Grazing livestock require many different nutrients to support growth, milk production and body-tissue maintenance.
Often, minerals are separated into two categories. The minerals that are required in relatively large amounts are called major or macro minerals. These usually are listed on feed tags with a percentage sign after the name.
Those needed in lesser amounts are called micro, minor or trace minerals and are generally listed in parts per million (ppm).
A trace mineral can be just as important to health and performance of an animal as a macro mineral. Factors that influence the amount of specific minerals that cattle need include age, rate of growth, stage of pregnancy and stage and level of lactation.
The essential macro minerals for beef cattle are calcium, phosphorus, chlorine, magnesium, potassium, sodium and sulfur. Trace minerals needed are copper, chromium, cobalt, iodine, iron, manganese, nickel, molybdenum, selenium and zinc.
These minerals may function as structural components of bones and teeth, electrolytes in body fluids, metabolism of nutrients, nerve conduction, reproduction, immune response and many more functions.
Various body functions require different amounts of minerals. The daily intake of trace minerals needed for maximum immune response is greater than the amount required for optimal growth or reproduction. Cattle can have sufficient trace mineral intake to support optimal growth or reproduction. However, cattle may not consume adequate trace minerals for maximum immune function. Intake and absorption of minerals must be adequate to meet all the animal’s body functions.
Although many factors affect the intake and absorption of minerals by cattle, a major factor is the mineral content of the forages they consume. The first step in developing a mineral supplementation program is to determine the feed or forage mineral content.
It is important to understand the bioavailability of minerals from forages may be low. As a rule, when figuring mineral values in forages, the suggested usefulness should be divided in half to account for potentially low bioavailability. For example, if a forage has a concentration of 0.2 percent of a mineral, the amount absorbed would be 0.1 percent. Mineral supplements are calculated making adjustments for the bioavailability of the sources.
You should always take time to read the mineral product label. Key things to note: target species (beef cattle, dairy cattle, etc.), mineral levels (percentage or ppm), target intake (ounces per day), feeding method (free-choice or mixing), and the ingredients or source of the minerals.
Because a minerals source greatly influences absorption or bioavailability, mineral supplements must contain sources of high bioavailability. The levels listed on the feed tag as well as the targeted intake must then be considered. There can be various mineral mixtures with both different mineral levels and intakes.
The supplement should provide adequate intake of the various minerals to balance the supply from the forage and the animal’s needs while also being cost effective.
For further information about minerals and their functions see: Trace Mineral Supple-mentation for Kentucky Beef Cattle publication available at the Madison County Extension Office or online at www2.ca.uky.edu/agc/pubs/asc/asc155/asc155.pdf
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