ANSC 301 - Minerals

• The essential macrominerals are calcium, magnesium, sodium, potassium, phosphorus, chlorine, and sulfur.
• The essential microminerals are iron, copper, zinc, iodine, selenium, molybdenum, cobalt, fluorine, and manganese.
• An essential mineral results in an abnormality when removed from the diet.
• The general functions of the essential minerals include constituents of skeletal structure, maintaining osmotic pressure, regulation of acid-base balance, and component or activator of enzymes (cofactors).
• Arsenic, barium, bromine, cadmium, and strontium are currently under investigation as essential minerals.
• Lead and mercury are non-essential and can be very toxic when occurring in high amounts.
• Minerals are excreted through the urine, feces, and sweat. Other routes to eliminate extra minerals include bile, pancreatic juice, or direct secretion into the large intestine.
• The chemical form of the mineral determines the bioavailability/requirement. In inorganic salt forms, sulfates are the most bioavailable and oxides the least. Chelates, the mineral bound to an organic element, are either the most bioavailable or the same as sulfates.
• Other factors affecting mineral requirements include species/breed, rate of growth, physiological state, and level of other minerals/interactions.
• Calcium and phosphorus make up 75% of the total body minerals, whereas the other macrominerals make up the other 25%.
• Mineral sources of calcium include calcium carbonate (limestone), which is cheap, or dicalcium phosphate which is more bioavailable and commonly fed to young poultry and swine.
• Roughages are rich sources of calcium, whereas cereal grains are poor sources. Grazed animals will be more likely to need phosphorus supplementation.
• 99% of the body calcium is in the bones and teeth. Ca and P are stored in the bone as hydroxyapatite crystals.
• The ideal Ca to P ratio is 2:1.
• The remaining 1% of bodily calcium is in the cells and intracellular fluid.
• Calcium is responsible for enzyme activation, blood clotting, membrane permeability, neuromuscular transmission, and muscle contraction.
• In muscle contraction, calcium binding is responsible for triggering contraction and its release allows relaxation.
• Calcium circulation is regulated by three things. Calcitonin pulls calcium out of circulation by increasing excretion or bone deposition. Parathyroid hormone and 1,25-dihydroxyvitamin D put calcium into circulation by increasing absorption or pulling from the bone.
• A primary deficiency occurs when there is simply not enough of the nutrient in the diet to meet the requirement.
• A secondary deficiency occurs when there is enough nutrient in the diet but something is causing it not to be utilized.
• Ca deficiency symptoms are the same as vitamin D deficiency. Excess phosphorous and magnesium can cause a secondary deficiency and cause symptoms.
• Similar to vitamin D, a calcium deficiency causes rickets in young animals. Not enough calcium deposited into the long bones causes bending, along with lameness and stiffness.
• In mature animals, a calcium deficiency causes osteomalacia, a softening of the bones due to calcium being pulled out and not replaced.
• In cases of osteoporosis, Ca and P are not typically deficient, but there is a decrease in bone mass. More common in women after menopause.
• A calcium deficiency results from absence of vitamin D, low Ca intake, low P intake, abnormal Ca:P ratio, Ca soap formation in a high fat diet, or a high requirement during pregnancy/lactation.
• Milk fever is a common calcium deficiency in dairy cattle, occurring in high producing animals 12-72 hours post-calving. The blood calcium drops due to high requirement, causes muscle contraction and inability to stand.
• Phosphorous is low in roughages but high in concentrates.
• Sources of phosphorous include dicalcium phosphate and monocalcium phosphate. In dicalcium phosphate, the ratio of calcium to phosphorus is roughly equal. In monocalcium phosphate, there is a higher proportion of phosphorus than calcium.
• Phosphorous functions in acid-base balance, carbohydrate metabolism, allosteric regulation of enzymes, and similar functions as calcium in the hydroxyapatite crystal.
• Phosphorous is key in the synthesis of phospholipids, DNA, RNA, ATP, and ADP.
• High Ca and low P causes the formation of insoluble calcium phosphate in the gut lumen.
• High P and low Ca leads to reduced absorption.
• A large portion of phosphorous in plant sources is present in an unavailable form, phytic acid. Phytates are mineral salts of phytic acid where it binds other minerals like Ca, Ng, Cu, and Zn.
• The availability of phytate phosphorous is lower, ranging from 30-90%. Should formulate available phosphorous into the diet of nonruminants.
• The enzyme phytase liberates the phosphorous from the phytate/phytic acid molecule.
• Phytase is generally produced by bacteria and fungi. Commercial phytase is available and often fed to poultry and swine.
• In ruminants, formulating for total phosphorous is appropriate because rumen bacteria produce phytase.
• Phosphorous deficiency causes rickets and osteomalacia, similar to calcium and vitamin D.
• A phosphorous deficiency can also trigger a condition called pica, or a depraved appetite, where the animal will eat almost anything to try and get the mineral.
• Phosphorous deficiency is a concern more in tropical and subtropical areas because soils are often deficient in P.