Minerals Flashcards
Concentration of major elements in animal tissues
(all in g/kg)
Calcium 15
Phosphorous 10
Potassium 2
Sodium 1.6
Chlorine 1.1
Sulphur 1.5
Magnesium 0.4
Concentration of trace elements in animal tissues
(all in mg/kg)
Iron 20-60
Zinc 10-50
Copper 1-5
Molybdenum 1-4
Selenium 1-2
Iodine 0.3-0.6
Manganese 0.2-0.5
Cobalt <0.1
Functions of calcium (Ca)
Structural component of skeleton (dynamic)
Controls cell excitability (nerve & muscle)
Regulates muscle contraction
Regulates blood coagulation
Many enzyme actions
Rigid homeostatic control of plasma calcium ion concentrations
- (Vitamin D & hormones)
Sources of calcium (Ca)
Must take relative availability Ca:P into account
Ideally should be within the range 1:1 to 2:1
Foods which supply an Ca:P in an ideal ratio:
Leafy greens
Hay / silage
Animal products (milk, meat, eggs)
Some foods contain more P than Ca & require artificial ration balancing:
Bran
Cereals
Roots
Legume & oil seeds
Corrective sources of calcium :
Limestone flour
Poultry: soluble grit (e.g. limestone/oyster shell)
Factors affecting absorption of calcium (Ca)
Much plant Ca is bound as phytates (prevents absorption in monogastrics but rumen microflora can release (phytases)
Oxalates: Bind Ca to form insoluble salts bound in this form, calcium cannot be absorbed by animals
(Significant quantities in spinach, sugar beet tops etc)
Total absorption of dietary Ca & P decreases as dietary concentration becomes excessive
High fat diets Excess dietary free fatty acids bind Ca (& Mg) to form insoluble soaps
Enteritis: Inflamed mucosa will not absorb Calcium
Causes of acute deficiency of calcium (Ca)
HYPOCALCAEMIA
Occurs if sudden decrease in blood calcium (sometimes also Mg & P) concentrations homeostatic control sluggish to correct
Female mammals at the onset or peak of lactation
-High demands of mammary gland for calcium to synthesise milk
Laying hens
- High calcium demands of eggshell production
Details of deficiency of calcium (Ca) in dairy cattle
MILK FEVER
Commonly from 1 day before calving to 3 days post-partum
High demand for Ca for lactation
High-yielding cows in their third & subsequent lactations most susceptible
Slow homeostatic adaptation to increased Ca demand; mechanisms unable to prevent a sudden decrease in blood Ca levels
Signs of deficiency of calcium (Ca) in dairy cattle
MILK FEVER
Flaccid paralysis (progressive) general uneasiness, dullness, paddling/shifting of hind legs, dry muzzle, constipation, inability to stand, coma & death
Recumbency (‘Downer Cow’)
Rumen stasis
Pupil dilatation
Signs of deficiency of calcium (Ca) in bitches, sows, and beef cattle
ECLAMPSIA (lactation tetany)
General signs of chronic deficiency of calcium (Ca) in growing animals
HYPOCALCAEMIA
High rate of skeletal growth (↑Ca & P demand)
- beware of breeds / species with high growth rates
Osteodystrophy = abnormal bone growth
- Deficiencies of Ca, P, Vitamin D
- Nearly always accompanied by osteoporosis -> loss of Ca & P from bones making them thinner & weaker, increased incidence of fractures
Rickets = failure of bone to ossify
- Vitamin D deficiency (classically)
- In ruminants a deficiency of either Vitamin D or P can cause rickets
Treatment involves correcting Ca:P balance in diet
Signs of chronic deficiency of calcium (Ca) in puppies and kittens
Excessive P (secondary Ca deficiency)
Signs of chronic deficiency of calcium (Ca) in foals
Poor artificial rearing; gut parasites; low hay & high cereal diets (secondary deficiency)
Signs of chronic deficiency of calcium (Ca) in calves and lambs
Unsupplemented high cereal / straw diet
Signs of chronic deficiency of calcium (Ca) in piglets
Failure to supplement dietary Ca, P, vitamin D
General signs of chronic deficiency of calcium (Ca) in growing animals
Except in late pregnancy & early lactation, skeletal Ca & P reserves are high and can be withdrawn upon if temporary imbalance
Mobilisation of skeletal Ca & P long term = osteomalacia
- Weakened, thin bones; easily fractured
- Increased incidence of osteoarthritis
Decreased milk yields
Urethral calculi in entire and castrated male lambs fed high concentrate diet
Horses, goats & pigs - demineralisation of bones of skull & compensatory collagen deposition causing thickening of the bones (‘bran disease’ - excessive P)
Sources of phosphorous (P)
Must take relative availability Ca:P into account
Ideally should be within the range 1:1 to 2:1
Foods which supply an Ca:P in an ideal ratio:
Leafy greens
Hay / silage
Animal products (milk, meat, eggs)
Some foods contain more P than Ca & require artificial ration balancing:
Bran
Cereals
Roots
Legume & oil seeds
Function of phosphorous (P)
Same as Ca me thinks (might wannna check that)
Factors affecting absorption of phosphorous (P)
Oxalates & phytates much plant P is organically bound as salts of phytic acid - in simple-stomached animals little of the phytate is available
Excess dietary Ca or P inhibit the absorption of P or Ca
General signs of deficiency of phosphorous (P)
HYPOPHOSPHATAEMIA
Abnormal bone growth & osteomalacia
Reduced growth rates
‘Pica’ (abnormal appetites) eg. bone/wood chewing
Infertility??
Functions of magnesium (Mg)
Closely associated with calcium & phosphorous
~70% total body magnesium is present in bone;
Most common enzyme activator
Muscle contraction
Propagation of nerve impulses
NB: There are no body reserves and no homeostatic regulation; it is dependant on dietary intake to maintain function
Sources of magnesium (Mg)
All green plants (chlorophyll)
Meat & bone
Colostrum
Magnesite & calcined magnesite
Absorption of magnesium (Mg)
20–30% of dietary Mg
Decreased by high copper & high phytate P intakes
Signs of deficiency of magnesium (Mg) in calves
HYPOMAGNESAEMIA
Calves fed (unsupplemented) all-milk diets (2 – 3 months)
- Milk is a poor source of Mg
- Mg absorption decreases with age
Signs of deficiency of magnesium (Mg) in beef cattle and sheep
HYPOMAGNESAEMIA
Beef cattle & sheep fed on low quality roughage (straw) or fodder crops (kale, beet)
- Symptoms may occur over several days
- Dullness, hyperaesthesia, convulsions, death
Signs of deficiency of magnesium (Mg) in lactating cattle and sheep
HYPOMAGNESAEMIA
GRASS STAGGERS = EMERGENCY!
Signs: Hyperaesthesia Recumbency
Incoordination Convulsions
Muscle tremor Death
Frequent cause of SUDDEN DEATHS
Sub-clinical hypomagnesaemia
Possibly a cause of reduced fertility & milk production in dairy cattle
Predisposing factors for grass staggers:
Spring
Rapid grass growth = Mg uptake by plant
Grass diarrhoea = faster passage of digesta through the gut decreases Mg uptake
Bad weather = grass intake reduced as cows shelter
Fertilisers: Nitrogen fertilisers - ↑rumen NH3 which depresses Mg uptake
Potassium fertilisers - ↑Mg excretion
Liming – ↓ grass Mg concentration
Autumn
Gradual ↓ in grass Mg
Year round
Stresses which decrease food intake (eg. Bad weather/ dog worry)
Control or prevention of deficiency of magnesium (Mg)
Provide shelter
Introduce to spring grass slowly
Use fertilisers with care & avoid K fertiliser in spring
Provide mineral (Mg) licks
Top dress pastures (calcined magnesite)
Increase clover in swards
Supplement diet or water with Mg
Mg rumen boluses
AVOID STRESS!
Deficiency of … is uncommon or rare
Sodium
Potassium
Chloride
Sulphur
Functions of copper (Cu)
Important in formation of some plasma proteins (eg. ceruloplasmin)
Component of other blood proteins & plays a role in oxygen metabolism
Vital role in many enzyme systems, eg. component of cytochrome oxidase in oxidative phosphorylation
Essential for normal hair, wool & feather pigmentation & crimp in wool
Essential for immune function
Absorption of copper (Cu)
CuSO4 is the most readily absorbed copper salt
Metallic copper is poorly absorbed
Transport & tissue use of copper (Cu)
Loosely bound to albumen in the plasma
Stored & released from the LIVER to meet body requirements
General signs of deficiency of copper (Cu)
Anaemia (impaired RBC formation)
Abnormal bone growth
Abnormal hair, feather & wool growth
Loss of hair pigmentation
Cardiovascular disease
Most common in sheep and cattle
Signs of deficiency of copper (Cu) in sheep
SWAYBACK
Affects lambs born to Cu2+ deficient ewes
Failure or degeneration of normal neural development in the lamb
a) Congenital (from birth)
Signs: Stillborn, weak ataxia, paresis, unable to stand, death
Irreversible
b) Delayed onset (few weeks old)
Signs: Normal at birth depressed growth rate, rapid onset hind limb weakness,
ataxia then paresis & death
Can be prevented/reduced in Cu deficient lambs by parenteral injection of small
doses of Cu complexes
Signs of deficiency of copper (Cu) in cattle
Common 3–9 months of age
Especially in suckler calves, where the dam may not be Cu deficient
Signs:
- Failure to thrive
- Poor growth
- Stiff gait / lameness
- Loss of hair pigment
Problems with copper and molybdenum
Certain pastures in England & Wales (‘teart’ pastures – high Mo) are known to cause scouring & unthriftiness in grazing cattle
The molybdenum concentration in ‘teart’ pastures can be 10 to 50 fold greater than ‘normal’
Rumen microbes form sulphides which combine with Mo to form THIOMOLYBDATE
Thiomolybdate binds copper to form COPPER THIOMOLYBDATE
- decreases Cu absorption & causes signs of Cu deficiency, despite adequate dietary Cu provision
Signs of copper toxicity
Jaundice
Appetite loss
Hepatic coma & death
Cause of copper toxicity
Copper accumulates in liver, causing cell necrosis
Tolerance: pigs > horses > cattle > sheep
Problems with copper toxicity in sheep
Marked differences in copper tolerance between breeds
While sharing a common pasture, North Ronaldsay sheep may demonstrate copper toxicity while the Scottish blackface breed are copper deficient
Liver [Cu] varies considerably between breeds
Take care with copper treatments, especially in sheep
