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Macrominerals. Pages 36–37 in textbook. Calcium Sources. Minerals Limestone, dicalcium phosphate Animal sources Meat and bone meal, fish meal Milk products Roughages But not cereal grains. Calcium. Most abundant mineral in animal tissues Lots of functions Bone structure

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Pages 36–37 in textbook

Calcium sources

Calcium Sources

  • Minerals

    • Limestone, dicalcium phosphate

  • Animal sources

    • Meat and bone meal, fish meal

    • Milk products

  • Roughages

    • But not cereal grains



  • Most abundant mineral in animal tissues

  • Lots of functions

    • Bone structure

    • Nerve function

    • Blood clotting

    • Muscle contraction

    • Cellular metabolism

Calcium ca

Calcium (Ca)

  • Functions

    • Bone/teeth formation and maintenance

      • 99% of body calcium

      • In 2:1 ratio with phosphorus in hydroxyapatite Ca5(PO4)3OH

    • Soft tissues

      • Enzyme activation

      • Blood clotting

      • Muscle contraction

        • Transmission of nerveimpulses to muscle

        • Calcium binds to troponin C

Calcium absorption

Calcium Absorption

  • From duodenum and jejunum

    • Active or passive

    • Dependent on vitamin D – stimulates calbindin in small intestinal cells and enhances absorption

  • Absorption depends on need

    • Particularly high during growth, pregnancy and lactation

  • Bioavailability decreased by

    • Phytates (grains)

    • Wheat bran

    • Low estrogen levels (postmenopausal women)

    • High fat diets (form soaps with fatty acids)

Calcium ca1

Calcium (Ca)

  • Dietary ratio of 1:1 to 2:1 ideal for most animals (except for laying hen, optimal ratio is 13:1; Ca:nonphytate phosphorous)

    • Never want P > Ca

Grains tend to be low in calcium while forages are moderate to high

Calcium regulation

Calcium Regulation

  • Three hormones involved in regulation

    • Vitamin D3

      • from kidney

    • Parathyroid hormone (PTH)

      • from parathyroid gland

    • Calcitonin

      • from thyroid gland

  • PTH and vitamin D3 act to increase plasma Ca, while calcitonin acts to decrease plasma Ca


GI Tract

Dietary Ca

Fecal Ca

Endogenous Ca

Absorbed Ca


1,25(OH)2D3 from kidney



Sweat Ca

Urinary Ca



Ca Apposition

Ca Resorption



Plasma Ca



Bone Ca

Plasma Ca

Calcium deficiency causes

Calcium Deficiency - Causes

  • Low calcium intake or absorption

    • Soap formation (fatty acids) in rumen

    • Competition with divalent ions for absorption

  • Abnormal Ca:P ratio (2:1)

    • High calcium and low phosphorus leads to formation of insoluble CaPO4 in intestinal lumen

    • High phosphorus (and low calcium) also inhibits absorption

  • Vitamin D deficiency

Calcium deficiency symptoms

Calcium Deficiency - Symptoms

  • Reduced growth or production rate

    • Egg-shell strength

  • Rickets

    • Young, fast-growing animals

    • Misshapen bones, enlarged joints, lameness

  • Osteoporosis

    • Decalcification of bone and loss of bone mass

      • Estrogen involved, bone mass decreases following menopause

      • Isoflavones (estrogen-like compounds) in soy help alleviate losses


Osteoporosis – Symptoms

Wedged Upper Vertebrae and Crushed Lower Vertebrae



  • Decrease bone mass

  • Related to aging, poor diet, and estrogen loss

  • Leads to 1.5 million bone fractures per year

  • Slender, inactive women who smoke are at highest risk

  • Type I (postmenopausal)

  • Type II (senile)

Bone strength

Bone Strength

  • Depends on bone mass

  • Related to age, gender, activity level and genetics

  • Peak bone mass in women achieved by age 20-30

    • Same in females of all mammalian species – peak mass achieved as animal reaches maturity and then decreases thereafter

      • Cannot increase bone density after this point, but can slow rate of bone density loss

    • By age 65, some women have lost 50% of bone mass

Calcium deficiencies

Calcium Deficiencies

  • Rickets

    • in growing animals

  • Osteomalacia and osteoporosis

    • in adult animals

  • Milk fever (parturient paresis)

    • in lactating animals

Calcium deficiency milk fever

Calcium Deficiency – Milk Fever

  • High demand for milk calcium during early lactation – calcium pulled from blood

    • Cannot absorb enough calcium from gut or reorb from bone rapidly enough to keep up

    • Severe hypocalcemia (low blood calcium) results

  • Factors associated

    • Parturition

    • Onset of lactation

      • Breed

      • Age

      • Diet

Hypocalcemia at parturition

Plasma calcium

Hypocalcemiaat Parturition



Absorption from GI tract

Plasma calcium increased

Absorption from kidney

Resorption from bone

Milk fever

Milk Fever

  • Symptoms

    • Listless

    • Staggers or weaves when walks

    • Lies down in characteristic pose

      • head retraction

    • Decreased plasma calcium

Milk fever1

Milk Fever

  • Treatment

    • IV calcium solution

    • Oral calcium gels

  • Prevention options

    • Dietary acid–base balance, not calcium level

      • Alter dietary cation-anion balance

        • Feed anion salts or adjust dietary potassium

      • Increased calcium release from bones and increased calcium absorption from diet

        • Mediated through parathyroid hormone

Phosphorus sources

Phosphorus Sources

  • Minerals

    • Dicalcium phosphate

    • Monocalcium phosphate

    • Deflourinated rock phosphate

  • Animal sources

    • Meat and bone meal

    • Fish meal

  • Cereals

    • Large portion of phosphorus unavailable for non-ruminants

      • Phytic acid (poorly absorbed)

Phosphorus p

Phosphorus (P)

  • Functions

    • Component of bones/teeth

      • 80% in bone (hydroxyapatite)

      • 20% in soft tissue

        • Membrane phospholipids, DNA, RNA

    • Similar to calcium

    • Vitally important in energy metabolism

      • ATP and creatine phosphate

      • Sugar phosphates

    • Acid-base balance (HPO4–)

    • Regulation of metabolism

      • Glucose-6-phosphate

      • Phosphorylation activates or inactivates enzymes

Phosphorus p1

Phosphorus (P)

  • Absorption

    • Both active and passive mechanisms

    • High phosphorus limits calcium absorption

    • Plant phosphorus often unavailable to animal

      • Phytic acid

        • Released by phytase (enzyme often supplemented)

  • Blood levels controlled by vitamin D and parathyroid hormone

Phosphorus deficiency

Phosphorus Deficiency

  • Deficiency

    • Symptoms similar to calcium deficiency

      • Reduced growth or production rate

      • Rickets or osteomalacia

    • Pica (depraved appetite) – chewing of wood fences, bones, soil

    • Low fertility and poor milk production or growth



  • Impact on environment has scientists revisiting nutritional requirements

    • Requirements are being lowered without any negative effects on reproduction or milk production

  • Bioavailability could be improved if phytate phosphorus can be reduced

    • Increasing availability would reduce dietary requirements and fecal excretion

      • Feeding phytase

Magnesium sources

Magnesium Sources

  • Mineral sources

    • MgCO3, MgCl2, MgO (“mag-ox”)

    • MgSO4

      • a.k.a. Epsom salts, milk of magnesia

Magnesium mg

Magnesium (Mg)

  • Functions

    • Bone formation

      • ~60% in bone

    • Enzyme activation

      • Carbohydrate, lipid metabolism

        • 7 enzymes in glycolysis require magnesium as a cofactor

      • Urea cycle

    • Binds mRNA to ribosomes

    • Associated with ATP metabolism

      • ATP–Mg2+ complex

Magnesium and muscle function

Magnesium and Muscle Function

  • Magnesium required for energy releasing enzyme activity in skeletal muscle

    • ATP needed for detachment and calcium uptake

  • Calcium is the link between excitation and contraction

    • Lack of ATP to return calcium to storage results in tetany



  • Deficiency

    • Vasodilation

      • Results in reduced blood pressure

    • Hyperirritability, convulsions

    • Anorexia, reduced weight gain

    • Hyperemia

    • Hypomagnesemic tetany (grass tetany)

      • Early lactating cows on grass

      • Poor nervous and muscular control

  • Usually not an issue, adequate levels present in most diets

Magnesium deficiency grass tetany

Magnesium Deficiency – Grass Tetany

  • Also called grass staggers, hypomagnesemia

    • Low blood magnesium

  • Symptoms

    • Nervousness

    • Tremors, twitching of face muscles

    • Staggering gait or convulsions

  • Etiology not completely understood

Grass tetany

Grass Tetany

  • Spring pastures, lush grasses

    • Low magnesium content

    • Some magnesium absorption in rumen

      • Requires relatively low pH

      • High potassium forages raise rumen pH and impedes Mg absorption

        • Potassium alters acid-base balance (cation induces alkaline environment)

    • Pasture contains organic acids that bind magnesium

  • Solution

    • Dust pasture with MgO

    • Feed 1:1:1 magnesium oxide:TM salt:grain starting 2 weeks before turning ruminants out on pasture

Sodium and chloride sources

Sodium and Chloride Sources

  • Minerals

    • Salt (iodized, 0.007% iodine added)

      • Add at 0.25–0.50% of diet

    • Free-choice salt blocks

      • May be combined with other minerals

  • Animal sources

    • Meat and bone meal, meat meal

    • Fish meals may have a (very) high salt content

  • Cereal grains

    • Low sodium and choride content

Sodium na and chloride cl

Sodium (Na) and Chloride (Cl)

  • Functions

    • Electrolytes

    • Absorption of glucose and amino acids

    • Transmission of nerve impulses

      • Action potential

    • Osmotic pressure balance

      • 10% sodium and chloride intracellular, 90% extracellular

      • Sodium is main extracellular cation

        • Maintained by Na/K ATPase

      • Chloride is main extracellular anion

    • HCl and chloride salts in gastric secretions

Sodium and chloride

Sodium and Chloride

  • Blood concentrations highly regulated

    • Excess intake = increased excretion

    • Little danger of toxicity if water available

  • NaCl added to diets to increase palatability

  • Causes of deficiencies:

    • Lactation

      • Sodium and chloride secreted in milk

    • Rapid growth

      • On a diet of cereals or forages

    • High temperatures or hard work

      • Sweat

Symptoms of sodium and chloride deficiency

Symptoms of Sodium and Chloride Deficiency

  • Decreased osmotic pressure

    • Leads to weakness

    • Circulatory failure

    • Metabolic alkalosis (decreased chloride) or acidosis (decreased sodium)

  • Poor growth

    • Reduced appetite and feed consumption

    • Reduced carbohydrate and amino acid absorption

  • Diminished HCl secretion from parietal cells

    • Reduced bacterial defense and protein digestion

  • Pica or salt craving

    • Animals will seek out salt sources

      • Soil, urine, sweat of other animals, etc.



  • Animals do not necessarily seek out sources of the mineral that is deficient in diet – just consume “non-feed” items

    • Coprophagia (consumption of excrement)

    • Geophagy (consumption of soil, clay, or chalk)

      • Consumption of dust or sand in iron deficient patients.

    • Vampirism (ingestion of blood)

    • Hyalophagia (consumption of glass)

    • Pagophagia (pathological consumption of ice)

    • Self-cannibalism (rare condition where body parts may be consumed; sometimes called Lesch-Nyhan syndrome)

    • Trichophagia (consumption of hair or wool)

    • Urophagia (consumption of urine)

    • Xylophagia (consumption of wood)

    • Cautopyreiophagia (consumption of burnt matches)

Sodium and health

Sodium and Health

  • High blood sodium is associated with high blood pressure and risk of heart disease

  • However, high blood sodium rarely due to dietary excesses

  • Genetics is primary factor, although other factors are involved

    • 10%-15% of adults are “salt-sensitive” and should limit salt intake

Potassium sources

Potassium Sources

  • Plants generally have a high potassium content

    • Grains 0.3–0.8%

    • Vegetable proteins 1.0–2.5%

      • Alfalfa ≈ 2% or more

      • Implications for dairy in developing anionic diets for preventing milk fever!!

    • Animal products vary



  • Functions:

    • Third-most abundant mineral in the body

      • 2/3 of whole-body potassium content in skin and muscles

      • >95% of potassium intracellular (major intracellular cation)

        • Maintained by Na/K ATPase

    • Regulation of osmotic and acid-base balance

    • Transmission of nerve impulses

      • Potassium is the major determinant of the resting membrane potential of all cells

    • Cofactor for several reactions in carbohydrate metabolism

Potassium deficiency

Potassium Deficiency

  • Rare

    • Has to be induced

    • Major salt in ruminant sweat

      • Increases requirement in heat stress

  • Reduced appetite and growth

  • Other symptoms

    • Tetany, nervous disorders

    • Degeneration of organs

    • Abnormal heart function

Sulfur s

Sulfur (S)

  • Located in organic compounds

    • Thiamin & biotin; methionine, cystine and cysteine

    • Chondroitin sulfate matrix of cartilage

    • Feathers, wool, etc.

      • Wool contains about 4% sulfur

  • Minimal involvement in acid-base balance

  • Ideal N:S ratio of 10:1 in ruminant diets

  • Potential for toxicity

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