Mineral nutrition is very important for successful beef production
because it impacts animal growth, reproduction, milk production and
health. Cattle obtain part of their mineral requirements from forage,
water and protein supplements, but the remainder of their requirements
must be met through mineral supplements.
The big question is: “Which mineral supplement is needed for my
cattle?” Selection of the right mineral is dependent on the geographical
region, forage system, cattle production stage and other factors. Jason
Banta of Texas A&M AgriLife Extension provided some considerations
in mineral supplement selection at the School for Successful Ranching
during the 2019 Cattle Raisers Convention in Fort Worth. The majority of
this article was taken from Banta’s presentation.
Components of a complete mineral supplement include salt (primarily
for its sodium content), macro minerals and trace minerals (also called
micro minerals). The supplement also may contain vitamins A, E and maybe
D. Macro minerals are expressed as a percentage of the diet, whereas
trace minerals are measured in parts per million (ppm) or milligrams per
kilograms (mg/kg). The macro and trace minerals are listed in Table 1.
All mineral supplements are not the same due to differences among
manufacturers. There are variances among formulations as well as mineral
sources. Manufacturer reputation is important. Does it stand behind its
product with good technical service? Is the formulation based on a
solid research program? Some mineral supplements contain palatability
enhancers and some don’t. A mineral supplement should have rain and wind
resistance. It is not desirable for a mineral formulation to turn into a
hard block when it is rained on.
In addition, you don’t want the particles ground so fine that they are easily blown out of the feeder.
Targeted intake varies among mineral products. Previously, it was
generally two or four ounces. Today, most of the formulations have a
target intake of four ounces. An average intake of three to four ounces
per day is acceptable for beef cattle. If targeted intake for a mineral
is not listed on the tag, it is easily determined by the selenium
content. Commonly, 25 to 27 mg/kg of selenium indicates a four-ounce
intake. If the selenium content is 50 to 54 mg/kg, target intake is
approximately two ounces per day.
There are three common mineral supplement formulations available in
Texas. One of the formulations is a high calcium (typically 14% to 18%)
and lower phosphorus (typically 5% to 8%) product.
A second formulation has similar calcium and phosphorus levels, which
are commonly around 12% each or 12% calcium and 10% phosphorus.
The third mineral formulation is suitable for cattle on green winter
pasture (small grains and/or ryegrass) because it contains moderate to
high concentrations of magnesium to help prevent grass tetany. Ensure
that salt is included in the mineral supplement because it is important
for absorption of magnesium by cattle.
Generally, 5% magnesium is adequate to prevent grass tetany problems.
Make sure cattle are eating targeted amounts of minerals because when
magnesium is increased, intake decreases. One manufacturer has been able
to raise the magnesium content to 13% and maintain consumption with a
palatability enhancer.
Additive options
Common additives found in mineral supplements include insecticides,
antibiotics and ionophores. Insect growth regulators are added primarily
for horn fly control. Cattle pass the insect growth regulators through
their digestive tract and excrete it in their feces. Horn flies are
controlled as they hatch in the manure.
Certain mineral supplements contain chlortetracycline antibiotic and
are sometimes used in areas where anaplasmosis is prevalent. These
supplements require a Veterinary Feed Directive, which is a written
statement that authorizes the owner or caretaker of animals to obtain
and use animal feed containing Veterinary Feed Directive drugs such as
antibiotics.
The ionophores — Bovatec and Rumensin — are used in some mineral
supplements. These ionophores are used to increase feed efficiency or
body weight gain by altering ruminant fermentation patterns. Make sure
to follow label directions if using a mineral supplement with an
ionophore. The product may be approved for use in growing cattle, but
not for use in cows.
There is a long list of additives offered for sale that are not
well-researched and have limited or no benefits. Use caution in
accepting claims that are not supported by legitimate research. Also
watch for selective research reporting where partial results are
reported to make the product look better than it is. Ask for research
sources to establish whether the studies were done by qualified and
impartial investigators. Obtain the original research reports to
determine if they support the claims made by the company selling the
product.
Performance of many additives on the market will not justify their cost.
Macro mineral considerations
On native rangeland, mineral concentrations decrease over time in
dormant grass, especially phosphorus and potassium. Rangeland grasses
include species such as big bluestem, little bluestem, Indiangrass and
switch grass. Bermuda, bahia, dallis and old world bluestems, such as KR
bluestem, are examples of introduced grasses. A different mineral
supplement may be required when cattle graze dormant range grasses than
the one fed during the growing season.
A two-to-one ratio of phosphorus to calcium is recommended for beef
cattle diets, but this ratio often is altered by protein and energy
supplements. The ratio is corrected by adding calcium to the feed
supplement when needed. Many people think that high levels of phosphorus
will improve reproduction; however, once nutrient requirements are met,
extra phosphorus will not have any effect.
Many rangeland soils are high in calcium or they overlay a limestone
base. This does not mean, however, that the range grasses take in more
calcium. Bermudagrass averages 0.43% calcium whereas native forages
average 0.48%.
In coastal regions, mineral intake by cattle often is challenging
because of the forage salt content. It is possible to increase intake by
feeding a low-salt mineral formulation such as ADM AMPT-T Low Salt or
Purina Coastal Cattle Mineral. Molasses-based mineral tubs also can
increase mineral consumption.
Milk fever is a disease characterized by reduced levels of calcium in
the cow’s blood. The disease occurs following calving at the onset of
lactation when calcium demand for colostrum and milk production exceeds
the cow’s ability to mobilize it. Increasing calcium content in the
mineral supplement and lowering the phosphorus level can help avoid milk
fever.
Trace mineral considerations
Dietary requirement of copper, zinc and manganese in mineral
supplements is a ratio of 10-30-40, but most formulated minerals have
either 1-4-2 or 1-3-2 ratios. Many products contain considerably more
copper than needed. A few products have amounts of copper that are
concerning because high levels have been reported to reduce average
daily gain. Copper has no effect on female reproductive capability and
probably none on bulls. Zinc is important for ovarian remodeling and
corpus luteum production which is essential for establishing and
maintaining pregnancy. In males, zinc impacts testicular growth.
Manganese possibly affects estrous, but there are no reports of the
mineral affecting reproduction in the male.
A 1,250-pound cow requires about 1.30 milligrams of selenium per day.
The FDA limit for feeding selenium is three milligrams per day, which
is about 2.31 times the nutritional requirement for cattle. Toxicity
could result from cattle obtaining selenium from multiple sources in
amounts that raise their intake well above requirements.
Preferred forms of iodine in mineral supplements are calcium iodate
and EDDI, an organic form. Too much calcium iodate in a supplement has
been reported to reduce weight gain and feed intake. Don’t use potassium
or sodium iodate, because they are less stable than calcium iodate and
EDDI.
Vitamin considerations
There are two types of vitamins: water soluble and fat soluble. The B
vitamin complex is water soluble and vitamins A, D, E and K are fat
soluble. Vitamin A deficiency can occur during winter and drought, but
when cattle are grazing green grass, they get plenty of vitamin A.
Symptoms of Vitamin A deficiency include birth of dead or weak calves,
frequent occurrence of retained placentas and impairment of sperm
production. To avoid vitamin A deficiencies, make sure it is in the
mineral supplement when green grass is not available.
When selecting a mineral supplement, it is wise to consult a
qualified animal nutritionist for help in matching the right product to
your situation.
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Via Source
The Eagle |
Extra good: Which mineral supplement is needed?
