Mineral Supplementation for High Producing Beef Cows.

Ted Perry

Beef Technical Services, Land O Lakes Purina Feed, LL

The single most important event in a cow-calf operation is producing a live calf. Beef cattle require a number of minerals for reproduction and lactation.  Selecting the correct mineral supplement is important for efficient reproduction, high milk production and animal health of both the cow herd and calves. Quality forages and other feedstuffs can furnish a large portion of the required minerals. Minerals not provided by feed can be easily and inexpensively supplied with a balanced mineral supplement.

Macro Minerals

Cows will voluntarily consume about 1 ounce of salt per day. They will consume more salt when forage is succulent (spring grass / silage) than when it matures (stocked piled forages / hay). Salt provides for the proper function of the nervous and muscular systems.  A salt deficiency causes loss of appetite and body condition loss.  Salt is one of the main drivers of free choice intake and can be used to maintain mineral consumption at the recommended levels.

Calcium and phosphorus are in the greatest amounts.  Ninety-nine percent of total body calcium and 80 percent of total body phosphorus are stored in the bones. Skeletal stores of calcium and phosphorus are used to meet short-term deficiencies.  These minerals must be replaced because long-term deficiencies of either mineral can cause bones to weaken and even break.  A decrease in either or both can cause a decrease in efficiency of gain and lead to lower body condition scores. During lactation, low amounts of either calcium or phosphorus will reduce milk production. A superior milking cow requires two times more calcium than does a non-lactating cow. A phosphorus deficiency can also delay mature beef cows from returning to heat following parturition and can delay puberty in developing heifers. Calcium and phosphorus utilization is affected by both the amount of each mineral fed, and the ratio of the two elements. The optimum Ca:P ratio is about 1.5:1, with a range of 1:1 to 4:1 being satisfactory. Most grasses are adequate in calcium, but grains, corn co-products and grain silages are poor sources of calcium and will require supplementation to balance Calcium and Phosphorus in their proper ratio’s. 

Most forages are low in phosphorus late in summer and fall.  Cattle are more likely to be phosphorus-deficient during the winter and early spring after they have been fed stored forages for the winter.  Most by-product feeds such as distillers grains, corn gluten feed and wheat midds, have high phosphorus concentrations which needs to be accounted for when selecting a mineral.

Magnesium is essential for proper enzyme activity, carbohydrate metabolism and nervous system function.  Magnesium deficiency is most commonly associated with Grass Tetany.  Grass Tetany is most common in older high producing cows grazing lush spring or small grain pastures.  Low Magnesium levels have also been shown to decrease reproduction and milk production in brood cows.  This may be a bigger economic loss to the herd than tetany.  High fertilization rates also contribute to grass tetany. Excess potassium inhibits magnesium absorption in cows. Grass tetany can usually be prevented by feeding cattle a mineral mixture containing magnesium oxide before turn out on lush pastures.

Grasses usually contain adequate amounts of potassium for grazing cattle.  Potassium can be low in low quality forages.  Potassium functions in acid-base balance, osmotic pressure and the amount of water retained in the body. High levels of potassium may inhibit magnesium absorption and be cause metabolic problems.

A deficiency of sulfur in beef cattle diets is not likely to occur under normal feeding conditions. Sulfur is more likely to be in excess, which can interfere with the metabolism of copper resulting in trace mineral deficiencies and reduced reproduction effeciency. Co -products such as distillers grains and corn gluten feed contain higher concentrations of sulfur, which should be taken into account in ration balancing.

Microminerals

There are 10 microminerals required by beef cattle.  Three of the microminerals (copper, zinc and selenium) are likely to be deficient in forages.  Many trace mineral deficiencies are caused by antagonists, which tie up the minerals and reduce availability absorption. Therefore special attention should be made to ensure they are provided in adequate amounts.  Copper is the most common micromineral deficiency in grazing cattle.  Deficiency signs include reduced fertility, increased post partum interval, delayed puberty in heifers and depressed immunity. Copper should be supplemented as copper sulfate, tribasic copper chloride, or an organic complexed copper.

Zinc is also a component of many enzymes and important for immunity, male reproduction, and skin and hoof health. Cattle have a limited ability to store zinc and thus zinc supplementation is always necessary. Zinc absorption is closely tied to copper absorption, and the zinc to copper ratio should be kept at approximately 3:1.

Selenium deficiency causes white muscle disease (similar to muscular dystrophy) in newborn calves. Selenium deficiency can also cause calves to be weak at birth and increase their susceptibility to diseases like scours. Increased rates of retained placentas and poor reproductive performance are often observed in cows with selenium deficiencies.  Selenium can be very toxic and should only be fed in a complete mineral. In areas where deficiencies occur, use the maximum legal level 0.3 ppm in the diet. Selenium deficiency should not be a problem if adequate amounts of selenium are consumed in the mineral supplement.   

Selecting a Mineral Supplement

Phosphorus supplementation may not be needed when feeding high phosphorus feeds such as cottonseed meal, distillers grains or corn gluten feed.  When feeding co-products in the diet select a mineral designed these diets that contain higher amounts of calcium and trace minerals with little or no phosphorus.  Forage maturity may be used as a guideline when selecting minerals.  High quality forages require lower amounts of phosphorus and late season mature forages require higher amounts.

Management for consistent mineral intake

Most minerals are not stored in great amounts, therefore, consistent intake of a balanced mineral supplement is important.  Feeder location is an important factor in getting consistent free choice mineral intake. The best areas to place mineral feeders are near water, in shaded loafing areas and near the best grazing areas. Check feeders at least once a week and keep a clean, fresh supply of minerals present at all times.

There are two preferred forms of mineral supplements designed to provide consistent intake with little or no waste.  Feeding minerals free-choice in a loose mix form is most common method of mineral supplementation. A common problem with loose mineral is waste from blowing in the wind and bricking after getting wet. Wind & Rain or RangeLand large particle minerals are designed to reduce losses associated to blowing and bricking during bad weather.  RangeLand and Wind&Rain mineral tub products are very resistant to weather issues.  In addition, research trials have concluded that intake is more consistent with mineral tubs the traditional loose mineral products.  Finally, mineral tubs can be moved to areas of the pastures that are poorly utilized to entice cattle to graze under utilized pasture areas.

In summary, mineral nutrition is important because cattle perform better and more efficiently utilize feed when minerals are balanced in the diet. Mineral nutrition is vital to reproductive efficiency, milk production and herd health and.  Calcium, phosphorus and salt are usually the first limiting minerals in cattle diets. Magnesium may be a problem during late winter or early spring, especially in mature lactating cows. A well balanced mineral program is more important than providing high amounts of certain individual elements while not providing adequate amounts of other minerals.  Management strategies to meet recommended daily intake and proper mineral selection will help ensure mineral requirements are met, with little of no waste of feed dollars.  For more information on mineral supplementation programs please contact your local Purina or Land O Lakes feed dealer.