Understanding Commercial Free-Choice Mineral Mixes for Beef Cattle1 (AN245)
Bob Myer, Travis Maddock, and Lee McDowell2
Publication #AN245
Beef cattle require a number of dietary minerals for optimal growth, reproduction, and health. There are several important minerals that are often deficient in forages and pasture. To make up for these deficiencies, beef cattle are often offered a mineral mix ad libitum or "free-choice."
Selecting the correct free-choice mineral supplement product is important for maintaining healthy animals and optimizing growth and reproduction. Producers should select supplements that will meet animal requirements and avoid excesses that reduce profits and lead to unnecessary mineral excretion. A good mineral program for beef cattle is one of the best investments that cattle producers can make.
Selecting a mineral mix
There are many commercial mineral supplements available with different formulations. A free-choice mineral supplement should provide the following minerals: calcium, phosphorus, sodium and chloride (salt), magnesium, copper, zinc, iodine, cobalt, and selenium. Mineral requirements for beef cattle are shown in Table 1. Iron and manganese are also essential and are included in many mineral supplements; however, the concentrations of these minerals in forages are usually more than adequate in the lower Southeastern U.S.
The most important considerations when purchasing mineral mixes are phosphorus level, calcium to phosphorus ratio, salt level, bioavailability of "trace" minerals (especially copper), and the presence or absence of a high level of magnesium. An example mineral mix is presented in Table 2.
Mineral concentrations in forages and feeds
Average concentrations of important minerals of several forages and common concentrate feeds are shown in Table 3. Mineral concentrations in various feeds and forages will vary; thus it would be desirable to test for concentrations of minerals, especially phosphorus, calcium, magnesium, potassium, copper, and zinc. Mineral concentrations in forages and concentrate feeds can be used as a guide in selecting a proper mineral mix.
Two multiyear surveys have been conducted in North Florida to measure mineral concentrations in pasture forage. For beef cattle grazing warm-season bahiagrass pastures, sodium concentration in the pasture forage was found to be very deficienta; copper, selenium and cobalt were deficient; calcium and zinc were slightly deficient; phosphorus was marginally deficient to marginally adequate; magnesium, iron, and manganese were adequate; and potassium was in excess when compared to requirements for beef cattle. For cattle grazing cool-season annual grass pastures, sodium in the pasture forage was very deficient; copper, selenium, and cobalt were deficient; calcium was slightly deficient; zinc was marginally deficient; magnesium was marginally deficient to adequate; phosphorus was marginally adequate to adequate; iron and manganese were adequate; and potassium was in excess. Please note that iodine and chloride were not measured in the above surveys.
Phosphorus concentration
Phosphorus is expensive and there is concern about excessive phosphorus excretion by cattle into the environment. Phosphorus, however, can be marginally deficient in grass forages, especially warm-season grasses such as bahiagrass. Phosphorus is often discussed in conjunction with calcium because the two minerals function together in bone formation.
Phosphorus concentration in a commercial free-choice mineral mix can vary from 0 to 12%. Since phosphorus is typically the most expensive component in a mineral mix, purchasing a supplement based on price alone may result in inadequate phosphorus supplementation. The level of phosphorus that should be in a supplement will be dependant upon what forages and/or other feedstuffs the cattle are grazing or being fed (Table 3).
Because of the variation in phosphorus level among various commercial free-choice mineral products, the product name on the tag will often have a number on it that indicates the phosphorus level. For example, "Beef 8 Plus" would indicate that the mineral mix contains 8% phosphorus. If two numbers are present, the first will be the concentration of calcium and the second, phosphorus. If ingredients other than mineral sources are included, such as a protein source, the tag will give information about the added ingredient(s) instead of phosphorus content (e.g., crude protein content if a protein source is added).
Some general guidelines on choosing a mineral mix with the proper phosphorus concentration:
For beef cattle grazing warm-season grass pastures (e.g., bahiagrass) and/or are fed grass hay, 4 to 8% phosphorus is suggested in the mineral mix (in fact this level is adequate for most situations in Florida). In instances where grass forage is consistently lower than 0.2% phosphorus, 6 to 10% phosphorus is suggested. However, the best advice would be to have the forage tested for phosphorus concentration to be sure.
For cattle grazing cool-season pastures (e.g., annual ryegrass), 2 to 4% phosphorus in the mineral mix is suggested.
For cattle supplemented with co-product feedstuffs, such as corn gluten feed or distillers grains, 0 to 4% phosphorus in the mineral mix is preferred (various co-products are high in phosphorus; for example, corn gluten feed contains about 1% phosphorus—refer to Table 3. An exception is citrus pulp, as it is quite high in calcium and low in phosphorus; soy hulls are low in phosphorus as well).
For cattle grazing legume pasture or fed legume hay (e.g., perennial peanut), 8 to 12% phosphorus is suggested for the mineral mix (legumes are low in phosphorus but high in calcium, averaging 1.2% calcium).
Also be aware that the phosphorus need of the beef cow is greatest during lactation, especially early lactation.
