Fat soluble vitamins Flashcards
Vitamin A
Known as retinol
Pale yellow crystalline solid
Insoluble in water but soluble in fat and fat solvents
Destroyed by oxidation on exposure to air and light
Accumulates in the liver
Cod liver oil
Main source of vitamin A in farm animals
B carotene (is converted to vitamin A)
Vitamin A toxicity
Hypervitaminosis (excess vitamin A) rarely occurs due to food intake
Usually caused by supplementation excess
Acute vitamin A toxicity
Chromic vitamin A toxicity
Babies and children more susceptible
Vitamin A function
Cyclical conversion in retinal cells of the eye is responsible for the ability to see in low light intensities
Regulation of cellular differentiation
Formation and protection of epithelial tissues and mucous membranes
Growth, reproduction and immune response
Scavenger of free radicals
Vitamin A deficiency symptoms
Night blindness
Susceptibility to infection
Severe deficiency unlikely in adult animals (except after prolonged deprivation)
Skin, eye, reproduction problems
Importance of colostrum
Vitamin D
Two forms: Vitamin D2 (ergocalciferol) and D3 (cholecalciferol)
Insoluble in water, soluble in fat and fat solvents
Very limited distribution in nature
Some fish, cod liver oil, egg yolk, colostrum
Action of sunlight on skin
- UV light on skin, then hydroxylation in liver then kidneys
Interaction with parathyroid hormone
Increases intestinal absorption of calcium, enhances calcium and phosphorus reabsorption form the kidney and bone
Strong bones and teeth
Immune function – receptors found in many cells
Vitamin D deficiency
Affects bone integrity
Swollen joints, rickets, weak bones ect.
Vitamin D toxicity
Impossible from sunlight production (self limiting process)
Very unlikely due to food intake
Usually due to excess supplementation
Elevated blood calcium levels, kidney damage
Basis of a rat poison
Vitamin E
Group name that includes a number of compounds
Not stored in the body in significant amounts – needs regular intake
Green fodders are rich sources
Cereal grains good sources
Susceptible to destruction in storage, especially in moist conditions
Vitamin E - functions
Biological antioxidant
Protects cells against oxidative damage caused by free radicals
Free radicals are produced during metabolism
Must be converted into less reactive substances
Relationship with selenium (forms glutathione peroxidase)
Role in development and function of the immune system
Vitamin E - deficiency
Muscle degeneration
Vitamin K
Essential factor in the prevention of haemorrhagic disease in chicks
Originally isolated from putrefied fish meal (egg yolk, liver, fishmeal)
Found in green leafy materials (Lucerne, cabbage, kale)
Synthesised by gut bacteria
Necessary for the synthesis of prothrombin in the liver
Essential substance for blood clotting
Bacterial synthesis considered sufficient for ruminants, pigs and horses
‘
Sweet clover’ disease – coumarins lower the prothrombin content of the blood – decreases clotting ability (‘anti-vitamin’)
In chicks anaemia, blood clotting ability decreased
Human babies given vitamin K injections at birth
