Balancing water & minerals for beef cattle

Water is often referred to as the most important nutrient. Providing beef cattle with clear and odorless water is a good first step in meeting nutritional requirements, but looks can be deceiving.

In a recent presentation, Cheryl Waldner, DVM, Beef Cattle Council, Western College of Veterinary Medicine, discussed water quality for beeves.

“Poor water quantity can lead to reduced calves on the ground, reduced calf weight gains and increase risk of disease,” Waldner said. “Occasionally, poor water quality can result in sudden animal death on pasture.”

There are numerous challenges related to water quality. Ground water is usually higher quality compared to surface water, which is influenced by repeated cycles of drought and evaporation. Manure and nutrient contamination from runoff are also challenges. Some deep wells tap into old aquifers with a low recharge rate and high concentrations of salts and minerals.

Water sources are influenced by drought, flood, runoff and other factors that result in contaminants and other undesirable components. Total dissolved solids (TDS) are the primary indicator of water quality. This value is most often expressed in parts per million (ppm). Factors that impact TDS include pH, bacteria, algae, nitrates and nitrites and high or low pH.

TDSs include calcium, magnesium, potassium, sodium, bicarbonates and chloride. The most problematic is sulfates. An electrical conductivity (EC) device can screen water for TDS – higher conductivity means higher TDS. Water with greater than 2,000 ppm TDS should be analyzed by a laboratory for more precise assessment.

“High TDS by itself can reduce salt intake and potentially trace mineral intake in cows,” Waldner said. “This is what happens with evaporation and concentration of elements in summer. If we sample water only at the beginning of the grazing season, we would potentially be misled into thinking we had safe water for the entire grazing season.”

Sulfates are a concern in drinking water for cattle. High sulfate levels can result in potentially deadly polioencephalomalacia (PEM). This nervous system disease, also known as polio, results from the rumen conversion of sulfate to hydrogen sulfide, which is a toxic gas. Further compounding the problem is that the presence of sulfates in water ties up copper. Penn State recommends sulfate levels below 500 ppm for calves and below 1,000 ppm for adult cattle.

“High sulfate water under experimental conditions hasn’t been associated with dry matter intake, water intake or animal growth,” Waldner said, “but it has consistently led to increased ruminal hydrogen sulfide and reduced copper status.”

Copper deficiency is the most common trace mineral inadequacy, with evidence linking insufficient copper to decreased reproductive performance and impaired immune function.

“The traditional way to look for copper deficiency is loss of color, or bleaching, of the hair coat,” Waldner said. “It’s more than just not having enough copper in forage and feed. The little copper that is there is often tied up with a secondary type of copper deficiency where it’s bound by molybdenum, sulfur, sulfates in water or iron. These can act independently or together to tie up copper that is originally in the feed and supplements. It can complicate supplementation.”

With excess molybdenum or sulfates in water, chelated or hydroxy minerals may be necessary to raise cows’ copper levels. However, it’s often difficult to determine precisely how much trace mineral cows are consuming. Intake varies by how a mineral supplement is presented to cattle: block, loose, lick tubs, mixed with salt or through added molasses. Most cattlemen feed free choice minerals or mix minerals with concentrate.

Another health risk to cattle from poor water quality, especially with surface water, is blue-green algae. This isn’t true algae – it’s cyanobacteria. Cyanobacteria thrive in stagnant water, especially where excess nutrients from manure are present. This becomes especially problematic in hot, dry summer weather. Cattle can become quite ill from cyanobacteria and may show signs of toxicity through tremors, diarrhea and difficulty breathing. Severe cases result in liver damage and often death.

“We can reduce the chances of high levels of nutrients in the water that promote bacterial growth in water by aeration or treating with copper sulfate,” said Waldner. “However, if water is treated, dead bacteria release toxins, leading to a secondary problem.”

Nitrates consumed in low concentrations can be converted to nitrites by microbes in the rumen. Further conversion results in ammonia, which produces protein. However, nitrates consumed at high concentrations overwhelm the ruminal conversion process and result in nitrite buildup. Excess nitrite enters the bloodstream and binds to hemoglobin, reducing the capacity for blood to carry oxygen. Nitrate/nitrite toxicity can result in respiratory distress, stillbirths, abortions and sudden death.

Cattle are at highest risk of problems due to nitrate when they consume feed or pasture grown under stressful conditions such as drought, heat stress or frost. Certain crops, including oats, millet, rye, corn and sorghum, tend to accumulate nitrates. Weeds such as lamb’s-quarters, smartweeds, dock and johnsongrass can also be a source of excess nitrates.

Animals can adapt to small amounts of high-nitrate feeds but it’s risky to rely on guesstimates of nitrate content. The key to managing nitrates is to test water for nitrate levels and ensure feed and pasture don’t contain excess nitrates.

Collecting water samples for laboratory analysis is the best method to determine what’s in drinking water. The results can help the cattleman and nutritionist decide how to balance any excesses or deficiencies that could interfere with mineral uptake.

If the farm doesn’t have a water collection kit, Waldner suggested using a clean, well-rinsed one-liter jug for sample submission.

“If you are collecting for more than a routine analysis, such as specific bacteria or blue-green algae, contact the lab to be sure you are doing everything right to ensure a useable sample,” Waldner said.

by Sally Colby