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What if Cows Don’t Drink Enough Water? – Part 2

24 December 2007

By Neil Broadwater, Regional Extension Educator-Dairy, University of Minnesota Dairy Extension. This is the second of a two-part feature. A link to the first part is available below.

In Part 1 of this topic (Oct 27 publication), water intake needs of the lactating dairy cow, flow rate to the waterers, and water space needs for the cow were discussed. In this article, we will cover issues related to the quality of water that the cow is consuming.

If water is highly contaminated, dairy cattle are exposed to disease-causing organisms. If the drinking water has an offensive odor and taste, dairy cattle can detect it. If the water smells or is unpalatable, cows may not drink enough to meet production needs or it could even be completely refused. So, if health and production problems are showing up in the herd, the quality of the water should also be investigated and analyzed for coliform bacteria and other microorganisms.

Here are some items to consider:

  • Bacteria counts – According to Looper (New Mexico State) and Waldner (Okla State), in their publication “Water for Dairy Cattle,” total coliform count should be under 15/100 ml. Fecal coliform counts should be under 10/100 ml. Total bacteria counts in excess of 500/100 ml may indicate water quality problems. Water sources with total bacteria counts in excel of 1 million/100 ml should be avoided for all livestock classes.
  • Clean waterers – Bacterial contamination most often occurs in the waterers. Cleaning water sources such as drinking cups, bowls and tanks routinely (daily, every 2 days, weekly) is very important.
  • Water temperature – Cows prefer to drink water with moderate temperatures (63-82°F) rather than very cold or hot water, if given a choice.
  • Check for nitrates – Nitrate sources can come from fertilizers, animal waste, fecal material, crop residue. Nitrate poisoning results from a bacterial reduction of nitrate (NO3) to nitrite (NO2) in the rumen [conversion is: nitrate nitrogen (NO3-N) x 4.43 = Nitrate (NO3)]. The nitrite absorbed into the blood can reduce its oxygen carrying capacity. The following table can serve as a guide for dairy cattle:
Concentration of NO3 and NO3 - N in drinking water and expected response
NO3 ppn
NO3 - N ppn
0 - 44
No harmful effects
45 - 132
11 - 20
Safe if diet is low in nitrates and nutritionally balanced
133 - 220
21 - 40
Could be harmful if consumed over a long period of time
221 - 660
41 - 100
Dairy cattle at risk; possible death losses
661 - 800
101 - 200
High probability of death losses; unsafe
over 800
over 200
Do not use; unsafe

  • Total dissolved solids (TDS) or salinity – The summation of all inorganic constituents present in water. It is a measurement of the amount of sodium chloride, bicarbonate, sulfate, calcium, magnesium, silica, iron, nitrate, strontium, potassium, carbonate, phosphorus, boron and fluoride in water. Research indicates that high levels of TDS combined with increased environmental temperature have a detrimental affect on milk production. Water containing <5,000 ppm may be fed to lactating cattle, but >7,000 ppm is unacceptable for all cattle, according to the 2001 National Research Council guidelines.
  • pH level – A guideline for pH of water has not been established due to a lack of research determining the effects of water pH on water intake, milk production and dairy cattle health.
  • Blue-green algae – Cattle should be prevented from drinking water with heavy algae growth. Symptoms in blue-green algae poisoning include ataxia or in-coordination of voluntary muscle movement, bloody diarrhea, convulsions and sudden death. This is an occasional problem in freestanding water, such as farm ponds.
  • High iron, manganese, or molybdenum content may increase needs for copper, or result in more iron-bacteria problems. Iron concentrations in drinking water of greater than 0.3 ppm are considered a risk for human health, and are a concern for dairy cattle health and performance. The first concern is that high iron in drinking water may reduce the palatability (acceptability) and, therefore, consumption. Also, a dark slime formation in plumbing and waterers formed by iron-loving bacteria may affect water intake and even the rate and volume of water flow through pipes (Beede, “Assessment of Water Quality and Nutrition for Dairy Cattle”).
  • Water sampling and testing – Take 1 or 2 quarts of water from the source in question. Send samples to any accredited commercial or state operated laboratory for analyses. Consult with your herd veterinarian for assistance in selecting a laboratory as well as for assistance in selecting appropriate tests and interpreting test results.
  • Any water treatment needs to be cost effective and bring about health and/or milk production benefits. Dairy farms use large volumes of water and treatment systems must be sized to fit the need. Reverse osmosis and ion exchange are treatment methods for removing or reducing nitrate, sulfate and minerals in water, but there is a high cost of setup and operation of these systems.

Further Reading

       - You can view part one of this publication by clicking here.

October 2007


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