Livestock Water Quality

You may think about livestock nutrition on a regular basis, but do you consider the water they drink? Water is arguably the most important nutrient for livestock, and poor-quality water can negatively impact both animal health and performance, just like the grain or forage they consume.

Water intake varies throughout the year, but as a general rule of thumb, livestock consume about 1 to 2 gallons of water per 100 pounds of body weight per day. This equates to about 8 to 20 gallons for cattle or 2-3 gallons for sheep. Water intake will vary based on the animal's weight, reproductive status, age, diet, and weather conditions. Animals also consume more water when they are pregnant or lactating. In addition, intake will increase during high temperatures and when animals' diets consist of higher levels of dried forages.

Total dissolved solids (TDS) is the main indicator of water quality and is a measure of the concentration of dissolved inorganic salts in water, expressed as either ppm or mg/L. Factors that impact TDS include excessive mineral levels, high or low pH, salinity, nitrates, sulfates, algae, and bacteria. During periods of high heat and low moisture, the water levels may be lower or evaporate from surface waters more quickly. Therefore, these TDS values could increase due to inorganic salts becoming more concentrated.

Alkalinity or pH

Alkalinity measures a water's ability to neutralize an acid. Most water consumed by livestock is mildly alkaline, but a preferred range is between 6.8 to 7.5. A pH of 7 is neutral. A pH of 5.5 can cause acidosis and a pH of 10 is considered highly alkaline and can cause physiological and digestive upset. This includes diarrhea, poor feed conversion, and reduced intake.

Salinity

Salinity refers to the total dissolved salts found in water sources. Common salts include sodium chloride (common salt), magnesium (Epsom salt), calcium, sulfates, and nitrates. Bicarbonate, which contributes to alkalinity, heavy metals, and others, is also included in TDS.

Values less than 1,000 ppm are considered safe to drink, and anything from 1,000 to 5,000 ppm is considered satisfactory for all classes of livestock. Higher levels may cause mild diarrhea and refusal by animals that aren't used to it and decreased growth in poultry. Beyond 5,000 and up to 7,000 ppm can be reasonably safe for all classes of livestock except for poultry and should be avoided for pregnant and lactating animals. Greater than 7,000 ppm should be avoided. At this level, water is now unfit for swine and poses an even greater risk for pregnant or lactating cows, horses, sheep, and young animals. Any water indicating amounts greater than 10,000 ppm has very high risks and is not recommended for any classes of livestock.

Mineralized (salty) water does not automatically mean that there will be health issues because some cattle do adapt to lower levels. Young and pregnant or lactating animals are typically at a greater risk. Higher concentrations cause increased water consumption and animals may continue drinking to the point of overconsumption. Poisoning results in symptoms such as weakness, dehydration, tremors, and death (within 24 hours of seeing clinical signs).

Water hardness is caused by calcium and magnesium. Water systems that use an exchange of sodium as a softener may cause more problems when water is already high in salinity.

Nitrates

Nitrates are naturally occurring, soluble, and move with runoff water. This is why ponds and shallow wells near heavily fertilized or manured fields are particularly susceptible to high nitrate levels. Toxicity from water alone is not common, but contaminated water combined with a high nitrate feed, such as summer annual grasses (sorghum, sudangrass, johnsongrass, corn), could result in problematic levels. Forages often contain high levels of nitrates during a period of stress like drought.

Nitrates are not especially toxic and can be converted into usable products in the rumen. However, at high levels, the conversion from nitrate to nitrite to ammonia does not occur fast enough. The nitrite that isn't converted gets absorbed into the blood and interferes with hemoglobin, reducing the ability of the blood to carry oxygen. The cecum in horses contain microbes that can also convert nitrates to nitrite, but at a slower rate than ruminants.

Safe nitrate levels are below 100 ppm. At levels of 100 to 300 ppm, the water itself should not harm livestock but problems may occur if any hay or silages are also high in nitrates. Any levels higher than 300 ppm could cause nitrate poisoning and is not recommended to be used. Levels above 300 ppm also contribute to a higher salt content, so the water is not suitable for swine or poultry either.

Sulfates

In Pennsylvania, elevated levels of iron, manganese, and sulfate can be found in shale and sandstone aquifers or in areas impacted by mining. Just like with nitrates, ruminants are susceptible to health issues from the combination of high sulfate water with a high sulfate feed. These high levels of sulfates cause reduced availability of copper, zinc, iron, and manganese availability in the diet. This leads to depressed growth rates, infertility, and poor immune response. Very high levels (greater than 4,000 ppm) can contribute to neurological diseases.

Sulfates in water should remain below 500 ppm for calves and sheep and less than 1,000 ppm for adult cattle and chicks. Swine should have water with levels less than 3,000 ppm. Diarrhea can occur at 500 ppm and higher levels could result in water refusal from animals that are not acclimated to sulfates. Trace mineral deficiencies start to occur at 1,000 to 2,000 ppm.

Cyanobacteria

Cyanobacteria, also known as blue-green algae, is a bacteria, not an algae, that releases a toxin that can poison livestock. Cyanobacteria growth occurs most often in places where there is stagnant water that has an excess of manure or other nutrients. This is particularly common in ponds during hot, dry weather. The water can be treated, but use caution because as the bacteria dies, it releases higher doses of toxin. Cattle sick from cyanobacteria experience diarrhea, lack of coordination or tremors, labored breathing, liver damage, and death.

Leptospirosis and Fusobacterium

Leptospirosis is a bacterial contaminant that spreads from one animal to another through water. This occurs when the urine of a carrier animal contaminates the drinking water source for the herd.  Leptospirosis can survive for long periods of time in surface water. This bacterium can cause reproductive issues such as infertility, low milk production, or late-term abortion.

Fusobacterium is a bacterial contaminant that uses mud as its mode of transport from animal to animal. The contaminated mud travels on the feet of animals, which can then walk through surface waters utilized for drinking. It can then enter the bloodstream of animals through cuts, bruises, or other wounds. This bacterium can cause foot scald in sheep, foot rot, and liver abscesses in cattle.

Coliform

Coliform bacteria are a large group of many types of bacteria that occur throughout the environment. Shallow dug wells, ponds, and other surface waters are prone to contamination because they are impacted by surface drainage. The presence of coliform bacteria in deep wells would indicate that surface water is finding its way into the well, potentially because of poor drainage or a cracked casing.

There is no legal limit on the amount that can be present in water except for Grade A dairy operations. Looking at fecal coliform specifically, it should be near zero. Cattle will avoid water with as little as 0.005% manure by weight, meaning that some ponds may be less palatable than assumed. Remember that wildlife also have access to the same areas as pastured livestock and could be contributing to contamination.

Other Considerations

As mentioned, hard water does not typically cause issues in livestock health, but it can cause problems with lime build-up, particularly on milking equipment. High iron content can clog pipes or increase iron bacteria, which can clog screens in pumps. Sulfur water is corrosive and can have an offensive odor.

Achieving High Quality Water

When possible, livestock should consume groundwater as it will typically be higher quality and less likely to contain contaminants than surface waters. Most surface waters are exposed to water runoff and the pollutants that could be carried in it. Only apply nutrients to fields at a rate necessary to meet crop needs. Determine these needs using soil tests, plant tissue testing, and manure tests.

When using surface water for livestock, be sure to incorporate a grassed watershed or buffer to catch pollutants like bacteria, manure, and fertilizers before they enter the water. Allow limited access to a pond or stream to minimize contamination from livestock while they are drinking and prevent loafing in water. This can be done using designated stream crossings or fencing livestock out of ponds. Livestock can utilize pond water by using a pump or gravity feeding water to a trough, rather than allowing animals to drink directly from the water source. Natural springs should also be pumped to a desired location or a spring development could be created to collect the water and use gravity flow to fill a trough for livestock to drink from. Make sure to properly grade well sites so that surface water drains away from the casing. Eliminating animals' ability to walk through or stand in their drinking water and providing lush vegetation to take up excess nutrients are two of the best ways to maintain clean water supplies.

Water Quality Testing

Private wells should be tested annually, especially shallow wells, and whenever a problem is suspected.  Steps should be taken to make sure livestock drinking water sources stay clean, and animals should be observed daily to identify any signs of a health issue. If a health issue from the water source is suspected or animals begin to show symptoms, contact a veterinarian for a diagnosis and treatment.

Livestock drinking water can be tested at the Penn State Ag Analytical Services Lab. The lab offers two packages for testing livestock drinking water.  One package includes pH, TDS, nitrates, calcium, copper, iron, manganese, magnesium, sodium, chloride, sulfate, and hardness. The second test is the same as the first, but also includes total coliform bacteria and E. coli. Be sure to follow the instructions for collecting and shipping the sample to impact the accuracy of the results.

Water testing kits are available at the laboratory or from many of the Penn State Extension county offices.