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Introduction to Mineral Supplements

Minerals are inorganic compounds. Chemically, minerals are elements. Dietary minerals are classified based on their concentration in the body and dietary requirement. Macrominerals are minerals present at greater than 100 ppm. In general, the concentration of macrominerals in the ration is expressed as a percent of dry-matter. In general, the quantity of each macromineral required per day is in the order of tenths of one gram (decigrams) to one or more grams.

Table 10.1 lists the macrominerals and their abbreviations.

Microminerals, also referred to as trace minerals, are the minerals present at less than 100 ppm. In general, the concentration of microminerals in the ration is expressed as milligrams per kilogram. One ppm is equal to one milligram per kilogram. In general, the quantity of each micromineral required per day is on the order of millionths of a gram (micrograms) to thousandths of a gram (milligrams).

Table 10.2 lists the microminerals and their abbreviations.

Each of the macrominerals and microminerals is essential for supporting maintenance and production functions; each mineral has at least one specific, exclusive function.

Table 10.3 lists the primary functions of each of the macrominerals and microminerals.

Total quantity of minerals in a feedstuff may be determined via the ash procedure of proximate analysis; ash is an estimate of total mineral content of a feedstuff. The quantity of individual mineral components requires specialized analysis performed via a spectrophotometer. In addition to quantity of a mineral, it is also important to consider quality (i.e. bioavailability) of a mineral source. Bioavailability refers to the ability of the mineral source to supply a digestible and absorbable form of the mineral which may be subsequently utilized by the animal to support maintenance and production functions.

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. Sodium chloride, also known as salt, is the common form of supplementation. As a result of the various factors, information provided on bioavailability is an estimate versus a precise measure. Quantity and quality of a mineral varies by mineral source and within a mineral source.

In addition, the book values of mineral contents may not consistently represent the actual mineral contents of a feedstuff. Therefore, it is recommended to establish a schedule to analyze the mineral content of feedstuffs. In general, the mineral contents of feedstuffs such as grains will be relatively consistent. Generally, an estimate of ash content will provide information regarding significant deviations from book values. For significant deviations, it is recommended to perform an analysis for individual minerals. As the mineral content may be variable in forages and by-product feedstuffs, it is recommended to perform individual mineral analyses on a more frequent schedule.

Table 8-1 on page 168-169 in 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.

Mineral supplements may be classified as either natural or synthetic and inorganic or organic. Inorganic sources do not contain carbon. Organic sources do contain carbon. Generally, natural sources are minerals processed to concentrate the mineral component and minimize the presence of contaminants. Synthetic minerals are produced by chemical synthesis. Natural sources may be either organic or inorganic. Synthetic sources may also be organic or inorganic. One group of synthetic, organic minerals are chelated minerals. Chemically, chelated minerals are composed of the mineral bound to an organic compound. Chelated minerals are relatively expensive per unit of mineral provided in the supplement. Research data do not conclusively support chelated minerals based on the premise of improved utilization of the mineral component. As an additional note, in general, mineral sources in feedstuffs are in the organic form.

Mineral supplements may be added to the ration or offered ad-libitum. In general, micronutrients require a carrier. As consumption of a supplement offered ad-libitum varies by animal, it is recommended to add the mineral and vitamin supplements to the complete feed at the appropriate rates to promote adequate consumption of the supplement by each animal. Given feeding situations may not allow addition of supplements to a complete feed, various mineral and vitamin supplements in combination with salt, to control consumption, may be offered ad-libitum.

In general, minerals provided in the various feedstuffs of the ration and water do not fulfill the animal's dietary requirements for each mineral, therefore additional supplementation of one or more of the minerals is required. Selection of supplemental minerals is dependent upon cost per unit of available mineral, absence of antinutritional factors, and physical form. The specific mineral and quantity of each mineral to be supplemented is influenced by factors such as animal species and physiological state, available mineral content in the feedstuffs of the ration, and available mineral content of the water source. Given the number of minerals, interrelationships between the minerals, varied requirements for each of the minerals, and varied ranges of subclinical and clinical toxicities for each of the minerals; mineral supplementation is complex. Figure 8-1 on page 167 of the text illustrates identified interactions between the various minerals.

As subclinical deficiencies and toxicities have the potential to impact animal health and productivity, it is essential for a feed manager to match mineral requirement to the mineral available to the best of their ability. As a feed manager it is also important to realize commercial mineral sources may not effectively meet the mineral requirements of the animal. As evidenced by the data in Table 8-3 on page 175, mineral supplements, even specialized formulations, may be deficient in or provide excess levels of one or more minerals. In comparison to the potential impact on profitability, the cost of mineral supplementation is minimal.

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