Clare M. Staveley, DVM
Water is an essential nutrient, but water quality is often an area of livestock production that is overlooked. Water quality should be considered to be as important as evaluating the nutritional content of feeds, and supplements in the diet, as some elements, or contaminants, when present in sufficient concentration, can negatively impact ruminant health.
It is important to know the source of your livestock’s water supply. Municipal water sources are the easiest to evaluate. Municipal water districts distribute water for human consumption, and are held to strict contaminant limits. Local water districts are required to publish water quality data publicly. If your herd is supplied water through your local water district, you can contact them directly for a copy of their most recent water quality report.
If your farm is supplied by an on-farm well or local spring, it will be up to you to test your water supply. Analysis should be conducted by an accredited laboratory. If you are unable to locate a laboratory near you, consult with your local veterinarian or livestock extension specialist for assistance.
In the context of ruminant health, your water analysis should include testing for the presence or absence of protozoa, coliform bacteria, and key mineral antagonists, including iron, sulfates, and nitrates. Do not rely on the reports of neighboring parcels, unless you are using a shared water source. Regional geologies can result in significantly different results from one property to another. Well depth and spring sources vary, and affect water quality, so analyzing your own water source is important.
Once you receive your testing report, some key elements to look for, that can impact ruminant health, include:
Iron - Iron is widely distributed, and most ground water sources contain iron. Deep well water sources are more likely to have higher content of iron than shallow wells. Excess iron in the diet is not directly toxic per se, however, it can result in reduced feed intake, growth, and reduces the palatability of drinking water. The form of iron affects its bioavailability. In some water sources, iron may be most likely present in a form of insoluble iron oxides, and therefore its bioavailability is rather low. If present in its ionized form iron can interfere with the bioavailability of zinc, copper, magnesium and calcium. As iron is a direct antagonist to copper, copper deficiency, in small ruminants, is the most likely consequence.
Sulfates - High levels of sulfur in the water supply can interfere with mineral metabolism and result in copper deficiencies. Elevated sulfates, paired with a high grain diet, may increase the risk of sulfur-associated polioencephalomalacia. Sulfates can also have a laxative effect, and contribute to dehydration. Sulfates have been shown to decrease average daily gains, and dry matter intake (DMI).
Nitrates - Nitrate is almost always found in higher concentration in water supplies than the more toxic nitrite. However, in ruminant animals, and horses, bacteria reduce nitrate to nitrite, which enters the bloodstream and interferes with the ability of hemoglobin to carry oxygen. Animals may succumb due to the effects of hypoxemia. As nitrates may also be present in feeds (hay/forage), it is important to consider the content of nitrates in both feeds and water.
Sodium - Elevated levels of salts in water can cause reduced productivity. Sodium ion toxicosis can occur in some species at high levels. Sodium sulfates are of particular concern due to its laxative effect.
Note that water quality may change over time. While a past analysis may serve as a baseline reference, water testing should be repeated every 12-24 months, or during periods when there is an observed change in water quality affecting color, odor etc. Periods of drought, or heavy winter rainfall, will cause groundwater levels to change, and may result in significant changes in water quality.
If a water quality problem is identified through testing, consulting with a water treatment specialist on a case-by-case basis will be necessary to devise the most satisfactory and economical solution. Each situation is unique, and correction of toxic water issues is not always straightforward, and often expensive, but ensuring your herd has access to clean, palatable drinking water is essential for successful dairy production.
German, Dave; Thiex, Nancy; and Wright, Cody, "Interpretation of Water Analysis for Livestock Suitability" (2008). Agricultural Experiment Station Circulars. Paper 330. http://openprairie.sdstate.edu/agexperimentsta_circ/330
Olkowski, Andrew A., PhD., DVM., MSc., BSc., (Biochemistry) University of Saskatchewan “Livestock Water Quality: A Field Guide for Cattle, Horses, Poultry and Swine” https://www.ag.ndsu.edu/waterquality/livestock/Livestock_Water_QualityFINALweb.pdf
Soltanpour, P.N., and Raley, W.L Colorado State University "Livestock Drinking Water Quality no 4.908" http://veterinaryextension.colostate.edu/menu2/Cattle/04908LivestockDrinkingwaterquality.pdf