ansc314 - intro to minerals, Ca+

mineral classes

• macro minerals

• micro minerals

macro minerals

> 0.01% in diet (> 100 mg/kg)

• Ca

• P

• Na

• Cl

• K

• Mg

• S

micro minerals

< 0.01% in diet (< 100 mg/kg)

• Fe

• Cu

• I (iodine)

• Zn

• Mn

• Se

• Cr (chromium)

• F

• + ultratrace minerals

ulltratrace minerals

• Mo (molybdenum)

• Co (cobalt)

• Si (silicon)

• V (vanadium)

• Ni (nickel)

• As (arsenic)

nutritionally important minerals

• elemental compositions of various species relatively uniform

  • except in young animals (Ca & P ↓)

• dietary requirement & body levels highly correlated

mineral functions

• structural

• electrochemical

• catalytic

mineral function: structural

component of bone & tissues

• e.g. Ca, P, & S

mineral function: electrochemical

acid-base balance, osmotic control, H₂O balance

• K+, Na+, Cl^-

mineral function: catalytic

component of hormones & enzymes

• S, Mg, Fe, Sn, Cu, I, etc

calcium (Ca²⁺)

• most abundant mineral element in body

• milk keeps casein in solution by forming a micelle w/ casein, Ca+, & P

Ca sources

• humans

  • milk & dairy products

  • legume seeds

• animals

  • milk (nursing)

  • legume roughage

  • animal by-products

  • fish meal

  • ground limestone & dicalcium phosphate

    • dairy cows & laying hens

• bad sources

  • cereal grains & roots < 0.2% of DM

Ca functions

• bone & teeth - 99% body Ca in bone

  • mineral salts in bone/teeth

• egg shells - almost pure CaCO₃

• muscle contraction & nerve impulses

• acid-base balance

  • cation-anion balance of diets

• blood clotting

Ca blood clotting cascade

Ca⁺⁺ions required at all steps in fibrin formation & allows coagulation factors to bind to membranes

• EDTA - binds Ca²⁺ & reduces clot formation

• Ca crucial for fibrin formation

  • allows coagulation factors to bind to membranes

Ca body distribution

• 99% in bone & teeth

• 1% in blood, body fluids & w/in cells

• hens have ↑ blood Ca to favor Ca deposition into eggshell

Ca absorption

• IN duodenum & jejunum

• neonatal stage (mammal)

  • ↑ [milk]

  • passive transport

  • non-saturable

  • paracellular (between cells)

• after neonatal stage

  • saturable

  • active transport

  • transcellular (through cells)

  • regulated by vit D, parathyroid hormone, calcitonin

calcitonin

hormone that is produced by the parafollicular cells of thyroid gland

• help regulate Ca & P lvls in blood

  • oppose action of parathyroid hormone

phytic acid

plant storage of phosphorous

• natural substance in plant seeds

• impairs absorption of Fe, Zn, Ca

• promote mineral deficiencies → anti-nutrient

phytic acid chelation

• Mg, Zn, Cu, Ca, Mn, Fe, K (all cations)

• occurs in plants (grains) & precipitates minerals

• ↑ phytate prevents digestion of cations (Ca+)

Ca excretion

• urine (20-30%)

• feces (70-80%)

Ca absorption factors

• Ca sources - cereals ↓ Ca + phytates (reduce absorption)

• diet acidity - ↑ absorption by ↑ solubility of Ca-chelates

• sugars - lactose ↑ Ca passive absorption in suckling animals

• vitamins - vit D ↑ Ca via calbindin (Ca binding proteins)

• estrogen - ↑ Ca absorption

  • post menopausal women (↓ estrogen) at risk of osteoperosis

• age - ↓ w/ age

• excess P - & other minerals ↓

• phytate - ↓ absorption (chelates bind Ca)

• oxalates - forms Ca-oxalate (insoluble) → ↓ absorption

• diet fat content - excess fat ↓ absorption b/c FA Ca-soap formation

Ca homeostasis

hypocalcemia

low blood Ca+

• stimulates PTH release from parathyroid gland

parathyroid hormone (PTH)

• ↑ Ca & P resorption (de-mineralization) from bone

• ↑ P excretion into urine

  • Ca ↑ but not P

• ↑ synthesis of active vit D

• ↑ Ca absorption from GI tract

• ↑ Ca resorption from kidney

  • result: ↑ blood Ca lvl to normal

hypercalcemia

high blood Ca+

• stimulates calcitonin release from thyroid gland

  • calcitonin reverse PTH function

  • results ↓ blood Ca lvl to normal

Ca homeostasis regulators

• vit D → ↑ Ca & P

  • ↑ bone resorption

  • ↑ intestinal Ca & P absorption

  • ↓ Ca & P excretion from kidney

• parathyroid hormone (PTH) → ↑ Ca

  • ↑ bone resorption

  • ↑ intestinal Ca & P absorption

  • ↑ P excretion from kidney

• calcitonin

  • ↓ bone resorption

hyper-parathyroid

• primary → ↑ blood Ca & bone resorption

• secondary → → ↓ Ca, ↑ P, ↓ vit D → ↑ PTH

  • both cause bone resorption → osteomalacia

Ca deficiencies

• rickets

• osteomalacia

• milk fever (hypocalcemia)

• osteoporosis

rickets

• occurrences

  • young animals

• causes

  • defic. of Ca, P, or vit D

  • imbalanced dietary Ca:P (not 1:1 or 2:5:1 ratio)

  • parathyroid tumor ↑ PTH & ↑ blood Ca

• mechanisms

  • continued growth of collagen & organic matrix

    • no / insufficient mineralization for support

• results

  • soft, light bone

  • muscles grow, ↑ weight on soft bone → bone bends

osteomalacia

softening of the bone

• occurrences

  • adult animal counterpart of rickets

• causes

  • defic. diet in Ca, P, vit D

    • fail to replace Ca in bone after resorption

• result

  • brittle, demineralized bones

  • easily breakable

milk fever (hypocalcemia)

acute metabolic deficiency of Ca

• occurrence

  • w/in 72 hrs after calving

  • prevalent in ↑ producing cow s

    • cant meet milk secretion demands

milk fever symptoms

• ↓ HR

• ↓ body temp (↓ blood circulation)

• tetany (muscle tremors)

• collapse

• possible coma/death

milk fever clinical signs

blood Ca+ half of normal (5-6 mg/mL)

milk fever metabolic basis

bone Ca release inadequate to meet Ca demands for milk production

• casein micelle

milk fever treatment

I.V. injections of Ca-salts

• CaCl₂, Ca-lactate, Ca-gluconate

milk fever prevetion

• change ↑ Ca → ↓ Ca diet 14 days before calving (stimulates mobilization)

• ↓ dietary cationic anionic difference (DCAD)

• ↑ vit D injection → ↑ Ca absorption 5 days before calving

osteoporosis

reduction of bone mass

• occurrence

  • human females > 50 yr or near menopause

• causes

  • age, gender (male), ↓ Ca & vit D diet, ↓ physical activity

• result

  • ↓ height & ↑ susceptibility to fractures

• metabolic

  • ↓ mineralization of organic matric of bone → ↓ bone mass

• prevention

  • ↑ Ca intake (halts progression, not reverse dmg)

  • mineralization replenishes, organic matrix doesn’t (permanent dmg)

transcellular transport

transportation of solutes by a cell through a cell

• e.g. glucose mvmt from intestinal lumen → extracellular fluid by epithelia cells

paracellular transport

transfer of substances across an epithelium by passing through intercellular space between cells

anion

ions w/ negative charge

cation

ions w/ positive charge