Cattlemen, researchers, veterinarians and nutritionists have
known for years that the health of an animal is closely tied
to the nutritional plane the animal is on. Animals who live
with substandard nutrient intake are commonly seen to have any
number of complications to overall healthfulness, having a greater
problem with resistance to disease and in fact, simply maintaining
a normal, productive existence.
An area that has gained quite a bit of attention over recent
years is the relationship of mineral nutrition in this picture.
Feeding of minerals, while generally accepted as necessary,
is probably one of the most misunderstood components of a sound
cattle production system. As you go across the country and talk
to producer after producer, you normally find that they will
have some type of a mineral program. These programs
will be as diverse as stars in the sky and unfortunately in
many cases completely unsuitable for what the cattleman needs.
In many cases this is true regarding any component of their
nutritional program but it seems especially applicable to mineral
supplementation. It is vitally important for cattlemen, whether
they are commercial or purebred producers, stocker cattle operators
or feedyard managers to develop and adopt a sound mineral program
in order to be productive and profitable. To help develop a
sound program for your area contact a nutritionist specializing
in beef cattle, either independent or one affiliated with a
feed or mineral company. You can also talk to your veterinarian
or local extension agent who should be able to give you some
We will discuss here the implications of the producers mineral
program on herd and in following issues continue this discussion
on ways that herd health can be improved by improving nutritional
status or through the use of other tools available in the industry.
Minerals are inorganic materials that are involved in countless
normal metabolic functions in the body. They are vital to everything
from normal bone growth to components of the smallest enzyme
involved in the most minute of physiological processes. A deficiency
of one can create major complications in normal bodily function,
growth or as we are about to see, animal health.
Normally, in cattle diets we consider the macro or major minerals
which include Calcium (Ca), Phosphorus (P), Magnesium (Mg),
Potassium (K), Sodium (Na), Chlorine (Cl) and Sulfur (S). micro
or trace minerals are Cobalt, (Co), Copper (Cu), Iodine (I),
Iron (Fe), Manganese (Mn) Selenium (Se) and Zinc (Zn). The macro
minerals are those which are required in larger quantities in
the body. Dietary requirements are typically measured in grams
per head per day or as a percentage of the diet. Micro minerals
are needed in very small quantities and are measured in terms
of milligrams per heads per day or in parts per million (ppm)
in the diet.
Dietary Sources of Minerals
Over the life of a cow, the majority of her nutrient intake
comes from forages, growing, dormant or harvested and stored.
This is how God designed her and one of the reasons cattle production
is a viable enterprise. In light of this, it is reasonable to
assume that since the majority of the cow's nutrient source
is from forages, a large percentage of the minerals in her diet
are from this source. This is where the complications arise.
Forages are highly variable in mineral content in general. Throw
into this the effect that previous land use, fertilization,
environmental conditions, stage of production and a host of
other factors have on the mineral availability and a highly
complex feeding/supplementation scenario is created. It is important
that the producer is aware of the strengths and weaknesses in
the mineral component of his forage program and that he build
his mineral program around these circumstances. Additionally,
in many cases, in a given area we may encounter a mineral “deficiency”
that is apparent not so much from the fact that there is actually
a shortage of a given mineral. It may be that there is the existence
of a high concentration of another mineral that competes with
the mineral in question for an absorption site. This, therefore,
creates a deficiency in one mineral simply because not enough
is available to overcome this competition with another. There
are multitude of interactions between the various minerals both
in the digestive tract and in the animal itself.
All this is said to show the importance of the basic mineral
program in the cow's diet and also how complicated it can become.
As discussed originally, the actual premise of this article
is to discuss the interactions of minerals as related to animal
health. The preceding discussion simply set the stage.
Animal Health and Mineral Relationships
Animal health can be described as the maintenance of normal
physiological functions which allow for a productive existence.
A multitude of components must work together to maintain this
“steady state” in the animal. The availability of the mineral
components in the diet is one very important part of this overall
picture. Most significantly the animal's immune system must
be maintained. If the immune system is not functioning she cannot
be resistant to the various pathogens in the environment. Additionally,
without an effective immune system, no amount of vaccination
can compensate for this deficiency.
Minerals are not related only to the immune system. If we
look at normal calf development, a shortage of calcium, phosphorus
and magnesium can lead to impaired skeletal growth and an animal
that is not nearly as efficient as it should be, therefore not
achieving it's genetic potential. Similarly, these minerals
are closely tied to milk production in the cow and can suppress
normal milk production if not found in the diet in sufficient
amounts. Deficiencies in magnesium has long been tied to conditions
such as grass tetany which is a malfunction of the nervous and
muscle system. More recent research has shown interactions of
calcium and phosphorus in this condition as well. Potassium,
Chlorine and Sodium are closely related to movement of water
in and out of the cells as well as transmission of nerve impulse
across the cell walls.
The Immune System
The immune system in animals (and people) is an amazing mechanism
and is quite frankly, not all that well understood. Let's take
a minute to examine this system and it's complexity. The animal
is able to defend itself from infectious microorganisms by employing
three distinct lines of defense. The first and most obvious
defense mechanism includes the skin, the lining of the respiratory
and gastro-intestinal tracts with accompanying mucous secretions
and general body fluid secretions. The skin prevents microorganisms
from entering the body, while secretions of sweat, tears and
oils kill invading disease-causing organisms. Mucous from the
linings of the lungs and respiratory or digestive tracts adhere
to bacteria and also contain some bactericidal compounds.
The second defense mechanism involves two types of white blood
cells. These cells are found in the blood stream and in lymphoid
tissues (thymus, lymph nodes, spleen, bone marrow and areas
of the gastro-intestinal tract lining). When the body is damaged
or invaded, these cells travel to the injured area where they
ingest and destroy alien microorganisms.
Three sub-groups of these white blood cells are produced from
stem cells of the bone marrow. These white cells attack some
parasites and they also inactivate regulatory compounds released
during allergic reactions. Finally, they seek out, ingest and
kill bacteria and are part of the defense system against bacterial
Still a different type of white blood cell invade areas of
infection and actively ingest bacteria, other foreign material
and dead cells. As part of the inflammatory response, these
cells follow the first group into the area of infectious inflammation
and act as a second line of defense. These cells live in the
body a total of about 12 hours. In light of this about 100 billion
must be produced every day. Even a slight inhibition can seriously
degrade the immune system.
Yet another group of white blood cells act as a third line
of defense. The individual cell types are known as T and B cells
respectively. Once these cells make contact with an invading
organism, it becomes "sensitized" to the specific
antigen. The result of this action is a "memory" by
the T cells for this particular antigen so that when encountered
again, a defense mechanism is already intact. An example of
this is the immunization of cattle against Infectious Bovine
Rhinotracheitis Virus (IBRV) at which time the T cells will
produce antibodies that will bind to IBR but not to unrelated
viruses. Once T cells have been sensitized to a particular infectious
organism, they are able to act quickly in the event of a recurrence
of the attack by the particular organism. The B cells act very
The complexity of this system becomes obvious. As with any
type of complex design, biological or otherwise, the increased
intricacy will allow the system to become more easily disrupted
due to any number of internal or external factors. Such factors
may be nutritional imbalances, attack by infectious agents or
any of a host of stress conditions. Thus, every precaution must
be taken to cover as many bases as possible to insure appropriate
nutrients are provided.
Specific Trace Mineral Effects
Two of the trace elements which have been identified to be
critical in the function of the immune system are Zinc (Zn)
and Copper (Cu). Research has repeatedly shown that many of
the important immunological functions discussed above may be
adversely affected when Zn is deficient because of it's critical
role in the metabolism of nucleic acids and protein. A deficiency
in Zn can lead to a deficiency of an enzyme which is then associated
with severe T cell deficiency. The granulocytes from individuals
with Zn deficiency are shown to be limited in mobility and thus
are not capable to move to areas of infection in a timely fashion.
The immune system depends on rapid cell production and movement
when functioning properly, thus the immune system may be adversely
affected during periods of Zn deficiency.
As an aside, dietary shortages are not the only cause of deficiencies.
Body Zn levels have been shown to be affected by various stressors,
including infectious diseases, transportation, environmental
stress, etc., which results in a redistribution of Zn from plasma
to the liver which makes it unavailable for many normal processes.
In a similar manner, recent findings suggest that Cu may also
play an important role in immune function. Cells involved in
the immune response obtained from blood of Cu deficient-calves
had a decreased ability to kill ingested microorganisms in the
laboratory. Copper deficiency has also resulted in decreased
numbers of antibody-producing cells which reduces the ability
to fight off antigens.
These studies and scores similar have shown that the deficiency
of these minerals as well as many others are closely related
to an immune system that does not function properly and therefore
does not fight off infection as it was designed. In many cases
the deficiency of a given mineral may not be directly related
to the functioning of the immune system but may be tied to a
system that must operate in conjunction with it in order to
maintain a normal state in the body. It also becomes obvious
that small discrepancies can have a significant effect on how
the animal's body maintains it's healthfulness.
While the contribution of a mineral program to the bottom
line is not always apparent, the lack of one will soon show
up in terms of decreased production, efficiency and profitability.
It is vitally important to have a sound mineral program in place,
well matched to your operation and forage programs. In many
cases apparent production and health problems are corrected
by simply identifying one or more mineral deficiencies or imbalances.
A small correction can often lead to significant improvements
in your productivity.
Dr. Steve Blezinger is a nutrition and management consultant
with an office in Sulphur Springs, TX. He can be reached at
667 CR 4711, TX 75482, by phone at (903) 885-7992 or by e-mail