Water is the single most essential nutrient for humans and livestock. It plays a critical role in numerous physiological functions in the body. Unfortunately, because water is an excellent solvent, it frequently contains solutes and suspended particulate that can influence the appearance, odor, taste, and physical and chemical properties of water. Some of these items, such as sulfates, can have a direct impact on animal health and(or) performance. These and others may simply reduce water intake, which in and of itself, is not immediately problematic. However, water intake is closely related to feed forage intake. Consequently, as water intake decreases, so does feed intake and animal performance.

High-sulfate water is found throughout the United States, but appears to be particularly problematic in the western and Great Plains regions of the country. High-sulfate water can be detrimental to animal health and performance via two distinct mechanisms: as a substrate for hydrogen sulfide production and as an antagonist to copper absorption. Hydrogen sulfide is a neurotoxic compound that can be quickly fatal to cattle when produced and absorbed in significant quantities. Sulfur can enter the rumen in many different forms: sulfur-containing amino acids, sulfate forms of minerals in supplements, high-sulfate water, and feed ingredients that contain more sulfur than would be expected from sulfur-containing amino acids (i.e., corn co-products from ethanol production). Sulfur that enters the rumen, regardless of source, is reduced to sulfide by the microbial population. Consequently, to effectively assess the risk in a given situation, estimation of total sulfur intake becomes much more critical than water sulfate concentration alone. A portion of the sulfide produced in the rumen is eructated, or “belched out”, and is subsequently inhaled by the animal. This hydrogen sulfide is readily absorbed though the lungs and can have neurotoxic effects on the animal. Traditionally high-sulfate water was previously thought to result in polioencephalomalacia (PEM) or “brainers”, a condition associated with a thiamin deficiency. However, some researchers suggest that a distinct form of PEM exists that may elicit similar pathological signs to traditional PEM, but without altered thiamin status. This newly described condition has been coined sulfur-associated PEM, and may or may not respond to supplemental thiamine or thiamine therapy.

The first step in the process of addressing high-sulfate water concerns is to sample each water source. These samples can be tested quickly with a simple hand-held electro-conductivity meter. County Extension offices in South Dakota are equipped with electro-conductivity meters and can test samples free of charge. If the reading from the electro-conductivity meter is greater than 2000, the sample should be submitted to a water quality laboratory for further analysis. When submitting the sample for further analysis, it is important to specifically request a sulfate analysis. Water hardness and salinity cannot be used to assess sulfate concentration. This table provides guidelines for what can be expected from cattle on forage-based diets (40% or more forage in the diet) at various water sulfate concentrations. Sulfur from other sources would be in addition to what is included in this table.

Because of precipitation, runoff, and evaporation, it is quite likely that the quality both surface and subsurface water may change over time. As such, it is critical for beef producers in high risk situations to monitor water quality closely, especially during summer months when water intake will be greatest.

The most effective means of purifying water for livestock is by reverse osmosis. These systems can be quite expensive and may not be practical on most farms and ranches. However, in situations where high-sulfate water has had a substantial financial impact, a reverse osmosis system may be warranted.

The second means of dealing with high-sulfate water is to simply develop new water sources…rural water, for example. Rural water systems often tap very high quality water sources and may be more consistent in their ability to supply high quality water to livestock. It may also be possible to develop a new well on an operation. However, caution should be exercised before spending substantial capital drilling a new well. The water quality of potential aquifers should be investigated to avoid drilling a well that does not provide higher quality water.

The third, and least expensive, option to cope with highly saline or high-sulfate water is simply to manage grazing. In some situations, it may be possible to graze cattle in pastures with poor-quality water early in the grazing season when the water intake of the animals and the concentration of the contaminants are likely the lowest. Because their water consumption is lower, grazing non-lactating animals may be advisable. Then, as the ambient temperature and water intake begin to increase, move cattle to pastures with better quality water. The success of this strategy depends heavily on routine testing of water quality throughout a given operation. Efforts to alleviate problems associated with high-sulfate water have produced mixed results. Supplemental thiamine (125 mg to 1 g) may be beneficial in coping with high-sulfate water, but minimal research has examined this as an option and the results have been inconsistent. High concentrations of molybdenum have also been used to prevent sulfate problems; however, this strategy simply creates another problem by antagonizing copper absorption. Regardless of any dietary manipulations, it is important to become familiar with the signs of sulfur-associated PEM and develop an appropriate treatment plan with your veterinarian.

It is also essential to carefully evaluate the copper concentration in any mineral supplement. Providing enough copper to the cattle will be critical to maintaining growth and reproductive performance, and immune function. In some cases, the mineral mixes may be formulated to provide adequate copper, but the cattle do not consume as much as they are supposed to. When this happens, identifying a means of “convincing” the cattle to eat mineral is very important.

Water quality can have a profound impact on animal health and performance and consequently the profitability and sustainability of beef cattle operations. Routine monitoring of water sources and appropriate intervention or management poor-quality water sources can provide beef producers with a desirable return on investment. Careful thought and calculation should be incorporated into any major capital improvements related to water quality.