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There are 10 micro-minerals required by beef cattle. Seven of the 10 micro-minerals have established requirements and include iron, manganese, copper, zinc, selenium, cobalt and iodine. The micro-minerals chromium, molybdenum and nickel do not have an established requirement and are not normally added to mineral mixes fed to beef cattle. Only three of the micro-minerals (copper, zinc and selenium) are likely to be deficient in grazing beef cattle diets.

Cobalt
Cobalt functions as a component of vitamin B-12, which is synthesized in the rumen by bacteria. The primary deficiency symptom is loss of appetite and poor growth.

Copper
Copper is the most common micro-mineral deficiency in grazing cattle. Copper is an important component of many enzyme systems essential for normal growth and development. Deficiency signs include reduced fertility, depressed immunity and reduced pigmentation of hair (black hair changes to red). Dietary deficiencies can occur, but most deficiencies are caused by the consumption of antagonists, which reduces copper absorption. Copper should be supplemented in multiple forms, including one or more organic or chelated forms.

Iodine
Iodine is an essential mineral for function of the thyroid hormones that regulate energy metabolism. The first sign of iodine deficiency is goiter in newborn calves. Iodine deficient areas range throughout the US, and this mineral is easily depleted from soils and forages.

Iron
Iron is primarily required for the formation of hemoglobin. Deficiency symptoms include anemia, depressed immunity and decreased weight gains. Iron deficiency is rarely observed in grazing cattle.

Manganese
Manganese is required for normal reproduction and fetal and udder development.

Selenium
Selenium deficiency is very common with depleted soils, pastures and forages. 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 calfhood diseases like scours. Increased rates of retained placentas and poor reproductive performance are often observed in cows with selenium deficiencies.

Zinc
Zinc is deficient in most livestock and the majority of humans. Zinc is 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.

Vitamins are closely linked to mineral metabolism and absorption.

Vitamin A helps skin and mucous membranes stay healthy. Vitamin A requirements usually are met by grazing fresh, green, growing grass. Oxidation deteriorates vitamin A during storage, so diets based on stored feeds should be supplemented with vitamin A. Supplement diets with vitamin A anytime the major portion is stored feeds.

Vitamin D aids the absorption of calcium and phosphorus from the intestine and their deposition in the bone matrix. Signs of vitamin D deficiency are similar to a calcium or phosphorus deficiency.

Vitamin E is usually present in the diet in sufficient quantities for all classes of cattle; however, a selenium deficiency could lead to an apparent deficiency of vitamin E. Vitamin E can be helpful for short term periods of stress that may occur when calves are co-mingled and transported at weaning.

A mineral deficiency in cattle is difficult to diagnose and can silently rob profits from the herd. Most deficiencies are related to copper, zinc and selenium, but other mineral deficiencies can occur.

Mineral deficiencies are classified as either primary or secondary deficiencies. Primary mineral deficiencies occur when cattle consume forages that are deficient in a particular mineral such as magnesium. Failure to provide a mineral supplement is the most common cause of primary mineral deficiencies. Primary mineral deficiencies rarely occur in well-managed herds that receive mineral supplements.

A secondary mineral deficiency occurs when cattle consume mineral antagonists, which interfere with the normal absorption or metabolism of another mineral. In the case of copper deficiency, cattle are consuming enough copper to meet requirements, but some other mineral antagonist such as sulfur binds to the copper and prevents it from being absorbed and used by the animal. Secondary mineral deficiencies are the most common type of mineral deficiency. Take the following steps to ensure that the problem is due to a mineral deficiency.

1. Rule out other possible causes of poor performance such as disease, plant toxins, or inadequate protein and energy in the diet. The first sign of a problem in most herds is poor reproductive efficiency. Inadequate body condition, due to protein or energy deficiency, is the most common cause of reproductive failure.
2. If a secondary mineral deficiency is suspected, then a laboratory analysis of forages must be conducted. In some instances, water should be tested if it is suspected that it might be high in iron or sulfur.
3. Blood samples and liver biopsies may also be used to assess the mineral status of a cow. Liver samples are a more accurate indicator of mineral status. These tests are expensive and should be pursued once the above steps have been taken.