This is an excerpt from information provided by the Beef Cattle Research Council of Canada, so naturally it’s focused on cattle. Because sheep and goats have different requirements, don’t use this information for them. We can cover their needs in future issues.
At least seventeen minerals are required by beef cattle and are divided into two groups: macrominerals and microminerals. Macrominerals are those required in relatively large amounts for bodily functions, while micro or trace minerals are required in much smaller amounts.
The seven macrominerals required by cattle are calcium (Ca), magnesium (Mg), phosphorus (P), potassium (K), sodium (Na), chlorine (Cl) and sulphur (S). Macrominerals are required in amounts over 100 parts per million (ppm) and are often expressed on a percent (%) dry matter (DM) basis of the animal’s diet.
Beef cattle require ten microminerals, also referred to as trace minerals. These microminerals, required in relatively small amounts are usually expressed in parts per million, (ppm) or mg/kg, rather than as a percentage of the diet. They are chromium (Cr), cobalt (Co), copper (Cu), iodine (I), iron (Fe), manganese (Mn), selenium (Se), and zinc (Zn).
Producers strive to provide adequate levels of macro and microminerals without over-supplementing. Over-supplementing increases costs, can create nutritional antagonisms (when one element interacts negatively with another), and increases potential for mineral loss through manure and urine6.
Minerals are required for several functions:
• Skeletal development, bone, tooth formation and maintenance (includes Ca, P, Mg, Cr)
• Energy, growth, immunity, and reproduction (includes P, Cu, Zn, Mn, Se)
• Milk production (includes Ca and P)
• Nervous system function and carbohydrate metabolism (Mg, K, Na, Cl, S, Co, I, Fe)
Although minerals are required in relatively small amounts for optimum beef cattle health, a deficiency can cause significant reductions in growth, immune function and reproduction.
The concentration of individual minerals in forages varies greatly depending on soil, plant, and management factors. It is important to include mineral analysis of forages as part of regular feed testing. There are also several interactions that can occur between minerals, vitamins and water or feed sources that can limit availability or absorption. As a result, the minerals that are actually available to the cattle may be much lower than anticipated because of these interactions. Even though concentrations found in forages may appear to be sufficient, availability to the animal may be significantly less. This can cause deficiencies which may not be noticed by producers until a significant reproductive or health issue arises.
Dr. Cheryl Waldner, NSERC/BCRC Industrial Research Chair in One Health and Production-Limiting Diseases, and Professor at the Western College of Veterinary Medicine explains that first and second calf heifers are most likely to exhibit signs of copper deficiency, such as lower conception rates. The cost of open cattle can quickly impact profitability. Waldner suggests that a properly balanced, palatable mineral mix be offered year-round to ensure optimal herd health and fertility. Recent research in Saskatchewan revealed that forages sampled in spring and fall contained inadequate levels of copper and zinc for beef cows and growing calves in all soil zones. Additionally, up to 43% of the cows involved in the study were deficient in copper. Producers may notice some early signs of copper deficiency manifesting as a brownish or reddish tinge in black haired cattle.
Other problems that can arise due to mineral deficiencies include grass and winter tetany, white muscle disease, weak bones, hairless calves, goiter, scours, foot rot, retained placentas, low weaning weights, and reduced fertility.
Trace mineral supplements are divided into three groups: inorganic, organic and hydroxy trace minerals.
Inorganic minerals are bonded to an inorganic molecule such as sulphate or oxide. They are usually less expensive but often have more variability in formulations and are less bioavailable. Inorganic minerals are often a first choice for producers due to affordability but may sacrifice availability and absorption. The absorption of inorganic mineral from the gastrointestinal tract can be less than five percent7. In certain instances, such as with copper, inorganic minerals may be more prone to antagonisms with other minerals8. Simply feeding more inorganic mineral to offset these potential issues will not be successful and may cause more problems if levels of particular minerals become too high.
Organic (chelated) minerals are bonded to a carbon containing molecule. These are usually more expensive but have improved absorption and availability to the animal. Producers generally use chelated minerals if mineral antagonisms exist in their area, such as high molybdenum or sulphur, which reduces copper availability. Chelated minerals are also used when animals are stressed, such as during weaning, or to ensure a high nutritional plane for procedures such as synchronization or artificial insemination on heifers.
Hydroxy trace minerals have a crystalline structure that protects metal ions and allows trace minerals to bypass rumen digestion, thereby increasing bioavailability. Often available at a mid-range price, they are being utilized by some producers for cattle in high stress situations, such as weaning or artificial insemination.
With improved trace mineral absorption, producers report heavier weaning weights, increased average daily gain, improved reproductive efficiency, improved calving outcomes, and fewer health problems. Some also report reduced incidence of pinkeye, foot rot, scours and respiratory problems.
Mineral needs will vary between herds based on many factors, including water and feed sources, stress, animal type and stage of production. There is no “one size fits all” mineral type or program. Many mineral mixtures are available on the market, from loose mineral that can be offered free choice or mixed into a ration, to various molasses-based lick tubs that contain vitamins, minerals, and often some protein.
Producers must monitor animals for signs of deficiencies or potential toxicity, and work with their veterinarian and nutritionist to ensure adequate levels and to correct any issues. Mineral toxicity may be indicated by decreased animal performance, anorexia, weight loss and diarrhea. It can lead to urinary calculi from excess phosphorus or inadequate calcium to phosphorus ratio, grass tetany from excess potassium leading to reduced absorption of magnesium, and polioencephalomalacia from excess sulphur. Some minerals such as copper, can become “tied up” or bound to other minerals present in feed and water. In these instances, the mineral will not be available to the cattle in the amounts required. If producers are using feed tests to balance mineral needs, animals may still be deficient due to reduced bioavailability.
An animal’s diet or ration will determine the type of mineral mix required to meet animal requirements. Grass is often low in calcium, phosphorus, magnesium and sodium, while alfalfa or other legumes are generally higher in calcium.
The following label contains the breakdown of a loose mineral that would be considered a 3:1 calcium to phosphorus ratio and may be used by producers feeding cereal greenfeed forages. (Please note the warnings about copper, both for sheep and goats, and for eye injury.)
Free Choice Feeding
Cattle will often demonstrate a preference for certain mineral mixes or molasses lick tubs, which can create challenges in terms of daily intake when feeding free choice. While recommended mineral intake is about 60 grams (2 ounces) per head per day, when fed free choice some cattle will over-consume mineral, while others may avoid it altogether. Monitor the herd to determine which cattle are frequently at the mineral stations and which cattle may not be consuming adequate amounts. Some producers report better intake when they offer choices of different mineral mixes, such as loose and lick tubs. Others report that moving the mineral stations a little farther from water sources to encourage grazing on less utilized areas of pasture caused mineral consumption to drop off slightly.
Ensure that there are enough stations for the number of cattle; a common recommendation is one mineral station for every 20-30 head. When feeding cows with calves at side, more stations may be necessary to ensure that the calves have access, as dominant, mature cows will often out-compete calves for mineral. When possible, work with a nutritionist to formulate an appropriate mineral blend for each operation.
Want more on free choice mineral feeding? Here you go: