Trace Mineral Nutrition in Beef Cattle

Minerals can be divided into two main categories, 1) macro-minerals and 2) micro or trace minerals. Macro minerals are minerals that are needed/required in relatively large amounts in comparison to micro or trace elements which are needed/required in relatively small amounts. In general macro minerals are required at concentrations greater than 100 ppm of the diet and are often expressed as a percentage of the diet while trace minerals are required at concentrations less than 100 ppm (McDowell, 1992; NRC, 1996). Macro minerals such as phosphorus, potassium, sulfur, magnesium, sodium, and chloride and trace minerals such as copper, zinc, iodine, manganese, selenium, cobalt, and iron are considered essential for beef cattle (NRC, 1996). Macro minerals have important physiological functions in beef cattle and therefore must be supplemented to beef cattle diets when forages or rations are deficient or have the incorrect proportions of macro minerals. If not supplied in the correct amounts and ratios, specific metabolic diseases and/or toxicities can be produced. However, several of the mineral imbalances commonly observed in beef cattle are due to imbalances in trace minerals. To promote normal tissue growth, homeostasis, enzyme function, cell regulation, and immune function, it is imperative that trace minerals be maintained within narrow concentrations within the body (McDowell, 1989, 1992; Underwood and Suttle, 1999). Trace mineral deficiencies, toxicities, and imbalances require the animal to metabolically compensate for the nutrient deviation (McDowell, 1989, 1992; Underwood and Suttle, 1999). In doing so, certain metabolic diseases can be produced and overall animal performance can be depressed (McDowell, 1989, 1992; Underwood and Suttle, 1999). Due to the magnitude of this topic – Mineral Nutrition in Beef Cattle, this review will focus primarily on trace minerals involved in beef cattle production. Focusing this review on trace minerals involved in beef cattle production by no means indicates that macro minerals (phosphorus, calcium, potassium, etc) are not important in beef cattle production. In fact the macro minerals play a significant role in beef cattle production. However, the majority of mineral questions/problems observed in the field seem to focus around trace minerals. Therefore, the intent of this review is to: 1) give a general description of the function of trace minerals in beef cattle 2) discuss the impact of trace minerals on performance parameters in beef cattle, and 3) discuss factors that can potentially affect trace mineral requirements in beef cattle. For an in depth review of both macro and trace minerals see the textbooks written by McDowell, (1992) and Underwood and Suttle, (1999).