Trace Minerals for California Beef Cattle 

University of California, Cooperative Extension

How to supplement minerals

There are numerous methods to provide supplemental trace minerals to cattle. The most appropriate supplement depends on specific circumstances.

Supplemental feeds including blocks and salt mixes which are intended for limited consumption can be effective. Variable intake may present problems with some individual cattle consuming insufficient supplement. Variable intake problems are reduced when formulations are high enough to adequately support the lowest expected intake.

Products administered to individual cattle help to assure adequate supplementation, but are more labor intensive. Injectable products may suffer from short duration of adequate supplementation, requiring re-administration. Rumen-resident boluses administered orally may provide longer-term supplementation but are not widely available for each of the trace minerals.

Often overlooked is merely substituting or providing alternative feed commodities. When cattle are consuming hay that is deficient, a solution might be to purchase hay from non-deficient areas. The new hay source could be feed alone or in combination with the deficient source.

Regardless of the supplement, periodic monitoring must be conducted. Supplements are widely used and generally are safe. However, the potential exists for excess supplementation and toxicity. Excess supplementation can be avoided by periodically monitoring mineral status.


Several methods of selenium supplementation are available including injections, salt mixes and rumen-resident boluses. Fertilization of soil is used in other countries with selenium deficiencies. However, in the United States selenium fertilization is not legal at present.

Several injectable selenium preparations are available for use in beef cattle. Injectable selenium products also contain vitamin E, which works similar to, but not in place of selenium. Most trials indicate vitamin E is not deficient and no response is seen to supplemental vitamin E (vitamin E is also called alpha tocopheral). Animal response as measured by increased whole blood selenium is rapid (within 24 hours) to injectable selenium. Unfortunately, depending on animal age, growth rate and other factors, injectable selenium provides partial selenium supplementation for only 30 to 45 days or less. Generally, younger, faster growing cattle will need selenium by injection every 1 to 2 months. This is often impractical under typical cattle-raising conditions. The minimum injectable-selenium supplementation schedule for Se-deficient adult cows would be before the breeding and calving seasons. Bulls would be supplemented prior to breeding time.

Newborn calves from selenium adequate mothers will also be selenium adequate. However, milk does not contain large amounts of selenium, and fast growing calves will likely need individual selenium supplementation within 3 to 5 months of age. This is most conveniently done, and cost effective, with an injection sometime during the first three months of age. Usually this is done in conjunction with some other calf management procedures.

Rumen-resident boluses containing selenium are an effective method of supplementation for cattle. Approved boluses release up to 3 mg. Se per day. Therefore, if livestock are retained for more than 3-6 months it is generally cost effective to use selenium boluses. The boluses are given orally with a balling gun. Due to their weight the boluses stay in the rumen of cattle, slowly releasing selenium. To be retained the boluses should only be used in cattle with a functioning rumen which generally restricts use to calves at least three (3) months of age and about 300 pounds or more. The boluses provide a convenient, long-term, effective method to supplement selenium to replacement heifers, cows and bulls. Since the operator can be sure each animal has received an adequate dose there is high confidence of adequate selenium supplementation. These boluses have been available in California, but, unfortunately, currently they are not available.

Salt mixes can also be prepared with selenium for free-choice selenium supplementation. Regulations govern the amount of selenium that can be added to salt mixes. Over-the-counter salt mixes are restricted to 120 ppm selenium. The source of selenium is typically sodium selenite.  Field observations with selenium salt at 120 ppm selenium suggest adequate supplementation with salt consumption of at least 1 ounce per head per day. Due to the highly variable consumption of salt and the severe consequences of inadequate selenium, selenium salt mixes require periodic monitoring to evaluate selenium status. Sample salt mixes are provided.


Excess selenium can be harmful. Cattle have a large range of acceptable selenium levels and under ranch conditions are generally not susceptible to excess selenium. In carefully controlled, planned experiments to investigate safety of rumen-resident selenium boluses, up to eight (8) boluses, four times the recommended amount, have been given at one time without harmful effects to cattle. Potential harm to wildlife and the environment will be avoided by use of all selenium products according to label directions. Extensive testing of the environment shows livestock use of selenium supplements does not pose problems to the environment.


When additional copper is required three (3) methods of supplementation are available: injections, salt mixes or rumen-resident capsules. Specific label recommendations must be followed. Injectable copper glycinate (30 percent copper by weight) is given to adult cattle at the rate of 400 mg (120 mg copper) subcutaneously. Calves are given 100 to 200 mg of copper glycinate (30 to 60 mg of copper), depending on their age. One injection may be effective as a treatment or supplement for 4 to 6 months in cases of primary copper deficiency. However, in cases of excess molybdenum, sulfates, and/or sulfur, additional injections may be necessary. Injections of copper glycinate frequently result in large swellings, granulomas, or abscesses and may be cosmetic considerations for some cattle. The reactions can be minimized by using sterile technique and using the subcutaneous tissue of the brisket as the injection site. Copper glycinate injection products are available only by prescription from your veterinarian.  Follow-up blood sampling can evaluate supplementation effectiveness.

Salt mixes with copper can be obtained commercially. Specific amounts of copper required in a salt mix should consider the degree of deficiency, interfering compounds and the amount of salt consumed.  Daily salt consumption varies, making supplementation by salt mixes problematic. Salt consumption usually varies between 1 and 4 ounces but may be zero or higher than 4 ounces. Salt mineral mixes for copper supplementation usually vary between 0.2 and 0.6 percent copper. Feed grade copper sulfate is 25 percent copper (as fed basis). Copper oxide is 50 percent copper (as fed basis). To prepare a 0.4 percent copper salt mineral mix use 7.2 gm. copper sulfate or 3.6 gm. copper oxide for each pound of salt. A 100-pound batch would use 720 gm (25.4 ounces) of copper sulfate or 360 gm. (12.7 ounces) of copper oxide. Plain or iodized loose salt should be the base mix. Thorough mixing is important. In most cases trace mineral salt contains relatively low copper (typically less than 0.2 percent). Usually this is too low to adequately supplement copper-deficient cattle. However, this should be considered on a case-by-case basis since trace mineral salts vary in copper content. Where high molybdenum is also a problem, higher levels of copper supplementation are needed. Repeated blood and/or liver sampling should be used to evaluate the effectiveness of any supplementation program. Sample salt mix specifications are provided.

Another supplementation method is use of rumen-resident capsules. These are available commercially and contain copper oxide wires that remain in the rumen. The capsules are given orally. Copper is slowly released providing a steady source of copper for about 12 months.


Excess copper can be harmful.  Cattle are generally not susceptible to excess copper. Salt mixes containing 0.5 percent copper have been fed without apparent problems. However, sheep cannot tolerate high levels of copper and have a much smaller range of acceptable copper levels. Under some supplementation levels for cattle, sheep if also exposed to the salt may develop copper toxicity. Therefore, copper supplemented salt for cattle should not be available to sheep. Copper sulfate (bluestone) can also be harmful to fish at high concentrations.  Undiluted copper sulfate should therefore be protected from mixing with water or entering water that supports fish.


The most widely used products for zinc supplementation are zinc oxide, zinc sulfate and zinc methionine. Zinc oxide is a non-water soluble mineral that can be added to rations or salt mixes. For use by the animal, zinc from zinc oxide must join with protein in the intestines and become absorbed. Also in the intestine are compounds that may bind to the zinc making it unavailable (chelating agents). Zinc sulfate has been used in place of zinc oxide but tends to be irritating.

Another option for zinc supplementation is zinc methionine. In this case, zinc is already bound to a protein and ready for absorption from the intestine. ZinproŽ (zinc methionine) was not digested in the rumen of cattle in field trials and thus was available at the intestine. In some trails Zinpro (zinc methionine) has been slightly more effective than zinc oxide in animal response.

Suggested amounts of supplemental zinc vary but a salt mineral mix of 0.4 percent would be typical. It is prepared using 2.5 gm of zinc oxide or 5.0 gm of zinc sulfate per pound of salt. A 100-pound batch would use 250 gm of zinc oxide (8.8 ounces) or 500 gm of zinc sulfate (17.6 ounces). Zinc oxide contains aobut 72.5 percent zinc and zinc sulfate about 36.2 percent zinc on a 100 percent dry matter basis. Either loose plain or iodized salt would be used. Mixing should be thorough.

Proper supplementation should be verified by repeating the blood sampling and laboratory analysis for zinc. If different amounts of salt are consumed then the zinc concentration should be adjusted up or down.

Zinc methionine containing supplements are commercially available. Varying concentrations can be obtained but should provide approximately 400 mg. of zinc daily.  Monitoring consumption levels and blood sampling should be used to verify proper zinc supplementation levels. Example salt mixes are provided.


Excess zinc can be harmful. Care must be taken to avoid excess zinc consumption by cattle or other animals. During handling of zinc, care should be taken by humans to minimize exposure. All on-farm mixing of zinc should be done in a well ventilated area and inhalation minimized. Skin contact should be flushed with water



When additional phosphorus is needed, a change in the ration to include more phosphorus rich feeds may be the best solution. Cereal grains, oilseed feeds or fishmeal will increase dietary phosphorus levels. Three pounds of grain (rich in phosphorus) also provides additional nutrients that might be needed for the lactating cow. Mineral supplements that contain phosphorus can also be used to increase phosphorus consumption.

Common sources of phosphorus are dicalcium phosphate, bone meal, various rock phosphates, sodium phosphates and several other forms. The percentage of calcium and phosphorus of several mineral sources are shown (Table 1). The phosphorus in these ingredients is not equally available or usable by the animal. Availability is indicated in the column titled "Biological Availability, %". When availability is considered, the amount of available phosphorus may be quite different from the actual phosphorus content. Therefore, when comparing phosphorus sources use the column titled "Available Phosphorus, %". Since phosphorus is relatively expensive compared to other minerals, potential supplements should be compared to determine the cost per pound of available phosphorus.

Table 1. Sources of phosphorus.


Calcium %

Phosphorus %

Biological Availability %

Available Phosphorus %

Dicalcium phosphate





Monocalcium phosphate





Bone meal, steamed





Tricalcium phosphate















Sodium tripolyphosphate





Defluorinated phosphate





Low fluorine phosphate





Soft phosphate





Phosphoric acid





Ammonium phosphate, dibasic







To calculate the cost of available phosphorus in supplements, apply the following formula and definitions.



2000 X A = B

A is the decimal percent of phosphorus in the ingredient or mix.

B is the pounds of phosphorus in 1 ton of ingredient or mix.


B X C = D

C is the decimal percent of biological availability.

D is the pounds of phosphorus available in 1 ton.


E X D = F

E is the cost on one ton of ingredient or mix.

F is the cost for 1 pound of available phosphorus.

This principal can be used to compare two (2) purchased phosphorus supplements provided the percent of total phosphorus and the source of phosphorus is available. For example, supplement A has 6% phosphate and costs $475 per ton and supplement B has 9% phosphorus from defluorinated phosphate and costs $500 per ton. At first, it would appear the higher phosphorus supplement (B) is a better value because it has quite a bit more phosphorus for only somewhat more cost per ton. However, the following calculations show supplement 1 is clearly a less expensive source of phosphorus.


Example. Supplement A costing $475 per ton containing 6 percent phosphorus using dicalcium phosphorus as the phosphorus source.

A=.06 phosphorus (from supplement tag)

B= 2000 X .06


C=110 % biological availability (from table)


D=120 X 1.10


E=$475 per ton (from supplement tag)

F=E / D


F= $3.59 per lb. of available phosphorus

Example. Supplement B costing $500 per ton containing 9 percent phosphorus using defluorinated phosphate as the phosphorus source.

A=.09 phosphorus (from supplement tag)

B= 2000 X .09


C= 65 % biological availability (from table)


D=180 X .65


E=$500 per ton (from supplement tag)

F=E / D


F= $4.27 per lb. of available phosphorus

On-ranch prepared phosphorus supplements

A traditional phosphorus supplement has been a salt mix combining one of the above phosphorus sources (Table 1), commonly dicalcium phosphate, with a loose salt on an equal weight basis (50:50 mix). The loose salt can be either plain salt (sodium chloride), iodized salt, or trace mineral salt. This produces a salt mixture of about 7 to 12 percent phosphorus, depending on the phosphorus source. This traditional mix has been generally satisfactory in supplementing dietary phosphorus.

Because of the high cost of phosphorus, the user should consider the various phosphorus sources more carefully for biological availability, phosphorus content and cost, to develop the least expensive phosphorus supplement. The most critical times to supplement with phosphorus are during breeding season, lactation and when on mature forage, crop residues and alfalfa hay.

Sample salt mineral mixes

For convenience commercial mineral mixes are usually formulated to satisfy regional demands or needs. Processing and distributing large quantities reduces costs. Some examples of potential supplements for specific regions or areas are shown.  The examples are not appropriate for general or statewide use.  They are appropriate for specific areas that have deficiencies, interfering compounds and specific conditions that have shown the sample formulations are generally safe.   When using any supplement it is important to monitor trace minerals to determine adequacy of the supplement.

Application:  Deficient selenium, copper, zinc and phosphorus areas.

Sample salt mineral mix for areas needing selenium, copper, zinc, and phosphorus.  *Note the level for copper is higher than generally regarded as safe.  The copper levels in this mineral mix may be toxic in areas with adequate, or marginal copper levels and/or areas without interfering compounds.  When beginning copper supplementation, initial levels are usually not greater than 0.3 percent.  Monitoring of cattle is used to adjust copper level to an appropriate amount.


Amount, percent

Amount, ppm

Amount, mg/lb.










0.5 - 0.7*

5,000 - 7,000*

2269 - 3175*


0.5 - 0.7

5,000 - 7,000

2269 - 3175





E.D.D.I. (Iodine)
































*Note the level for copper is highly than generally regarded as safe.  The copper levels in this mineral mix may be toxic in areas with adequate, or marginal copper levels and/or areas without interfering compounds.  When beginning copper supplementation, initial levels are usually not greater than 0.3 percent.  Monitoring of cattle is used to adjust copper level to an appropriate amount.