Minerals Lecture 18 PDF

Minerals Constitute ~4% of the animal body’s weight Expression and regulation of g...

Minerals Constitute ~4% of the animal body’s weight Expression and regulation of genes and Minerals are enzymes. more integrally a part of all Cellular function, biological osmotic balance, functions in the Functions: detoxification, body than any immunity, acid- base balance other single and growth. class of nutrient. O2 transport requires Fe Thyroid hormone made using I Macro and Micro (trace) Minerals: Macro Micro McDonald et al., Animal Nutrition 7th Edition Calcium and Phosphorus Structural – growth and maintenance Nervous and Muscle contraction. Nearly 99% of the Ca and 80% of the P occur in bones and teeth as a compound called hydroxyapatite. About 1% of Ca is distributed in cellular fluids, and involved in: Growth or maintenance of bone mass. Blood coagulation, nerve impulse and cell permeability maintenance. Enzyme activation, muscle contraction, and ion channels.  Calcium and Phosphorus P in the soft tissues is involved in phosphorylation reactions that are part of cellular oxidative pathways for energy metabolism: - ATP - DNA and RNA contain phosphorylated pentose sugars - Cell membrane phospholipids (cellular fluidity and transport of nutrients)  Phosphorus Cereal grains are rich in P. But P present in the bound form as phytate or phytic acid. The availability of P from bound sources varies (20%–60%). Monogastric animals lack the enzyme phytase to release P from the bound form. The term available P is commonly used to designate unbound forms of P in the diet of monogastric animals. Ruminant animals produce microbial phytase enzyme that can split and liberate P. Regulation of Blood Calcium Levels Body has a strict homeostatic regulation — steady state blood plasma Ca. Parathyroid hormone (PTH), calcitonin, and active forms of vitamin D. In hypocalcemia, PTH is released from the parathyroid gland, increasing Ca and P resorption from bone, P excretion into urine, and synthesis of active forms of vitamin D. This in turn increases absorption of dietary Ca from the gastrointestinal (GI) tract.  Ca:P Ratio of Ca to P very important. Excess dietary Ca forms insoluble complexes with phosphorus, resulting in decreased P absorption. High P or phytate P in the diet can inhibit Ca absorption. 1:1 small animals 2:1 large animals  Ca:P Excess P and low Ca common in animals fed: grain-based or low quality hay diets pets fed homemade meat-based diets. Developmental bone-related disorders can occur in: young horses fed high-energy diets large breeds of dogs fed extra Ca. Ca-P imbalance also reported in large cats (tigers, cheetahs) kept in a zoo when fed meat-only diets compared with the meat and bone diets they consume in the wild.  Ca & P Deficiency or Imbalance Bone growth disorders in food producing animals as well as eggshell quality in egg-laying hens. Rickets is a condition occurring in young animals due to normal growth in the organic matrix but insufficient mineralization. Osteomalacia occurs in adult animals (excessive loss of Ca causing brittle, demineralized bones. In both rickets and osteomalacia, bones become soft and often deformed due to improper calcification.  Hypocalcemia Tetany and convulsions - severe Ca deficiency. Milk fever, or parturient paresis - classic example of hypocalcemia and Ca tetany. - drop in body temperature, animal collapses with head bent over the flank. - treatment - raise blood Ca through intravenous supply of Ca salts such as CaCl2, Ca-lactate, or Ca-gluconate. - a high-dose of Vit D should be given five days before calving to enhance Ca absorption. Providing a low Ca diet during the dry period is recommended to minimize the incidence of milk fever  3rd most abundant element in the body Present as phosphate, and carbonate in bone and in liver and skeletal muscle cells. Structural role In the skeletal system Activation of enzymes in the cells Metabolism of carbohydrates and Magnesium proteins. Important for muscle contraction and transmission of nerve impulses (along with Ca, Na and K). Homeostatic control of blood and tissue Mg is not well understood, and PTH increases the release of Mg from bone.  Magnesium Deficiency Grass tetany - common problem with grazing livestock. Also known as “wheat grass poisoning.” Affects livestock on lush green pastures of cereal forages or native pastures in the spring season. N and K inhibit Mg absorption. (lush fertilized pastures high in N and K). Symptoms Muscle tetany, head retraction, staggering, convulsion, and extreme sensitivity to noise or touch. Treatments include intravenous injection of Mg solution, feeding Mg from different sources, pasture rotation, and providing dry forages. Grass tetany is the most common Mg deficiency in grazing animals Sodium, Potassium, and Chlorine All three electrolytes are electrically charged. Acid-base balance is determined by the difference between total anion and cation intake and excretion. Create an ionic balance to keep cells alive. Maintain osmotic pressure in intra- and extracellular fluids. Normal ratios are remarkably constant among species. Cannot be stored so required on a daily basis. Sodium Common salt (NaCl) is added to the diets of all animals and is given free choice to grazing animals. Na+ is the main extracellular cation found outside the cells. Na+ maintains cell permeability in the active transport of nutrients across membranes. The Na+ - pump controls electrolyte balance and is a major part of the basal metabolic rate in the body. Na+ is also required for muscle contraction and nerve impulse transmission. Potassium (K+) major cation found in greater concentrations in intracellular fluid. Ionized K+ inside cells provides osmotic force & maintains fluid volume. Cellular K+ is also involved in enzymatic reactions. K+ balance important for normal heart muscle function. Chlorine (Cl- ) Negatively charged anion. Counterbalances the role of K+ and Na+. Accounts for 2/3rd of anion present in extracellular fluid. Also regulates osmotic pressure. HCl, activation of gastric enzymes, protein digestion. Supplied through NaCl in the animal diet. Dietary Electrolyte Balance in Food Animal Health and Production Increased interest in the balance of electrolytes in food animal production to maintain animal health, welfare, and productivity. Alterations in acid-base balance leads to acidosis or alkalosis affecting animal health and productivity. Under most circumstances, dietary electrolyte balance is expressed as Na+K-Cl (meq/kg).  Dietary Electrolyte Balance in Food Animal Health and Production In ruminants, electrolyte balance is important in preventing acidosis and alkalosis. DCAD reduces the incidence of milk fever. Prepartum alkalosis may increase the incidence of milk fever whereas acidosis may prevent it. Prepartum diets high in forages ( K) could reduce the ability of the cow to maintain Ca homeostasis and cause milk fever. Diets that reduce blood pH can increase blood Ca and reduce the milk fever.  Chromium and Glucose Cr is part of a Supplemented molecule into piglet diets ‘glucose Enhances milk and pregnant production in tolerance factor’ sows to improve & required for lactating cows glucose normal glucose utilization entry into cells  Chromium and Glucose Carbohydrates in the Diet Glucose Transporter Blood Glucose A Chromium – Protein Complex Insulin Insulin Receptor Intracellular Glucose Pancreas Anabolic rxs (protein and fat synthesis)