Research is currently being conducted on maintaining water quality especially that which escapes agriculture enterprises. Unfortunately, we often get caught up in water quality leaving a farm and forget about the quality of water needed for efficient livestock production. With this in mind, I thought it would be a good time to review the importance of water in the maintenance of healthy cattle.

The first factor in water quality is quantity. If sufficient quantities of water are not available, research has shown that dry matter intake decreases with a subsequent reduction in production. The following table lists typical water requirements for beef cattle. It should be noted that as air temperature increases, water requirements increase. The same is true when overall nutritional needs are the highest, such as during lactation or during the finishing period.

Water requirements for cattle - Gallons Per Day ¹
Air Temperature In ºF	40 ºF	60 ºF	80 ºF
Growing Heifers/Steers @800 lbs	6.3	7.9	10.6
Finishing Cattle @800 lbs	7.3	9.1	12.3
Wintering Pregnant Cows	6.0	7.4	----
Lactating Cows	11.4	14.5	17.9
Mature Bulls @1600 lbs	8.7	10.8	14.5

Availability of water is also important to consider. In grazing systems, delivery of water to individual pastures is preferable to centralized water sources. Centralized water systems force cattle to expend energy while walking to the water source. Areas around central water systems often contain heavy parasite and bacteria loads because of increased traffic. When central water supplies are at a distance from grazing areas, cattle tend to move to water and drink as a group thus requiring larger water reserves and higher flow rates. A rule of thumb for central water systems is to provide enough tank space for 10 percent of the cattle to drink at one time and a flow rate adequate enough so that all cattle can drink within 20 minutes. In confined areas where individual water sources are used, one drinking space per 20-25 animals should be provided.

Most ground or surface waters are adequate for cattle consumption. However contaminated water can result in poor performance or even death in cattle confined to them.

Water quality can be an important factor in consumption and overall performance of cattle. Similar to you and me, cattle will drink less of poor tasting or contaminated water. Decreased water intake results in less dry matter consumption with a subsequent drop in production. Additionally, certain contaminants can directly affect the health of cattle resulting in reduced performance and even death.

The U.S. environmental protection agency recommends that water intended for livestock should have less than 5000 coliform bacteria per 100 milliliters. The recommended coliform level for human consumption is zero. Although research data is limited, observations are that reduction of water coliform concentrations can result in dramatic improvement in overall herd health. The major source of coliforms in water is fecal contamination.

Salinity (or salt concentration) is a major factor in the palatability of water. Salinity is determined by the concentration of dissolved inorganic salts such as calcium chloride, sodium chloride, magnesium chloride, sulfates and bicarbonates. High concentrations of salt create osmotic imbalances which can have harmful effects on cattle. Over time, cattle are able to adapt to high salinity water, but abrupt changes from low to high saline concentrations can be harmful. Cattle offered water of high salinity will refuse it in favor low salinity water. If offered as the only source, water consumption may be initially erratic which tends to magnify health problems. Water consumption may actually increase in cattle that have adjusted to high saline water. The following guidelines are useful in assessing water salinity ².

Salt concentration mg/l *

<1000 mg/l Low salt concentration. Excellent for all cattle.

1000-3000 mg/l Satisfactory for cattle. Initial exposure may result in transient diarrhea.

3000-5000 mg/l Satisfactory for cattle. Initial exposure may result in temporary refusal or diarrhea.

5000-7000 mg/l Marginal quality for cattle. Should not be used in pregnant or lactating cattle.

>7000 mg/l Considerable risk for all cattle. Should be avoided if at all possible.

* Milligrams per liter (mg/l) is equivalent to parts per million (ppm).

Nitrates are another common concern in water quality. Nitrates are metabolized in the rumen to nitrite. Nitrite is absorbed into the blood stream where it converts hemoglobin, the oxygen carrying molecule, to methemoglobin which is incapable of carrying oxygen. The most common source of nitrate toxicity is from plants which accumulate high levels following drought conditions. High levels of nitrates in water are rare. Deep wells under highly fertile soil or surface water from recently fertilized fields are the most common sources of high nitrate water. The following guidelines are useful when assessing nitrate levels in water ².

Nitrate concentration mg/l *

<100 mg/l No evidence that this level is harmful to cattle.

100-300 mg/l Under normal conditions, no harmful effects should be expected. However, when consumed in addition to other high nitrate feedstuffs, toxic levels may be approached.

>300 mg/l Water with this concentration of nitrate could cause toxicity in cattle and should be avoided.

* Milligrams per liter (mg/l) is equivalent to parts per million (ppm).

Sulfates concentrations may occasionally be high in water. Information on toxic effects in cattle is limited. In humans, a laxative effect is often seen when sulfate concentrations are greater than 700 mg/l. Sulfate concentrations of greater than 1000 mg/l has been shown to cause diarrhea in young calves. Studies with beef heifers have demonstrated reduced rate gains at sulfate concentrations of 1500 mg/l .

Sulfur can also tie up dietary copper, zinc, and manganese resulting deficiencies of these minerals. It is generally recommended that water sulfate concentrations should not exceed 1000 mg/l.

Poisoning by certain species of blue-green algae can occur in cattle where the primary source of water is stagnant and algae overgrowth is heavy. Outbreaks of algae toxicosis, or "water bloom" poisoning, are rare, occurring usually in the late summer when water temperatures are high, water depth is low and water nutrient concentrations are high thus facilitating algae growth. Although the algae that grows in water tanks is not considered toxic, keeping the build up minimized is good practice. Gold fish, whose diet consists largely of algae, have been used successfully to limit algae growth in water tanks. Temperature extremes may limit the use of gold fish in Michigan, but if nothing else, it's a great conversation starter.

Occasionally water can be contaminated by toxic substances such as heavy metals, radioactive waste or organic pesticides. Concerns for these substances exist not only for the health of the animal but also for the potential accumulation in animal products consumed by humans.

If water quality is of concern, contact your veterinarian or local beef extension specialist about having water analyzed and the results interpreted.

¹ Source - NRC Nutrient Requirements for Beef Cattle, 7th Edition (1996).

² Source - University of Nebraska Cooperative Extension publication G79-467-A.

April 2007