FROM THE FARM REPORT: MAYBE WE HAVE STARVED WATER OF SO MUCH ATTENTION

Water, known as the “universal solvent” is a crucial nutrient for life and it makes up about 60% of the human body. In dairy cattle, water is the most consumed nutrient, and it makes up about 65% of a mature cow’s body composition, and about 80% of an unborn calf. Water serves very essential purposes in the metabolism of dairy cows, including digestion, transport of nutrients, regulation of body temperature, waste removal, and importantly, milk production (85% of milk is made up of water). The importance of constant water availability to dairy cattle for drinking cannot be overemphasized, especially for the fact that they cannot store large amounts of water in their system for long periods, and they keep losing water through respiration, sweat, milk production, evaporation, and excretion (urine and feces). In a research study where cows were only allowed to get 50% of their normal water intake for four days, the authors saw a 74% drop in milk yield and negative impacts on their blood profile, but when they increased the offering to 90% of expected water intake, they observed only a 3% drop in milk. However, beyond the quantity, the quality of water provided is paramount.

Water contains dissolved minerals, organic compounds, and microbes which come from the leaching of rocks and soils, and even the water channel (in cases of dirty pipes, etc.). These elements can negatively affect lactation performance and animal health if they are beyond tolerable levels. Hence, the proportion of these contaminants/elements goes a long way to determine the safety of water for drinking. The total dissolved solids (TDS) also known as salinity is an estimate of the concentration of organic and inorganic substances in water, and it is an important indicator of water quality. One of the major determinants of water quality is the source. Approximately 60% of the freshwater used for livestock production in the US comes from groundwater, and some parts of the US and Canada are susceptible to the mineralization of groundwater (i.e., the addition of minerals to water as it flows). Therefore, more attention should be paid to the water being offered to animals, especially pregnant and lactating cows, as the tolerable level of TDS is higher for heifers and dry cows than the former group. A TDS of <1000 mg/L is generally considered safe for cattle to drink, but levels >7000 mg/L pose a health risk and reduced production and should not be offered to cattle.

A recent study was done at South Dakota State University by Casper and Acharya (2025) to determine the effect of water quality and source on rumen fermentation and nutrient digestion in an in-vitro (laboratory) setting. They used a Dacron bag to incubate a high-producing lactating dairy cow TMR (with the following as a percentage of dry matter: 25% alfalfa hay, 25% corn silage, and 50% concentrate supplements), along with rumen fluid and buffers prepared with water from four sources for 30 hrs. In in-vitro fermentation experiments, buffers are used as artificial saliva to mimic feed ingestion in live animals. The water sources used in this study were laboratory distilled municipal water (DW), untreated ground water from a local South Dakota dairy farm (UGW), treated ground water from the same source as UGW (TGW), and treated rural municipal water (MW). The striking results from the water quality assessment conducted for each water source showed that UGW and TGW were above the normal ranges for TDS, sulfates, calcium, magnesium, manganese, iron, and water hardness. The authors noted that UGW and TGW also tended to have lower dry matter digestibility compared to the other sources, but fiber (NDF) digestibility was similar for all water sources. It would be interesting to see what the ruminal and total tract digestibility results would be in an animal study, and maybe a palatability trial to see if the water intake of animals will vary based on the water source.

Although there is a dearth of research studies investigating the impact of water quality on the productivity of dairy cows, animals still rely on us to always provide them safe drinking water, and while adult cows can tolerate some level of dissolved elements in water, calves are more affected by poor quality water, especially hard water. The tolerable limits of elements in water for dairy cows are usually based off the recommended levels for humans due to limited research, hence, periodic water sampling is strongly encouraged. The guideline is to sample from the water trough and along the water channel to identify potential contamination points. It is also important to understand the laboratory results from such tests because the quantity of a mineral in water is not as important as the form in which that mineral is present, which determines the biological availability of that mineral, and the toxicity of that water. So, it is advisable to confirm that from the labs in order to make informed decisions based on those results. Another question may be how often to sample water on the farm. The recommendation is to sample when the water source is changed, and during different seasons of the year. Consistent sampling over time provides you with records of the typical figures obtainable on your farm, so irregularities can be easily picked up when they arise. I will add that when you perceive something is off about the water, then it’s time to take a sample. Remember the first test is that if it is not odorless, colorless, tasteless, and free of visible particles, then it is not clean water, take a sample. Maintaining a regular cleaning routine for water toughs is also very fundamental to minimize the risks of contamination.

As I wrote this article, I thought to myself, “maybe it’s time to take a look at our drinking water at home too…”

* References available upon request.

— Gift Omoruyi

gomoruyi@whminer.com