Minerals and Mineral Deficiencies Calcium
Functions
Required
for healthy bones and teeth, muscle contraction, nerve impulse
stimulation, blood clotting, enzyme activation, ion transport in cell
membranes, cardiac rhythm, and hormone secretion. Approximately 99% of
the body's calcium present in bones and teeth. Laying hens require
significant quantities for production of egg shells.
Deficiency symptoms
Rickets(young animals). Osteoporosis (older animals). Milk fever or or lambing sickness is a disease associated with a deficiency of calcium.
Thin-shelled eggs, drop in egg production, and lowered hatchability in poultry.
The calcium to phosphorus ratio is important.
Vitamin D is critical because a deficiency of vitamin D in the feed prevents the proper utilization of calcium.
Excess calcium reduces the absorption and utilization of Zinc.
Excess magnesium decreases calcium absorption, replaces calcium in the bones, and increases calcium excretion.
Sources
Legume
forages, such as alfalfa or clover hay. In laying hens, the provision
of Oyster Shells, other broken or coarse ground shells, or Limestone
grit provides a good source of calcium.
Phosphorus |
Functions
Phosphorus has more known functions in the animal body than any other element.
- Part of bone structure
- Component of some proteins, lipids and nucleic acids
- Energy metabolism
Deficiency symptoms
There
are extensive areas of phosphorus-deficient soils in tropical and
sub-tropical areas of the world, and phosphorus deficiency is the most
widespread of all the mineral disorders affecting grazing livestock.
- Rickets (young animals), osteomalacia (older animals)
- Depraved appetite (animals will chew wood, bones, rags etc.)
- Stiff joints, muscular weakness
- Poor fertility
- Low growth rates
Sources
- Cereal grains
- Fish meal and bone products
The
phosphorus in cereals (and other plants) is in the form of phytate.
This is an organic compound which binds the phosphorus and makes it
unavailable to pigs and poultry. In sheep and goats, the rumen
micro-organisms break down the phytate and make the phosphorus
available to the sheep or goat. Phosphorus in cereals is therefore used
much more efficiently by sheep and goats than by pigs and poultry.
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Potassium |
Function
- Maintains the right concentration of salts in the body fluids, and the acid balance of the body.
- Involved in nerve signals
Deficiency symptoms
Generally
rare because the potassium content of plants is high. Areas where soil
potassium concentrations are low ( Brazil, Panama and Uganda) may give
rise to potassium deficiency in grazing animals especially at the end
of the dry season.
- Low growth, weakness, paralysis and death.
Excess
potassium is normally excreted from the body (usually in the urine).
High intakes of potassium may inhibit magnesium absorption and cause
magnesium deficiency.
Sources
Found in all plants.
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Sodium |
Function
- Maintenance of salt concentration in body fluids
- Maintenance of acid-base balance.
- Transmission of nerve impulses
-
Deficiency symptoms
This occurs in many parts of the world, but especially in tropical areas of Africa.
Sources
- Common salt
- Plants are relatively poor sources of sodium.
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Chlorine |
Function
- Acid-base balance
- Maintenance of salt concentration
Deficiency symptoms
- Alkalosis (excessive bicarbonate in the blood)
- Growth retarded in extreme cases.
Sources
Salt
is important in the diet of livestock, but too much salt in the diet is
harmful. Salt poisoning is quite common, especially when the supply of
drinking water is limited. Diets containing high concentrations of salt
(40 g/kg for hens, just 20 g/kg for chicks and pigs) will kill the
animal if the supply of water is limited.
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Sulphur |
Function
Component of some amino acids, which are rich in certain proteins (e.g. keratin that forms hooves, horn and hair).
Sources
- Proteins. Generally a deficiency of sulphur would arise from a deficiency of protein in the diet.
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Magnesium |
Function
- Component of the skeleton
- Essential for carbohydrate and fat metabolism
Deficiency symptoms
- Paralysis and death
- Convulsions
Sources
- Bran
- Oilseed meals and cakes
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Iron |
Function
- Component of haemoglobin (transports oxygen round the body)
- Major role in energy metabolism
Deficiency symptoms
The
most widely recognized symptom is anaemia (observed as pale pink
membranes round the eye). Piglets are particularly susceptible to
anaemia and need access to soil to root around. Piglets suffering from
anaemia also have poor appetite and growth, and ‘thumps’ (laboured and
spasmodic breathing).
Sources
- Green, leafy materials
- Most legumes and seed coats
Iron
toxicity is not common, as the animal usually reduces its absorption of
iron when it is overloaded, and increases its absorption during times
of iron need.
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Zinc |
Zinc
has been found in every tissue in the animal body. High concentrations
are found in the skin, hair and wool; the highest concentration is
found in semen. Zinc accumulates in the bone, unlike all the other
trace elements that tend to accumulate in the liver.
Function
- Component of several enzymes
- Involved in cell replication
- Production, storage and secretion of hormones
- Involvement in the immune system
- Involved in maintaining salt balance.
Deficiency symptoms
Rarely seen; the requirements for zinc are not high and zinc is widely distributed in feeds.
- Pigs: below normal growth, low appetite, reddening of skin which then erupts and forms scabs (parakerotosis)
- Chicks: retarded growth, foot abnormalities, ‘frizzled’ feathers, parakeratosis, ‘swollen hock syndrome’.
- Calves: inflammation of the nose and mouth, stiffness of the joints, swollen feet, parakeratosis
Sources
- Bran and germ of cereal grains
Most
animals are fairly tolerant of high doses of zinc, and zinc toxicity is
rare. Large amounts of zinc in the diet reduce feed consumption and may
induce copper deficiency.
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Copper |
Copper
is stored in the liver. Acute copper poisoning is rare, but if small
excesses are continually fed then eventually the accumulated copper
reaches a toxic threshold. Susceptibility to copper poisoning varies
between species. Pigs can tolerate large amounts of copper, and it is
relatively unusual to cause copper toxicity in cows. However, sheep are
extremely sensitive to copper poisoning. Copper poisoning causes
jaundice and death from liver failure.
Functions
- Involved in haemoglobin formation.
- Involved in iron absorption from the gut, and in the use of iron in haemoglobin manufacture
- Needed for normal colouring of hair, fur and wool.
- Reduces susceptibility to infection in lambs.
Deficiency symptoms
- Anaemia, poor growth, bone disorders
- Diarrhoea, infertility
- Discolouring of hair and wool
- Gut disturbances and damage to the brain and spinal cord.
- ‘Swayback’
in lambs. If this occurs at birth it is irreversible and can only be
prevented by supplying the ewe with sufficient copper. If signs do not
show for several weeks after birth, then the effects can be prevented
or postponed by supplementing the lamb with copper.
- Stringy or steely wool
Copper deficiency can also be caused (in sheep and goats) by grazing them on molybdenum-rich
pastures. Too much molybdenum and/or sulphur reduces the availability
of copper and cause copper deficiency. The copper, molybdenum and
sulphur form an insoluble complex in the rumen, which renders the
copper unavailable to the animal.
Sources
- Found in a wide range of feeds and the diet will usually contain sufficient copper.
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Molybdenum |
Although
molybdenum does have a function in the body (it forms part of a complex
with some enzymes), requirements are extremely small. Molybdenum
deficiency has not been observed under natural conditions with any
species. Problems with molybdenum are much more likely to occur when it
is in excess, as it reduces the availability of copper
to ruminant animals. Scouring and weight loss are the main signs of
molybdenum toxicity, although sheep and goats are less affected by this
than large ruminants.
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Selenium |
Selenium works with Vitamin E
to protect the animal’s tissues from oxidation. Vitamin E keeps
selenium in its active form, while selenium increases the absorption of
Vitamin E from the gut and keeps it in the body’s circulation. As part
of the process of oxidation, peroxides are formed (which damage the
cells). Vitamin E prevents the production of peroxides and selenium
destroys peroxides that are formed. Supplementing the diet with Vitamin
E will therefore reduce the requirement for selenium (and vice versa).
There are limits to this substitution, though. Vitamin E cannot
completely replace selenium and selenium cannot completely replace
Vitamin E.
Functions (with Vitamin E)
- Prevent oxidation damage to the cells of the body
- Involved in the functioning of the immune system
- Protection against heavy metal toxicity
Deficiency symptoms
- ‘Ill thrift’ in kids and lambs: weight loss and sometimes death
- Reduced hatchability and egg production in hens.
These
deficiencies will probably only occur if the soil is deficient in
selenium and livestock are only fed pasture grown on those soils. Extreme
care should be taken if supplementing the diet with selenium, because
it is extremely toxic and the margin between required dose and toxic
amount is small.
Selenium toxicity
Some
areas have soils with very high selenium contents. Browse and pasture
growing on this soil also has a high concentration of selenium, which
can produce chronic disease called "alkali disease"or "blind staggers".
Signs of this are:
- Dullness
- Stiff joints
- Loss of hair from tail
- Hoof deformities.
A concentration of 5 mg selenium/kg diet may be dangerous.
If
the animal eats a single very high dose of selenium, it will suffer
from acute poisoning, which causes sudden death from respiratory
failure.
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Iodine |
Iodine
is found in small amounts throughout the body but its only known
function is as a component of thyroxine. This is a hormone that is
responsible for increasing the animal’s growth and metabolic rate.
Deficiency symptoms
- Goitre (swelling of the neck).
- Breeding animals give birth to hairless, weak or dead young.
Goitre
may also be caused by toxins (goitrogens) in brassicas, soya, linseed
and groundnuts. Some of these goitrogens inhibit the incorporation of
iodine into thyroxine, and the symptoms cannot be alleviated by
supplementing the diet with more iodine. The effect of the goitrogens
in some plants, however, is overcome by ensuring adequate iodine is
supplied.
Sources
The
amount of iodine found in plants depends on the iodine status of the
soil in which the plant was grown, and so there wide geographical
variations in the iodine status of feeds (and livestock).
Iodine
toxicity can occur even at relatively low concentrations of iodine in
the diet (50 mg/kg or less for calves). Reduced hatchability and
delayed hatching occurred in eggs laid by hens fed 312 mg iodine/kg
diet. Pigs seem to be more tolerant to higher concentrations of iodine
in the diet.
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Manganese |
Manganese is involved in many reactions occurring in the body.
Deficiency symptoms
These have been observed in ruminants, pigs and poultry. Symptoms of acute deficiency are similar in all species and include:
- Retarded growth
- Skeletal abnormalities
- Reproductive failure
- Loss of co-ordination in the newborn.
- Perosis (slipped tendon) in chickens.
- Head retraction in chicks.
- Widely distributed in feeds.
- Higher in forages grown on acid soils.
- Most green feeds contain adequate amounts
Poultry
are quite tolerant of high concentrations of manganese in the diet, but
pigs are more susceptible. They will show signs of manganese toxicity
(depressed appetite and retarded growth) with concentrations of 0.5 g
manganese/kg diet.
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Cobalt |
Cobalt
is a component of Vitamin B 12 (cobalamin). Pigs and poultry need to be
provided with this vitamin. The rumen micro-organisms make enough of
this vitamin to meet the requirements for sheep and goats provided
there is a sufficient supply of cobalt. This is usually the case, as
most feeds contain some cobalt.
Excessive cobalt
can be toxic, but there is a wide margin of safety between the
nutritional requirement and the toxic amount. Unlike copper, cobalt is
not retained in the body to any significant extent and so regular,
small excesses of cobalt intake should not result in the animals later
developing acute cobalt poisoning.
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Vitamins and Vitamin Deficiencies Vitamins are an essential component of a well-balanced diet and
their major function is the metabolism and utilization of nutrients.
The
important vitamins for survival and growth of grazing animals are
either manufactured in the rumen by the rumen microbes, in the body
from sunlight, or are stored in sufficient quantity in the liver or
contained in adequate amounts in available feed. Vitamin B Complex |
All
of these vitamins are soluble in water, and are not stored in the body
to any great extent. A regular, dietary supply is therefore essential.
However, in sheep and goats, all of the vitamins in this group are made
by the bacteria in the rumen and this will generally provide enough of
these vitamins to meet the animal’s needs. A rabbit’s requirements for
B group vitamins should also be met by the bacteria in its gut, the
vitamins being absorbed from the soft faeces that it consumes. Supply
of B group vitamins is therefore only an issue for pigs and poultry.
Functions
The B group vitamins have a range of functions, generally associated with the metabolism of energy and protein in the body.
Deficiency symptoms
The
particular symptoms will depend on the actual vitamin that is
deficient, but common deficiency symptoms to all the vitamins include:
- Loss of appetite
- Emaciation
- Weakness
- Dermatitis
- Feathering abnormalities
Sources
- Green leafy materials
- Oilseeds
- Some vitamins found in cereal grains
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Vitamin C |
Livestock
can synthesize Vitamin C, and so it is not required in the diet. The
only exception may be for poultry. There is some evidence that poultry
subjected to heat stress have a higher requirement for Vitamin C than
can be met by their own synthesis of the vitamin, and a dietary supply
may then be beneficial. Guinea pigs require a dietary supply of Vitamin
C.
Function
A range of functions in the body associated with oxidation and reduction reactions.
Sources
- Citrus fruits
- Green, leafy vegetables
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Vitamin A |
Vitamin
A itself does not occur in plants, but the precursors or "provitamin"
carotene in green plant material is converted in an animal’s body to
vitamin A. The efficiency with which this conversion takes place
depends on the precursor and also on the animal. Poultry are very
efficient at it, ruminants slightly less so and pigs are quire
inefficient. Pigs therefore need to be supplied with much more
provitamin to produce the same amount of active Vitamin A.
Function
Vitamin A has two distinct roles.
- Eye. It is involved in sending messages from the eye to the brain in response to light.
- Membranes.
It is involved in the formation and protection of the epithelial
tissues (e.g. gut lining) and mucous membranes (e.g. lining of the
windpipe and the eye).
Deficiency symptoms
- Lower ability to see in dim light (night blindness)
- Decreased resistance to disease
- In cattle, roughened, scaly skin, drying of the eyes and blindness in calves
- Infertility and abortion
Deficiency symptoms are unlikely to occur unless animals get no access to green forage.
Sources
- Green forage (concentration of the provitamin declines rapidly in sun-dried forages and hays).
- Yellow maize
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Vitamin D |
As
with Vitamin A, Vitamin D does not exist as such in plants, and needs
to be converted into its active form by the animal. The precursor to
Vitamin D can be made in the animal's skin when it is exposed to
sunlight. Further conversions then occur in the liver and kidney.
Function
Vitamin
D is involved with increasing the absorption of calcium and phosphorus
from the gut. It also mobilizes stores of calcium and phosphorus from
the kidney and bone so as to provide the animal with enough calcium and
phosphorus when required (for example, for producing the egg shell in
laying hens, and for milk production in lactating ewes, does and sows).
Deficiency symptoms
- Rickets in young animals (this can also be caused by an inadequate supply of calcium or phosphorus, or an imbalance in the two)
- Osteomalacia in adult animals (not common)
- Poultry: bones and beak become soft and rubbery; reduced growth and egg production.
Sources
The
provitamin is widely distributed in plants, but requires the animals to
be exposed to sunlight to enable the conversion to the precursor to
take place.
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Vitamin E |
Unlike
Vitamins A and D, the active form of Vitamin E exists in a wide range
of feeds. However, it is not stored in the animal’s body to any great
extent and so a continual dietary supply is needed. Vitamin E works
closely with selenium.
To some extent, increasing the supply of Vitamin E reduces the
requirement for selenium (and vice versa), but neither nutrient can
completely replace the other.
Function
- Antioxidant, protecting the body from oxidative damage.
- Development and function of the immune system.
- Protection against heavy metal toxicity
Deficiency symptoms
- Muscle degeneration (myopathy or muscular dystrophy): difficulty in standing and then a trembling and staggering gait.
- Inability to raise head in young animals
- Heart failure
- Crazy chick disease.
Sources
- Green leaves
- Green forages
- Cereal grains
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Vitamin K |
Vitamin
K is an essential factor in the blood clotting process. A number of
forms are known to exist, which animals are unable to make for
themselves but which plants and bacteria can.
Function
- Involvement in blood clotting
Deficiency symptoms
- Not
reported in sheep, goats and pigs kept under normal conditions. The
bacteria in the digestive tract produce sufficient Vitamin K for the
animal’s needs.
- Chicks: anaemia, easily injured
and may bleed to death. Vitamin K made by bacteria in the bird’s gut
cannot be absorbed because it is made too far down the gut and so can
only be used if the animal subsequently pecks at faecal material.
Sources
- Most green, leafy materials.
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Information from: NR International
managers of the Livestock Production Programme (LPP) http://www.smallstock.info/
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