Tri-State Swine Nutrition Guide

Bulletin 869-98

Minerals

The macro minerals required by pigs are presented in Table 1 and are usually expressed as a percentage. Although these minerals are indigenous in the various feed grains, some are at low concentrations. Consequently, it is essential that the diet be balanced using supplemental mineral sources. Calcium, phosphorus, and magnesium are involved in bone development, but they also serve in many metabolic functions. Sodium, potassium, and chloride are involved in nutrient transfer across cell membranes, body pH regulation, water balance, and digestion. Sulfur is a component of several organic compounds in the body. Generally, magnesium, potassium, and sulfur do not need to be added to swine diets.

Other minerals are referred to as trace or micro minerals because they are required in the diet at very low concentrations (Table 1). These minerals are generally expressed in parts per million (ppm) with 1 ppm being equivalent to 0.0001% of the diet. These minerals are often involved in the structure of enzymes or body hormones and/or involved in activating metabolic enzymes. Although these trace minerals are present in grains and by-products, iron, zinc, copper, selenium, and iodine need to be supplemented. Nickel, silicon, vanadium, and arsenic have not been shown to be dietary essentials for the pig, but they are found in the body. The role of chromium as a dietary essential is currently unclear. Some research has shown that added chromium as chromium picolinate enhances muscle formation and improves reproductive performance, whereas other research has not confirmed these observations. It is possible that the chromium in many feed grains may be adequate to meet most of the metabolic functions of the element.

Mineral bioavailability is important, particularly for the trace mineral sources. Bioavaila-bility not only includes its absorption but also its transport into the cell to perform a biological function. Several factors can influence mineral bioavailability:

• The chemical form of the mineral.
• The amount provided in the diet.
• The amount stored in the body.
• The health, age, and physiological state of the animal.
• The concentration of other minerals in the diet.

Recently, several organic forms of minerals have become commercially available. These minerals are most frequently bound to a protein or amino acid and are referred to as "proteinates" or "chelates" and often times are referred to as "organic minerals." These mineral sources have a relatively high bioavailability, but they are generally more expensive than the inorganic forms. Their value as part of the pig's diet will depend on the specific mineral. The major mineral sources used today and their relative bioavailabilities are listed in Table 2.