Importance of Micronutrients for Beef Cattle

Beef cattle production, whether on range, improved pasture, or in the feedlot, is most economical when feedstuffs are used effectively. Immature growing grass or other high-quality pasture crops usually supply ample nutrients, such that mature and young growing cattle can consume sufficient good-quality mixed pasture (grasses and legumes) for normal growth and maintenance. However, mature pasture, ingather residues, or fodder crops harvested in a manner that results in shattering, leaching, or spoilage may be so reduced in nutritive value (especially free energy, protein, phosphorus, and provitamin A or β-carotene) that they are suitable only in a maintenance ration for adult cattle. Such feedstuffs should exist supplemented if used for whatever other purposes.

The mineral content of forages is influenced by the corresponding mineral levels in the soil and past backlog levels of some minerals that reduce the availability of others. Mature forages also may be lower in mineral content, especially phosphorus. Normally, supplemental minerals are supplied in a gratuitous-pick mineral mix or force-fed in the total mixed ration.

Sure nutrients are required by beef cattle in the daily ration, whereas others tin be stored in the trunk. When body stores of a food are high, eg, vitamin A, dietary supplementation is unnecessary until such stores are depleted. Still, it may be difficult to determine when trunk stores have been depleted until avant-garde signs of deficiency start to announced.

The following are dietary requirements for maintenance, growth, finishing, reproduction, and lactation in beef cattle.

Water, although not considered a food per se, is required for regulation of body temperature, equally well every bit for growth, reproduction, lactation, digestion, metabolism, excretion, hydrolysis of nutrients, transportation of nutrients and waste material in the body, joint lubrication, plus many more functions. Restricting water intake results in impaired performance. An animal will expire more quickly from a water deficiency than from a deficiency of whatever nutrient.

Because feeds themselves contain water, and the metabolism of ingested feeds releases water (called metabolic water), not all of the animal's water needs have to be met by drinking water. Thirst is the consequence of need, and animals drink to meet this need. The demand for water results from an increment in the electrolyte concentration in the body fluids, which activates the thirst mechanism.

Many factors, including temperature and body weight, impact h2o consumption in cattle. An 800-lb (364-kg) heifer at an environmental temperature of four.four°C (twoscore°F) can be expected to swallow 6.3 gal. (23 Fifty) per mean solar day; at 21°C (70°F), this will increase to 9.2 gal. (34.8 50). At the same 4.iv°C temperature, a 400-lb (182-kg) heifer volition consume ~four gal. (fifteen.1 Fifty). Notation that water consumption and torso weight are not correlated past a straight-line relationship. A 900-lb (409-kg) lactating cow at the 4.4°C temperature volition consume eleven.four gal. (43.1 L) per day.

Except for preruminant calves, beef cattle tin meet their maintenance energy requirements from roughages of reasonably good quality (green, leafy, fine-stemmed, free of mold and weeds). A shortage of energy may exist on overstocked pastures, with inadequate feed allowance or poor-quality forages, or during a drought. For production, additional energy from concentrates or co-product feeds may be necessary, especially when forages of off-white to poor quality are consumed.

Especially in cold weather, roughages of varying quality may accept like maintenance energy values. Heat released during digestion and assimilation—called "heat increment"—contributes to the maintenance of body temperature for wintering stock.

Protein requirements currently are evaluated equally metabolizable protein, which is interchangeable with absorbed protein. Metabolizable protein defines the protein more almost as that which is available to the beast for maintenance and production. It is defined every bit the combination of the truthful protein absorbed by the intestine, supplied by microbial synthesized protein plus undegraded intake protein (UIP). The latter often has been called "featherbed" poly peptide.

Energy deficiency due to low feed intake or intake of poor quality feed is the well-nigh common deficiency that limits growth, evolution in heifers and bulls, milk product, and reproduction, with protein deficiency beingness the next most common. Poly peptide deficiency of long elapsing eventually depresses appetite, with eventual weight loss and unthriftiness, even when ample free energy is available.

Feedstuffs vary profoundly in protein digestibility. For example, the protein of common grains and near protein supplements is ~75%–85% digestible, that of alfalfa hay ~seventy%, and that of grass hays ordinarily 35%–fifty%. The protein of low-quality feeds, such as weathered grass hay, range grass, or cottonseed hulls, is digested poorly. Thus, fifty-fifty though total protein intake may appear to be acceptable, metabolizable protein might be deficient.

A lack of protein in the diet adversely affects the microbial poly peptide production in the rumen, which in turn reduces the utilization of low-protein feeds. Thus, much of the potential nutritive value of roughages (peculiarly energy) may exist lost if poly peptide levels are inadequate.

Urea and other sources of nonprotein nitrogen (NPN) are used ordinarily in commercial protein supplements to supply ane-third or more of the full nitrogen requirement. Such products are broken down readily past the ruminal microbiota protein to ammonia so synthesized to high-quality microbial protein. The utilize of NPN needs available sources of ample phosphorus, trace minerals, sulfur, and soluble carbohydrates for the microbial synthesis of utilizable protein. The corporeality of rough protein (% Northward × vi.25) supplied by NPN must exist stated on the feed tag accompanying commercial supplements. Toxicity is not a serious trouble when urea is fed at recommended levels and mixed thoroughly with the other ingredients of the ration. However, rapid ingestion of urea at levels >xx k/100 lb (45 kg) body wt may lead to toxicity (come across Nonprotein Nitrogen Poisoning Nonprotein Nitrogen Poisoning ). Several urea-molasses liquid supplements, containing as much as 10% urea, currently are cocky-fed to beef cattle. Circumspection should be exercised when cattle are started on such supplements.

Qualitatively, beefiness cattle crave the aforementioned mineral elements every bit exercise dairy cattle; however, the relative quantities of the several minerals are different (see Table: Requirements and Maximum Tolerable Levels of Minerals for Beefiness Cattle a Requirements and Maximum Tolerable Levels of Minerals for Beef Cattle a ). The minerals most apt to be deficient in beefiness cattle diets are sodium (as salt), calcium, phosphorus, magnesium, zinc, copper, and selenium. In some areas, including the interior of the United states of america, iodine may be scarce in diets for pregnant cows; also, there are regional deficiencies (probably reflecting soil deficiencies) of several trace minerals, including copper, cobalt, and selenium. Nevertheless, there are areas where some mineral elements (eg, selenium, molybdenum) are present at toxic levels. Attempts accept been made to correct natural soil deficiencies for trace minerals by soil fertilization practices. Thus, it is implied that a beef producer needs to know the mineral and trace mineral content of the feedstuffs used in cattle rations. A general approach to forestall such deficiencies is to feed a commercial salt mineral mix developed for the geographic location of the herd.

The salt (NaCl) requirement for beef cattle is quite low (0.2% of the dry matter); however, there appears to be a satiety gene involved—almost all animals appear to seek out salt if it is not readily available. Range cattle may consume 2–2.5 lb (1 kg) table salt/head/mo when fodder is succulent but about one-half that amount when forage is mature and drier. When salt is added to a costless-choice protein feed to limit intake, beefiness cows might eat >1 lb salt/twenty-four hour period over long periods of time without agin effects if they have plenty of drinking water. Signs of a salt deficiency are rather nonspecific and include pica and reduced feed intake, growth, and milk production.

Calcium is the almost arable mineral chemical element in the body; ~98% functions equally a structural component of bones and teeth. The remaining 2% is distributed in extracellular fluids and soft tissues and is involved in such vital functions as blood clotting, membrane permeability, muscle contraction, manual of nerve impulses, cardiac regulation, secretion of certain hormones, and activation and stabilization of sure enzymes. Most roughages are relatively good sources of calcium. Cereal hays and silages and such crop residues are relatively low in calcium. Although leguminous roughages are excellent sources of calcium, fifty-fifty nonlegume roughages may supply adequate calcium for maintenance of beefiness cattle. When cattle are fed such roughages produced on low-calcium soils, or when finishing cattle are fed loftier-grain diets with limited nonlegume roughage, a calcium deficiency may develop. Because lactating beef cows do non produce well-nigh the corporeality of milk that dairy cattle practice, their calcium requirement is much less. All the same, it is sound management to provide a costless-choice salt mineral mixture tailored to the surroundings and production class of the grazing cattle. Salt should always be mixed with mineral, because table salt drives intake. Cows have almost zero "nutritional wisdom," ie, they do non seek out feedstuffs or minerals when they are deficient, with the exception being sodium, so adding mineral to the salt by and large improves intake amongst cattle with free-option access to the mineral mix. The total ration should provide a calcium:phosphorus ratio of 1.ii to two:i, with cows at minimum of 1.2:1 and feedlot steers at minimum of two:1. Wider ratios appear to be tolerated if the minimum requirements for each mineral chemical element are met and if adequate vitamin D (exposure to sunlight) is available. Range cattle should exist provided a mineral supplement that has as much or more phosphorus than calcium, because green forage is many times higher in calcium. Research has shown that intake among cattle receiving complimentary-option mineral mix is highly variable. One study showed that 14%–15% of cows with complimentary-choice access to mineral in block or loose course consumed nil mineral. The only time cattle should be offered mineral free choice is when they are grazing and no other feed is beingness fed. If cows are consuming whatsoever other feed, the common salt and mineral should be mixed with the ration so all cattle will ingest the prescribed amount of mineral.

Approximately 80% of the phosphorus in the body is establish in the bones and teeth, with the balance distributed among the soft tissues. Phosphorus may be deficient in some beef cattle rations, considering roughages frequently are depression in phosphorus. Furthermore, equally forage plants mature, their phosphorus content declines, making mature and weathered forages a poor source. Phosphorus has been described equally the virtually prevalent mineral deficiency for grazing cattle worldwide. Most natural protein supplements are fairly good sources of phosphorus. Because adequate phosphorus is critical for optimal operation of beef cattle, including growth, reproduction, and lactation, a phosphorus supplementation program is recommended using either a free-choice mineral mixture or direct supplementation in the diet. In a phosphorus deficiency, reduced growth and efficiency of feed conversion, decreased appetite, impaired reproduction, reduced milk production, and weak, delicate basic can be expected. There does non announced to exist any advantage to feeding more phosphorus than is recommended. Furthermore, feeding excess phosphorus contributes to increased environmental pollution. Good sources of supplemental phosphorus include steamed bone meal, mono- and dicalcium phosphate, defluorinated rock phosphate, and phosphoric acrid. Corn co-products like corn gluten and distillers grains with solubles are also high in phosphorus. Because most grains are relatively good sources of phosphorus, feedlot cattle rarely suffer a phosphorus deficiency, although phytic acid chelation of phosphorus in grains may render up to half of it unavailable—especially for monogastric animals such equally swine and poultry.

Magnesium maintains electric potentials across nerve endings. In a deficiency, the lack of command of muscles is obvious. However, commonly deficiencies are non anticipated. A magnesium deficiency in calves results in excitability, anorexia, hyperemia, convulsions, frothing at the mouth, and salivation, but such a condition is uncommon. Unremarkably, a magnesium deficiency is seen in the spring in more mature grazing cattle under field conditions (ie, grass tetany, encounter Hypomagnesemic Tetany in Cattle and Sheep Hypomagnesemic Tetany in Cattle and Sheep Hypomagnesemic tetany is a complex metabolic disturbance characterized by hypomagnesemia (plasma tMg The disorder occurs later a decrease in plasma Mg concentration when absorption of dietary... read more ). The initial signs are nervousness, reduced feed intake, and muscular twitching near the face and ears. Animals are uncoordinated and walk with a stiff gait. In advanced stages, affected cows fall to the basis, convulse, and dice shortly after. A blood sample from affected cows would show a serum magnesium level of <two mg/dL, with a respective calcium deficiency. This condition is sufficiently prevalent that many beef cow herd managers supplement in the jump with magnesium oxide at 28–56 g/head/twenty-four hours. Beef cows generally do not like magnesium oxide; dilution by mixing it with ground corn or incorporating it into a costless-choice liquid supplement improves acceptability.

Potassium is the major cation in intracellular fluid and is of import in acid-base of operations residuum; it is involved in regulation of osmotic force per unit area, h2o balance, muscle contractions, nerve impulse transmission, and several enzymatic reactions. Potassium deficiencies normally are non anticipated in cattle diets because most forages are skilful sources, containing i%–4%. In fact, the loftier potassium content of jump pasture grass is one of the highest hazard factors for grass tetany (see Hypomagnesemic Tetany in Cattle and Sheep Hypomagnesemic Tetany in Cattle and Sheep Hypomagnesemic tetany is a complex metabolic disturbance characterized by hypomagnesemia (plasma tMg The disorder occurs after a subtract in plasma Mg concentration when absorption of dietary... read more ). A potassium deficiency might exist predictable when diets extremely high in grain are fed (eg, in finishing cattle), considering grains may contain <0.5% potassium. A marginal to deficient level of potassium in growing and finishing cattle results in decreased feed intake and rate of gain. However, this effect is subtle and probably would not exist noticed other than past the very experienced cattle feeder. Torso stores of potassium are modest, and a deficiency may develop apace. It is good exercise to supplement rations for growing and finishing cattle such that they will contain >0.6% potassium on a dry-matter basis.

Copper and cobalt deficiencies are likely more widespread than previously idea. Cobalt functions as a component of vitamin B₁₂. Cattle do not depend on dietary vitamin B₁₂, because ruminal microorganisms can synthesize it from dietary cobalt. In cattle, therefore, a cobalt deficiency is a relative vitamin B₁₂ deficiency, and such cattle evidence weight loss, poor immune part, unthriftiness, fatty degeneration of the liver, and stake pare and mucosa. Copper functions every bit an essential component of many enzyme systems, including those that involve the production of blood components. Recommended levels of cobalt and copper should exist provided in the nutrition, either by supplementation of the full mixed ration or as function of the complimentary-option mineral mix or supplemental mix.

Iodine is an integral role of thyroxine and, as such, is largely responsible for control of many metabolic functions. Typically, coastal regions subjected to iodine-carrying winds off the ocean accept abundant supplies of iodine; withal, in inland soils (in the United states, particularly between the Allegheny and Rocky mountains), the soil more often than not does not have sufficient iodine to see most livestock needs. Iodine requirements in cattle can be met adequately past feeding stabilized iodized common salt.

Although cattle probably have a metabolic requirement for all the known vitamins, dietary sources of vitamins C and Thou and the B-vitamin complex are non necessary in all simply the very immature. Vitamin Yard and the B vitamins are synthesized in sufficient amounts by the ruminal microflora, and vitamin C is synthesized in the tissues of all cattle. Even so, if rumen office is impaired, every bit past starvation, food deficiencies, or excessive levels of antimicrobials, synthesis of these vitamins may exist impaired.

Vitamin A can exist synthesized from β-carotene contained in feedstuffs such as green forages and yellow corn. Nevertheless, this ability varies amidst breeds; Holstein cattle perhaps are the nearly efficient converters of carotenes, whereas some of the beef breeds are much less efficient. Therefore, providing supplemental vitamin A to beef cattle should be considered. Vitamin A is one of the few vitamins that cattle shop in their livers—as much as a 6-mo supply. Cattle on a diet deficient in vitamin A may non begin to bear witness signs for several weeks. Newborn calves, which have pocket-sized stores of vitamin A, depend on colostrum and milk to come across their needs. If the dam is fed a ration low in carotene or vitamin A during gestation (eg, in winter), severe deficiency signs may get apparent in the young suckling calf inside 2–4 wk of nascence, while the dam may announced good for you.

It is sound exercise to provide 2–five lb (1–2 kg) of early-cut, good-quality legume or grass hay in the daily ration of stocker cattle and pregnant cows to prevent vitamin A deficiency. About commercial poly peptide and mineral supplements are fortified with dry, stabilized vitamin A. The daily requirements for beef cattle appear to be ~5 mg of carotene or two,000 IU of vitamin A/100 lb (45 kg) torso wt; lactating cows may require twice this amount to maintain loftier vitamin levels in the milk.

Vitamin A deficiency under feedlot conditions can cause considerable loss to cattle feeders, specially if high-concentrate and corn silage rations low in carotene have been fed. Destruction of carotene during hay storage or in the GI tract, or the failure of beef cattle to convert carotene to vitamin A efficiently, may increment the need for supplemental vitamin A. Growing and finishing steers and heifers fed depression-carotene diets for several months require 2,200 IU of vitamin A/kg of air-dry out ration. Commercial vitamin A supplements are not expensive and should be used when such rations are fed and whatever danger of a deficiency exists. An alternative way to supply supplemental vitamin A is by IM injection: studies prove that an extremely loftier dose (half-dozen million U) would be needed to supply adequate vitamin A for 7 mo. As with all vitamins and minerals, a steady supply in the diet is the ideal method for supplementation.

Vitamin D deficiency is comparatively rare in beef cattle, because they are unremarkably exterior in direct sunlight or fed sun-cured roughage. In northern latitudes during long winters, or in show calves kept in the barn or turned out only at dark, a deficiency is possible. The ultraviolet rays of sunlight catechumen provitamin D found in the skin of animals (7-dehydrocholesterol) or in harvested plants (ergosterol) to agile vitamin D. Straight exposure to sunlight, consumption of sunday-cured feed, or supplementary vitamin D (300 IU/45 kg body wt) prevent a deficiency.

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Source: https://www.merckvetmanual.com/management-and-nutrition/nutrition-beef-cattle/nutritional-requirements-of-beef-cattle