The most common cattle trace element deficiencies are copper, selenium, and cobalt

Copper: is essential for the activity of certain enzymes and, along with iron, is necessary for the synthesis of hemoglobin, a component of various body pigments, involved in the central nervous system, bone metabolism and heart function. Symptoms of a copper deficiency include retarded milk yield.

Selenium: is a structural component of an essential enzyme system - glutathione peroxidase and functions in association with vitamin E, certain fats and sulfur amino acids. Selenium has also been recognized as an immune-stimulant in ruminants and reduced udder edema.

Cobalt: is essential for ruminants as it is incorporated into vitamin B12 by rumen microbes and, therefore, affects the formation of blood. The presence of sufficient cobalt may lead to synthesis of adequate amounts of vitamin B12. Symptoms of cobalt and vitamin B12 deficiencies include reduced conception rates and reduced milk production.

Calcium: is a component of milk. A deficiency of calcium may result in an increased incidence of milk fever, decreased feed intake which results in a drop in milk production.

Magnesium: is essential for the formation and maintenance of strong bones. This element is a major intracellular cation involved in over 300 metabolic processes that also functions in the enzyme systems of the body which affect muscle tone, dietary energy utilization and in the manufacture of milk.

Sodium: is the primary extra-cellular cation. The heart function and nerve impulse conduction and transmission are dependent on the proper balance of sodium and potassium.

Potassium: is the third most abundant mineral in the cow's body. This element is involved in several enzyme systems. Deficiencies produce reduced body weight and milk yield.

Iron: is involved in cellular respiration, oxygen transport and as components of hemoglobin, myoglobin, and enzyme systems. About 60 to 70 percent of the iron in the body is found in the hemoglobin.

Manganese: appears to play a vital role in reproduction through cholesterol synthesis, which is required for the synthesis of the steroid hormones, estrogen, progesterone and testosterone.

Chromium: is required for normal sugar and fat metabolism. Chromium works with insulin in the metabolism of sugar and stabilizes blood sugar levels, which is important during early lactation. A chromium deficiency in lactating cows may result in increased incidence of ketosis and decreased milk production.

Zinc: is an essential component of over 200 enzyme systems. The relation between zinc and clean milk production is well known, as it reduces the SCC. There are no significant stores of body zinc so the animal must rely on a daily supply to meet requirements.

Chlorine: is essential for transport of carbon dioxide and oxygen. It is the chief anion in gastric secretions (HCl), kills pathogens, required for protein digestion and for activation of pancreatic amylase.

It has been shown in cattle with reduced lactation that the grass, forage and silage fed to the cattle is lacking minerals. Analysis of these former excellent sources of minerals and the ground they are grown in has been stripped of these elements by over harvesting and provide ever reduced critical trace minerals that the bovine system requires for lactation. Naturally, without replenishing these essential elements in soil, expensive mineral supplements are required to keep dairy cows healthy.