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Some minerals, like calcium and
phosphorus, are required in fairly large amounts by the body,
but deficiency is generally not a problem because these
macro-minerals are often present in high levels in many feeds.
Other minerals are needed in very tiny amounts and are thus
called trace minerals, but they are also very important to the
health of the animal. Serious problems can occur if diet is
deficient in these crucial minerals.
If several animals in a herd
experience health problems, poor fertility, poor response to
vaccination, low weight gains or other signs of poor
performance, a trace mineral deficiency may be to blame. A good
way to find out is to have your vet take blood samples, liver
biopsies or urine samples from live animals. This type of
sampling is usually adequate to measure the level of most
minerals in the body, though illness may skew the results.
Diarrhea, acidosis, stress, fever, trauma, etc. can alter the
concentrations of certain minerals in body fluids and tissues.
If you are testing for mineral
deficiencies it is important to test several animals in the herd
and not just a sick one or one that died. Traditional
recommendations were to check 10 animals or 10 percent of the
herd, whichever is the most logical number for your herd size.
But if you only have 20 cows, 10 percent (2 cows) is not an
adequate number; you’d need to test at least 5 or 6 cows. At the
other end of the spectrum, if you can get a good sampling of 10
cows from a 300-cow herd, this might be enough animals to test.
There can be a lot of individual variation in cattle, so you
need to make sure you have enough samples to get a true picture
of the herd’s mineral status.
Selenium Deficiency
The soils (and therefore the feeds) in many regions are low
in selenium, and a few areas have too much. Selenium is a tricky
element in the diet, since cattle can be unhealthy if they don’t
have enough, and unhealthy if they get too much. Selenium is
vital for proper body function, reproduction and a healthy
immune system, but in excess it is toxic—causing loss of tail
hair or even loss of hooves.
Selenium, along with vitamin E,
is crucial for producing an enzyme that protects muscle cells
from damage during exercise, and is important for muscle
function. Much of the U.S. and Canada is deficient in this
important metalloid, and selenium leaches out of pastures and
hayfields that have been irrigated for many years, making the
deficiency more pronounced. Soils in valleys with irritation or
heavy rainfall are often short on selenium, whereas foothills
and uplands in the same region may have adequate amounts.
Selenium deficiencies are common
in parts of 42 states, including the Northwest and northern
California. Some soils are so deficient that supplementation is
always needed, while other areas have adequate amounts, and some
others have areas with toxic concentrations. In these regions
livestock may be poisoned when they eat plants that are selenium
accumulators.
Lack of selenium is much more
common that toxicity, however. Selenium deficiency can lead to a
wide variety of muscle diseases and weakness, reproductive
problems, decrease in fertility, increased susceptibility to
disease, and impaired heart function in young animals—especially
if their dams have inadequate selenium during pregnancy. Calves
may be stillborn or die within a few days of birth. In some
regions, white muscle disease can occur unless the dam, was
supplemented or the calf is given an injection of selenium at
birth. Calves with white muscle disease may be weak, or die
suddenly because the heart muscle is impaired.
Selenium deficiency may
sometimes develop if sulfur or zinc inhibits proper utilization
of selenium. Stockmen need to be careful when adding zinc to
trace mineral supplements, and not overdo it.
Clover and alfalfa don’t pick up selenium as readily as some
other plants. Cattle grazing legume pastures or feeds grown in
soils that contains sulfur may develop deficiency. Fields with
high crop yield, intensive irrigation (that leaches selenium out
of soil) and fertilization (which stimulates plants to grow
faster, with less time to accumulate as much mineral from the
soil) may contribute to selenium deficiency in some crops. The
higher the crop yield, the smaller the concentration of selenium
in each plant. Slower growing plants with less yield per acre or
less hay cuttings per season have time to accumulate more
minerals. When in doubt, have feeds tested.
Copper Deficiency
Low copper levels in cattle can result in many
problems—everything from poor hair coat to reduced weight gains,
impaired immune system, broken bones, or lower reproduction
rates. Often it’s a subtle problem you don’t suspect unless you
check the copper levels in your animals. When the deficiency is
corrected, they do better and have fewer problems.
One of the most visible signs of
copper deficiency is change in hair color. Black animals develop
a red or gray tint and red animals become more bleached and
light colored. The coat becomes dull instead of shiny, and the
animals may be slow to shed in the spring. In young animals,
copper deficiency can result in diarrhea and more incidence of
calfhood diseases, lameness and poor response to vaccination.
Affected animals may have a stiff gait and the ends of the
cannon bones may be enlarged and painful, with sore fetlock
joints. Pasterns may be upright and the calf seems to be walking
on its toes. Bones may be weak and brittle, and easily broken.
Heifers may be late reaching puberty and their fertility may be
impaired, and cows may be slow to cycle after calving.
Cattle may develop severe copper
deficiency due to excess of other trace minerals such as
molybdenum or sulfur. Deficiency may be primary (when there’s
not enough copper in the soil or in plants grown on those soils)
or secondary when other factors prevent utilization of copper.
Some of the elements that bind with copper to prevent its
absorption by the body include molybdenum, iron, zinc, sulfur,
lead and calcium carbonate. In the West, many regions have
problems due to presence of molybdenum. Red clover and other
legumes are some of the plants that seem to accumulate
molybdenum, and this may add to the problem in certain pastures.
This is most common with alkaline soils, since molybdenum uptake
is influenced by the pH of the soil.
Molybdenum is often an issue in
valley bottoms since there’s more of this element in low areas
than on uplands. Copper deficiency is more likely to occur in
animals that graze the valley floor (or eat legume hay) than in
animals grazing high ground or range pastures. When evaluating a
forage sample for copper, always look at the copper to
molybdenum ratio. If forages contains less than 8 to 10 parts
per million of copper, they are borderline deficient. The
problem is compounded when molybdenum levels are in excess of 1
to 3 parts per million or when the copper to molybdenum ratio
falls below 3 (or 4) to 1.
Even if you don’t think you have
a copper problem, it pays to check. Many people think that if
they keep cattle well fed and healthy, they won’t have this
problem. But copper levels in forages can vary from year to
year, depending on weather conditions, soil factors,
fertilization of fields and pastures, etc. Another thing that
makes it difficult to recognize a copper problem is that you
often don’t see any obvious signs (like discolored hair). Cattle
may have subtle symptoms such as more incidence of disease,
increased numbers of animals that develop respiratory problems,
or calves with diarrhea or disappointing weight gains.
Forage samples, blood tests or
liver biopsies can help determine whether there’s a problem.
There are several strategies that can be used to correct a
problem. You can supplement with extra copper in a loose
salt/mineral mix, or individually dose each animal with oral
drenching, copper boluses or injections. Some of the early
copper injection products were notorious for injection site
swellings, but newer products such as Multimin (providing
copper, selenium, zinc and manganese) are less irrigating.
Trace mineral blocks, which some
ranchers rely on, generally do not contain enough copper to
correct any deficiencies. Even a salt/mineral mix is not 100
percent effective because cattle have variable salt intake. Some
animals will consume enough of it but others won’t eat enough,
and some will eat too much and risk poisoning. There’s always
some risk of copper toxicity with long-term
over-supplementation.
It can be a challenge to get
calves to eat enough mineral. Some stockmen think that if the
cows are eating it the calves will be ok, but minerals are not
transferred through the milk very well. Zinc levels in calves,
for instance, often drop dramatically after they are born. To
make sure all calves have adequate trace minerals, some stockmen
give each calf an injectable product before the grazing season.
Even if calves have adequate
levels of copper, zinc and selenium, stress (such as weaning)
may still cause problems. If calves are short on these important
elements they are even more at risk when stressed. This is often
the cause of big “wrecks” at weaning. Even if they don’t get
sick, they may not gain as well as they should. They may also be
at risk for “silent pneumonia” which will lower weight gains.
Iodine Deficiency
Iodine is another trace mineral that is very important, yet
toxic if consumed in large amounts. Most of the iodine in the
body is in the thyroid gland; it regulates metabolism and the
rate at which the body converts simple compounds from food into
energy and building blocks for body cells, and the rate at which
the body breaks down and eliminates waste materials.
Iodine-containing hormones influence metabolism, the birth
process, and ability of newborn calves to withstand cold stress.
Iodine deficiency results in
enlarged thyroid gland (goiter), seen as a lump on the underside
of the neck. Iodine deficient cows may be infertile or give
birth to hairless, weak or stillborn calves. Bulls may have
lower fertility. Many areas of the U.S are deficient in iodine,
so this important trace mineral is often added to protein
supplements, salt mixes and salt blocks.
Trace minerals are the very
important but unsung heroes in keeping cattle healthy and
performing optimally. Working with a cattle nutritionist to
develop a mineral program specifically tailored to your region
and ranch and your own herd’s needs—and working with a
veterinarian if you suspect that health issues may be due to
deficiency problems—can have a huge impact on your profit or
loss when raising cattle.
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