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Copyright 2005, Board of Trustees, University
ne 1991 Circular 1017
June 1991 Circular 1017
and its importance to animals
Barney Harris, Jr. and H.H. VanHorn
Florida Cooperative Extension Service
Institute of Food and Agricultural Sciences
University of Florida
John T. Woeste, dean
Barney Harris, Jr. professor and extension dairy nutritionist. H.H. VanHorn professor and waste management specialist, Department
of Dairy Science, IFAS, University of Florida, Gainesville, FL 32611.
Water is the most important nutrient in animal
feeding and animal health. It is the most abundant
ingredient of the animal body in all phases of
growth and development. A calfs body contains 75
percent to 80 percent water at birth and about 55
percent to 65 percent water at maturity. Of all
farm animals, lactating dairy cows require the
greatest amount of water in proportion to their size
because water constitutes 86 percent to 88 percent
of the milk they yield.
Sources of water include water obtained from the
ground or surface, water in the feed supply and
metabolic water obtained from the oxidation of fat
and protein in the body. Water intake usually
refers to free-drinking water plus that available in
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.
In its major functions, water acts as follows:
* an ideal lubricant to transport feed.
* an aid in excretion.
* a regulator of body temperature.
* a buffering agent to regulate pH of body fluids.
Water's physical properties make it an important
factor in the transfer of heat and in the regulation
of temperature in the body. Specific heat is the
ability to absorb or give off heat with a relatively
small change in temperature. 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,
retention of nitrogen and loss of nitrogen in the
feces. It also results in increased excretion of urea
in the urine. Cattle that are gaining weight require
more water than those that are losing weight.
Animals may lose nearly all the fat and about one-
half the protein of the body and still survive, but a
loss of about one-tenth of the water from the body
results in death.
Animals need a continuous supply of water for
maximum efficiency. Because water functions as a
lubricant in the transport of feed and aids in the
excretion of waste products from the body, the
intake must equal the output lost through urine,
feces and evaporation. As an example, during
protein metabolism, uric acid and urea are
produced and must be removed through the
kidneys. Water is needed to dissolve the urea, uric
acid, phosphates, and other minerals for easy
passage through the urinary tract.
The water consumption of dairy animals is
influenced by many factors including breed, body
size, ambient environment, water temperature,
humidity, feed supply, salt and level of production.
Generally, cattle consume 2 to 4 pounds of water
for each pound of dry matter consumed and an
additional 3 to 5 pounds of water per pound of milk
produced. Rations high in salt or protein increase
Milk production and feed intake decline when
water intake is not adequate. At environmental
temperatures above 700 Fahrenheit, the animal's
respiration rate begins to increase, and increasing
amounts of water are lost through respiration and
perspiration. Increased losses of water signal the
animal to consume more water to replace the
An equation for estimating water consumption
has been proposed by Murphy et al. (6). The factors
identified as affecting water intake were dry matter
(DM) intake, milk production, sodium intake and
environmental temperature. Water intake was
predicted from the following:
Water intake (lb/day)= 35.2 + 1.58 x DM intake
+ .90 x milk produced (lb/day) + .11 x sodium
+ 2.64 x weekly mean minimum temperature
Thus, the equation predicts water consumption
will change 1.58 pounds for each 1.0 pound change
in dry matter consumed, 0.90 pounds for each 1.0
pound of milk produced, 0.11 pound for each gram
of sodium consumed, and 2.64 pounds for each
degree Celsius change in weekly mean minimum
temperature (1.47 pounds change for each degree
Fahrenheit). Usually in hot weather, dry matter
intake and milk yield decline, but water intake
usually increases, particularly if shade is not
available. With shade, location of water in relation
to the shade can have a major effect on water
intake. Field studies by Bray et al. (1) showed
decreased water consumption in hot weather when
the water troughs were located in the sun requiring
cows to leave the shade in order to drink.
Table 1. Estimated dally water consumption as influenced by mean daytime temperature and milk Production (gal/day).1, 2
Body Wt. (Ibs) Estimated DM Intake 10-400F 500F 60F 700F 800F 90F
Heifers, 200 Ibs 2.1 2.3 2.4 2.8 3.2 3.8
Heifers, 600 Ibs 6.3 6.8 7.9 9.7 10.5 11.8
Cows, 1400 Ibs
Dry 30 10.0 11.7 13.4 15.2 16.9 18.6
Milk 40 Ibs/day 36 15.5 17.2 18.9 20.6 22.4 24.1
Milk 60 Ibs/day 40 18.4 20.1 21.9 23.6 25.3 27.0
Milk 80 Ibs/day 44 21.4 23.1 24.8 26.5 28.3 30.0
Milk 100 Ibs/day 48 24.3 26.0 27.7 29.5 31.2 32.9
'Gallon of water = 8.5 Ibs.
2Estimation of water intake for cow from equation of Murphy et. al., (5).
Table 1 shows estimated water consumption at
various body sizes, levels of milk production and
temperatures using the Murphy (5) equation for
lactating and dry cows. The weekly mean
minimum temperature was assumed to be 10F
lower than the mean daytime temperature. Dry
matter intake was assumed to change from 30
pounds per day for dry cows up to 48 pounds per
day for cows producing 100 pounds of milk per day.
As an example, a 1400 pound cow producing 60
pounds of milk during temperatures of about 80F
would consume about 25.3 gallons (215 pounds) of
Dry matter intake and moisture content of the
feed influence the amount of water consumed. In
general, lactating dairy cows will consume 1.5 to 2
pounds of water per pound of increase in DM intake
(1.5 pounds in Murphy equation). Davis et al., (2)
demonstrated a decrease in water consumption as
ration moisture content increased (Table 2).
Table 2. Effects of diet moisture content on DM intake and
source of water Intake.
Moisture content of diet (%)
Intakes 30.7 42.6 48.3 53.6
DM, Ib/day 43.3 40.0 37.6 32.6
Drunk 17.8 15.7 13.8 11.2
In feed 3.7 5.5 5.3 4.8
Total 21.5 21.2 19.1 16.0
Diets high in salt, sodium bicarbonate and
protein increase water intake. Also, diets high in
fiber may increase water intake by increasing the
losses of water in the feces.
Environmental temperature and water
temperature affect water consumption. Research
at Texas A & M (4) has shown cooling water from
between 68F and 86F to below 50oF decreases
intake but helps reduce heat stress during summer
months. A 1987 summer study, (8) showed chilled
drinking water (86F vs. 500F) significantly
increased dry matter intake and milk yield but had
only a slight positive effect on water intake.
Florida research has not found benefit from cooling
drinking water below the 75-80oF temperature of
the well water (1).
Water quality is important for maximum
performance of dairy cattle. It is estimated that 40
percent of the nation's livestock are watered from
streams, lakes, springs and impoundments. One
should not assume cattle are resistant to the spread
of bacterial diseases through the drinking of
Contamination of the water supply from
barnyard drainage and the presence of nitrates,
pesticides, algae and certain parasites such as
tapeworms and liver flukes add additional stress to
cows. Also, water palatability and odor as well as
high levels of minerals such as iron and sulfur
Water quality is measured by laboratory tests
performed on water samples drawn periodically
from the water supply. This information and/or
service may be available through your regulatory
agency or health department. If not, consult with
your county Extension agent, regulatory agency or
service representative about private or commercial
laboratories. Basically, the first laboratory tests
should include items listed in Table 3.
The chemical tests are a measure of the presence
of elements in the water from the earth's soil,
sediments and rocks. The elements may be in the
form of individual ions, pairs of ions or complexes of
several ions. The principal elements are hydrogen,
sodium, potassium, magnesium, calcium, silicon,
chlorine, oxygen, sulfur and carbon.
Table 3. Laboratory analysis useful in determining water quality.
Chemical Bacteriological Physical
1. pH 5. Calcium and magnesium 1. Total bacterial plate 1. Color,
2. Hardness 6. Sulfate and chlorides count odor,
3. Total dissolved 7. Iron and sulfer 2. Coliform turbidity
solids presence or absence
4. Nitrates and
The pH is a measure of acidity or alkalinity.
Water below pH 7 is acidic and water above pH 7 is
alkaline. Water consumed by cattle may range from
6.5-8.0. The pH influences taste, corrosivity and
efficiency of chlorination and other treatments.
Water "hardness" is generally expressed as the
sum of calcium and magnesium concentrations.
Other cations such as zinc, iron and manganese
may also contribute. Hardness of water is
classified as shown in Table 4.
Hardness is not really a problem in livestock
drinking water. The concentrations of toxicants in
the water are important. Hardness is measured by
the amount of soap needed to develop a permanent
Table 4. Classification of water by hardness content.'
'Natl. Acad. Science, Washington, D.C. 1980.
Total dissolved solids (TDS)
The TDS is a measurement of all constituents
dissolved in water. The principal inorganic anions
dissolved in water include carbonates, chlorides,
sulfates and nitrates. The principal cations are
sodium, potassium, calcium and magnesium. For
fresh water, salinity and TDS are equivalent. TDS
provides a useful index to the suitability of a water
supply for livestock use.
Growing cattle tolerate concentrations of salt in
water up to 1 percent; higher levels are toxic. As
the concentration of salt increases to 1.2 percent,
the intake of water increases. Concentrations
higher than 1.2 percent reduce the water intake.
Nitrates and nitrites
The nitrate content in water in Florida has been
less of a problem than that occurring on occasion in
forages. Both a water and a feed analysis is needed
to determine the total nitrate intake. Corrective
action is needed where nitrates-nitrites are
occurring in water and should begin with
determining the source of the nitrate. The lab
results may be reported as potassium nitrate
(KNO,), or as nitrate-nitrogen (NO,-N).
Nitrate toxicity or poisoning is generally a result
of eating forages high in nitrate content. While
nitrates themselves are not toxic, nitrites are toxic.
Table 5. Two classifications on quality of water in terms of total dissolved solids (TDS).
Description Concentrations of TDS (mg/liter)
Fresh water 0-1,000 No problems
Brackish water 1,000-10,000 Risk
Salty water 10,000-100,000 Unsafe
Brine > 100,000 Unsafe
Slightly saline 1,000-3000 Satisfactory
Moderately saline 3,000-5,000 Possible diarrhea
Very saline 5,000-7,000 Avoid usage
Approaching brine 7,000-10,000 High risk
> 10,000 Unsafe
Table 6. Levels of nitrate In water and expected response.
Nitrate in water (ppm)'
'% = 10,000 ppm
Nitrates entering the rumen are converted to
nitrites by rumen bacteria prior to entering the
bloodstream. There the nitrites convert the oxygen
carrying red pigment hemoglobin into a brown
pigment called methemoglobin, which will not
carry oxygen. As the conversion develops in the
bloodstream, the animal shows distress and
shortness of breath. Symptoms of acute nitrate or
nitrite poisoning are:
* labored breathing
* rapid pulse
* frothing at the mouth
* blue muzzle and bluish tint around eyes and
* chocolate-brown colored blood.
Infusing a bottle of 4 percent methylene blue
solution is the primary therapeutic treatment.
When the conversion reaches 70 percent to 80
percent, the animal usually dies from asphyxiation.
Nitrate toxicity from water is most likely to occur
when animals drink from ponds or ditches that
have been contaminated from run-off coming from
heavily fertilized fields.
Since not all laboratories report results of
nitrates and nitrites the same, the conversion
factors in Table 7 may be useful.
Safe if feed is low in nitrates and
Could be harmful over long period of time.
Possible losses, risky for dairy cattle.
Increased possibility of losses, unsafe.
Unsafe. Do not use.
While sulfate guidelines are not well defined,
levels above 500 ppm for calves and 1000 ppm for
cattle may affect water intake. The specific form of
sulfate should be identified since some forms are
more toxic than others. Hydrogen sulfide is the
most toxic form and amounts as low as 0.1 ppm
may reduce water intake. Common forms of sulfate
in water are calcium, iron, magnesium and sodium.
All are laxatives, but sodium sulfate is the most
potent. Cattle tend to become resistant to the
laxative effect over a period of a few weeks. It
appears that iron sulfate depresses water intake
more than the other forms of sulfate.
Contaminants and toxic
It has been recognized for a number of years that
cattle are sometimes poisoned when they drink
lake water invaded by blue-green algae. Six species
of the algae have been identified as potential
causes of toxicity. Cattle should be prevented from
drinking water from lakes or ponds having heavy
Under certain conditions, water may contain
levels of toxic minerals that are potentially toxic to
livestock. More common elements are lead,
cadmium and mercury. Additional elements are in
Table 7. Nitrate and nitrite expressions and conversion factors for converting from one form of expression to another.'
Form A N NO2 NO, KNO, NaNO,
Nitrate-Nitrogen (N) 1.0 3.3 4.4 7.2 6.1
Nitrite-Nitrogen 1.0 3.3 4.4 7.2 6.1
Nitrate (NO,) 0.23 0.74 1.0 1.63 1.37
Nitrite (NO2) 0.3 1.0 1.34 2.2 1.85
Potassium Nitrate (KNO3) 0.14 0.64 0.61 1.0 0.84
Sodium Nitrate (NaNO3) 0.1 6.54 0.72 1.2 1.0
'Form A x factor under form B = Form B.
Table 8. Recommended limits of concentration of some potentially toxic substances in drinking water for livestock.1
Item mg/liter or ppm Item mg/liter or ppm
Upper limit Upper Limit
Aluminum 5.00 Lead 0.10
Arsenic 0.20 Mercury 0.01
Cadmium 0.05 Molybdenum 0.50
Chromium 1.00 Nitrate-N 100.00
Cobalt 1.00 Nitrite-N 10.00
Copper 0.50 Selenium 0.05
Fluoride 2.00 Zinc 25.00
'Nutrients and toxic substances in water for livestock and poultry. National Academy of Sciences. 1974.
Bacteriological and physical
A reasonable effort should be made to provide
animals with a clean and sanitary supply of water
if maximum performance is expected. Several
studies have shown that bacteria such as E. coli
are destroyed by the bacteria population in the
rumen of the cow. Therefore, though determining
the numbers of bacteria such as E. coli in the water
supply is essential for human consumption, it is of
little value for animal consumption.
In summary, water represents a vital part of the
nutrient intake of livestock. In quantity, water
intake is greater than feed intake. Water quality is
important for maximum performance. Likewise,
the temperature of the water affects water
consumption and performance. Cooling the water
temperature in high environmental temperatures
reduces water consumption, but increases
performance. Water troughs should be located in
areas where cows have easy access. High levels of
milk production are dependent on having plenty of
clean, fresh water available. Keeping the troughs
clean so that the cows will be more aggressive in
drinking the water is a recommended practice.
1. Bray, D. R., D. K. Beede, M. A. DeLorenzo, D.
Wolfenson, R. G. Giesy and R. A. Bucklin. 1990.
Environmental modification update. Proc.
Florida Dairy Production Conf., Florida Coop.
Ext. Serv., Univ. of Florida, Gainesville.
2. Davis, C. L., D. A. Grenwalt and G. C. McCoy
1983. Feeding value of pressed brewers grains
for lactating dairy cows. J. Dairy Sci. 66:73.
3. Linn, J. G., S.D. Plegge, D. E. Otterby and S. A.
Hansen. 1987. Water: Quality and importance
of in dairy and beef production. Midwest PMS,
4. Milam, K. Z., C. E. Coppock, J. W. West, J. K.
Lanham, D. H. Nave, J. M. Labore, R. A.
Stermer and C. F. Brasington. 1986. Effects of
drinking water temperature on production
responses in lactating Holstein cows in summer.
J. Dairy Sci. 69:1013.
5. Mineral tolerance of domestic animals. 1980.
Natl. Acad. Science. Washington, D. C.
6. Murphy, M. R., C. L. Davis and G. C. McCoy.
1983. Factors affecting water consumption by
Holstein cows in early lactation. J. Dairy Sci.
7. Nutrients and toxic substances in water for
livestock and poultry. 1974. Natl. Acad. Sci.
8. Wilks, D. L., C. E. Coppock, J. K. Lanham, K. N.
Brooks, C. C. Baker, R. G. Elmore, and W. L.
Bryson. 1988. Response of lactating Holstein
cows to chilled drinking water in high ambient
temperatures. J. Dairy Sci. 71:212(Suppl. 1).
COOPERATIVE EXTENSION SERVICE, UNIVERSITY OF FLORIDA, INSTITUTE OF FOOD AND AGRICULTURAL SCIENCES, John T.
Woeste, director, in cooperation with the United States Department of Agriculture, publishes this information to further the purpose of the May 8
and June 30, 1914 Acts of Congress; and is authorized to provide research, educational information and other services only to individuals and
institutions that function without regard to race, color, sex, handicap or national origin. Single copies of extension publications (excluding 4-H
and youth publications) are available free to Florida residents from county extension offices. Information on bulk rates or copies for out-of-state
purchasers is available from C.M. Hinton, Publications Distribution Center, IFAS Building 664, University of Florida, Gainesville, Florida 32611.
Before publicizing this publication, editors should contact this address to determine availability. Printed 6/91.