Water: An Essential Nutrient

Dr. Ronald L Boman
USU Extension Dairy Specialist

Over the past few months I have seen a number of situations on dairy farms where there was either not enough water pressure to keep the watering troughs filled up or there were not enough watering places for the cows to drink sufficient water. Remember that milk is 87% water (Holsteins). Be aware that the water requirement per unit of body mass of the high producing dairy cow is greater than for any other land-based animal (1).

The importance of adequate clean and safe drinking water should not be overlooked at any time, but it is extremely important during the heat of the summer months. Water is the medium in which all chemical reactions in the body take place. Blood, which contains 80 percent water, is vital in oxygen and carbon dioxide transport to and from the tissues, as well as being the life support system for the body. Since water has a high specific heat, it is ideally suited as a temperature buffering system for the body. A restriction of water intake lowers feed intake. Animals can lose nearly all the fat and about one-half the protein of the body and still survive, but a loss of 20% of the water of the body results in death. Dairy cattle need a continuous supply of water for maximum efficiency and they need to be able to get to the water. WHAT ABOUT YOUR DAIRY ANIMALS? ARE THEY ABLE TO CONSUME ENOUGH WATER WHEN THEY NEED AND WANT IT?

All too often in the Summer months I see cows standing in line waiting to get a drink of water. Also, the algae grow faster in hot weather and too often the water in the watering troughs is not clean and fresh. Here are a few reminders concerning drinking water management:

1. Cows are usually thirsty when they leave the milking parlor. Top dairy managers have ample water and watering space available for cows to easily drink all they want when they leave the milking parlor.

2. In the free stall barns and open lots we want to have enough watering devices so that cows can freely access water whenever they get the urge. Large open watering troughs with ample reserves that allow more than one cow to drink at a time are highly recommended, especially during the hot Summer months. LACTATING COWS HAVE BEEN OBSERVED GOING TO THE WATERING TROUGH TO DRINK AN AVERAGE OF TEN (10) TIMES IN A 24-HOUR PERIOD.

3. Adequate water pressure to refill the watering trough is a must, especially if the volume of the watering trough is reduced. Remember that lactating cows need 2 to 4 lbs of water for each lb of milk they produce and that this requirement goes up as temperature increases. We are talking about over 25 gallons/day or more for high producing cows. Of course, that amount goes even higher during hot weather. IDEALLY, COWS SHOULD NEVER HAVE TO WALK MORE THAT 65 FEET TO GET A DRINK OF WATER!!!

4. Heifers and dry cows will consume less water than lactating cows (3 to 8 gallons/day depending on their size). The important thing is to make sure that they can get a drink anytime they desire without having to stand in line or wait for a watering trough to fill up.

5. Pre-weaned calves need drinking water separate from the milk or milk replacer all year round. Starter intake is profoundly increased if they have access to water. This is especially true in the heat of the summer.

6. Cleanliness of the water is critical for maximum consumption. If you would not want to drink out of the cow�s watering trough, then the water is not clean enough for the cows.

7. Water quality for dairy cattle should approach the same quality standards as for humans to be on the safe side. Some things to be concerned about are: (1) Total Dissolved Solids over 2,000 ppm; (2) Sulphur present as hydrogen sulfide, imparting a rotten egg smell; (3) Sulfate over1500 ppm; (4) Nitrate over 80 ppm; (5) Nitrite over 8 ppm; and (6) iron over 0.3 ppm (reduces palatability and the ferrous form of iron is readily absorbed and can cause iron toxicity).


(1) Beede, David K., 2005. �The Most Essential Nutrient: Water�. Proceedings of the 7th Western Dairy Management Conference. March 9-11. Reno, NV.

For more information contact: Ron Boman at ronb@ext.usu.edu or (435) 797-2163. ©