Minerals

Classification: Minerals are inorganic micronutrients (do not contain C-H bonds) required in small amounts. Classified into macrominerals and microminerals (trace minerals).

Macrominerals: Present at larger levels in the body or required in larger amounts in the diet (>50mg/kg tissue). Include Calcium (Ca), Phosphorus (P), Sodium (Na), Magnesium (Mg), Potassium (K), Chloride (Cl), and Sulfur (S).

Microminerals (Trace Minerals): Present at low levels in the body or required in low amounts in the diet (<50mg/kg tissue). Include Chromium, Cobalt (Co), Copper (Cu), Fluorine, Iron (Fe), Iodine, Zinc (Zn), Manganese, Molybdenum, Nickel, Selenium (Se), and Silicon.

General Functions:Structural role (bones and teeth: Ca, P, Mg).

Nerve and muscle function (nerve impulses: Na, K; muscle contraction: Ca, Mg; muscle relaxation: Mg).

Regulate water balance (Na regulates extracellular fluid volume).

Facilitate absorption of other nutrients (Na, K in glucose and amino acid absorption).

Enzyme activators/cofactors (enhance enzyme activity, e.g., Mg for pyruvate kinase).

Absorption: Mostly absorbed in the small intestine. Two mechanisms:

Transcellular Absorption: Active transport, uses ATP and transporter proteins, moves minerals from low to high concentration. Activated by Vitamin D3 (for Ca).

Paracellular Absorption: Passive transport, no ATP or transporters, moves minerals from high to low concentration. Becomes prominent when dietary mineral content is high.

Mineral absorption can be affected by breed, sex, physiological state, age, body weight, level of production, level of other minerals in the diet (antagonism), and certain drugs (e.g., laxatives decrease Ca absorption).

Mineral Antagonism: One mineral's absorption is hindered by the presence of another. Examples: High zinc inhibits copper absorption, high phosphorus impairs calcium absorption, calcium interferes with iron absorption, potassium interferes with magnesium absorption, sulfate interferes with copper absorption.

Key Minerals:Calcium (Ca): Most abundant mineral. Roles in bones/teeth (99%), nerve impulse transmission, muscle contraction, blood clotting, milk production. Regulated by Vitamin D3, Parathyroid Hormone (PTH - increases blood Ca), and Calcitonin (decreases blood Ca). Deficiency can cause rickets (young) and osteoporosis (adults), and milk fever (hypocalcemia) in dairy cows.

Phosphorus (P): Essential for bones/teeth, ATP, DNA/RNA synthesis. Absorption in small intestine via transcellular and paracellular mechanisms. Vitamin D enhances absorption. Phytic acid in grains/seeds binds phosphorus, making it unabsorbable for monogastrics (pigs, poultry) unless phytase enzyme is added. High P in diet interferes with Ca absorption.

Magnesium (Mg): Structural component of bones/teeth, required for nerve impulse transmission/muscle function (relaxation), cofactor for enzymes in energy metabolism. Deficiency can cause grass tetany (hypomagnesemia) in grazing animals, often due to low dietary Mg and/or high dietary K interfering with Mg absorption.

Sodium (Na), Potassium (K), Chloride (Cl) - Electrolytes: Control body fluid volume (e.g., blood volume), create nerve impulses, support nutrient absorption, control blood pH. Forages are rich in K but not Na & Cl; NaCl supplementation is often needed. Electrolyte supplementation needed with significant losses (e.g., sweating, diarrhea, vomiting, lactation).

Sulfur (S): Found in sulfate salts, sulfur-containing amino acids (methionine, cysteine), and sulfur-containing vitamins (B1, B7). Required for structural protein synthesis (keratin, collagen), enzymes, DNA repair. Wool sheep have high S requirement. Rumen microbes require S to produce methionine and cysteine. Sulfate in water can cause diarrhea and interfere with copper absorption in ruminants.

Iron (Fe): Required for hemoglobin production. Deficiency causes anemia. Heme-iron (from animal tissues) is more easily absorbed than non-heme iron (from plants).

Copper (Cu): Required for hemoglobin production and red blood cell production. Deficiency causes anemia. Absorbed in stomach and small intestine. Sulfur and iron interfere with copper absorption. Stored in the liver.

Zinc (Zn): Poorly stored in the body, requires continuous intake. Cofactor for >100 enzymes, promotes structural protein synthesis (keratin, collagen), vital role in male reproduction (seminal fluid production, sperm viability). Deficiency affects skin health and male fertility.

Selenium (Se): Trace mineral and powerful antioxidant, protects cells from oxidative stress. Key role in smooth muscle contraction. Concentration in forage depends on soil concentration.