Supplemental Feeds and Protein Blocks
Many supplemental feeds or protein blocks may also contain supplemental minerals mixed directly into the product. This can be a good source of mineral supplementation, but the feed tag should be read carefully to ensure that the product meets all mineral and vitamin requirements and no additional supplemental forms of minerals or vitamins are required to meet the animal's needs. As an example, some products may not contain salt and recommend providing free-choice salt.
Injectable Trace Minerals
Injectable forms of trace minerals are also available via a prescription from a licensed veterinarian. These products are not intended to be a complete mineral program but can provide a quick dose of select trace minerals, including copper, zinc, manganese, and selenium. These products can quickly elevate circulating levels, as they enter the blood within hours and the liver (the primary storage site for trace minerals in the body) within 48 hours. However, research regarding benefits to reproductive and immune function shows mixed results. These products might benefit high-risk calves that may have trace mineral deficiencies due to previous low mineral intake. It is important to note that injectable trace minerals are designed not to replace a conventional mineral supplementation program but to work alongside free-choice supplementation. As with any product, care should be taken to read the label instructions and dosage information carefully.
Supplemental Mineral Sources
Most minerals can be supplied from one or more sources. However, it is important to note that not all mineral sources are considered equal, due to differences in bioavailability. Bioavailability refers to the amount of the mineral that is consumed and absorbed from the gastrointestinal tract for use by the animal. Thus, a source with greater bioavailability can provide more of the desired mineral to the animal. This is especially important for trace minerals such as selenium. Selenium concentrations in animal feed are regulated by the FDA and are not to exceed three
milligrams per head per day. Forages can be deficient in selenium, and selenium deficiency is common throughout the region. Since the concentration of selenium cannot be increased in mineral supplements, it is important to provide a selenium source with increased bioavailability to prevent selenium deficiency. There are three main types of mineral sources: inorganic, organic, and hydroxy. Inorganic minerals are mined from the earth. These sources are available in the form of sulfates, oxides, and carbonates. They are termed inorganic because they lack a carbon-hydrogen structure. Organic or chelated minerals include a mineral that is bound to a carbon-containing molecule, typically an amino acid or sugar. Common organic or chelated sources include amino acid complexes, proteinates, and minerals bound
to lysine, methionine, and glycinate. Hydroxy minerals, which include a mineral bound to a hydroxy group, encompass sources like zinc hydroxychloride or basic copper chloride. In general, organic, or chelated, and hydroxy sources have greater bioavailability than inorganic sources of minerals. For cattle in Kentucky, it is especially important to pay attention to sources of copper and selenium in supplemental mineral products, as these are the most common deficiencies observed in the region. Information about the sources of supplemental minerals included in a product can be found in the ingredient section of the product mineral tag. For a more in-depth discussion of interpreting information from a mineral tag, refer to the UK Cooperative Extension Services publication Reading the Fine Print: Understanding Mineral Tags (ASC-249).
High-Magnesium (High-Mag) Mineral
High-magnesium (high-mag) mineral supplements contain a greater inclusion of magnesium than typical beef-cattle minerals. These products aid in the prevention of grass tetany. Grass tetany is typically observed in lactating cows during spring months when forages are rapidly growing or when lactating animals are grazing cereal grains such as wheat, rye, oats, or triticale. These forages are high in potassium and low in magnesium. When consumed, this excess potassium interacts with magnesium in the rumen, resulting in reduced magnesium absorption. Therefore, supplementing additional magnesium can help prevent grass tetany. It is generally recommended that high-mag minerals be fed to cattle susceptible to developing grass tetany, especially cows in early lactation, when environmental conditions for grass tetany exist. These conditions include grazing of ryegrass, small grains, and cool-season grasses in late winter to early spring, when pastures are lush and high
in potassium. High-mag minerals should be fed to cattle at least 30 days before calving and continued through late spring, when grasses are more mature and daily temperatures reach at or above 60°F. High-mag mineral products should contain 10 to 15 percent magnesium from magnesium oxide for a free-choice mineral formulated with a target intake of four ounces. For more information on grass tetany, check the UK Cooperative Extension Service publication Forage-Related Cattle Disorders: Hypomagnesemic Tetany or “Grass Tetany” (ID-226).
Co-product Balancing Mineral
Beef-cattle requirements for calcium are twice that of phosphorus, based on the skeletal mass having a calcium to phosphorus (Ca to P) ratio of 2:1. Thus, the Ca to P ratio of beef-cattle diets should be close to 2:1. Common co-product and grain feedstuffs fed to cattle, including corn, distillers by-products, and corn gluten feed, are often low in calcium and high in phosphorus. When these ingredients are used in beef-cattle diets, often this results in a diet with a low Ca to P ratio (less than 1:1). When this occurs, cattle are at risk of developing urinary calculi or stones, which result in the condition known as water belly. Unfortunately, this condition is often fatal, but it can be prevented by ensuring an adequate Ca to P ratio in the diet. Additional calcium can be added to the diet either as feed-grade limestone or by selecting a co-product balancing mineral high in calcium (typically 20 percent or greater) and low in phosphorus (typically less than two percent). Aside from
changes to the calcium and phosphorus content, these minerals are typically formulated to provide both macro- and microminerals and vitamins. However, most co-product balancing minerals are designed to be mixed directly into the feed, rather than being fed free choice through a mineral feeder.
Medicated Minerals
A mineral supplement can be a convenient method to deliver medication or other feed additives to cattle through the feed. For example, commonly available medicated minerals can contain chlortetracycline to control anaplasmosis, ionophores for the prevention of coccidiosis, or products for fly control. These products can be purchased through your local feed dealer, except for those that contain antibiotics such as chlortetracycline, which require a prescription from a licensed veterinarian. As with any supplement, the efficacy of medications delivered through minerals is largely dictated by mineral intake. It is important to pay attention to mineral intake to ensure adequate intake of the included medication.
Conclusion
Minerals are essential nutrients that are required in the diets of beef cattle and support many economically important traits, such as reproduction, growth, lactation, and health. Mineral supplements should be provided to cattle throughout the year. However, certain times of the year may warrant changing the formulation, such as delivering high-mag mineral in the spring to lactating cows or medicated minerals for control and treatment of anaplasmosis. The use of certain feedstuffs may also influence the mineral supplement needs of the herd. It is important to supplement with a complete mineral that provides macro- and microminerals and necessary vitamins to the herd. Take care to evaluate mineral products, as there can be variation across products in both concentration and mineral source. The most expensive product may not be the best product available. Once a mineral has been purchased, manage the mineral’s delivery to ensure the products’ efficacy and minimize risks of mineral deficiencies. Monitor intakes and compare them to the listed targeted intake on the product tag. For further guidance on selecting a suitable mineral for your herd, please contact your local county Extension office.