Graziers, livestock need minerals

cattle feedlot

Thanks to a long cold spring, many of us had to feed hay much longer than usual, but finally, the animals are out on pasture.

Although the feeding chores are reduced and most of the nutrients needed by the animals are supplied by grazing, it is still important to make sure they have supplemental mineral available.

Deficiencies in mineral availability to animals are often not observed in the animal’s ability to survive, but can become apparent with the ability to reach peak productivity and maximum reproductive performance.

Most of you have seen the charts showing the prioritization of nutrient use by animals: First for maintenance to keep the animal alive; second, for lactation to provide milk for the young; third, for growth of animals that have not reached full maturity; and, finally, for reproduction once all the other requirements are met.

We are usually thinking about protein and energy when we refer to this distribution, but this is also true for mineral and vitamin usage.

Pasture forages meet most mineral needs for maintenance, but the extra needs for milk production and growth can leave an animal short when it comes to reproduction.

Cows in spring calving herds are either in early pregnancy or in the process of breeding right now. Forages are lush, which is great, except that means the moisture content is high and the animal will have to eat more pounds to receive the same nutrients.

Minerals are listed as macro minerals and trace minerals. These designations refer to the amount needed and not necessarily to the importance.

Macro minerals

Sodium, often supplied by salt, is used by the body to maintain correct fluid levels as well as for muscle and nerve function. Forages do not supply adequate amounts of sodium.

Calcium is critical for bones, with nearly 99% located in the skeleton. It also has roles in nerve impulses and the immune system. Large amounts are used in milk production, therefore lactating animals have greater requirements than non-lactating animals.

Milk fever can occur when too much calcium is drawn from bone reserves.

Calcium is also important in pregnancy for proper bone growth.

Typically, levels of calcium on pastures are sufficient to supply the needs of the animals. Legumes have higher levels of calcium than grasses and can help prevent calcium deficiencies.

The ability of the body to utilize calcium is closely tied to phosphorous and Vitamin D.

Phosphorous is also very important in the skeleton as well as being important for rumen microbes and energy utilization. It is an important component of DNA and therefore heredity.

When looked at globally, phosphorous is considered the most prevalent mineral insufficiency in grazing livestock. Unlike calcium, forages are not a great source of phosphorous. Deficiencies can result in poor performance, reduced milk production, and poor reproductive efficiency.

Calcium to phosphorous ratios are important and ratios between 1.5:1 and 3:1 are recommended.

Potassium is more likely to cause problems because of overabundance in lush pastures. Forages tend to accumulate high levels of potassium in the spring, which can reduce magnesium absorption. These conditions can lead to grass tetany.

Magnesium is important for controlling enzyme reactions for energy and cell division. Levels tend to be low in the lush pastures and can lead to grass tetany. The addition of magnesium with a high magnesium mineral in the spring can help prevent this problem.

Trace minerals

Selenium is deficient in Ohio soils and forages. Unlike many minerals, there is a narrow range between deficient and toxic. Deficiency can lead to increased incidence of retained placentas, infertility and white muscle or stiff lamb disease. Vitamin E is closely tied to the utilization of selenium.

Copper deficiency is often linked to reproductive problems such as early embryonic death and delayed estrus. High iron levels in forages can reduce the availability of copper and cause a deficiency.

Consumption of cattle mineral can be fatal to sheep over time as sheep are not able to excrete excess copper and buildup occurs in the liver. Sheep mineral does not contain high enough levels of copper for cattle.

What are my options?

  • Complete mineral mixes are around 25% salt, but also contain both macro and trace minerals as well as vitamins. These complete mixes can be loose mineral or in tubs.
  • Salt blocks provide sodium chloride and iodine to animals, which are important minerals; however, they do not address the rest of the mineral needs of the animals.
  • Trace mineral blocks are typically around 95% salt and supply some of the needed trace minerals, but do not include macro minerals such as calcium, phosphorous and magnesium.
  • Complete mineral mixes will do the best job of meeting all of the animal’s needs.

There is not one mineral mix that is designed for all locations for all times of the year. For example, high magnesium mixes may be important in the spring, when animals are first turned out on grass, to help prevent grass tetany. The mix can then be changed for breeding herds or non-breeding herds to supply the correct calcium to phosphorous ratio.

Not all mineral supplies are equal. The availability and utilization will vary with different sources. Minerals may come chelated, organic, or as oxides.

Typically, you get what you pay for, and trying to save money on a mineral program may cost you in the end.

If animals have not had free choice, loose mineral, they may consume large amounts initially but will reduce consumption once their needs are met. It is important to keep the mineral available at all times.

A good mineral program can help with productivity and reproductive performance. Work with your mineral supplier to find the mix that best matches your needs.


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Dean Kreager is an OSU Extension agriculture and natural resources educator in Licking County. Send questions or comments to or write c/o Farm and Dairy, P.O. Box 38, Salem OH 44460.



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