Cow/Calf Mineral Supplementation
Lance Kennington, PhD
CHS Nutrition, Sioux Falls, SD
Introduction
Various mineral elements are needed by animals to support life.
These minerals are essential to certain physiologically important
systems within the body and can only be provided through the diet.
If not provided in the basal ingredients of the diet (for example,
hay, grass, grains or water), supplementation of these minerals
is required. This concept is particularly important in the third
trimester of pregnancy and through rebreeding as range forages will
be deficient in some minerals.
Minerals are characterized as either major (macro) minerals or
trace (micro) minerals. The major minerals refer to those minerals
needed by the animal in larger amounts and they include calcium,
phosphorus, potassium, magnesium, sulfur, sodium and chorine. Trace
minerals are those minerals needed in smaller amounts and include
zinc, copper, iron, manganese, cobalt, iodine and selenium. Although
trace minerals are needed in smaller amounts than the major minerals,
they are no less important to the physiological well being of the
animal. In other words, deficiencies can result in major problems
for the animal as well as the producer.
Some general physiological functions of minerals include regulating
acid-base balance, providing essential components of cell membranes,
certain proteins and the skeletal system, activating certain enzyme
and immune systems, and as an important component of energy utilization
and growth. Deficiencies of certain minerals can result in severe
physical problems for the animals including poor performance and
immune status. Therefore, providing adequate supplementary amounts
of minerals can increase average daily gain, body condition scores,
and feed efficiency in cattle on range.
The most critical time to ensure cattle are receiving adequate
amounts of minerals is 90 days prior to calving (3rd trimester of
pregnancy ) and throughout lactation and rebreeding. If breeding
cattle are deprived of adequate mineral at this time, energy utilization
will be inhibited and uterine involution may be delayed. Subsequently,
estrus will be suppressed and the cow will not be able to rebreed.
As a result, more cows will come in open at the end of the breeding
season. This will reduce production and economic viability of your
operation.
Major Minerals
Calcium is required in large amounts in the diet of cows because
of the important role it plays in bone and teeth formation. The
Beef NRC (1996) recommends the Ca concentration of the beef cow
diet to be 0.25-0.27% of diet dry matter. Calcium is particularly
important in early lactation because deficiencies may result in
the condition known as milk fever. Milk fever occurs when the cow
is unable to mobilize enough calcium from her bone for milk production.
This lack of mobilization coupled with reduced dry matter intake
results in low blood calcium levels. Although this condition is
rare in beef cattle operations, some incidences have been observed
in cows capable of high milk production. Deficiencies of calcium
in cattle can also lead to osteoporosis, a condition where bones
become weaken due to prolonged withdrawal of calcium deposits from
the bone.
Phosphorus is also important to bone development in the beef cow
and is the major mineral of the energy compound ATP, which is the
molecule that provides energy to the cells. The phosphorus requirement
of beef cows is approximately 0.18-0.22% of diet dry matter (Beef
NRC, 1996). Phosphorus receives high consideration in mineral supplementation
programs primarily due to the fact that most range forages are low
in phosphorus and high in calcium. Due to the fact that most cow/calf
operations utilize forage-based grazing systems, a need to supplement
adequate phosphorus is critical. Since plants receive minerals from
the soil, it is important to be familiar with phosphorus conditions
of your soils. For instance, when soils are low in phosphorus, forage
material will also be low in phosphorus. Therefore, the mineral
provided to your cattle must contain additional phosphorus. On the
other hand, if your soils are sufficient, less phosphorus needs
to be supplemented, saving you money.
Potassium needs of the range animal can usually be met mainly by
the forage consumed. Potassium requirements are approximately 0.70%
of diet dry matter. Potassium functions in the body by activating
transport systems that move nutrients in and out of cells. Potassium
needs are greatest when animals are stressed such as during transport
or high ambient temperatures. The level of potassium following periods
of stress should be increased to replenish potassium levels in the
body.
Magnesium can be deficient in the early spring when lush pasture
growth is utilized by cattle. Providing cattle with additional magnesium
prior to turnout is critical to prevent a condition known as grass
tetany. It is recommended cattle be given additional magnesium 45
days prior to turnout. Grass tetany incidence increases when cattle
are placed on fertilized pastures and when grasses containing high
levels of potassium are fed.
Trace Minerals
Trace minerals are just as important as the major minerals to the
animal but are sometimes neglected in supplementation programs.
Deficiencies in trace minerals in cows can lead to lower reproduction
rates and immune compromised calves. Ensuring cows have adequate
trace minerals status is especially important when producers retain
ownership of calves through backgrounding and finishing. If calves
are deficient in minerals, immune function will not be as strong
and morbidity and mortality rates will be high.
Zinc activates certain enzyme systems in the cow and is particularly
important in immune functions. Zinc has also been implicated as
an important mineral for hoof health. The requirement for range
cows is 30 ppm in the total diet (Beef NRC, 1996). It is important
to remember that zinc and copper are antagonistic to one another.
A zinc:copper ratio of less than 3- 4:1 should be maintained.
Copper is an important part of some enzyme systems as well. Copper
requirements of beef cows are 10 PPM of the diet dry matter (Beef
NRC, 1996). Copper, sulfur and molybdenum can form insoluble compounds
known as thiomolybdates, which prevent the copper from being absorbed
and utilized by the animal. Therefore, it is important that when
grazing cattle in areas with high sulfate containing water and high
molybdenum containing soils that the copper concentration in the
supplement be increased to ensure the cattle are receiving enough
copper. Deficiencies of copper can lead to poor performance, rough
and discolored hair coats in cattle and lower resistance to disease.
Manganese functions in skeletal development and has been implicated
as a contributor in reproductive efficiency. The cow requirement
for manganese is 30 PPM Manganese deficiencies are not common; however
it is important to monitor the diet to ensure adequate levels of
manganese are being fed.
Iron is a component of the protein hemoglobin in the red blood
cells which is responsible for transporting oxygen and carbon dioxide
to and from the cells. The iron requirement of beef cows is 30 PPM
of the diet dry matter (Beef NRC, 1996). Iron oxide, which provides
the red color to mineral, has no value as an iron supplement due
to low digestibility. Therefore, eliminating its use will allow
more space within the formulation to add digestible ingredients.
Selenium is an important element in reproduction and immune functions.
Selenium works in conjunction with vitamin E in reducing damage
to cells caused by substances called free radicals. Low selenium
diets have been involved in low reproductive performance due to
retained placentas. Also, cattle fed low selenium can develop white
muscle disease and have poor immunity due to damage to cell membranes
in the muscle and cells involved in the immune system. The legal
limit for Se supplementation has been set at 0.3 PPM
Iodine requirements of the beef cow are 0.5 PPM Iodine functions
in the thyroid gland and is important in growth and metabolism.
Low iodine intake leads to unthriftiness and poor performance.
Cobalt is not utilized directly by the cow but is needed by ruminal
microbes to synthesize vitamin B 12, which is used by ruminants
to convert propionate to energy. Cobalt needs can be met by feeding
a diet containing 0.1 PPM cobalt.
Vitamins
Vitamins are compounds that are involved in many systems throughout
the body including energy metabolism, reproduction, nutrient absorption
and tissue development and integrity. Vitamins that are needed in
supplementation programs include vitamins A, D, and E. The B vitamins,
and vitamin K are synthesized by ruminal microbes in sufficient
quantities under normal conditions.
Vitamin A enhances immunity and decreases the incidence of reproductive
disorders. Supplementing cows with 40,000 IU of vitamin A 90 days
before and throughout the calving and breeding season can increase
conception rates 10 % and decrease calf morbidity by as much as
50 %. Vitamin D is important in Ca and P absorption from the small
intestine and in bone formation. Normally, vitamin D is produced
when cows are exposed to sunlight. However, supplementing cows with
4,000 IU of vitamin D may be beneficial to replenish stores during
the low sunlight days that are common prior to and following the
calving season. Vitamin is an antioxidant important in decreasing
cell damage by neutralizing free radicals, which are byproducts
of metabolism. Deficiencies of vitamin E can lead to white muscle
disease in calves and decrease immune function due to free radical
damage to immune cells. Supplementing brood cows with 50 IU of vitamin
E prior to calving and throughout the breeding season can help to
alleviate these problems.
Diet Sampling
The easiest way to determine excessive or inadequate mineral content
of the plants in your area is to obtain a representative sample
of the plants your cows are eating and have it tested by a well
respected forage lab. The Nutrition Consultant in your area can then
recommend the mineral product that will best suit your particular
operation.
February 2003 |
