Water for Dairy Cattle.

 By Heather Smith Thomas.

 Water is the cheapest nutrient, but also the most important, especially for dairy cows, yet availability and cleanliness of the water supply is often overlooked.  Milk is 87% water and a dairy cow’s body water content ranges from 56% to 81% of her weight. Per unit of body weight, a high-producing dairy cow has a greater water requirement than any other land mammal.

Providing an appropriate supply of clean water is essential since it is necessary for basic body functions such as digestion and normal rumen function, nutrient absorption, urination, respiration, blood circulation, heat dissipation, etc.  If adequate water is available, a lactating dairy cow will consume 30 to 50 gallons of water each day. This may be more than 415 pounds of water per day. It takes between 4 and 5 pounds of water to produce 1 pound of milk. This equates to roughly one-half gallon of water for every pound of milk secreted, so, a cow producing 100 pounds of milk daily could consume as much as 50 gallons of water.

Insufficient water or water of poor quality can limit milk production and growth, and can cause health problems. When experiencing heat stress, a cow’s water intake can double--making it even more important to provide ample water. The size of the cow, her milk production level, the amount of dry matter consumed, salt intake, air temperature and relative humidity of the environment, temperature of the drinking water, quality and availability of the water, and amount of moisture in feed will be factors that determine how much water a cow drinks during the day.  It’s also important to make sure that heifers and any cows out on pasture also have clean drinking water available that is easily accessible.

Dairy cows obtain 60% to 80% of their fluid intake from drinking water and 25% to 35% from moisture in feed. Water can be lost from the body via saliva (such as drooling in hot weather), urine, feces, milk, sweating and evaporation on body surfaces and via the respiratory tract (exhaled air is always moist).  

Cows rely on saliva and other fluids to assist in digestion of feed. The increased need for saliva as a cow eats requires water.  If water intake decreases, digestion decreases. A decrease in water intake results in decreased feed intake. Decreased feed intake can have detrimental effects on dairy cows.

Even a small limitation in water intake will decrease dry matter intake by 1 to 2 pounds daily, which could limit peak milk production by 2 to 5 pounds.  Cows in tie stall barns drink about 14 times per day compared to cows in loose housing that drink about 7 times a day. A dairy cow spends between 10 to 60 minutes each day drinking water.
Cows can drink a lot of water quickly but if the waterer space is not large enough or the water flow rate is too slow some cows may have to wait to meet their water needs and some may not get to drink at all during that visit to the waterer.  Factors that affect drinking behavior include the cow’s eating patterns and ease of access to the watering area, temperature of the water, whether the water is in a trough (tank) or a bowl, and cow dominance if water bowls are shared.

Water Systems
You’ll want a water system that is easily accessible and allows for a flow of at least 30 gallons per minute into the tank to ensure that water does not become limited when cows are actively drinking.  For water bowls, as flow rate increases, their drinking time decreases and overall water intake increases. Providing an appropriate flow rate for water bowls is just as important as for a water tank.  Cows must have access to water when they are in the barn.

The water trough should be centrally located or located where all cows in a group can access it easily. Supplying enough water stations throughout the barn can help ensure that even the more submissive cows in the group will have a chance to drink.  Have at least 2 watering locations per pen to prevent dominant cows from guarding the waterer.  Provide enough space at the waterer so that 20% of the cows in a group can drink at once.  

There should always be plenty of space for multiple cows to drink at once. Each cow should have 3 to 5 inches of water space available. Height of the trough should be 2 to 3 feet. The fill rate of the waterer should be a little over 2.5 gallons per minute. If the herd is split into multiple groups, each group should have its own water trough.

One water trough should be present for every 20 cows. The number of cows in the barn will determine the number of waterers needed. A water trough should hold no less than 5 gallons at a time, with water depth a minimum of 3 inches.

The trough should be clean and provide fresh water at all times. An automatic waterer ensures cows will have the correct amount of water offered at all times. However, automatic waterers and float valves must be cleaned at least once a week.  There should be a water tank within 50 feet of the feed bunk or at every crossover in a free-stall barn.

In pens, placing the water trough close to the feed bunk allows cows to drink after eating.  Water should be immediately accessible to cows after they return to their pen from milking. Heifers should have access to one appropriately sized water space per 20 animals and the same recommendations apply to cows and heifers on pasture.
Cows tend to drink the most after eating and being milked.  It is advisable to have ample sources of water available in spaces where cows may be passing after milking.

Cows will drink 30% to 50% of their total daily water intake within about an hour or so after milking.  This time is also a peak period for cleaning milking equipment and in some systems the water flow going to waterers may decrease during that period. Flow rates should be observed at these heavy use times and altered accordingly. Cows should never have to wait for the water tank or bowl to fill. Limiting availability of fresh, clean, water, even for just 2 hours on pasture on pasture for instance, can decrease milk production quicker than a deficiency in any other nutrient.

Waterers that are located in an area that allows cows to drink and eat at the same time can boost dry matter intake and milk production.  Cows have peak water intake during the hours when feed intake is greatest. When given the opportunity, cows tend to alternately consume feed and drink water. Ideally, fresh, clean water should be available to the cow whenever she consumes feed.  If placed in a separate location than the feed area, cows should not have to travel more than 50 feet to access a water source. Alley width should be taken into consideration when choosing a place for a water tank; there should be enough space for the tank, the length of the cow drinking, and additional width for cows to pass through going both directions while other cows are drinking.

Quality
Water quality is another important factor and should be checked at least a couple times a year.  A water sample can be collected and sent to a laboratory to be evaluated for chemical and physical aspects such as minerals, nitrate-nitrogen, total dissolved solids, and bacteria content.  Many commercial laboratories offer water testing services. For information about where water can be tested, contact your extension office.

Total dissolved solids over 1,000 mg per liter can lead to health issues and decreases in milk production depending on the contaminant.  Levels over 3,000 mg per liter will cause water to have an “off” taste resulting in decreased water intake.  If manure contaminates a water source the presence of E. coli bacteria can cause serious issues.
To prevent manure contamination of water, use a raised base around water bowls and tanks. Water bowls and tanks should be cleaned frequently to prevent bacteria build up. Waterers should be emptied and cleaned with a weak chlorine solution and refilled with fresh water at least weekly to maintain water freshness and quality. This includes calf and heifer water buckets, bowls, and tanks.

Water quality problems can occur with wells and springs, especially when associated with poor environmental management if septic tanks, milk-house wastes, and industrial drainage may be involved.  Cows allowed to drink from surface water sources such as ponds and creeks are potentially at risk from bacteria and cropland runoff containing pesticides.  It’s usually best to fence off these areas.

Hard water or antibacterial water treatment usually has no adverse effect on cows but high levels of sulfate and magnesium may cause diarrhea and increase dietary requirements for selenium, vitamin E, and copper. Water with high iron levels may increase the need for dietary copper, especially in lactating dairy cattle.

Water with pH less than 5.5 (acidic) may increase problems related to mild acidosis such as reduced milk yield, lower milk fat percentage, low daily gains, off-feed problems, more infectious and metabolic disease, and infertility.

Alkaline water (pH greater than 8.5) may result in problems related to mild alkalosis such as amino acid and B-vitamin deficiencies, and symptoms similar to mild acidosis. When cows are drinking alkaline water, rations high in alfalfa, buffers, and minerals are more likely to contribute to mild alkalosis.

Nitrate (NO3) levels over 100 to 150 parts per million may cause reproductive problems in adult cattle. Replacement heifers have reduced growth rates.  Generally, there is no significant effect of mildly elevated water nitrate levels on milk production. Nitrite levels in water that are over 4 parts per million may be toxic to cattle—causing infertility, reduced gains, abortions, respiratory distress, and eventually death.

Water must contain no coliform bacteria for calves.  Coliform count should be under 10 per 100 milliliters for adults. Bacterial pollution may increase susceptibility or contribute to a variety of calf and cow diseases. Drinking bowls, cups, and troughs should be kept clean to prevent buildup of old feed and other debris.

Water For Calves
Water plays an important role in rumen development of young calves and should be offered from day one.  Calves might not drink any at first but if it is available they will be curious and sample it—and start drinking sooner.
Calf performance can be improved by giving calves free access to water early in their lives. Feed intake is related to free water intake in young calves. Water intakes may be higher when air temperatures are over 80°F, and lower than expected when air temperatures fall below 50°F, and even lower at very cold temperatures.

Signs Of Inadequate Or Excessive Water Intake
Low water intake results in low urine output and firm manure. This may also be a sign of dehydration from disease or fever.  Inadequate water intake leads to reduced milk yield and may also lead to intestinal disease if cattle drink from puddles of dirty water.  Lack of salt, potassium, and crude protein in the ration may also cause this behavior.

Excessive water intake leads to excessive urine production, abnormally loose manure, and a bloated appearance--especially in young calves. Diarrhea caused by excessive water intake will still be normal in color and odor.   

[sources of information – Penn State Extension, Nebraska Extension, and University of Kentucky]