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Macrominerals

In general, the macrominerals added as supplements to the rations of the various animal species are sodium, chlorine, calcium, phosphorus, magnesium, potassium, and sulfur. Table 8-1 on page 168-169 of the text lists sources of mineral supplements utilized in feed supplements, complete feeds, or in mineralized salt. The sources with an asterisk are sources most commonly utilized in commercial feeds.

Table 10.4 lists various mineral sources with intermediate and high relative bioavailability.

In addition to this table, the macrominerals sodium and chlorine are also commonly supplemented.

The most common mineral supplement added to rations is sodium chloride, also known as salt.

Figure 10.1 illustrates salt.

Salt provides sodium and chlorine; dietary required macrominerals. Salt is almost pure sodium chloride. Salt may be fed alone or fed with additional components, both nutritive and nonnutritive components. Salt may function as a carrier when fed with additional components. Iodized salt is sodium chloride with an iodine-containing compound added. Trace-mineralized salt is salt with microminerals added. Common microminerals added in the trace-mineralized mixture are cobalt, copper, iron, iodine, manganese, and zinc. In addition, sulfur and magnesium and a limited amount of selenium may be added.

Figure 10.2 illustrates trace-mineralized salt.

Trace-mineralized salts are appropriate in a number of production situations. As trace-mineralized salt may pose an issue is specific regions, it is important to analyze each specific production situation. In addition to microminerals, nonnutritive additives such as antibiotics and anti-bloating compounds may be added to salt. For ruminants and horses, supplemental salt may be added to the ration or fed ad-libitum separate from the ration. Salt added to the ration should be fine in texture and free-flowing. Offered ad-libitum, salt may be provided loose or as a compressed block; form of feeding is influenced by factors such as cost per unit, climate, and competition for supplement. Figure 8.4 on page 170 of the text illustrates an example of a feeder that provides loose salt protection from the elements. Figure 8-3 on page 170 of the text illustrates cattle consuming salt from a compressed block. For poultry and swine, in general, supplemental salt will be added to the ration.

In general, sodium chloride is added to the majority of animal rations. The requirements for sodium and chlorine will increase as fluid losses of an animal increase. Two common forms of fluid loss are sweat and milk. The requirements will also increase for ruminants and horses consuming forages high in potassium content. For ruminants and horses, in general, 0.5-1.0% is added to commercial formulas. In addition, various supplemental concentrates may contain 1.0-3.0% salt. For poultry and swine, in general, feedstuffs contain 0.25-0.5% salt. Excess salt is a potential issue for all species. Poultry and swine are more susceptible to toxicity compared to other animals. To prevent toxicity, the producer should have knowledge of the relative salt contents in feedstuffs and water and provide adequate water. Salt is an attractive and palatable feedstuff to animals. Animals may be expected to consume enough salt to at least meet their requirement for sodium and chlorine.

In general, supplementation of calcium and phosphorus to animal rations is required. Regarding the various types of feedstuffs in rations, forages are relatively low in P and high in Ca and grains and similar concentrates are relatively low in Ca and high in P. In general, the bioavailability is similar across calcium sources. In contrast, the bioavailability of phosphorus varies significantly between phosphorus sources.

In plant-based sources of phosphorus approximately half of the phosphorus is bound with phytic acid in a phytate complex. For monogastrics, phytin P is relatively unavailable. Therefore, for plant-based sources of phosphorus fed to monogastrics, consider approximately half of the phosphorus available for absorption. In contrast to monogastrics, microorganisms in the rumen synthesize phytase which releases phytin P, making it available for absorption by the ruminant. Therefore, for plant-based sources of phosphorus fed to ruminants, consider a greater amount of the phosphorus available for absorption. The bioavailability of inorganic sources of phosphorus also varies. Well utilized sources include phosphoric acid and mono, di, and tricalcium phosphates.

Dicalcium phosphate is a common source of calcium and phosphorus.

Figure 10.3 illustrates dicalcium phosphate.

The average composition of calcium and phosphorus is 25-28% and 18-21%, respectively. In addition to a favorable bioavailability, dicalcium phosphate is also low in fluorine.

Additional bone-based products include steamed bone meal, bone charcoal, spent bone charcoal, and bone ash.

Figure 10.4 illustrates steamed bone meal.

The contents of calcium and phosphorus in the various bone-based products vary. In general, the bone-based products are favorable sources of calcium and phosphorus.

Monocalcium phosphate contains approximately 20% calcium and 21% phosphorus. Tricalcium phosphate contains approximately 38% calcium and 18% phosphorus. Each of these is a favorable source.

Defluorinated phosphate is another source of phosphorus.

Figure 10.5 illustrates defluorinated rock phosphate.

The average phosphorus content is 14% and the bioavailability is favorable.
The average phosphorus content of phosphoric acid is 23-25%. The bioavailability of phosphoric acid is high. Phosphoric acid is often added to liquid supplements for ruminants.

Ammonium phosphate is produced by treating phosphoric acid with ammonium. Ammonium phosphate is available as monoammonium and diammonium. In addition to a source of phosphorus, ammonium phosphate is a source of nitrogen for ruminant species. The minimum nitrogen content for monoammonium and diammonium phosphate is 9 and 17%, respectively. As a source of nitrogen for ruminants, the maximum inclusion rate is at the point the product provides 2% of the total crude protein of the ration. The phosphorus content for monoammonium and diammonium is 25% and 20%, respectively.

Additional sources of phosphorus are mono and disodium phosphate. Availability of these sources is also favorable.

Additional sources of calcium are various sources of calcium carbonate and calcium sulfate. Sources of calcium carbonate include limestone and oyster shells.

Figure 10.6 illustrates ground limestone.

Calcium sulfate provides a source of sulfur. Sulfur is essential for microbial protein synthesis of sulfur-containing amino acids. Dolomite limestone also contains at least 10% magnesium. Although the minimum magnesium content for dolomite limestone is 10%, the bioavailability is low for some species. In general, these are favorable sources of calcium.

In general, the supplementation of magnesium to animal rations is required. The preferred source of magnesium is magnesium oxide. The average magnesium content is 54-60% and the bioavailability is favorable. Additional sources are magnesium carbonate and magnesium sulfate; the respective magnesium contents are 21-28% and 10-17%. The bioavailability of each source is also favorable.

Potassium is generally required for ruminants on high-concentrate rations and in the rations of monogastrics. Sources of potassium include potassium chloride, sulfate, and carbonate. The content and bioavailability of the sources is favorable.

Supplemental sulfur is generally required for ruminants, especially ruminants consuming NPN compounds. Favorable sources of sulfur include potassium sulfate and magnesium sulfate. Elemental sulfur may also be added to rations. To fulfill the sulfur requirements of monogastrics, monogastrics should be fed sulfur-containing proteins.

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