Water is considered the single most important nutrient for dairy cattle; yet it is one that frequently gets the least attention. I would even suggest that when we look at agriculture as a whole, there is no more important resource than water. This statement is supported by the fact that The World Economic Forum lists water crisis among the top 10 likely and impactful global risks. We, in Nebraska, are fortunate as we sit above portions of the High Plains Aquifer. This aquifer underlies an area of approximately 112 million acres in 8 states and supplies water for 27 % of the irrigated land in the US and 30 % of the US ground water, which is used for irrigation. However, it has been estimated that since predevelopment times the aquifer has overall declined 267 million acre-feet. Clearly, this is a resource that must be understood and cared for. It has been estimated that agriculture accounts for approximately 70% of the world’s total water consumption. Furthermore, this use is likely to increase as the words demand for food also increases. Research from the Netherlands has estimated that dairy production accounts for approximately 19% of the total global water footprint related to animal production. Of this footprint, 98% is made up of water used to produce feed, while only 1% is used for drinking. Even through 1% may seems like a small amount, water acquired through drinking is vital for production because we know that water deprivation has severe and negative effects on feed intake and milk yield. In addition of availability, below is a quick checklist of items that may be considered when evaluating water quality for dairy cattle:
- Total Dissolved Solids (TDS) is a measure of inorganic constituents and is influence by local geology. Major ions and ionic compounds include: carbonate, bicarbonate, chloride, fluoride, sulfate, phosphate, nitrate, calcium, magnesium, sodium and potassium. TDS alone is not enough to understand water quality. TDS is really seen as a “pre-indicator” or water quality but anything less that 1000 mg/L is generally thought as good.
- Hardness is generally affected by calcium and magnesium. Hardness is not believed to have great affects on cattle but may affect accumulation of scale and negatively affect water delivery systems and cleaning efficiency of milking equipment.
- Sulfate may negatively affect water intake and may reduce the animal’s ability to utilize some minerals and may also tie up copper. There also is some evidence that if sulfate is greater that 500 mg/L, you should do further testing to determine the specific salt or sulfate present in water. You may also want to consider feeding chelated minerals.
- Iron in water is easy to recognize, as the water appears rusty in color, contains sediment, and possesses a metallic taste. Iron may interact with some minerals and cause nutritional deficiencies. High iron may also cause oxidative stress in periparturent cows with compromised immune systems. If iron in water is 0.30 mg/L you may want to further explore potential problems and solutions.
- Nitrate presence in the drinking water may be a result of industrial pollution, heavy fertilization of fields or may be associated with shallow wells. High nitrate may reduce the oxygen carrying capacity of blood. An elevation in the nitrate concentration of drinking water has been shown to correlated with increasing calving interval. Nitrate nitrogen in drinking water of greater than 20 mg/L should be further evaluated.
- One last thing that is commonly measured in water is thermotolerant or fecal coliforms. It is important to know that this test provides no identification of the exact microbial pathogens that may be there so it is only a very general indicator of microbial presence. Nonetheless, median threshold for thermotolerant (fecal) coliforms for livestock has been recommended to be 100 thermotolerant (fecal) coliforms/100 mL.
In closing, water will continue to challenge the global dairy industry. We, in Nebraska, are generally fortunate with our supply, but it is also recommended that you test water to ensure that it isn’t causing some of the challenges that are keeping you from realizing production goals for your farm.