Vitamins Flashcards
What are vitamins?
Vitamins are organic compounds distinct from fats, carbohydrates, and proteins.
They are natural components of foods where it is usally present in minute amounts.
Vitamins are essential for normal physiological function (ex. maintenance, growth, development, etc.)
Would vitamins be found in proximal analysis?
No, because all organic material is burned off
Why are vitamins essential?
They are not synthesized by the animal in amounts adequate to meet normal physiological needs.
Absence of vitamins in the diet or their under-utilization can cause a specific deficiency syndromes.
Describe some caveats related to vitamins.
Some compounds are vitamins for one species and not for another. (ex. Vitamin C and choline)
Some compounds are vitamins only under specific dietary or environmental conditions. (ex. Vitamin D and niacin)
What is a vitamer?
Vitamers are different chemical compounds that show the same biological activity.
i.e. different structures but act as the same vitamin
What are pro-vitamins?
Compounds that can be metabolized to yield a vitamin (ex. some carotenoids to Vitamin A).
They do not have vitamin activity by itself but can become a vitamin in the body.
Why are vitamins generally important in terms of their overall function?
Vitamins act as coenzymes that aid in enzymatic reactions.
What is a coenzyme?
A small, organic non-protein molecule that carries chemical groups between enzymes.
In general, vitamins act as coenzymes
What is a cofactor?
A non-protein, chemical element that is bound tightly to an enzyme and it required for catalysis.
In general, minerals act as co-factors
Describe how some vitamins function as antioxidants.
Antioxidants are molecules that disrupt oxidation via free radicals. They themselves are easily oxidized by the free radicals in place of other molecules. Vitamins that are oxidized are destroyed, so it is important to keep them at appropriate levels.
Some examples of antioxidant vitamins are E and C.
What are the fat soluble vitamins?
A, D, E, K
They are stored in the liver or in adipose tissue
What are the water soluble vitamins?
B and C
They are not stored in the body and must be provided regularly
Describe the vitamers of Vitamin A
- Retinal: aldehyde form
- Retinol: alcohol form
- Retinoic acid: acidic form
- Retinyl esters: esters of all-trans retinol
What is the active form of Vitamin A?
Retinol
What is beta-carotene and how is it related to Vitamin A?
Beta-carotene is a pro-vitamin that is converted to Vitamin A in the body. (not in cats)
Describe the relationship between beta-carotene, Vitamin A, and milk fat.
There is an inverse relationship between Vitamin A and milk fat synthesis.
There is a positive relationship between beta carotene levels and milk fat percentage.
Efficiency of converting beta carotene to Vitamin A varies by and within species.
For example, Holsteins convert beta carotene to Vitamin A efficiently, and have more Vitamin A in circulation. Therefore, they have lower milk fat.
In contrast, Jerseys are less efficient at converting beta carotene to Vitamin A, so they have a higher milk fat percentage.
Describe the cat’s interactions with Vitamin A.
The cat is NOT ABLE to convert beta carotene to active vitamin A. Sources of vitamin A are required in the diet.
Cats are obligate carnivores that have not evolved the mechanism to convert beta carotene to Vitamin A.
What are some chemical properties of Vitamin A?
- good reducing agent
- forms of vitamin A are soluble in organic solvents and insoluble in water
- unstable in the presence of oxygen and acids
- it is oxidized over time, so when feeding stored forages, we supplement them with vitamin A to meet requirements (Vitamin A activity decreases the longer a forage is stored)
What are international units?
Standardized measure of biological activity or effect of a compound based on utilization of various forms of vitamin A by rats.
What are the general functions of Vitamin A?
- vision
- maintenance of mucous membranes
- glycoprotein synthesis
- reproduction
- growth
- corticosterone synthesis
- immune function
How is vitamin A associated with vision?
It is involved in the production of rhodopsin, the pigment used in low light.
Retinal (active form/vitamer) joins opsin to form rhodopsin. This helps the eye distinguish between light and dark changes. Conformational changes in the protein cause a nerve impulse to the brain.
How is Vitamin A associated with mucous membranes?
In maintains the epithelial linings of the soft tissues around the eye, digestive tract, respiratory tract, urogenital tract, and the corneal epithelium.
What is the relationship between Vitamin A and glycoproteins?
Vit. A helps synthesize glycoproteins, like mucins, which protects epithelial linings.
How is Vitamin A involved in reproduction?
Vitamin A is required for reproductive function in both males and females.
It is involved with the hatchability of eggs, neonatal development, and spermatogenesis.
How is Vitamin A related to growth?
It is required for growth and differentiation of cells. Proper bone growth is also associated with Vit. A.
How is Vitamin A associated with the synthesis of corticosterones?
Lack of Vitamin A causes atrophy of the adrenal glands; its needed for production of cortisol and adrenalin.
How is Vitamin A related to immune function?
Vitamin A helps produce the mucin and maintain the linings involved in immune response. Therefore, deficiency leads to a reduced immune response.
How is Vitamin A involved in such diverse functions?
It plays a key role in certain aspects of gene transcription. As a result, Vitamin A has the most functions.
How and where is vitamin A stored?
In the liver and adipose.
Cattle can store a 6-month supply when 1 million IU are given via injection. This is done for cattle on winter range.
What are some animal sources of Vitamin A?
cod liver oil, liver, egg yolk, butter
What are some natural or plant sources of Vitamin A?
carrots, kale, sweet potatoes, pumpkins, spinach (all high in beta carotene)
What are some deficiency symptoms of Vitamin A?
- night blindness
- xerophthalmia (inability to produce tears, dryness of the conjunctiva and cornea)
- keratinization of respiratory epithelium
- death
What foods are low in vitamin A activity?
Grains
Yellow corn is the only grain with “significant” Vit. A activity
What is hypervitaminosis A?
ingestion of a large excess of vitamin A
Vit. A is one of the few vitamins that can be toxic
What are gross toxicity signs for Vitamin A?
- roughened hair coat
- scaly skin
- hyper irritability and sensitivity to touch
- blood in urine and feces
- loss of control of legs and inability to rise
- periodic trimmers
Describe vitamin A toxicosis in cats
- most often reported in cats that have been fed diets composed exclusively of liver and other organ meats
- syndrome called deforming cervical spondylosis
- causes bony exostoses (outgrowths) to develop along the muscular insertions of cervical vertebrae and the long bonds of the forelimbs
Discuss the first observed instance of Hypervitaminosis A in humans.
In 1913, Arctic explorers lost their rations and resorted to eating wild animals like seals and other high fat animals. The members of the expedition exhibited fatigue, abdominal pain, bone and joint pain, and insomnia. Only one member survived the trip back to their base.
What are some sources of Vitamin D?
- exposure to sunlight/UV is a factor that contributes to the formation of Vitamin D
- most foods contain a small amount of vit D.
- fortification of vit. D in food has become widespread
What are the two forms of vitamin D?
ergocalciferol (D2) and cholecalciferol (D3)
these are vitamers
What is the plant form of Vitamin D?
ergocalciferol (D2)
What is the animal form of Vitamin D?
cholecalciferol (D3)
Describe Vitamin D metabolism in animals starting with exposure to sunlight.
Sunlight stimulates conversion of 7-dehydrocholesterol to Vitamin D3, which goes to the liver. It is then converted to 25-hydroxyvitamin D3. Next, it goes to the kidneys and is converted to the active form 1,25-dihydroxyvitamin D3. (aka 1,25 (OH)2D3)
What is the active form of Vitamin D called?
1,25 (OH)2 D3
What are some functions of the active form of Vitamin D in the intestines?
Induces synthesis of calcium binding protein (required for uptake of calcium from intestinal lumen); stimulates transport of phosphorous and magnesium
What is the active form of Vitamin A?
Retinol
How does active Vitamin D function in bone?
It causes mobilization of calcium.
It binds to receptors and appears in the nuclei of osteoblasts and osteocytes, mobilizing the uptake or release of calcium
How does active vitamin D function in the kidneys?
It is involved in calcium conservation and increases phosphorous reabsorption.
What are some natural sources of Vitamin D?
Cod liver oil, beef liver, sun-cured alfalfa, egg yolk, UV irradiated mushrooms
Describe the relationship poultry have with Vitamin D
In all species except for poultry, Vitamin D2 is equal to D3. Poultry require a preformed D3.
Describe the relationship dogs have with Vitamin D
Dogs do not absorb sunlight, and so they need a dietary supplementation of Vitamin D. They can use both D2 and D3.
How is Vitamin D stored?
It is stored in the liver and can be stored for a max of three months.
It can be produced by the animal, but housing conditions and hair coats are complicating factors.
Winter range cattle can get an injection.
Arctic animals get Vitamin D through their diet.
What animals absorb Vitamin D better from sunlight?
Adult animals and lighter skinned animals are better at absorbing sunlight and producing Vitamin D
What are some general effects of Vitamin D deficiency?
- causes a disturbance in the absorption of calcium and phosphorous
- results in insufficient bone calcification
- in swine: it takes 4 to 6 months for pigs fed a Vitamin D deficient diet to develop signs of deficiency
What is rickets?
Rickets is the development of soft bones in young animals due to Vitamin D deficiency
What is osteomalacia?
This is a disease in adult animals resulting from Vitamin D deficiency where there is decreased mineral content and softening of the bones
What are some subclinical signs of Vitamin D deficiency?
Reduced growth, milk production, egg production, and reproductive performance
- Lack of bone calcification and proliferation of ephyseal cartilage
- rib and vertebra fractures
- low plasma calcium, magnesium, and inorganic phosphorous levels
- elevated serum alkaline phosphatases
What does a primary deficiency in Vitamin D cause?
A secondary deficiency in calcium and phosphorous
What is the most toxic Vitamin?
Vitamin D
can be used as rat poison for this reason
How does Vitamin D toxicity usually occur?
Formulation errors
What are some symptoms or effects of Vitamin D toxicity?
- reduced feed intake (anorexia)
- reduced growth rate
- reduced liver weight
- excess calcium in blood (hypercalcemia)
- reduced weights of the radius and ulna
- calcification of the aorta, heart, kidney, and lung
- dehydration, vomiting, fatigue
What are the vitamers of Vitamin E?
tocopherol and tocotrienol
How was Vitamin E discovered?
Discovered in 1936 as a dietary fertility factor in rats
How does Vitamin E appear in its pure form?
light yellow oils
What are the differences between tocopherols and tocotrienols?
Tocopherol has no double bonds
Tocotrienol has double bonds
Both are vitamers of vitamin E
How can the vitamers/chemical forms of Vitamin E exist?
can exist in alpha, beta, gamma, or delta configurations
What is the most common chemical form of Vitamin E?
alpha-tocopherol
(synthetic dl-form)
What are some sources of Vitamin E?
cereal grains, vegetable oils, wheat germ oil, animal fat, alfalfa
What the intake of Vitamin E affected by?
affected by intake of:
- selenium
- unsaturated fatty acids
- antioxidants
- and by tissue reserves
These factors can cause secondary deficiencies
Describe the relationship Vitamin E has with selenium
Vitamin E has a selenium sparing effect, meaning it can fill in for selenium in metabolic pathways if it is deficient.
What are some chemical properties of Vitamin E?
- it’s an antioxidant (easily oxidized in presence of minerals and PUFA)
If oils are high in Vitamin E, why should we include a synthetic antioxidant?
Included because we don’t want all of the Vitamin E to be oxidized if we are trying to ensure high Vit. E activity
What are some functions of Vitamin E?
Its main function is as an antioxidant
- protects Vitamin A
- prevents oxidation of PUFA
- interrelated with selenium
Vitamin E also protects cell and mitochondrial membranes
What are muscular symptoms of Vitamin E deficiency? Examples of diseases?
Nutritional muscular dystrophy (or cardiomyopathy)
1. Mulberry heart disease (pig)
2. Stiff lamb disease
3. White muscle disease (calves)
4. Degeneration of nerve cells (poultry)
What effect does Vitamin E deficiency have on red blood cells?
Hemolysis of red blood cells
What effect does Vitamin E deficiency have on the reproductive system?
Males: inhibition of spermatogenesis
Females: fetal resorption (degeneration)
What disease results in cats from Vitamin E deficiency?
Pansteatitis - aka yellow fat disease
What is pansteatitis? What causes it?
This is a disease associated with Vitamin E deficiency in cats.
Results from diets with marginal or low levels of alpha-tocopherol (active vitamer of Vit. E) and high amounts of unsaturated fats
Characterized by inflammation and yellow-brown discoloration of body fat.
Fats are oxidizing in the tissue, and low Vitamin E cannot stop it.
Can be associated with cats fed canned commercial fish based food made primarily of red tuna or fish scraps
What are the symptoms of pansteatitis?
- depression, anorexia
- hyperesthesia (sensitivity to touch) of the chest and abdomen
- reluctance to move, decreased agililty
- presence of abnormal fat deposits under the skin and abdomen
- Dietary history includes items that are high in unsaturated fats and low in Vitamin E
How can pansteatitis be treated?
- elimination of fish from cat’s diet
- replace with a well-balanced, high quality commercial cat food
- administer Vitamin E (alpha-tocopherol) orally using a dose of 10-25 IU twice daily for 5-7 days
What is equine motor disease?
A disease in horses resulting from a Vitamin E deficiency.
Vitamin E cannot maintain nerve fibers, has poor connection to muscles, causing wasting
EMND is a spontaneous neurodegenerative disorder of the somatic lower motor neurons (spinal cord and brain) that results in a syndrome of diffuse neuromuscular disease in adult horses
How is Vitamin E related to meat quality?
Vitamin E supplementation is done in excess of requirements at the end of life as it adds antioxidant properties to the meat.
Has been successfully used to extend the shelf life of pork and poultry.
Maintains color (prevent hemoglobin oxidation) and prevents development of off-flavors (fatty acid oxidation)
Describe Vitamin E toxicity.
- not a practical problem
- Vitamin E is one of the least toxic fat soluble vitamins
Which Vitamin has the least amount of storage in the body of the fat soluble vitamins?
Vitamin K
What is unique about where Vitamin K can be synthesized?
In is synthesized by bacteria in the digestive tract
What is Vitamin K1 and where is it found?
Vitamin K1 is phylloquinone, a natural vitamer found in green vegetables
What is Vitamin K2 and where is it found?
Vitamin K2 is menaquinone, a natural vitamer produced in bacteria in the intestine
What is Vitamin K3 and where is it found?
Vitamin K3 is menadione, a synthetic vitamer and the most water soluble of the three Vitamin K vitamers. It is the only vitamer of Vit. K that has associated toxicity
What are the functions of Vitamin K?
Vitamin K is involved in blood coagulation and the blood clotting process.
There are four Vitamin K dependent coagulation proteins found in the liver. Deficiency in one or more of these factors delays clotting time.
What is prothrombin?
A Vitamin-K dependent clotting factor.
What does a deficiency of Vitamin K do to prothrombin?
It results in the production of abnormal prothrombin (factor II).
What is dicoumarol?
A chemical compound found in spoiled sweet clover that can cause fatal hemorrhaging in cattle. It prevents the synthesis of prothrombin by the liver (it is an antivitamin)
What is warfarin?
A rat poison made from synthetic dicoumarol
It is a blood thinner that causes internal hemorrhaging
It prevents the synthesis of prothrombin by the liver (it is an antivitamin)
What factors affect Vitamin K requirement?
- Bioavailability of Vitamin K in various ingredients
- level of dietary fats
- Use of antibiotics
- microbial synthesis in the digestive tract (hindgut and rumen)
- exposure and consumption of feces (copraphagy)
What form of Vitamin K is the most available?
Vitamin K2 (bacterial form) is more bioavailable than K1 (plant form)
What are some natural sources of Vitamin K?
Green leafy vegetables, eggs, liver, fish meal
How do we supplement Vitamin K in the diet?
We use menadione (K3, the synthetic version)
Since it is not stable on its own, we complex it to improve stability
Describe Vitamin K toxicity
Very large amounts of menadione compounds are well tolerated by animals
Describe Vitamin C storage in the body
Only stored in the body to a limited extent, so it needs to be supplied regularly
very soluble in water
Is Vitamin C of concern when it comes to toxicity?
No, it is essentially non-toxic
How is Vitamin C easily destroyed?
It is an antioxidant, is it is easily oxidized and destroyed by heat or exposure to air. It is also easily oxidized in the presence of minerals or oxidative enzymes
What forms of Vitamin C are there?
L-ascorbic acid (reduced form)
L-dehydroascorbic acid (oxidized form)
What form of Vitamin C is the most common?
L-ascorbic acid
This reduced form is present in foods
Which species require Vitamin C and why?
Humans, primates, and guinea pigs
Also some animals from India like red-vented bulbul bird and fruit bats
This dietary requirement exists because these species lack the enzyme L-gulonolactone oxidase, which converts glucose to ascorbic acid.
What is L-gulonolactone?
An enzyme that converts glucose to ascorbic acid, a form of Vitamin C.
Animals with this enzyme do not need dietary Vitamin C.
Why were megadoses of Vitamin C advocated?
The biochemist Linus Pauling advocated megadoses because it was thought at the time that Vit. C lessened severity of the common cold. Clinical trials showed that this was not the case though, and megadoses can cause kidney stones in men.
What are the general functions of Vitamin C?
- formation of collagen
- water-soluble antioxidant
- increases absorption of iron by reducing it from Fe 3+ to Fe 2+
Describe Vitamin C’s role in forming collagen
Vitamin C is a catalyst in this role. Collagen synthesis requires the synthesis of hydroxyproline from proline. The enzyme prolyl hydroxylase is involved.
Collagen makes up connective tissues such as bone, teeth, cartilage, tendons, ligaments, fibrous matrices of skin and blood vessels
What can deficiencies in Vitamin C cause?
Scurvy and anemia
What is scurvy? What symptoms does it have?
Scurvy is disease resulting from Vitamin C deficiency (in animals without L-gulonolactone oxidase)
Symptoms include:
- fragile capillaries
- swollen, bleeding, and ulcerated gums
- loose teeth
- skin lesions
- weak bones
The last three symptoms are because less Vitamin C means less collagen is being made
How is Vitamin C deficiency related to anemia?
Deficiency can cause anemia in two ways:
1. related to activation of folic acid
2. reduced absorption of iron
What are some sources of Vitamin C?
Citrus fruits and vegetables
Bell pepper»strawberry > orange
synthetic forms are also inexpensive
How does Vitamin C interact with poultry?
Poultry have shown some benefits of supplementation under heat stress conditions. Supplementation improves growth, feed efficiency, egg weight, shell quality, and livability during heat stress.
What are the B Vitamins?
- Thiamin (B1)
- Riboflavin (B2)
- Niacin (B3)
- Pantothenic acid (panthothenate, B5)
- Vitamin B6 (pyridoxine)
- Biotin (B7)
- Folate (folic acid, B9)
- Vitamin B12 (cobalamin)
What do all B Vitamins have in common in term of general deficiencies?
They all have similar general deficiencies because they relate to lower energy production
What is thiamin also called?
Vitamin B1
Describe some chemical reactions that affect thiamin
It is unstable when exposed to UV light and undergoes Maillard-type reactions
What are some general functions of thiamin?
- makes up Thiamin pyrophosphate (TPP), a coenzyme
What does thiamin pyrophosphate do?
It aids pyruvate dehydrogenase in converting pyruvate to acetyl CoA
It is also involved in the decarboxylation of alpha-keto acids , which is important in TCA cycle
It works with alpha-ketoglutarate dehydrogenase to convert alpha-ketogluarate into succinyl-CoA within TCA
It plays a role in the pentose phosphate pathway for ruminants
It can convert tryptophan to niacin (B3)
Why do cats have high niacin requirements in their diets?
They cannot convert tryptophan to niacin with the help of thiamin pyrophosphate
What are sources of thiamin?
yeast, yeast extracts, pork
cereal grains (whole grains in outer hull)
In the U.S., processed flour is required to be fortified with thiamin mononitrate, niacin, riboflavin, folic acid, and iron
Rumen microbes can synthesize B-vitamins
What are symptoms of thiamin deficiency?
- loss of apetite
- emaciation
- slowing of heart rate
- lowering of body temp
When pyruvate cannot be converted to acetyl CoA, lactic acid builds up and muscles weaken. This is explained by the role of thiamin pyrophosphate in decarboxylation reactions.
Lower acetyl CoA means lower lipogenesis
How does thiamin deficiency affect the nervous system?
It causes progressive dysfunction because there is less ATP synthesis. The ion pumps in nerves require ATP
Why is thiamin deficiency prevalent in Asia? What is beriberi?
Rice, a common grain, is polished and the husks (containing the thiamin) are removed.
Beriberi is a human disease
Dry beriberi causes wasting and partial paralysis due to peripheral nerve damage
Wet beriberi causes weakening of the capillary walls of the heart, causing edema in the tissue
What does thiamin deficiency in poultry cause?
Polyneuritis
What does thiamin deficiency cause in ruminants?
Polioencephalomalacia - Polio or stargazing
Caused by a rumen environment which destroys thiamin or inhibits thiamin production; thiaminase is an enzyme that destroys thiamin
Can be treated with thiamin injections
What are some anti-thiamin substances?
- foods/feeds containing thiaminase activity
- raw fish from certain species
- horses - bracken fern
What is thiamin requirement determined by?
- carb intake
- thiaminase activity
What is riboflavin also called?
Vitamin B2
Describe riboflavin’s colors
It imparts a yellow color on vitamin pre-mixes
Pure supplementation turns urine fluorescent yellow
What are the functions of riboflavin in regard to proteins?
They are a component of flavoproteins
a. component of coenzymes like flavin mononucleotide and flavin adenine dinucleotide
b. oxidation reduction reactions
c. important role in electron transport chain
What role and function does riboflavin play in certain metabolic functions?
It helps convert retinal to retinoic acid
It helps convert tryptophan to niacin
What is a poor source of riboflavin?
Cereal grains
Therefore supplementation is necessary
What are some sources of riboflavin?
It occurs in all biological materials
Synthesized by plants, yeasts, fungi, and most bacteria
Good sources are: yeast, liver, MILK, green leafy vegetables
What are general deficiency symptoms of riboflavin?
- poor growth
- diarrhea (secondary) due to impaired nutrient absorption
- eye abnormalities (link with Vit. A)
- hair loss and dermatitis
What is a specific riboflavin deficiency symptom? (hint, it deals with chickens)
Curled toe paralysis
In occurs in young chicks due to peripheral nerve degeneration
What is niacin also called?
Vitamin B3
What is the active form of niacin?
nicotinamide
What are the functions of niacin?
It is a component of two coenzymes:
1. NAD: nicotinamide adenine dinucleotide
2. NADP: phosphorylated NAD
Involved in oxidation-reduction reactions
Involved in carb, lipid, and amino acid metabolism
What relationship does niacin have with tryptophan?
Niacin can be synthesized from tryptophan
What are some good sources of niacin?
Animal proteins are good sources of niacin equivalents
What is niacinogen?
A compound found in corn that binds niacin and makes it unavailable
What are niacin complexes?
There are compounds in cereal grains. They are also called nyacitin, and niacin is unavailable in these forms.
What are general symptoms of niacin deficiency?
poor growth and diarrhea
What is Pellagra?
This is a disease in humans from niacin deficiency. It is called the disease of 4 Ds
- diarrhea, dermatitis, dementia, death
It causes hair loss and dermatitis around the neck, causing a necklace like lesion
It also causes black tongue in dogs
What are symptoms of niacin toxicity?
skin flushing, dry skin or rashes
maculopathy (thickening of macula and retina)
Acute toxic reactions
What affect does niacin have on lipids?
It has a lipid modifying effect, and reduces cholesterol, TAG, VLDL, and LDL
What is Vitamin B6 also called?
pyridoxine
What three forms does Vitamin B6 occur in?
pyridoxine, pyridoxamine, and pyridoxal
What is the metabolically active form of Vitamin B6?
Pyridoxal phosphate
What does pyridoxal phosphate do?
It is a coenzyme that works with glycogen phosphorylase to convert glycogen to glucose
What are the functions of Vitamin B6?
- coenzyme in macronutrient metabolism
- amino acid catabolism, gluconeogenesis, biosynthesis of sphingolipds - synthesis of neurotransmitters, histamine, and hemoglobin
What are some sources of Vitamin B6?
found in pretty much all foods
What is the plant form of B6?
pyridoxine, the stable form
What are the animal forms of B6?
pyridoxamine and pyridoxal, not as stable
What is the commercial form of Vitamin B6?
Pyridoxine HCl, very stable
What are general deficiency symptoms of Vitamin B6?
- poor growth rate
- scaling dermatitis
- hyper irritability
What are specific deficiency symptoms for Vitamin B6?
- muscular weakness and anemia
- infertility and fetal malformations
- insulin insufficiency (due to reduced pancreatic synthesis)
What is biotin also called?
Vitamin B7
What is biocytin?
A amide complex of biotin and lysine
What are the functions of biotin?
- essential component of certain carboxylase enzymes
- involved in both carboxylation and decarboxylation reactions
- most biotin functions occur in the mitochondria
Describe biotin as a coenzyme in certain reactions.
- Biotin-dependent carboxylase in the TCA
- pyruvate carboxylase, propionyl-CoA carboxylase - biotin-dependent carboxylase in lipid metabolism
- acetyl CoA carboxyalse - deamination reactions, tryptophan metabolism, and purine synthesis
What are some sources of biotin?
Wide variability of bioavailability is a concern.
Plant sources are oilseed meals
Animal byproducts and fermentation byproducts
What is avidin and how does it relate to biotin?
Avidin is a glycoprotein secreted by the mucosa of the oviduct in the hen, and it winds up in the egg albumin. It strongly binds avidin, so strongly that this bond is used to test biochemical assays in labs.
The biotin-avidin complex is the strongest non-covalent bond in nature. It cannot be hydrolyzed by enzymes in the body. Heating or cooking can break the bond.
What are specific biotin deficiency symptoms.
poor hoof health in horses and cattle
What is pantothenic acid also called?
Vitamin B5
What is the function of pantothenic acid?
It is usually in a bound form with acetyl CoA and and acyl carrier protein.
It is required for synthesize of coenzyme A.
It is a component of fatty acid synthase, which is required for synthesis of fatty acids, cholesterol, and acetylcholine.
What are sources of pantothenic acid?
LIVER and EGG YOLK
yeast, whole grains, peanuts, wheat brans
What are general deficiency symptoms of pantothenic acid
poor growth with secondary diarrhea
dermatitis and hair loss
What are specific deficiency symptoms of pantothenic acid?
Chickens are most susceptible to deficiency. Deficiency can cause the area around the eyes to become scaly.
Goose-stepping in pigs is also a symptom
What is folic acid also called?
Vitamin B9
What are the forms of folic acid?
- free folate (not naturally occurring)
- dihydrofolate (DHF)
- tetrahydrofolate (THF)
What are the functions of folic acid?
- Carrier of methyl groups that are added to or removed from amino acids (eventually can lead to DNA methylation)
- tetrahydrofolate is an essential coenzyme in the synthesis of thymidylic acid (thymine in DMA)
- Purine synthesis (A and G in DNA)
- initiation of translation (formylmethionine - start codon in protein synthesis)
What are sources of folic acids?
Richest sources are liver and brewer’s yeast
green leafy materials, grains, oilseed meals, animal protein meals
Mandatory fortification of breads, cereals, flours, pastas, and rice in the U.S. since 1996
What are deficiency symptoms of folic acid?
- reduced biosynthesis of DNA and RNA
- reduced cell division
- especially important in women of child bearing age because deficiency can cause issues for the fetus
anemia
leucopenia (reduced white blood cells
General deficiency symptoms the same as other B vitamins
What does folic acid deficiency cause in human fetuses?
Spina bifida, a disease where a pocket forms in the spinal column, where nerves grow
May also cause anecephaly (no skull) or encephalocele
What animal is most susceptible to folic acid deficiency and what does it cause in them?
Poultry are most susceptible.
It causes cervical paralysis (extended neck) and poor feather development
What is Vitamin B12 also called?
cobalamin
because it has cobalt in its structure
What color does Vitamin B12 impart?
red
What are the vitamers of Vitamin B12?
methycobalamin
adenosylcobalamin
How is Vitamin B12 tied to animal proteins in feed?
If animal proteins were removed from diet, performance was impaired
What are sources of Vitamin B12?
animal products and fermentation byproducts
Why is Vitamin B12 supplementation necessary?
It is necessary because it is not found in plant sources, or synthesized by plants or animals.
That is why it is very important in a vegetarian’s diet.
What synthesizes Vitamin B12 and what is required for its synthesis?
Can only be synthesized by a few species of microorganisms, and cobalt is required for synthesis (part of the structure)
How can we stimulate Vitamin B12 synthesis in ruminants.
Supplement dietary cobalt
What do we do to stimulate B12 synthesis in non-ruminants?
No cobalt requirement, only dietary Vitamin B12 will suffice
Synthesis by microflora in the hindgut is not adequate except for in horses, which the only known species with appreciable absorption of Vitamin B12 from the hindgut
What is intrinsic factor?
Intrinsic factor (IF) is needed for Vitamin B12 absorption.
It is secreted by the gastric mucosa (parietal cells)
This is the only essential function of the stomach.
Without the stomach, there is no absorption of Vitamin B12
What are the functions of Vitamin B12?
- synthesis of labile methyl groups
- glucose synthesis, important in ruminants because it converts methylmalonyl-CoA to succinyl CoA, which can be converted to glucose
What are deficiency symptoms of Vitamin B12?
Anemia
nervous system disorders
limited methyl group availability, increases fat deposition in liver, heart, and kidneys
Describe the relationship the giant schnauzer has with Vitamin B12
Giant schnauzers have had the intrinsic factor bred out of them over time. Therefore, they do NOT absorb Vitamin B12, and oral administration cannot treat this.
Long term treatment includes intramuscular injections of the vitamin, which supplies it to the tissues
What are quasi-vitamins?
Compounds proposed as vitamins that fit the vitamin designation for certain species
What is choline?
A quasi-vitamin required in pig and poultry diets.
It is a component of phospholipids.
What is taurine?
A qausi-vitamin found in meat. Cats are unable to synthesize it so they require it in their diets.
Deficiency causes feline dilated cardiomyopathy.
