Mineral Supplements for Beef Cattle

7/31/2019 Mineral Supplements for Beef Cattle

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Mineral Supplements

for Beef Cattle

Lawton StewartExtension Animal Scientist - Beef Cale


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Introduction

Beef cattle require a number of minerals for optimal growth and reproduction. Se-lecting the correct mineral supplement is important for maintaining healthy animals,and optimal growth and reproduction. Since high-quality forages and/or grains canfurnish a large portion of the required minerals, producers should select supplements

that will meet animal requirements and avoid excesses that reduce prots and leadto unnecessary mineral excretion. Minerals not provided by feed can be easily andinexpensively supplied with a simple mineral supplement. A good mineral program forbrood cows should cost about $10 to $20 per year. This bulletin provides informationon basic mineral nutrition for most forage and feeding programs in Georgia.

Minerals essential to cattle nutrition are classied as either macrominerals or mi-crominerals, depending on whether they are found at levels greater than or less than100 parts per million (ppm) in the animals body.


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Macrominerals

The macrominerals beef cale require includecalcium, magnesium, phosphorus, potassium, so-dium, chlorine and sulfur. Macromineral require-ments and maximum tolerable levels for beefcale are shown in Table 1.

Calcium and PhosphorusCalcium and phosphorus are the major min-

eral components of the skeleton. Ninety-ninepercent of total body calcium and 80 percent oftotal body phosphorus are stored in the bones.The skeletal stores of calcium and phosphorusare used to meet short-term dietary inadequacies.Long-term deciencies of either can cause bonesto weaken and even break.

Calcium and phosphorus also play impor-

tant roles in other bodily functions. A decreasein either or both can cause a decrease in weightgain and/or a decrease in eciency of gain. Dur-ing lactation, low amounts of either will reducemilk production. A superior milking cow requiresthree times more calcium than a non-lactatingcow. A phosphorus deciency can delay pubertyin heifers and can delay mature beef cows fromreturning to heat following parturition. Calealso need correct amounts of calcium for the ner-vous and muscular systems to function properly.

Proper utilization of calcium and phosphorusis aected not only by the amount of each mineralfed, but also by their ratio. The optimum Ca:Pratio is about 1.5:1, with a range of 1:1 to 4:1 beingsatisfactory. In some high-concentrate rations,ratios higher than 2:1 have been successful.

Most grasses are adequate in calcium. Le-gumes such as alfalfa, peanut, clover and soybeanhay are good sources of calcium, but corn silageand sorghum silage are poor sources of calcium.In general, most concentrates are relatively poorcalcium sources. One exception is citrus pulp,which is relatively high in calcium concentration(1.9 percent). Corn, corn by-product feeds andsorghum grain are particularly low in calciumcontent, and cale fed grain or corn silage-baseddiets require calcium supplementation.

Most forages are low in phosphorus, particu-larly late in the growing season. Cale are morelikely to be phosphorus-decient during thewinter, when they oen subsist on dry forages.

Concentrates contain moderate to high concentrtions of phosphorus. Protein supplements such acoonseed meal and soybean meal contain moderate concentrations, whereas many by-productfeeds such as distillers grains, corn gluten feedand wheat middlings, have high phosphorus

concentrations.

Sodium and ChlorineSodium and chlorine (salt) provide for the

proper function of the nervous and muscularsystems. They help regulate body pH and theamount of water retained in the body. A de-ciency of these elements causes loss of appetiteand inecient weight gains or body weight lossSodium is commonly decient in diets, but chlo-

rine levels are usually adequate. Both mineralsare present in so tissues and uids and there isvery lile storage of these elements, so a constandaily source of sodium and chlorine must be provided. Cale will voluntarily consume more saltwhen forage is young and succulent than when matures. Silage-fed cale will consume more salthan those fed hay, and consumption is higher incale fed high-roughage diets than in those onhigh-concentrate diets. As a rule of thumb, caleconsume 0.005 to 0.010 percent of their body

weight as salt daily. For example, a mature cowweighing 1,200 pounds would consume 0.06 to0.12 pounds (1,200 x 0.00005 = 0.6), or 1.0 to 1.9ounces of salt daily.

MagnesiumMagnesium is essential for proper enzyme

and nervous system function and for ecientcarbohydrate metabolism. A magnesium de-ciency is uncommon except for cows grazing

lush-growth fescue or small grain pastures dur-

ing the late winter and early spring, which maycause grass tetany, a serious and sometimes fatametabolic disorder. A high rate of nitrogen andpotassium fertilization contributes to grass tetanExcess potassium inhibits magnesium absorptioin both forage and animals. Grass tetany usu-ally occurs following an extended period of coldweather combined with high levels of nitrogenand potassium fertilization. Mature lactatingcows are particularly susceptible to grass tetany


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Grass tetany can usually be prevented byfeeding cale a mineral mixture containing mag-nesium oxide. A mineral mixture containing 10 to14 percent magnesium consumed at 4 ounces perday should provide adequate magnesium. Ad-equate salt intake is also important for preventinggrass tetany. Avoid using hard blocks to supple-ment salt when cale are at risk for grass tetany;

supply salt in a loose form to allow for adequatesalt consumption. When grass tetany is not a risk,blocks can be used to supplement minerals, pro-vided trace minerals are elevated to account forlower intake of block versus loose salt minerals.Animals with grass tetany respond almost im-mediately to an intravenous infusion of calcium-magnesium gluconate.

PotassiumPotassium functions in acid-base balance, os-

motic pressure and the amount of water retainedin the body. Grasses, particularly early lushspring growth, contains adequate amounts of

potassium for grazing cale and supplementatiois rarely needed. However, potassium may occasionally be low in stockpiled forages or hay thatwas rained on prior to baling because potassiumis soluble and will leach from the forage.

SulfurSulfur is a part of the essential amino acids

methionine and cystine, which make up proteinA sulfur deciency in beef cale diets is not liketo occur under normal feeding conditions. Sulfuis more likely to be in excess, which can interferewith the metabolism of copper, resulting in acopper deciency. Also, excess sulfur can reducefeed intake and cause a brain lesion conditionknown as polioencephalomalacia (PEM). Certainby-products such as distillers grains and corn glten feed contain higher concentrations of sulfur,which should be taken into account in ration

balancing. Sulfur is oen added indirectly to themineral mix through sulfate forms of the microminerals.

Table 1. Macro mineral requirements and maximum tolerable levels for beef cale.

Mineral Lactating Cows Dry Cows Growing Calves Maximum Tolerable Level

Calcium, % 0.31 0.18 0.58

Magnesium, % 0.10 0.12 0.20 0.40

Phosphorus, % 0.21 0.16 0.26

Potassium, % 0.60 0.60 0.70 3.0

Sodium, % 0.07 0.07 0.10

Sulfur, % 0.15 0.15 0.15 0.40

NRC, 1996. Adapted from NRC. Nutrient Requirements of Beef Cattle, Sixth Edition.


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Microminerals

Beef cale require 10 microminerals. Seven ofthe 10 microminerals have established require-ments, including iron, manganese, copper, zinc,selenium, cobalt and iodine. The micromineralschromium, molybdenum and nickel do not havean established requirement and are not normally

added to mineral mixes fed to beef cale. Onlythree of the microminerals (copper, zinc andselenium) are likely to be decient in grazing beefcale diets. Micromineral requirements and maxi-mum tolerable levels for beef cale are shown inTable 2.

CobaltCobalt functions as a component of vitamin

B-12, which is synthesized in the rumen by bac-

teria. The primary deciency symptom is loss ofappetite and poor growth. Most forages in theSoutheast have adequate levels of cobalt; how-ever, it is usually added in the mineral mix atapproximately 10 ppm to ensure no deciencies.High-grain diets require more cobalt than forage-based diets, and cobalt should always be includedin the mineral mix when feeding grain-baseddiets.

CopperCopper is the most common micromineral de-

ciency in grazing cale. Copper is an importantcomponent of many enzyme systems essentialfor normal growth and development. Deciencysigns include reduced fertility, depressed immu-nity and reduced pigmentation of hair (black hairchanges to red). Dietary deciencies can occur,but most deciencies are caused by the consump-tion of antagonists, which reduces copper absorp-tion. Copper should be supplemented as copper

sulfate, tribasic copper chloride or an organiccomplexed form because copper oxide is verypoorly absorbed.

IodineIodine is an essential mineral for function of

the thyroid hormones that regulate energy me-tabolism. The rst sign of iodine deciency isgoiter in newborn calves. Iodine is rarely decientin cow herds in the Southeast. Iodine is usually

supplemented as ethylenediamine dihydroidide(EDDI). The maximum legal supplementation ofEDDI is 50 mg per head per day. In some instances, EDDI has been included in diets to preventfoot rot; however, the amount of EDDI requiredto prevent foot rot is much higher than require-

ments and most likely will not prevent foot rotwhen included at the legal maximum.

IronIron is primarily required for the formation o

hemoglobin. Deciency symptoms include ane-mia, depressed immunity and decreased weightgains. Iron deciency is rarely observed in graz-ing cale. Iron oxide is oen included in mineramixtures, but is unavailable to the animal and

serves only as a coloring agent to give the minera dark red color. Iron sulfate is available to theanimal and should be used if iron supplementa-tion is needed.

ManganeseManganese is required for normal reproduc-

tion, and fetal and udder development. Manga-nese deciency is rare and unlikely to be a prob-lem in grazing cale in Georgia. Manganese oxidis the most common form of manganese used in

mineral mixes. Corn-based diets are low in manganese and supplementation is necessary whenfeeding these diets.

SeleniumSelenium can be decient in some areas

of Georgia. Selenium deciency causes whitemuscle disease (similar to muscular dystrophy)in newborn calves. Selenium deciency can alsocause calves to be weak at birth and increase the

susceptibility to calood diseases like scours.Increased rates of retained placentas and poorreproductive performance are oen observed incows with selenium deciencies.

Selenium is generally added to mineral mix-tures in the form of sodium selenite. Seleniumis very toxic and should be used in a premixedform only. The FDA allows selenium to be usedat a level not to exceed 0.3 ppm of the dry mat-ter in the total diet of beef cale. In areas where


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deciencies occur, use the maximum legal level.The FDA allows up to 120 ppm to be includedin a salt-mineral mixture for free-choice feeding.Selenium deciency should not be a problem ifadequate amounts of selenium are consumed inthe mineral supplement. However, the concen-tration of selenium in the supplement and thelabeled intake must not result in a total intake of

more than 3 mg per day. Thus, a mineral labeledfor intake of 4 ounces per head per day cannotexceed 26 ppm selenium.

ZincZinc is marginal to decient in most Georgia

forages. Zinc is a component of many enzymesand is important for immunity, male reproduc-tion, and skin and hoof health. Cale have a limited ability to store zinc and supplementation isalways necessary. Zinc absorption is closely tiedto copper absorption, and the zinc to copper rati

should be kept at approximately 3:1. In additionhigh levels of iron can decrease zinc absorp-tion. Absorption of zinc decreases once the ratioof iron to zinc exceeds 2:1. Some feedlots feedsupplemental zinc methionine to improve hoofhealth and thus improve daily gains and feed efciency.

Table 2. Micromineral Requirements and Maximum Tolerable Levels for Beef Cale.

Mineral Lactating Cows Dry Cows Growing Calves Maximum Tolerable Level

Chromium 50.0

Cobalt, ppm 0.1 0.1 0.1 10.0

Copper, ppm 10.0 10.0 10.0 100.0

Iodine, ppm 0.50 0.50 0.50 50.0

Iron, ppm 50.0 50.0 50.0 1000.0

Manganese, ppm 20.0 40.0 40.0 1000.0

Molybdenum, ppm 5.0

Nickel 50.0

Selenium, ppm 0.10 0.10 0.10 2.0

Zinc, ppm 30.0 30.0 30.0 500.0

NRC, 1996. Adapted from NRC. Nutrient Requirements of Beef Cattle, Sixth Edition.


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Vitamins

Vitamins are closely linked to mineral me-tabolism and absorption. Vitamin A helps skinand mucous membranes stay healthy. Vitamin Arequirements usually are met by grazing fresh,green, growing grass. Oxidation deteriorates vi-tamin A during storage, so diets based on stored

feeds should be supplemented with vitamin A.Supplement diets with vitamin A any time themajor portion is stored feeds.

Vitamin A can be added to a mineral mix ina stabilized form to prevent oxidation. The mini-mum amount should be approximately 120,000International Units (IU) of vitamin A per poundof mineral. Vitamin A can also be added to thegrain mixture to provide 15,000 to 30,000 IU perhead per day, depending on individual require-ments. An alternative method is to inject 1.5million IU subcutaneously if a source of dietarycitamin A is not available for 60 to 90 days, al-though unnecessary injections are discouraged in

consideration of National Beef Quality Assurancguidelines.

Vitamin D aids the absorption of calcium andphosphorus from the intestine and their deposi-tion in the bone matrix. Signs of vitamin D de-ciency are similar to a calcium or phosphorus

deciency. Most cale exposed to direct sunlighsynthesize enough vitamin D, but cale in a covered connement feedlot may need supplementvitamin D.

Vitamin E is usually present in the diet in sufcient quantities for all classes of cale; howevera selenium deciency could lead to an apparentdeciency of vitamin E. Vitamin E can be helpfufor short-term periods of stress that may occurwhen calves are co-mingled and transported atweaning.

Other essential vitamins are usually present adequate quantities in the diet or are synthesizeby bacteria in the rumen.


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Selecting a Mineral Supplement

The average mineral content of several for-ages, grains and by-product feeds are shown inTable 3. The actual mineral content of feeds, es-pecially forages and by-products, will vary, so allfeeds should be tested for actual mineral content.However, the mineral concentrations can be used

as a guide when choosing a mineral supplementto complement a particular feed ingredient. In ad-dition, an example mineral mix for lactating cowsis provided in Table 4. The calcium to phosphorusratio in most mineral mixes should be 2:1 to 4:1.Phosphorus supplementation may not be neededif forages have been fertilized with poultry lieror when feeding high-phosphorus feeds such ascoonseed, coonseed meal, distillers grains orcorn gluten feed. Salt is not stored in the animalsbody and should be made available continuously.Salt is the only mineral that cale crave, andsalt-deprived cale will oen eat dirt or wood. Amineral mix should contain 15 to 22 percent salt.Magnesium should be at least 14 percent in themineral mix when grass tetany is a concern. Also,closely examine mineral tags for addition of un-necessary products such as B-vitamins (thiamine,riboavin, folic acid). These vitamins are normal-ly not needed by grazing cale because they areproduced by the rumen bacteria and increase the

cost of the supplement.The most important points to consider when

purchasing minerals are calcium to phospho-

rus levels, salt level, bioavailability (particularlycopper), level of trace minerals in the supple-ment, and additives. You can learn a lot about thmineral you are feeding by studying the mineratag for a few minutes. In addition, minerals areoen used to deliver products such as ionophor

(Rumensin, Bovatec) and antibiotics (chlortetraccline, GainPro). Carefully read label instructionswhen using medicated mineral mixes to ensureadequate intake and to ensure the product is la-beled for the intended use.

Grain-based dietsThere are many dierences between mineral

supplements designed for a forage-based ver-sus a grain-based diet. Since grains and most

by-product feeds except citrus pulp contain lowconcentrates of calcium, supplements shouldcontain approximately 25 percent calcium and bfed at a rate of 4 ounces per day. Supplementalsalt should be provided at 1 to 1.9 ounces per daThe primary microminerals of most concern arezinc, copper, cobalt and selenium. Trace mineralsalt is usually added at 0.5 percent of the diet toprovide most supplemental trace mineral needsSelenium may need to be added to maintain atotal diet concentration of 0.1 ppm. Additional

phosphorus supplementation is rarely requiredwhen feeding grain-based diets.


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Factors Affecting Mineral Intake

Controlling intake at the desired level is verychallenging because mineral intake uctuates.Monitor mineral intake for several weeks priorto implementing management practices to altermineral intake. If mineral intake is too high orlow, move the mineral feeder either closer to or

farther away from the water source and loangareas. When cale are over-consuming mineral,salt is oen added to reduce the amount of miner-als cale eat. Salt level has a signicant impact onmineral intake and is easily changed to controlintake; however, you must account for the addi-tional salt when determining the correct intake.For example, if a mineral with a recommendedfeeding rate of 4 ounces per day is mixed in a50:50 ratio with plain white salt, the cale shouldconsume 8 ounces per day. This would supplythe cale with the targeted amount of 4 ounces ofmineral plus 4 ounces of added salt. When un-der-consumption is a problem, try adding driedmolasses or change brands to a more palatablemineral. In addition, keep in mind that calves canconsume signicant amounts of mineral and thisshould be considered before decreasing the feed-ing level.

If mineral intake is inadequate, try adding apalatable feedstu to the mix. Feeds such as cot-

tonseed meal, soybean meal, dry molasses anddistillers grains can improve mineral intake. Mov-ing the mineral feeder closer to the water sourcecan improve intake. In addition, changing min-eral brands will sometimes provide a mineral thatis more palatable.

Regularly monitor mineral consumption bykeeping a record of animal numbers and feed-ing amounts to combat potential mineral intakeproblems.

Mineral FeedersMineral feeder placement is a very important

part of supplying minerals to the cow herd. Besure an adequate number of feeders are avail-able for the stocking rate of the pasture. A rule ofthumb is to provide one mineral feeding stationfor every 30 to 50 cows. The best areas to placemineral feeders are near water, in shaded loangareas and near the best grazing areas. Check feed-ers at least once a week and keep a clean, fresh

supply of minerals present at all times. A goodfeeder should keep minerals dry, be portable andhold up to abuse and corrosion. Open tubs arenot adequate in the Southeast. Because mineralscan be corrosive to metals, feeders made of wooberglass or plastic usually last longer. Perma-

nent mineral feeders made of concrete also workwell, but portability is a problem.

Supplement FormFeeding minerals free-choice in a loose mix

form is most desirable for brood cows. For caleon complete diets, minerals are most optimallysupplied when mixed in a TMR. When supple-menting in a block form, trace minerals must behigher than what is contained in a loose mineral

mix, as the animal will usually consume only 1 t2 ounces per day. In addition, some blocks con-tain only trace mineralized salt, which will notmeet the animals requirements for macrominer-als such as calcium and phosphorus. Carefullyread the label on a block mineral supplement tomake sure the product contains all needed min-erals. Block minerals are sometimes used whensupplementing cale that have not had access tominerals for a long period of time. In this situa-tion, cale will greatly over-consume minerals

in a loose mix form if given free-choice access.Blocks can be used for a short period of time toprevent mineral over-consumption. Do not sup-ply plain white salt and mineral separately sinceintake of the mineral will likely be too low be-cause cale will crave only the salt.

Commercial protein and energy supplementare sometimes fortied with minerals. Com-mercial supplements come in the form of drypelleed feeds, liquid molasses supplements,hard molasses-based blocks, or hard-pressedgrain-based blocks. It is not necessary to providea free-choice mineral supplement along with thecommercial protein/energy supplement. Feedingminerals in both the free-choice mineral and theprotein/energy supplement should not negativeaect performance, but it is an expense that coulbe saved. It may be necessary to only oer plainwhite salt blocks when feeding the commercialprotein/energy supplements.


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SeasonMineral intake is usually higher when lush

forage is available and lower during the fall orperiods of drought. Mineral content and for-age digestibility declines with increasing plantmaturity. Mature forages are consumed in lowerquantity, further reducing mineral intake. Rapidlygrowing, lush forages have a higher availability

of minerals compared with mature forages. In ad-dition, mineral content is higher in forages grownon soils with greater fertility. Spring grass is usu-ally well fertilized and highly digestible, whichleads to greater intake of mineral from foragesand reduced consumption of supplemental min-eral during that time of the year.

Feeding MethodStocker calves are sometimes fed a complete

grain- or silage-based ration mixed on the farm.

Thoroughly mixing minerals in mixed rationsis dicult; only a small quantity of mineral isrequired and it separates easily from the largerparticle sizes of grain and forages. It may be wiserto use a mineral supplement that has a higherfeeding rate or feed the mineral free-choice or as atop dress.

A trial was conducted to compare feeding amineral supplement by free-choice feeding ortop-dressing the mineral on the feed each day.The mineral contained an ionophore (Bovatec)Results of the trial, in which heifers were fed haycorn, corn silage and minerals either in a free-choice feeder or where supplemental mineralswere top-dressed (4 ounces per day) on the feed

each day, are shown in Table 5. Supplementingminerals either free-choice or top-dressing re-sulted in similar daily gains. Heifers fed minerafree-choice consumed about 0.5 ounces per headless than the targeted intake of 4 ounces per daybut were within the range required for the iono-phore to be eective. If specic amounts of a particular mineral or feed additive are required perday, it would be desirable to top-dress or mix thmineral into the feed every day rather than allowfree-choice consumption. When feeding mineral

free-choice, closely monitor mineral consumptioto make sure intake is adequate. This is of par-ticular importance when feeding an additive sucas an ionophore or antibiotic.

Table 5. Performance of heifers provided supplemental mineralseither free-choice or top dressed onto feed daily.

Item Free- choice Top-dressed

Initial wt, lbs 574 579

Final wt, lbs 736 736

Total gain, lbs 162 157

Daily gain, lbs 1.93 1.87

Mineral intake, ounces/day 3.52 4.00


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Bioavailability

Consider the bioavailability of the mineralsupplements when purchasing minerals. Bio-availability of sulfates and chlorides is generallygreater than bioavailability of oxides. One excep-tion is magnesium oxide, which is absorbed wellenough to be used in beef cale minerals. How-

ever, avoid mineral supplements that use copperoxide, which is poorly absorbed. Iron oxide isalso poorly absorbed and is generally used to addcolor to the mineral mix. Because of the foragesand feedstus in Georgia, cale seldom requireiron supplementation, so the addition of ironoxide should not negatively aect cale perfor-mance and may be benecial since iron can bindother minerals and prevent their absorption.

Minerals are usually included in supplementsin the inorganic form but may also be combinedwith an amino acid or protein and fed in the or-ganic form (referred to as complexes, proteinatesor chelates). Minerals that are sometimes fed inthe organic form include copper, zinc, cobalt and

manganese with an amino acid or protein. Therelative bioavailability of copper, manganese anzinc from dierent sources is higher compared tinorganic sources as outlined in Table 6.

Organic minerals cost more than inorganicminerals; therefore, an increase in performance

must be realized to oset the higher purchaseprice. The response to organic minerals has beenvariable and they are only recommended incertain situations. Organic minerals have beeneective in increasing the reproductive eciencof young breeding females under nutritionalstress, or reducing morbidity and mortality ofnewly weaned calves that are highly susceptibleto bovine respiratory disease. For cows, organicminerals are usually fed from two months priorto calving through breeding. For calves, organicminerals are generally included only during thepreconditioning period. However, zinc methi-onine may be fed continually during the feedingperiod to decrease lameness.

Table 6. Relative bioavailability of microminerals from dierent sources1

Mineral Sulfate-form Oxide-form Carbonate Chloride-formOrganic-form

(complex, chelate)

Copper 100 0 105 130

Manganese 100 58 28 176

Zinc 100 60 40 159 to 206

1Availability relative to that of the sulfate form.Adapted from Greene, 1995.


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Identifying a Mineral Deficiency

A mineral deciency in cale is dicult todiagnose and can silently rob prots from theherd. Most deciencies are related to copper, zincand selenium, but other mineral deciencies canoccur.

Mineral deciencies are classied as either

primary or secondary deciencies. Primarymineral deciencies occur when cale consumeforages that are decient in a particular mineralsuch as magnesium. Failure to provide a mineralsupplement is the most common cause of primarymineral deciencies. Primary mineral decienciesrarely occur in well-managed herds that receivemineral supplements.

A secondary mineral deciency occurs whencale consume mineral antagonists, which inter-fere with the normal absorption or metabolism ofanother mineral. In the case of copper deciency,cale are consuming enough copper to meetrequirements, but some other mineral antagonistsuch as sulfur binds to the copper and preventsit from being absorbed and used by the animal.Secondary mineral deciencies are the most com-mon type of mineral deciency. Take the follow-ing steps to ensure that the problem is due to amineral deciency.

First, rule out other possible causes of poorperformance such as disease, plant toxins, orinadequate protein and energy in the diet.The rst sign of a problem in most herds ispoor reproductive eciency. Inadequate body

condition, due to protein or energy deciencyis the most common cause of reproductivefailure.Monitor mineral intake to ensure cale areeating the recommended amounts. A recom-mended intake is usually indicated on themineral bag.Evaluate the trace mineral levels and sourcesof each trace mineral. Remember that the bioavailability of sulfates and chlorides is generally greater than that of oxides.Breed can also aect the mineral requiremenof the cow herd. Simmental and Charolaiscale require more copper than Angus caleLevels may need to be increased 25 to 50 percent for these breeds.

If a secondary mineral deciency is suspectethen a laboratory analysis of forages must beconducted. In some instances, water should btested if it is suspected that it might be high iiron or sulfur.Blood samples and liver biopsies may alsobe used to assess the mineral status of a cow.Liver samples are a more accurate indicator omineral status. These tests are expensive andshould be pursued only aer the above steps

have been taken.Ask for help from county agents, specialists,veterinarians and feed dealers. No one persoknows all the answers and a team approach tsolving a mineral problem is oen required.


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Copper Deficiency

Copper deciency is an increasing concernin Georgia and other Southeastern states. Cop-per deciency causes a wide range of problemssuch as poor hair coat, brile bones, reducedweight gains and a weakened immune system.The University of Tennessee reported a copper

deciency in as many as 99 percent of tall fescueforage samples, and increased deciency in thefall rather than spring. Results of copper concen-trations in forages as reported by NRC are pre-sented in Table 7, but actual concentrations varydue to soil type, fertilization and climate. For bestresults, test forages and feed ingredients.

One of the most visible signs of copper de-ciency is change in hair color. Cale with blackhair will develop a reddish or gray tint. Calewith red hair will become more bleached. An-other common problem associated with copperdeciency is lowered immunity. The combinationof low copper and high sulfur concentrations inpasture grasses can result in copper being de-cient even in the most well managed herds.

Sulfur antagonisms are the most commoncause of copper deciencies in Georgia forages.Results of the NAHMS forage survey indicatedthat sulfur concentrations were marginal to highantagonistic in 79 percent of samples. Iron and

molybdenum showed marginal to highly an-tagonistic levels in 13 and 18 percent of samples,respectively. Sulfur is present in all feedstus andis incorporated in some mineral supplements.The most signicant sources of sulfur are directsupplementation, sulfur-containing fertilizers,water and energy/protein supplements.

Ammonium sulfate fertilizers are widelyavailable and their use is on the rise. In the past,fertilizers contained small amounts of sulfur.However, modern methods of fertilizer produc-

tion have eliminated any sulfur contamination.Therefore, sulfur-containing fertilizers are nowbeing used to supply this important nutrient topastures. In a University of Florida study, bahia-grass pastures were fertilized with either ammo-nium sulfate or ammonium nitrate to provide 60pounds of nitrogen per acre. Ammonium sulfateincreased forage yield in one of three years butincreased plant sulfur levels to 0.50 percent.Sulfur becomes a problem when the concentra-

tion reaches or exceeds 0.35 percent. Liver coppeconcentrations in cows grazing pastures fertil-ized with ammonium sulfate were considereddecient, but were adequate in cows that grazedforages not fertilized with ammonium sulfate. Inaddition, use of poultry lier as a fertilizer will

also elevate forage sulfur levels.Simply providing more copper in the min-

eral supplement may not improve copper statusbecause as long as sulfur is present in excessiveamounts in the forage, copper absorption willbe decreased. If sulfur levels are borderline high(0.35 percent sulfur), then it can be helpful toincrease copper concentrations up to 2,500 ppm.In the Florida study, even though the cows werecopper decient, no signs of deciency or poorperformance were noted. Many times, copperdeciencies do not show up until calves becomesick aer weaning and shipping. In a separatestudy, cows decient in copper were able to rap-idly replenish their liver copper concentrations tadequate levels when fed a low-sulfur diet.

Certain energy and protein supplements canalso contribute signicant amounts of dietarysulfur. Feedstus that contain sulfur in antago-nistic amounts include corn gluten feed, corngluten meal, distillers grains, molasses, soybean

meal and coonseed meal. Protein supplementsare fed in small amounts, so sulfur concentrationis diluted by the remainder of the diet. Molassesbased supplements are commonly used in wintefeeding programs. The University of Florida hasconducted studies to examine the eect of molasses on copper absorption in grazing heifers. Theresearchers compared a corn-based supplementto a molasses-based supplement. Accumulationof copper in the liver increased by 46 percent forheifers fed the corn-based supplement, but de-

creased nine percent for heifers fed the molassesbased supplement. Absorption of other microm-inerals (zinc, iron, manganese) was not aectedby supplement type.

Most high-sulfur feeds are only consumedduring the winter feeding period and should nosignicantly aect copper status. Cale are ableto utilize copper stored in the liver during thegrazing season, which should reduce the probleof depletion during the winter feeding period.


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Sulfur from pasture and hay is the primary causeof copper deciency because they are consumedyear-around. The only concern for winter feedingis when cale have been on pastures that are highin sulfur or are being fed hay that has sulfur lev-

els antagonistic to mineral absorption. Considerfeeding low-sulfur feeds during the pre-condi-tioning period, especially if your cale have hadhealth problems in the past when fed high-sulfufeeds.

Table 7. Classication of micro elements in forage relative to their abilities to meet eitherdietary requirements or cause an antagonistic problem with copper.

Microminerals Decient Marginally Decient Adequate MTC1

Aluminum (ppm) 1000

Copper (ppm)


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Literature Cited

Arthington, J.D., and C.K. Swenson. 2004. Eectsof trace mineral source and feeding methodon the productivity of grazing Braford cows.Prof. Anim. Sci. 20:155-161.

Arthington, J.D., and F.M. Pate. 2002. Eect of

corn- versus molasses-based supplementson trace mineral absorption in beef heifers.J.Anim. Sci. 80:2787-2791.

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Mineral Supplements for Beef Cattle