Arkansas Cooperative Extension Service Center of Excellence for Poultry Science
University of Arkansas, U.S.A.
Water serves as a vital nutrient that impacts virtually every physiological function in the body. Therefore factors which might alter water quality such as changes in bacterial content, pH, nitrogen levels, hardness, alkalinity or mineral levels can directly impact water consumption or the bird's ability to utilize consumed water.
While most of what is accepted about water quality standards for poultry is several years old, the modern broiler and turkey have undergone dramatic changes in growth rate, feed efficiency and immune system function. This means that we probably need to revisit water quality parameters for birds particularly bacteria, pH and minerals. Complicating the issue, many water supplies such as well water, are very dynamic and can change in quality as often as season to season. If a producer experiences poor flock performance as measured by feed passage, poor weight gains or health problems that can not be explained, it might be worth while to have the water supply evaluated.
Water Quality Parameters
The best guidelines available for acceptable and unacceptable water quality parameters for poultry are outlined in Table 1. Note that CFU/ml means colony-forming units of bacteria/milliliter of water and mg/l is also the same as parts per million or ppm. One way to understand how much is a ppm is consider one gallon of sugar dissolved into a million gallons of water. That would give 1 ppm of sugar. Although parts per million of anything seems quite small, remember, the birds already receive a balanced diet and if they are also receiving high levels of such nutrients as salt in the water in the form of sodium and chloride ions, then over time the birds may exhibit poor performance because they just have more than their systems can handle. In addition, water contaminants can also impact how nipple drinkers work. Even a fine buildup of mineral residue on seals or rims could be all that is necessary to limit water flow and thus result in less than adequate consumption for optimum bird growth and feed conversion.
Water pH
pH is the measure of how many hydrogen ions are in solution and is measured on a scale of 1 to 14 with 7 being neutral. A pH reading below 7 indicates an acid with the acidity becoming greater as the numbers become closer to 1. Numbers above 7 are in the basic range of the pH scale. While pH is not a chemical or specific contaminant, it can impact water quality. First, it impacts the effectiveness of disinfectants such as chlorine. If water does have a high pH then it may be necessary to acidify the water in order to create a favorable pH for effective sanitation with chlorine. However, acids and chlorine sources should never be mixed directly together to create stock solutions. This might result in a chlorine gas release dangerous to personnel. If it is necessary to adjust the pH then acidify the water prior to the addition of bleach. One way to accomplish this is by installing an inline pump with dual injectors. Then a stock solution of acid can be added prior to the addition of bleach. A company called Chem-Tech manufactures dual injection pumps suitable for poultry house use. If the pH is above 8.0, the chlorine is present mainly as hypochloric or chloric ions that add very little sanitizing quality. Chlorine is most effective when used in water with a pH of 6.0 to 7.0. This pH level results in a greater percentage of hypochlorous ions that are a strong sanitizer (See Table 2). In fact free chlorine residual levels are not considered a useful sanitizer unless there is at least 85% hypochlorous acid present.
Water treatments that acidify the water to a pH of 4 or below may provide beneficial protection against bacterial action in the bird's digestive tract, particularly in the crop where the modern broiler tends to store as much food as possible. Although water quality standards list a pH below 5.9 as being detrimental for broilers there is very little modern data that confirms this. A recent trial conducted at the University of Arkansas in which broilers were given either a continuous or intermittent water supply containing a pH of 3, 4, 5, 6 or city water (pH 8.3) showed that growth, feed conversion and livability through 42 days of age was unaffected by pH. Birds on the 4 and 5 pH water did have slightly higher incidence of tibial dyschondroplasia. The pH was adjusted using sodium bisulfate.
One important point about pH is the success that many producers have experienced by adjusting a high pH of 8 or more to below 7. Although alkalinity and pH are not the same thing they are often associated together in water supplies. (Alkalinity is a measure of carbonate, bicarbonate and phosphate ions). Chickens have only two taste sensors, salt and bitter. In nature most poisons are associated with bitter or alkaloids. Therefore it may be a natural response for birds to consume less water if there is a bitter taste associated with it and it may be possible to mask this with an acidifier. A word of caution on the overuse of organic acids, such as citric or acetic. These may also cause birds to consume less water. Organic acids are typically known as weak acids or they have a low tendency to turn loose of their H+ ions. Because of this, these acids tend to have a strong taste associated with them. The inorganic acids tend to dissociate or give up their hydrogen ion more readily and this results in less taste issues associated with the inorganic acids.
Minerals
A review of the acceptable mineral levels indicates the bird is very tolerant of some minerals such as calcium and sodium and very intolerant of minerals such as iron and manganese. Iron and manganese tend to give water a bitter metallic taste and iron also supports microbial growth such as pseudomonas or E. coli. If iron is a concern, the best method of control is chlorination and filtration. Also available are Chem Free systems from a company called Cuno. These have been found to be very effective for iron removal on poultry farms.
Hardness is a measure of the calcium and magnesium in the water. The biggest problem with these minerals is the scale that they form. Scale can reduce the volume of pipes and impact nipple drinkers. It also reduces the effectiveness of cleaners and disinfectants. A water softener can be used to reduce hardness. However do not use a sodium-based water softener if the water already has a high level of sodium. Nitrates are colorless and odorless and the only way to detect its presence is by testing. As little as 10 ppm nitrate can impact broiler performance.
Other Factors Which Impact Water Sanitation
Another important factor is the ORP value of the water. ORP stands for oxidation-¬reduction potential and it simply refers to the property of sanitizers such as chlorine to be a strong oxidizer. A strong oxidizer literally burns up viruses, bacteria and other organic material present leaving water microbiologically safe. An ORP value in the range of 650 millivolts or greater indicates good quality water that can be effectively sanitized by as little as .2 to .4 ppm free chlorine. The lower the value such as 250 millivolts indicates a heavy organic load that will most likely overwhelm chlorine's ability to properly disinfect the water. The ORP meter can be a useful tool for identifying water supplies that don't have adequate chlorine residual and for adjusting the residual without overusing chlorine. A reliable ORP meter costs around $80 and can be purchased from Hanna instruments. A word of caution is advised when it comes to utilizing chlorine pool test kits. These kits do not distinguish between free and bound chlorine. A heavy organic load would result in a greater percentage of bound chlorine resulting in a poor sanitizer even though the pool test kit might indicate chlorine levels of 4 to 6 ppm. The bottom line is utilizing information on pH, ORP and chlorine level to determine if the sanitation program is effective and to also prevent equipment damage by the overuse of chemicals.
Water Sanitation
A regular water sanitation and water line cleaning program can provide protection against microbial contamination and the build-up of bio-films, a clear slimy film, in water lines. While bio-films may not be a source of problem to birds, once established in water lines, bio-films provide a place for more detrimental bacteria and viruses to hide from disinfectants. Salmonella has been found to live for weeks in water line bio-films. On several occasions water samples taken at the well house have been compared to samples taken at the end of the water line in the poultry house and counts would be much higher in the latter samples (See Table 3). Once detrimental bacteria or even large numbers of normal bacteria become present in water supplies, then bird performance could be jeopardized. In addition, the warm environment of the poultry house can aggravate bacterial contamination in water lines. A single E. coli organism can multiply into 24 trillion organisms in 24 hours at a temperature of 90°F. Table 4 provides recommendations for routine water line cleaning and sanitizing.
Often acidifiers are added to the drinking water for short intervals (one day up to three days at a time.) Everything from acetic acid (vinegar) to proprionic acid to citric acid as well as blends of acids are used. Many growers and live production personnel believe feed passage is reduced when these types of products are utilized. Keep in mind that the pH of the gizzard is in the range of 2 and not one of the currently used products drops the pH of the drinking water below 3.5 (see Table 5 for an evaluation of water pH when different products are added.) One thought on how water acidifiers are improving performance is that they help to keep unwanted bacteria, mold and yeast levels limited in the crop and this in turn helps to keep the rest of the digestive system functioning properly.
Additional Sanitizers
Ozone (O3) is a very effective bactericide, virucide and chemical oxidant. Ozone will react with iron and manganese making both more easily removed by filtration. It also works independent of pH and it can inactivate chlorine if they are used simultaneously. However, ozone is a point of contact sanitizers that dissipate rapidly providing no sanitizing residual in the water system.
Chlorine dioxide is making its way on the market as a poultry drinking water sanitizer, partly because the application of chlorine dioxide has been resolved by new chlorine dioxide generation methods. Chlorine dioxide is as effective as chlorine as a bactericide and even more effective as a virucide and is also superior to chlorine for the removal of iron and manganese. It is not impacted by pH.
Hydrogen peroxide is gaining popularity as a water sanitizer. pH and bicarbonate alkalinity play a major role in the effectiveness of hydrogen peroxide because of the competition between. Hydrogen peroxide can be stored onsite but it will deteriorate over time. It is a strong oxidant but it does not provide any lasting residual. A hydrogen peroxide product stabilized with silver nitrate is proving to be a very effective sanitizer.
Conclusion
In conclusion, water is the most essential nutrient birds receive yet the quality of bird drinking water is often taken for granted. Providing flocks with a clean, wholesome supply can make a difference in performance. Should water be a suspect for flock problems, make arrangements to have water tested for total bacteria numbers as well as for mineral content. While total aerobic plate count won't tell exactly what is in the water, it is an indicator of excessive levels of bacteria that should be addressed. By promoting a regular water sanitation program on farm, producers can prevent environments in water systems that could lead to poor bird performance.
From Proceedings of the "Midwest Poultry Federation Convention", St. Paul, Minnesota, U.S.A.
