Group Title: Circular
Title: Mineral needs of dairy cattle
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 Material Information
Title: Mineral needs of dairy cattle
Series Title: Circular
Physical Description: 14 p. : ; 28 cm.
Language: English
Creator: Harris, Barney
Adams, A.L ( Amey Louise )
Van Horn, H. H
Florida Cooperative Extension Service
Publisher: Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida
Place of Publication: Gainesville
Publication Date: 1994
Edition: Rev.
 Subjects
Subject: Dairy cattle -- Nutrition -- Requirements   ( lcsh )
Dairy cattle -- Feeding and feeds   ( lcsh )
Minerals in animal nutrition   ( lcsh )
Dairy cattle -- Florida   ( lcsh )
Genre: government publication (state, provincial, terriorial, dependent)   ( marcgt )
bibliography   ( marcgt )
non-fiction   ( marcgt )
 Notes
Bibliography: Includes bibliographical references (p. 10-11).
Statement of Responsibility: B. Harris, Jr., A.L. Adams, and H.H. Van Horn.
General Note: Title from caption.
General Note: "April 1994."
General Note: "First published: April 1980; Revised: March 1994."
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Bibliographic ID: UF00014473
Volume ID: VID00001
Source Institution: University of Florida
Holding Location: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: ltqf - AAA6883
ltuf - AJZ2349
oclc - 30691525
alephbibnum - 001916813

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UNIVERSITY OF

Sr FLOR IDA

Florida Cooperative Extension Service



Mineral Needs of Dairy Cattle'


Circular 468
April 1994


B. Harris, Jr., A. L. Adams, and H. H. Van Horn2


MAJOR MINERALS

Proper mineral nutrition and supplementation is
essential to animal health and high levels of milk
production. A lack of attention to the mineral
content of the total ration frequently leads to
increased disease and reproductive problems.
Likewise, too great an emphasis on mineral
supplements frequently leads to using a variety of
costly supplements with no apparent justification.

Calcium and Phosphorus

Over 70% of the total minerals in the body are
calcium and phosphorus. About 99% of the calcium
and 80% of the phosphorus of the body are present
in bones and teeth. Bone, therefore, not only serves
as an organ of structure, but also as a reservoir of
both calcium and phosphorus.

Calcium and phosphorus are closely related
elements and are laid down in bone in a ratio of 2.2
parts calcium to 1 part phosphorus. This means that
a deficiency or an overabundance of either mineral
could interfere with the proper utilization of the
other. An imbalance of either mineral can cause
them to bind with each other and become unavailable
to the animal. Studies have also shown that phytate
phosphorus, the major form of organic phosphorus


occurring in plants, is generally available to the
ruminant unless the concentration of calcium in the
diet is very high. Utilization of other minerals such as
magnesium may also depend on adequate calcium and
phosphorus nutrition.

The importance of calcium and phosphorus in
dairy rations has been recognized for several years.
For a period of time, more minerals were frequently
added to the ration than needed. With the adverse
publicity about phosphorus getting into lakes and
streams, dairymen are now more concerned about
having an adequate but minimum amount of
phosphorus in the ration. Fecal excretion of
phosphorus does depend on the amount of
phosphorus in the diet, and it has been shown that for
every g/d decrease in phosphorus intake fecal
excretion decreases by 0.55 g/d, while for each g/d
increase, fecal phosphorus increases by 0.8 g/d.

No longer can we consider only the concentrate
and ignore such important feeds as silage, hay and
outside mineral mixtures. Availability of the minerals
in a forage depend on forage type. As an example,
studies have shown that absorption of calcium from
corn silage-alfalfa hay diets was higher than when
alfalfa was fed alone. Although alfalfa is higher in
calcium than corn silage, calcium in alfalfa appears to
resist digestion. True absorption of calcium was
shown to be lower from alfalfa hay and higher from


1. This document is Circular 468, Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida. First
published: April 1980. Revised: March 1994. Publication date: April 1994.
2. Professor, graduate student, and Professor, Department of Dairy and Poultry Sciences, Cooperative Extension Service, Institute of Food and
Agricultural Sciences, University of Florida, Gainesville FL 32611.
The use of trade names in this publication is solely for the purpose of providing specific information. It is not a guarantee or warranty of the products
named, and does not signify that they are approved to the exclusion of others of suitable composition.

The Institute of Food and Agricultural Sciences is an equal opportunity/affirmative action employer authorized to provide research,
educational information and other services only to individuals and institutions that function without regard to race, color, sex, age, handicap,
or national origin. For information on obtaining other extension publications, contact your county Cooperative Extension Service office.
Florida Cooperative Extension Service / Institute of Food and Agricultural Sciences / University of Florida / John T. Woeste, Dean






Mineral Needs of Dairy Cattle


corn silage than the values currently used by the
NRC. True absorption of phosphorus from these
forages was also found to be higher than the values
used currently.

The exact ratio of calcium to phosphorus needed
in the total ration is about 1.6 to 1.0. While
deficiencies and excesses of any mineral should be
avoided, several studies have shown equal
performance with ratios varying from 1:1 to 4:1. In
Florida we recommend a ratio of approximately 1.5:1
to 2:1. High-fat diets increase fecal calcium losses
through the formation of soaps and thus increase the
requirements for calcium. A number of nutritionists
increase the level of calcium in the total ration dry
matter to about 1% when feeding high-fat diets.

Milk fever has not been a problem in Florida
dairy herds receiving rations containing adequate
amounts of phosphorus and calcium. Several studies
have shown that rations narrower than 1:1 and wider
than 2.5:1 tend to increase the incidence of milk fever
when fed during the dry period. It seems only logical
that if such rations fed during the dry period can
reduce the incidence of milk fever, similar rations
would be optimum during lactation.

Vitamin D is associated with calcium absorption
and utilization. Since in the presence of vitamin D,
calcium is absorbed more efficiently, phosphorus is
also used more effectively.

While the bone stores of phosphorus are large, an
inadequate supply of phosphorus in the ration will
soon lead to borderline deficiencies. Such
deficiencies have been identified as reduced appetite,
lowered disease resistance, a decline in reproductive
efficiency, poor feed utilization and increased
incidence of milk fever. Since the two elements are
combined in bone, the mobilization of calcium as a
result of parathyroid gland actions is accompanied by
the incidental mobilization of phosphorus. Therefore,
if calcium is not being actively mobilized from body
stores, the ruminant depends on a daily intake of
phosphorus. Studies have shown that low phosphorus
diets for beef heifers have resulted in decreased bone
density and mineral content.

Calcium and phosphorus are important in several
body functions. Calcium functions in cell equilibrium,
heart beat and muscle contraction, and blood
coagulation. Phosphorus is present in all living cells
of the body as part of many enzyme systems and is
essential in the utilization, transfer and storage of


energy and in protein metabolism. Phosphorus is also
necessary for normal growth and function of rumen
microorganisms, especially cellulose digesters. It is
also a major blood buffer.

Several sources of minerals are available in
formulating mineral mixtures and balancing rations.
Some of the common sources are in Table 1.

Magnesium

Magnesium functions in many important enzyme
systems in the body, as a constituent of bone, and in
muscle contractions. Magnesium in the bone
probably has a structural function as well as a storage
function.

Grass tetany is the common condition associated
with a magnesium deficiency in ruminants. Several
states (Virginia, Pennsylvania, Maryland, West
Virginia, Georgia, Florida, and Alabama) have
reported grass tetany in beef cows on wintering
rations. The condition occurs more frequently in
cattle grazing small-grain pastures in early spring and
is usually related to low levels of blood magnesium.
Supplemental feeding of magnesium to cows grazing
such pastures has been very effective in preventing
the tetany syndrome. Dairy cattle receiving grain in
addition to such pastures have not been reported as
having a problem.

High levels of nitrogen and potassium fertilization
have been associated with a greater incidence of the
tetany syndrome, and appear to make that magnesium
which is present less available to animals.
Apparently, increased production of ammonia in the
rumen reduces magnesium absorption.

Some studies have reported that magnesium has
a relaxing effect on animals. This is probably true to
the extent that symptoms of a magnesium deficiency
include hyper-irritability, increased nervousness,
restlessness, muscle twitching, grinding of teeth and
excessive salivation.

Work at Florida shows a greater need for
magnesium than suggested in the 1989 NRC Update
(Table 2). Supplementation of magnesium above
current NRC recommendations (0.2 to 0.25% of DM)
resulted in increased FCM yield. Maximum response
to magnesium depended on stage of lactation.
However, early lactation, high-producing cows
produced maximum FCM when 0.45% magnesium
was added to the diet. In general, we recommend the


Page 2






Mineral Needs of Dairy Cattle


Table 1. Some common sources of the major minerals.

Supplement Ca Phos K Mg S Na
---.....---------------- % ----------------

Calcium carbonate 38.0 -- ----
Limestone, ground 33.0 -- -- -
Oyster shell flour 33.0 --- ---
Tricalcium phosphate 38.0 18.0 --- -
Monocalcium phosphate 20.0 21.0 --- ---
Deflourinated phosphate 32.0 18.0 -- ---
Dicalcium phosphate 26.0 18.0 --- ---
Disodium phosphate -- 21.6 -- -
Salt (NaCI) -- --- 39.3
Steamed bone meal 28.0 14.0 -
Sodium bicarbonate (NaHCO) --- -- --- --- 27.4
Diammonium phosphate1 -- 20.0 --
Monoammonium phosphate2 --- 24.0 --- ---
Monosodium phosphate -- 25.0 -
Sodium3 Tripoly phosphate -- 25.6 --- --
Biofos 18.0 21.0 --
Dyna-K --- -- 50.5 -
Dynafos3 22.0 18.5 -- -
Dynamate --- --- 18.5 11.6 22.3 ---
Dufos1.3 (Diammonium phosphate) --- 20.0 --- -
Dikal 213 19.0 21.0 --- -
Magnesium oxide --- --- --- 60.0
Potassium chloride --- --- 52.4 -
1Compound contains 18.0% nitrogen or 112.5 protein equivalent.
2Monoammonium phosphate (monofos) contains 68.75% protein equivalent (11% nitrogen).
3Trade names of products available in abundance in Florida.


magnesium content of the ration be increased from
0.25% to about 0.35% of the ration dry matter during
summer.

Potassium

The third most abundant mineral element in the
* cow's body is potassium. Potassium plays many
important roles in the body, It is involved in several
enzyme systems, influences muscle activity (notably
cardiac muscle), and within the cells it functions (like
sodium in the extracellular fluid) by influencing acid


base balance and osmotic pressure, including water
retention. Potassium is a major mineral component
of milk, and is also excreted in sweat, which makes it
an important consideration in hot climates such as
Florida.

The 1989 NRC standards suggest that the total
ration dry matter for high producing cows should
contain a minimum of 1.0% potassium. Under heat
stress management conditions, work at Florida shows
a greater need for potassium than suggested in the
1989 NRC Update on Nutrient Requirements of


Page 3






Mineral Needs of Dairy Cattle
Table 2. Mineral content recommended in rations for high-
producing dairy cattle (DM)*. NRC (1989).

Mineral Heat stress NRC
conditions (%) (%)
Calcium 0.65- 1.00 .66
Phosphorus 0.42 0.45 .41
Magnesium 0.30 0.40 .25
Potassium 1.20-1.50 1.00
Sulfur 0.20 0.25 .20
Sodium 0.40 0.60 .18
Chlorine 0.25 0.40 .25
*DM = dry matter


Dairy Cattle. Cows receiving higher levels of
potassium (1.5% dry matter) and sodium (0.5% to
0.6% dry matter) produced two more pounds of milk
and appeared less heat stressed on hot days.

Most rations appear to meet minimum potassium
requirements. Some ingredients, however, such as
brewers' grain, are notably low in potassium. Dairies
using large quantities of wet brewers' grain or other
feeds low in potassium should consider
supplementation. Most forages are quite high in
potassium.

Potassium has been linked to milk fever. High
levels of potassium in the diet of dry cows has been
related to increased incidence of milk fever. It is
recommended to limit the intake of these minerals
during the dry period.

Non-specific deficiency symptoms, including slow
growth, reduced consumption and efficiency, stiffness
and emaciation, have been reported.

Sulfur

Sulfur is an important element in the synthesis of
protein because two important amino acids,
methionine and cysteine, contain sulfur. These two
amino acids are prominent in protein structure and
proteins are involved in practically all body processes.
In ruminants, sulfur makes up about 0.15% of the
body tissue and about 0.03% of milk.

Sulfur is directly related to protein and nitrogen
utilization in the ruminant. It is now generally agreed
among researchers that the dietary N:S ration should


Page 4


be about 10:1 for dairy cattle. However, basing sulfur
supplementation on nitrogen:sulfur ration alone is not
enough. Diets high in fiber and low in nitrogen
should balance sulfur according to total sulfur content
of the ration. To meet this requirement, a complete
feed (90% dry matter) containing 13% crude protein
should contain about 0.2% sulfur. Sources such as
sodium sulfate, potassium sulfate, magnesium sulfate,
ammonium sulfate and calcium sulfate are effective in
meeting the requirements. Ruminant animals have an
advantage over other animals as they have the ability
to also utilize inorganic sulfur because of microbial
reduction in the rumen. Methionine and sodium
sulfate are utilized more efficiently than elemental
sulfur. Retention studies show that elemental sulfur
and sodium sulfate are retained about 38% and 80%
as well as sulfur from methionine.

Sulfur is an important anion for close-up dry cows
in the prevention of milk fever. Maximum sulfur
allowance during the dry period should be between
0.40 and 0.50% of the ration dry matter.

A number of indicators of sulfur deficiencies have
been reported. These symptoms are reduced feed
intake, slower gains, dullness, lower digestibility, and
reduced milk production.

Sodium Chloride (Salt)

Supplemental salt is needed in all current dairy
cattle rations fed in Florida. It is usually added as
trace mineral (TM) salt or as a packaged, complete
mineral in the ration rather than feeding free-choice.
A concentrate should contain about 1% TM salt (up
to 1.5% with high silage rations) and a complete feed
0.5 to 1.0%. Mixing salt with the other ration
components takes advantage of its condiment qualities
and assures adequate intake of salt. Dry cows and
heifers should have free access to salt and other
needed minerals when grain consumption is limited.
Salt intake to heavy springers should be limited or
blended with the ration to prevent udder edema. If
udder edema is a problem, reduce the sodium and
potassium content of the ration. Since pasture
forages are high in potassium, prepartum cows may
need pasture restricted.

Sodium functions in maintaining body fluid
balance, osmotic pressure regulation, and acid-base
glucose and for amino acid transport and is a
controlling factor in nerve transmission. Chlorine is
a factor in extracellular fluid. It functions in
maintaining the acid-base balance, in osmotic






Mineral Needs of Dairy Cattle


* regulation, and in the formation of hydrochloric acid
that is important to digestion in the abomasum.

The chlorine content of feedstuffs is quite
variable. When sodium is supplied in the form of
sodium bicarbonate or a similar source of sodium, it
may be necessary to add a source of chlorine to meet
the chlorine requirement. Salt is generally the
cheapest source of chlorine. Coppock et al. (JDS
62:723) have suggested that a diet of 0.18% chlorine
is adequate for lactating dairy cows. The NRC (1989)
has recommended 0.18% sodium and 0.25% chlorine
to be included in the total ration dry matter. Work at
Florida by Beede shows a greater need for sodium
than suggested in the NRC update, especially under
heat stress conditions. As a result of the Florida
Studies, we recommend the total diet dry matter
contain 0.3 to 0.4% sodium under normal Florida
conditions and 0.5 to 0.6% under heat stress
conditions.

Salt deficiency causes an intense craving for salt,
lack of appetite, poor growth, haggard appearance,
lusterless eyes, a rough haircoat and lowered milk
* production. Recovery is rapid with the addition of
salt to the diet.

TRACE MINERALS

The addition of trace minerals to dairy cattle
rations is usually considered to be good nutritional
insurance. The question that arises, however, is



Table 3. Trace mineral needs of high-producing dairy cattle
(NRC 1989),

Total Ration
Mineral DM Basis
Iron 50.0 ppm
Manganese 40.0 ppm
Copper 10.0 ppm
Zinc 40.0 ppm
Cobalt .1 ppm
Iodine .6 ppm
SSelenium .3 ppm
DM = Dry Matter


which trace minerals to add and how much of each
mineral? The trace minerals as recommended in the
1989 NRC update are shown in Table 3.

Dairy animals need trace minerals only in very
small quantities. For this reason, salt is sometimes
used as a carrier for all the trace minerals.

Trace minerals should not be added to dairy
rations indiscriminately. Many rations will contain
adequate levels without their addition. If a trace
mineral problem is suspected, have your ration tested
and make adjustments in the mineral mixture
accordingly. Too much of a particular mineral could
further antagonize the situation.

Iron

The role of iron in the body is mainly as part of
the processes of cellular respiration, as a component
of hemoglobin, myoglobin and cytochrome, and in
certain enzymes. About 60 to 70% of the iron in the
body is found in hemoglobin and 3 to 5% in
myoglobin. Traces of copper are required for the
utilization of iron in hemoglobin formation.

The need for iron in the diet of the adult dairy
cow is estimated at about 100 mg/day. Minimum iron
requirement for healthy dairy calves is about 30 mg
per day. Calf requirements for dietary iron depends
on the iron status of their dam and the calfs body
stores. Calves with high iron stores appear to use
those stores in preference to dietary iron, while those
with lower stores have a higher requirement for
dietary iron. Calves fed an exclusive whole milk diet
(milk is low in iron) will develop iron deficiency
anemia within 2 to 3 months. This practice is
desirable in growing veal calves.

Iron deficiency in most dairy cattle rations has
rarely been observed. Deficiency symptoms reported
in calves include reduced weight gains, listlessness,
inability to withstand circulatory strain, reduced
appetite and anemia.

Studies at the University of Florida show that iron
was available to dairy cattle from ferrous sulfate,
ferrous carbonate and ferric chloride in decreasing
order of availability. Ferric oxide iron was only about
12% as available as the iron from ferric chloride.

Iron deficiency seldom occurs in older dairy cattle
unless as a result of severe loss of blood caused by
parasitic infestations, injury or disease.


Page 5






Mineral Needs of Dairy Cattle


Manganese

Manganese is needed in the body for normal bone
structure, for reproduction and for the normal
functioning of the central nervous system. It is found
stored primarily in the liver and kidneys. Its functions
are believed to be in the activation of several
enzymes.

Studies with dairy cattle indicate that 40 ppm of
manganese in the ration would appear to meet the
requirements with a margin of safety. Most dairy
rations contain levels of manganese in excess of the
suggested requirements. This is especially true where
forages are available. Excessive amounts of
manganese in the diet increase blood lipids and
cholesterol and change the composition of fatty acids
in the blood, liver and heart which could affect their
normal function.

General symptoms of manganese deficiency
include impaired growth, skeletal abnormalities,
disturbed or depressed reproductive function, nervous
disorders of newborn, and defects in lipid and
carbohydrate metabolism.

Copper

Copper is essential to the activity of certain
enzymes and, along with iron, is necessary for the
synthesis of hemoglobin. It is also an important
element for normal immune function. Low copper
status may contribute to increased susceptibility to
infections such as mastitis. Studies have shown that
liver copper stores decrease dramatically in late
pregnancy, and reach their lowest point five weeks
prior to calving.

A variety of copper deficiencies have been
reported, including anemia, retarded growth rate,
failure to fatten, loss of body weight, diarrhea, and
depigmentation of hair. A characteristic of copper
deficiency is a swelling of the ends of the leg bones
above the pasterns.

A recent study in Florida showed that 11% of
animals on nine dairies were deficient in copper,
while 52% had marginal copper status. Only 38% of
the cattle had normal copper levels. According to the
study, heifers and dry cows in particular had marginal
or deficient copper levels in their blood and livers.
Some Florida soils are high in molybdenum which is
a copper antagonist.


Most data indicate that rations containing 10 ppm
of copper are adequate. In areas where rations may
be fairly high in molybdenum and sulfate, the copper
requirement may be increased two-fold.

Zinc

Zinc is closely associated with a number of
enzymes in the body and is a component of the
enzyme carboxypeptidase and the hormone insulin.
It appears that zinc is required for normal
mobilization of vitamin A from the liver. This is
verified by the fact that skin lesions and corneal
changes in zinc deficient animals are similar to those
occurring in animals deprived of vitamin A. In calves,
a zinc deficiency has resulted in leg and bone
disorders, parakeratosis, impaired vision, and rough
and thickened skin.

Zinc deficiencies reported are similar to many
other nutrient deficiencies. This observation indicates
that zinc is probably involved in the metabolism of
one or more nutrients. A number of sources of zinc
are available.

Supplemental zinc in organic form has often been
beneficial in prevention of, and as a therapeutic aid
to, hoof problems of dairy cattle and of foot rot. The
role of zinc in maintaining skin tissues and the
inflammatory response is probably responsible for this
effect.

Cobalt

Cobalt is a component of vitamin B12 and
therefore affects blood formation. A nutritional
anemia in cattle and sheep living in cobalt-deficient
soils has successfully been treated with cobalt.
Microorganisms in the rumen of these animals utilize
cobalt to synthesize B12.

Adding cobalt and copper to the diet of ruminants
has been shown to increase rumen microbial activity
and enhance digestion of some forages. A general
recommendation for ruminants is 1 mg per day per
1000 lbs body weight. Converted to ppm, a total level
of 0.1 to 0.15 ppm in ruminant rations should be
adequate to prevent any possible cobalt deficiencies.

Cobalt carbonate has been reported to be a good
source of cobalt. Other sources are cobalt sulfate and
cobalt oxide.


Page 6






Mineral Needs of Dairy Cattle


W Iodine

The primary physiological requirement for iodine
is the synthesis of hormones by the thyroid gland that
regulate energy metabolism. Since iodine functions as
a part of the hormone thyroxine and thyroxine is
produced by the thyroid gland, a deficiency of iodine
causes an enlargement of the gland. Birth of goitrous
calves which are sometimes weak or dead and may be
hairless is a sign of borderline or definite dietary
iodine deficiency even though the cows may appear
normal. Milk iodine levels reflect the cow's iodine
status. Goiter may develop in nursing calves as a
result of an iodine deficiency in the cows' diet.

A relationship between thyroid activity and
reproductive performance has been suggested.
Tennessee workers have reported an improvement in
conception rate of repeat-breeder cows by treating
with organic iodine 8 to 12 days before the onset of
estrus. Also, in one field study the number of
retained placentas and irregular breeding intervals was
reduced when iodine was added to the ration. Similar
* results have been reported in Maryland.

The requirement for iodine as recommended by
the NRC is 0.6 ppm of the ration dry matter. Iodized
salt should contain about .005 to 0.1% iodine.
Complete feeds (with CSH, etc.) containing 1% salt
that contains .01% iodine in the trace salt will contain
1 ppm in the finished feed. Therefore, salt containing
.005% to .01% iodine added to complete feeds at the
rate of 1% (20 Ib/ton) will meet the nutritional
requirements of dairy cows for iodine.

Iodine toxicity can be a problem where herds are
fed too much iodine to prevent diseases such as
footrot and lumpy jaw. Symptoms observed and
reported are tearing eyes, nasal discharge, bulging
eyes, nervousness, rough hair coat including loss of
hair, sluggish movement, reduced appetite, tracheal
congestion that causes coughing, and lowered milk
production. Recovery from iodine toxicity is rapid
after the excess iodine is eliminated from the diet.

Excessive levels of dietary iodine result in high
blood iodine, excretion of large amounts of iodine in
urine and feces, and increased secretion into milk.
* The Food and Drug Administration (FDA) is
concerned with high levels of iodine consistently in
milk.


Selenium

The importance of selenium in cattle feeding is
continuously being evaluated and has been considered
an essential element for cattle since 1957. The
current recommendation listed by the NRC is 0.3
ppm. However, in 1993 the FDA lowered the
maximum selenium allowance from 0.3 to 0.1 ppm,
citing concerns over environmental impact of
selenium excreted by animals.

The classic deficiency symptoms reported in the
literature for livestock are white muscle disease in
calves, stiff lamb disease, and muscle degeneration in
pigs, and is related to reproductive problems in cattle
such as retained placenta. Selenium plays a key role
in the immune system, protecting white blood cells
from the toxic by-products known as oxidants -
resulting from the destruction of pathogens. Both
selenium and vitamin E are necessary to prevent
white muscle disease and for normal immune
response in cattle.

Work at Ohio State University showed that
retained placenta may be controlled in herds with a
high incidence of this problem by either an
intramuscular injection of 50 mg of selenium as
selenite and 680 IU of vitamin E given approximately
21 days prepartum; or by feeding a total intake of 1.0
mg of selenium per day as selenite during the last 60
days of the dry period. Since protein feeds are
natural sources of selenium, dry cow rations low in
protein may lead to increased incidence of retained
placenta.

There are many factors which are related to
retained placenta. Disease, stress, and nutrition are
considered the primary factors related to a high
incidence of this problem. In many herds where the
incidence is high, the cause or causes need to be
determined and eliminated. Diseases should be
eliminated by developing a good herd health program
with the cooperation of your veterinarian.

Nutritional deficiencies of vitamin A, iodine,
selenium, phosphorus and calcium increase the
incidence of retained placenta. Nutritional
imbalances which have been reported to increase the
incidence include an imbalance of calcium and
phosphorus and to some degree their ratio.
Generally, the ration is of less importance so long as
each is adequate. We recommend a ratio range of
1.5:1 to 2:1 of calcium to phosphorus in the final
ration.


Page 7






Mineral Needs of Dairy Cattle


Other conditions associated with retained placenta
include infections, difficult calving, and hormonal
deficiencies. Also, retained placenta occurs more
frequently during the colder months and less during
the warmer months. As usual, high-producing cows
seem to be more susceptible than low-producing
cows.

There are three sources of selenium available,
and selenium concentration varies from one source to
another depending on water content. The most
concentrated source of sodium selenite (Na2SeO4)
contains 41.8% selenium while the next most
concentrated form (Na2SeO4*5H20) contains 30%
selenium. The addition of 307 mg of sodium selenite
as Na2Se4*5H2O or 220 mg of sodium selenite as
Na2SeO4 per ton of feed would provide 0.1 ppm of
selenium in the ration.


The selenium level of the hair of cattle is a useful
indicator of both selenium deficiency and selenium
toxicity. Most studies have shown that cattle with hair
values consistently below 0.25 ppm probably need
supplementation and that over 5 ppm may lead to
clinical signs of selenosis.

Selenium toxicity is common in certain parts of
the United States where soil selenium concentrations
are high. In Florida, however, soil selenium is low
and selenium concentrations in Florida grown forage
is not a concern. Excessive ingestion of selenium
causes alkali disease, sometimes called blind staggers
and bobtailed disease due to the loss of the hair from
the switch of cattle. Acute selenium poisoning is
characterized by dullness, slight ataxia, rapid weak
pulse, labored respiration, diarrhea, a characteristic
posture, and death due to respiratory failure. Less
acute signs include abnormal hoof growth and hair
coat. Alkali disease has been observed in animals
consuming diets with selenium concentrations in the
range of 5 to 40 ppm.

Table 4 contains the mineral composition of
several common feed ingredients used in Florida.
Table 6 at the end of this publication lists mineral
compounds commonly used as sources of essential
trace minerals.

Trace minerals are required in minute amounts
and therefore difficult to justify mixing by an
individual for feeding to a given dairy herd. A few
dairymen do, however, have complete and/or trace
mineral mixtures formulated to their specifications.


In doing so, one must remember that mineral
mixtures will need to be updated from time to time to W
keep pace with major ration ingredient changes. This
is especially true with the balance of calcium and
phosphorus.

Generally, about 60 to 1000 lbs of a complete
mineral is needed per ton of finished feed on a DM
basis. The ratio of calcium to phosphorus needed in
the mineral mixture varies considerably depending on
the ingredients used in the feed.

Blood is sometimes used to determine the
adequacy or deficiency of a mineral compound in the
ration. The normal values of certain mineral
elements reported in bovine blood are: calcium, 10
mg %; phosphorus, 4-6 mg %; and magnesium, 2-4
mg %.

Weight equivalents (Table 5) and conversion
notes are given below for your consideration.

Chelated Minerals

The term chelate comes from the Greek meaning
crab's claw. The term is applicable since the mineral
is surrounded by a molecule which holds the mineral
in a claw-like manner. Chelating and sequestering
agents which occur as natural compounds in feedstuffs
may increase or decrease mineral absorption and
utilization. Commercially-produced chelated minerals
may have greater bioavailability than nonchelated
forms of the same mineral, especially in nonruminant
animals such as the chick and pig, because they are
more soluble at the site of absorption. In ruminant
animals, chelated minerals have been of less concern
due to the rumen microbes and their involvement in
digestion.

Currently, several minerals are available in
chelated form. Among these are magnesium, copper,
cobalt, iron, manganese and zinc. Under certain
conditions ruminants have responded to mineral
chelates, but it is not clear from the studies reported
whether this response is due to the form of the
mineral or simply to increased mineral consumption.
Zinc-methionine may have an advantage in treatment
of footrot and its prevention in problem herds, as well
as improved immune response in cattle. However,
there is limited research to support these conclusions.
Copper availability may be low for ruminants in areas
where molybdenum and sulfur are high. Providing
copper in a form that does not interact with these


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Mineral Needs of Dairy Cattle


Table 4. Mineral element content of selected ingredients (as fed).

Ca P Mg K S Na Cl
Feedstuff (%) (%) (%) (%) (%) (%) (%)

Alfalfa, all analysis 1.30 0.20 0.24 2.20 0.24 0.13 0.45
Bahiagrass hay 0.30 0.20 0.15 0.90 0.20 0.30 0.15
Bermudagrass hay 0.30 0.18 0.15 0.90 0.26 0.30 0.15
Brewers' grain, dried 0.27 048 0.12 0.08 0.34 0.20 0.15
Citrus pulp 1.50 0.12 0.12 0.09 0.07 0.07 0.00
Corn, grain 0.02 0,31 0.09 0.26 0.12 0.03 0.05
Corn gluten feed 0.30 0.75 0.29 0.54 0.22 0.13 0.20
Corn silage (30% DM) 0.10 0.07 0.05 0.27 0.04 0.01 0.00
Cottonseed meal 0.20 1.20 0.56 1.40 0.40 0.03 0.03
Cottonseed hulls 0.10 005 0.13 0.76 0.15 0.02 0.02
Distillers grains 0.09 0.36 0.06 0.18 0.45 0.09 0.07
Hominy feed 0.05 0.55 0.23 0.60 0.03 0.08 0.05
Malt sprout pellets 0.25 0.70 0.18 0.21 0.20 0.90 0.15
Milo, grain 0.03 028 0.20 0 35 0.10* 0.01 0.09
Molasses, cane (muck) 1.00 0.08 0.50 4.00 0.90 0.20 0.30
Oats. grain 0.05 0.35 0.16 0.30 0.21 0.07 0.10
Peanut meal 0.20 0.60 0.24 1.15 0.29 0.40 0.02
Rice bran 0.08 1.40 0.95 1.74 0.18 0.03 0.07
Soybean hulls 0.40 0.15 0.14 0.72 0.09 0.04 0.00
Soybean meal 0.20 0.60 0.25 1.80 0.33 0.03 0.07
Wheat, grain 0.50 0.40 0.10 0.50 0.20 0.04 0.07
Wheat middlings 0.15 0.90 0.50 1.20 0.15 0.17 0.03
*Estimated values.


antagonists would be advantageous, but it is not clear
that copper chelates meet this objective.

While chelated minerals may have a special role
under certain conditions and in future dairy cattle
feeding programs, information presently available
does not consistently show advantages for their
inclusion in the diet. Also, some nutritionists find it
more economical to add more of a nonchelated
mineral rather than use a more bioavailable chelated
mineral.


Feeding Dietary Cation-Anion Rations in the
Prepartum Period

Dietary cation-anion balancing is a new concept
that has received much attention in recent years as a
nutritional tool for reducing the incidence of milk
fever and perhaps retained placenta. Minerals
considered in the balancing concept are sodium,
potassium, sulfur and chlorine. The ration is fed for
about 3 weeks prior to calving. The new concept is
discussed in Fact Sheet DS 86, Dietary Cation-Anion
Balancing of Rations in the Prepartum of Late Dry
Period.


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Mineral Needs of Dairy Cattle


Table 5. Weight equivalents.

1 pound (Ib) = 453.6 grams (gms) = 0.4535 kilograms (kg) = 16 ounces (oz)
1 kg = 2.2046 Ibs, or rounded to 2.2 Ibs = 1000 gms
1 oz = 28.35 gms
1 gm = 1000 milligrams (mg) = 1,000,000 micrograms (/g)
1 mg = 1000 /g = 0.001 gm
1 /cg per gm or 1 mg per kg is the same as ppm (50 mg/kg = 50 ppm)


Conversion Notes

ppm = parts per million (convert to percent)
100 ppm = .0001 or .01%
To convert to parts per unit (as parts per pound),
move the decimal place six places to the left. To
convert to percent, move four places to the left.
Percent means parts per 100 (as the fraction of a
pound per 100 pounds).

Convert 54 ppm to mg/lb
54 ppm = .000054 (must convert to grams and
then to milligrams)
.000054 x 453.6 = 0.02449 grams/pound
.02449 x 1000 = 24.49 mg/pound

Conversion from as fed basis to Dry Matter Basis
(DM)
Example: 3.0% Crude protein + 30% Dry Matter
= 10% CP (DM)

Conversion from dry matter basis to As Fed Basis
Example: 10% CP x 30% Dry Matter = 3.0% CP
As Fed Basis
3.0% CP + 30% Dry Matter = 10.0% CP DM
Basis

Calculate the nitrogen-sulfur ration in a ration
containing 14.4% crude protein and 0.15% sulfur.
Example: 14.4% + 6.25 = 2.3% nitrogen (amount
of nitrogen in protein = 6.25%)
2.3% nitrogen + 0.15% sulfur = 15.3:1.0 ration or
approximately 15:1 ratio.

REFERENCES

Beede, D.K., G.G. Davalos and E.M. Hirchert. 1992.
Comparison of four magnesium oxide sources,
each fed at three dietary concentrations to
lactating cows. Proc. Florida Dairy Prod.
Conference. p.85.


Brondani, A., R. Towns, K. Chou and R.M. Cook.
1991. Effects of isoacids, urea, and sulfur on
ruminal fermentation in sheep fed high fiber
diets. J. Dairy Sci. 74:2724-2727.

Henry, P.C., C.B. Ammerman and R.C. Littel. 1992.
Relative bioavailability of manganese from a
manganese-methionine complex and inorganic
sources for ruminants. J. Dairy Sci. 75:3473

Jenkins, K.J. and J.K.G. Kramer. 1991. Effects of
excess dietary manganese on lipid composition of
calf blood plasma, heart and liver. J. Dairy Sci.
74:3944-3948.

Lopez-Guisa, J.M. and L.D. Satter. 1992. Effect of
copper and cobalt addition on digestion and
growth in heifers fed diets containing alfalfa silage
or corn crop residues. J. Dairy Sci. 75:247-256.

Lough, D.S., D.K. Beede, and C.J. Wilcox. 1990.
Lactational responses to and in vitro solubility of
magnesium oxide or magnesium chelate. J. Dairy
Sci. 73:413-424.

Martz, F.A., A.T. Belo, M.F. Weiss, and R.L. Belyea.
1990. True absorption of calcium and phosphorus
from alfalfa and corn silage when fed to lactating
cows.

McDowell, L.R., J.H. Conrad, and F.G. Hembry.
1993. Minerals for grazing ruminants in tropical
regions. Second edition. Bulletin of the Center
for Tropical Agriculture. University of Florida.
Gainesville, FL.

Miltenburg, G.A.J., T. Wensing, J.P.M. van Vliet, G.
Schuijt, J. van de Brock, and H.J. Breukink. 1991.
Blood hemoglobin, plasma iron, and tissue iron in
dams in late gestation, at calving, and in veal
calves at delivery and later. J. Dairy Sci. 74:3086-
3094.


0


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Mineral Needs of Dairy Cattle


* Morse, D., H.H. Head, and C.J. Wilcox. 1992.
Disappearance of phosphorus in phytate from
concentrates in vitro and from rations fed to
lactating dairy cows. J. Dairy Sci. 75:1979.

Morse, D., H.H. Head, C.J. Wilcox, H.H. Van Horn,
C.D. Hissem and B. Harris, Jr. 1992. Effects of
concentration of dietary phosphorus on amount
and route of excretion. J. Dairy Sci. 75:3039.

Muirhead, S. 1993. FDA stays 1987 selenium
amendment. Feedstuffs. 65:1.

Sanchez, W.K., M.A. McGuire, and D.K. Beede.
1993. Macromineral nutrition by heat stress
interactions in dairy cattle. Unpublished.

Spears, J.W. 1991. Chelated trace minerals in
ruminant nutrition. Prc. of the 2nd Annual
Ruminant Nutrition Symposium. Gainesville, FL:
1-13.


Williams, S.N., T.M. Frye, H. Scherf, M. Frigg, and
L.R. McDowell. 1993. Vitamin E and selenium
for ruminants. Proc. of the 4th Annual Ruminant
Nutrition Symposium. Gainesville, FL:90-108.

Williams, S.N., L.A. Lawrence, L.R. McDowell, A.C.
Warnick and N.S. Wilkinson. 1990. Dietary
phosphorus concentrations related to breaking
load and chemical bone properties in heifers. J.
Dairy Sci. 73:1100-1106.

Xin, Z., D.F. Waterman, R.W. Hemken, and R.J.
Harmon. 1991. Effects of copper status on
neutrafil function, superoxide dismutase, and
copper distribution in steers. J. Dairy Sci.
74:3078-3085.

Xin, Z., D.F. Waterman, R.W. Hemken, and R.J.
Harmon. 1993. Copper status and requirement
during the period and early location in
multiparous Holstein cows. J. Dairy Sci. 76:2711.


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Mineral Needs of Dairy Cattle


Table 6. Mineral compounds commonly used as sources of essential trace minerals.
Molecular Weight Atomic Weight % Element
Source Molecular Compound Element in Physical
Element Compound Formula (grams) (grams) Compound Form

Cobalt cobaltous CoCO3 119.0 58.9 49.5 red
carbonate crystal
cobalt (CoCO3)4 571.9 4 x 58 9 41.2 black
tricarbonyl crystal
cobaltous CoCl2e6H20 238.0 58.9 24.7 red
chloride crystal
cobaltous CoSO4*7H20 281.0 58.9 24.8 red-pink
sulfate crystal
cobaltic (ous) Co304 240.7 3 x 58.9 73.4 black
oxide

Copper cupric CuCO3*Cu(OH) 221.11 2 x 63.54 53.0 green
carbonate 2 crystal
cupric CUC12*2H20 170.49 63.54 37 2 green
chloride crystal
cupric CuSO405H2O 249.69 63.54 25.5 blue
sulfate crystal
cupric CuO 79.54 63.54 80.0 blue
oxide _____powder

Iodine sodium Nal 149.92 126.9 84.6 clear
iodine crystal

potassium KI 166.00 126.9 76.4 white
iodide ____crystal


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Mineral Needs of Dairy Cattle


Table 6. Mineral compounds commonly used as sources of essential trace minerals.

Molecular Weight Atomic Weight % Element
Source Molecular Compound Element in Physical
Element Compound Formula (grams) (grams) Compound Form

Iron ferrous FeSO407H20 278.0 55.8 20.1 blue-green
sulfate crystal
ferrous FeSo4 151.8 55,8 36.7 powder
sulfate
ferrous NH Fe(NH4)2(SO42 392.2 55.8 14.2 fine
sulfate crystal
ferrous Few(C03H120 133,9 558 41.7 powder
carbonate
iron FEO 71.84 55.8 69.9 red-black
oxide powder

Magnesium magnesium MgO 40.32 24.32 60.3 white
oxide Powder
Magnesium MgCO3 84.33 24.32 28.8 white
carbonate crystal
Magnesium MgCl296H20 203.3 24.32 12.0 white
chloride crystal
deliquescent
magnesium MgSO407H20 246.5 24.32 9.9 white
sulfate crystal

Manganese manganous MnCo3 115.0 54.9 47.8 rose-pink
carbonate powder
manganous MnCl2*4H20 197.9 54.9 27.8 rose-crystal
chloride deliquescent
manganous MnSo4*H20 169.0 54.9 32.5 pale pink
sulfate crystal
manganous MnO 70.9 54.9 77.4 green
oxide ____ crystal


Page 13






Mineral Needs of Dairy Cattle


Table 6. Mineral compounds commonly used as sources of essential trace minerals.

Molecular Weight Atomic Weight % Element
Source Molecular Compound Element in Physical
Element Compound Formula (grams) (grams) Compound Form

Potassium potassium KHCO3 100.11 39.11 39.1 clear
bicarbonate crystal
potassium K2CO3 138.20 39.10 28.3 clear
carbonate crystal
potassium KCI 74.55 39.10 52.4 white
sulfate crystal
potassium K2S04 174 26 39.10 22.4 wnite
sulfate crystal

Selenium sodium Na2SeO4 188.95 78.96 41.8%
selenite
sodium Na2SeO41eOH2 369.11 78.96 21.4%
selenite O
sodium Na2SeO3e5H2O 263.03 78.96 30.0% white
selenite to red

Sulfur1 sodium Na2SO4*10H20 322.22 32.07 9.9 clear
sulfate crystal
sodium Na2SO4 142.06 32.07 23.0 white
sulfate powder

Zinc zinc ZnCI2 136.3 65.4 48.0 white
chloride crystal
deliquescent
zinc ZnS04*7H2O 287.6 65.4 22.7 white
sulfate crystal
zinc AnCO3 125.4 65.4 52.1 white
carbonate crystal
zinc ZnO 81.4 65.4 80.3 white
oxide crystal

1Commmonly used sources of iodine are calcium iodate and organic iodine (EDDI). Dynamate is more common source of sulfur.


Page 14




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