with water system sanitation, primarily because this type of system removed water supplies from being visually inspected and created a sense of “out of sight, out of mind” mentality. Since then more has been learned about biofilms and their role in creating microbial populations which survive and thrive within water lines and drinker systems and create health challenges that are not easily addressed.
Biofilms are complex communities of a matrix of different species of enclosed microbial cells cooperating with one another for survival and are firmly attached to hydrated surfaces .Waterlines over time with low or no disinfectant residual level in water form biofilms even if the water supplies are clean. A study conducted in University of Arkansas in 2012 shows that regardless of daily water sanitation, waterlines could get fouled by biofilms reoccurrence by at least 6th week of bird grow- out period even when the waterlines are clean initially. One can imagine system hygiene if water systems are not sanitized regularly. Therefore, line cleaning between flocks using strong disinfectant solution is highly suggested practice.
The material used in poultry water lines, polyvinyl chloride (PVC), do harbor biofilms and promote pathogens entrapment like Campylobacter. Opportunistic pathogens like Pseudomonas easily thrive in poultry waterlines. These biofilms not only deteriorate the water quality by intermittent shedding of microbes in drinking water supplied (which poses a greater health risk to chicks and immune compromised birds) but also clog the drinker lines limiting water availability to birds. Over time, it corrodes the pipe material as well.
Wholesomeness of water and water systems are not possible without addressing biofilm problems. Practicing regular water sanitation and line cleaning between flocks can solve much of the microbial problem in water including biofilm buildup in water systems.
3- Drinker line with biofilm and mineral buildup. 4- Line cleaning is essential before placing chicks.
Water Sanitation Options.
The goal of poultry water sanitation procedures and sanitizer/disinfectant products is to target microbial challenges that exist and thrive in water supplies whether they are bacterial, fungal, viral or protozoal. An ideal disinfectant used as a drinking water sanitizer should create disinfectant residual throughout the distribution system and should inactivate microbes, control biofilms or neutralize undesired contaminants.
Of the limited water sanitation options available in poultry operation, some common practices are discussed below.
Chlorination has been a highly accepted method in water disinfection both for human and animal drinking purpose for many years. It involves adding chlorine to water and can be performed using chlorine containing compounds. In poultry operations, the commonly used chlorine sources for poultry drinking water sanitation are sodium hypochlorite, elemental chlorine gas and calcium hypochlorite. Their presence in the optimal pH range will create hypochlorous acid on hydrolysis.
Cl2 (g) +H2O=> HOCl + H+Cl-
NaOCl +H2O =>HOCl + Na+ + OH-
Ca(OCl)2 + H2O =>Ca(OH)2 + 2HOCl
Hypochlorous acid has a strong germicidal action. However, in high pH conditions (>8.5 pH), it dissociates completely into hypochlorite ions which has a less germicidal action than the hypochlorous acid. The pH range between 6.5 and 8 .5 has incomplete dissociation, while pH below 6.5 has no or a negligible dissociation of the hypochlorous form.
HOCl <=> H+ + O Cl-
Therefore, chlorination is more effective at lower pH levels and often drinking water is acidified to support chlorine disinfectant efficacy for improved sanitizing residual which supports better bird performance. However, careful selection among various acid products available is necessary to avoid water consumption impacts. When using chlorine and acidifiers together in water, they should be mixed and injected separately to avoid poisonous gas formation.
When drinking water has 2-5 ppm free chlorine residual, it is effective against most microbial growth in water. E. coli O157:H7, most Salmonella and Campylobacter species, and avian flu virus are easily inactivated at these residual levels or at even lower levels. Disinfectant residual levels required for the microbial inactivation are governed by other water quality parameters as well.
An appropriate application strategy of chlorine in drinking water on poultry farms help reduce the microbial load and also minimize the biofilm buildup in water systems. One study conducted in U of Arkansas in 2012 showed that after line cleaning to minimal biofilm levels, daily drinking water disinfection providing free chlorine residual levels of 0.5 to 1 ppm when birds drink helps keep the microbial loads within the acceptable range of > 1000 cfu/ml throughout the flock period. At this residual level, however, biofilm formation does reoccur by the end of flock grow out period (6th week) requiring a mandatory line cleaning between flocks to ensure safe drinking water for the next flock of chicks.
Chlorine products have been the primary water disinfectant products for thirty-forty years in the poultry industry. Unfortunately, microbes are becoming resistant to these products because they have not been always used properly. Therefore, the industry also needs to identify other options of water sanitation and have clear guidelines on the efficacy of alternative disinfectants, as well as their optimal usage levels.
2. Hydrogen Peroxide: An alternative disinfectant to Chlorine.
Recent field experiences have shown that poor performing farms are greatly benefitted from water sanitation programs using hydrogen peroxide which is an alternative disinfectant to chlorine. Hydrogen peroxide has a rapid bactericidal action and is effective against a wide range of viruses, yeast, and fungi. Pseudomonas aeruginosa, Escherichia coli, Salmonella typhimurium, Staphylococcus aureus, Aspergillus fumigates and Fusarium species are well inactivated even in presence of organic matter. Hydrogen peroxide inactivates microbes creating oxidative stress by forming very strong oxidizing agents, hydroxyl radicals, from superoxide (O2.-) radicals, and readily oxidizes the proteins and microbial enzymes; however, efficacy differs between liquid and gaseous forms.
O 2.− + H2O2 =>O2 + OH− + OH.
Maintaining 25-50 ppm of hydrogen peroxide residuals in the water is considered the effective for limiting most microbial growth.
In market, both the stabilized and non-stabilized forms of hyrdrogen peroxide products are available. Studies conducted in U of Arkansas demonstrate stabilized hydrogen peroxide products in market hold higher concentrations of residuals for a longer time than non-stabilized. Heavy metal ions used as stabilizers like silver and copper, and organic acids like peracetic and ascorbic acid in hydrogen peroxide helps in synergize the disinfecting property of hydrogen peroxide and is effective against heavily contaminated water as well.
Successful cleaning of poultry waterlines with hydrogen peroxide products with minimal equipment damage can also be done. Bacterial biofilms such as Pseudomonas aeroginosa and Listeria monocytogenes and viral biofilm such as Infectious Laryngotracheitis (ILT) virus are effectively cleaned using hydrogen peroxide disinfectant.
3. Other Water Sanitizers in Poultry Operation.
Another successfully used water disinfectant for sanitizing poultry drinking water is chlorine dioxide. It acts as a selective oxidant as it has a single electron transfer mechanism and reduces to form chlorite ion which exists as the dominant species in water.
ClO2(aq) + e- => ClO2-
If the water is dirty or has a significant organic load, then disinfecting with chlorine requires higher free residuals of chlorine thus impacting taste and odor. Sanitizing with chlorine dioxide is a good option because its use in similar water supplies does not cause the taste or odor issues. Chlorine dioxide kills bacteria and viruses similar to or better than chlorine and is unaffected by a wide pH range.
Other disinfectants like quaternary ammonium compounds and iodophores are also used in poultry operation for disinfecting water and water system. Ozone and UV rays can also be used for water sanitation but not common in poultry practices. Advance Oxidation Processes that involves creating hydroxyl ions as disinfecting molecules during disinfection procedure have been also introduced recently in the industry.
As oxidizing agents are generally used during water disinfection, Oxidation Reduction Potential (ORP) values give the oxidizing ability of the chemicals in water to oxidize/kill microbes. The ORP values are affected by concentration of oxidizing residuals and are pH dependent and 650mV or above in water are considered enough to destroy most bacteria and viruses within few seconds. Added benefit of oxidizing agents in water includes its secondary function in oxidizing iron and manganese that minimizes drinker coagulation.
The poultry industry uses various water sources such as the municipal water, underground water, and to some extent, surface water and rain water. Regardless of the source, it is highly important that water provided should be free of microbial contamination to ensure flock health and performance, and food safety. Therefore, water sanitation is a very crucial step in a poultry operation and should be effectively carried out.
Various brands of water sanitizers or water line cleaners are available in the market under a few classes of disinfectants advocating its efficacy under worst case conditions. These products are required to monitor in field conditions for their true efficacy, applicability, and cost effectiveness along with safety aspects. Water being the prime nutrient for poultry, the industry should pay close attention in these regards to providing the best sanitizing option for poultry producers and to address any type of water quality issues.
Water sanitizers and line cleaners: Careful selection and application is essential among the products.