Functions include normal maintenance of the eyes
and epithelium (membrane) tissue of the respiratory,
digestive, urogenital systems, and the skin.
Vitamin A is also needed for normal bone growth, body
growth and normal tooth development
Sources
Vitamin A can be provided as a
synthetic vitamin or as carotene,
Vitamin A itself is only present in
animals, but plants contain the
precursor, carotene.
Carotene is found in good quality, fresh,
green forages in generally sufficient
amounts.
Excellent sources of carotene are green, leafy hays
that have been in storage less than one year;
dehydrated, pelleted legume hays; and good quality
grass or legume silage
Other carotene sources include yellow corn,
fish liver oil, dehydrated alfalfa meal and whole
milk
Deficiencies
Night blindness (inability to see in dim light) is a
symptom of severe vitamin A deficiency.
Vitamin A is part of the visual
purple of the eye, which is
depleted through the action of
light.
Visual purple is
required for vision
in dim light.
Animals suffering from night
blindness will recover when
sufficient amounts of vitamin A
are added to the diet.
Animals can become
permanently blind when
vitamin A deficient.
Excessive watering of the eyes and development
of cornea ulcerations are also indications of
possible vitamin A deficiency
Other indications include nervous incoordination shown by
a staggering gait, diarrhea, reduced appetite, poor growth
and weight loss
Also, unsound teeth and rough, dry skin
may be a sign of vitamin A deficiency.
Paralysis of some parts
can occur in some
species.
Young animals suffer from deficiency
sooner because of their greater
requirements and reduced storage ability
Reproductive problems
include poor conception rates,
reduced fertility in males,
shortened gestation periods,
and incressed retained
placenta.
In poultry, discharges from the eyes and nostrils can occur, as well
as wobbly gait in chicks, reduced egg production and hatchability of
eggs
Vitamin D
Sources
Diets that include sun-cued forages
generally provide sufficient vitamin D
Animals regularly exposed to sunlight or
ultraviolet light will not develop deficiency
symptoms
Green forages, barn-cured
hay, and silage have some
vitamin D
Grain, grain by-products, and protein feeds
have almost no vitamin D
Function
Vitamin D is important for
calcium absorption and
phosphorus metabolism in the
baody
Rickets is prevented by
vitamin D, along with
calcium and phosphorus
Vitamin D also promotes
sound teeth
Deficiencies
A shortage of vitamin D will
result in rickets in young or
osteoporosis in adults with
insufficient calcification of the
bones
However, less vitamin D is
required when a good
balance of phosphorus and
calcium is present
Symptoms of vitamin D deficiency are decreased appetite, slower growth,
digestive disturbances, stiffness in gait, and sometimes the developemnt
of tetany and convulsions
As the disease progresses, joints
enlarge and become swollen and
stiff
Pregnant animals might give birth to dead,
weak or deformed young because of vitamin D
deficiency
Chickens will show rickets, poor
feathering and growth with a
reduduction of egg production,
hatchability and poor eggshells
in laying hens
Vitamin E
Function
Vitamin E functions as an antioxidant,
which helps in absorption and storage of
vitamin A
As an antioxidant, it also acts in
other metabolic functions in the
cell
Vitamin E is essential for
the integrity of red blood
cells and in cellular
respiration, primary in
heart and skeletal muscle
tissues.
It is also a regulator in
the synthesis of DNA and
vitamin C
Sources
Good dietary sources of vitamin E include whole cereal grains, the germ
or germ oils of cereal grains, green forages, alfalfa meal, rice polishings,
wheat germ meal, and good quality hay
After a long storage
period, the vitamin e level
in feeds declines
It is rapidly
destroyed when
near rancid fat
Vitamin E is seldom
deficient in the diet unless
feeds were produced on
selenium-deficient soils
Vitamin e is
produced
commercially and
can be added to the
diet when needed
by using a vitamin
premix or injecting
into the muscle
Deficiencies
Vitamin E deficiency looks similar to selenium
deficiency-- white muscle disease or nutritional
muscular dystrophy
Hatchability of eggs is reduced,
although production does not appear to
be affected
Extended vitamin E deficiency in poultry
will cause permanent sterility in the male
and reproductive failure in the female
The addition of selenium to the diet can prevent some symptoms of
vitamin E deficiency
Vitamin K
Sources
Dietary sources of
vitamin K include
green, leafy feeds
(either fresh or dry);
fish meal; liver; and
soybeans
Vitamin K usually widely available in
normal farm rations, and is
synthesized by all classes of farm
animals
However, it is common to add vitamin K to
swine diets and chick starter rations
Deficiencies
Vitamin deficiencies K rarely occur
because it is synthesized in the rumen
and in the intestinal tract of
monogastric animals.
Feeding moldy feeds with
high dicoumarol content, such
as moldy sweet clover, might
cause a vitamin K deficiency
This can lead to bleeding
syndrome called sweet clover
poisoning or bleeding disease
Moldy feeds wit high dicoumarol content
fed to swine or poultry will also cause
internal bleeding and death
Feeding vitamin K or water-soluble
synthetic forms of the vitamin will
counteract deficiency effects.
Function
Vitamin K is necessary for the
formation of prothrombin in the blood,
which helps blood clot