Vitamin Nutrition Syllabus
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Vitamin Nutrition Syllabus Spring 2004 Texas Ag. Experiment Station – Amarillo Texas Tech University West Texas A&M University Instructor: C. Reed Richardson, Ph.D. Professor and Director of the Center for Feed Industry Research and Education, Texas Tech University Phone: (806) 742-2516 Fax: (806) 742-4003 Email: reed.richardson@ttu.edu Reference Text: Vitamins in Animal Nutrition by L.R. McDowell Grading: Hour Exams (2) 35% each = 70% Term paper (1) = 30% **Grade for the mineral/vitamin course will be calculated as 50% mineral section plus 50% vitamin section. Communication with students: All students are expected to have an e-mail address. Term Papers and general correspondence will be e-mailed to reed.richardson@ttu.edu Texas Tech students may hand deliver term papers or use e-mail. After grading, scores and comments will be returned via email. Hour Exams: Both hour exams will be closed book. The first exam will be given during regular class time and the second exam given during the scheduled time for final exams. For locations other than Texas Tech, exams will be sent to a faculty/staff person at each location who will deliver exams to the classroom and collect the completed exams. Each exam will be comprehensive over material covered up to the exam date. The second exam will cover only material after the first exam. Term Paper: * It should be 8-10 double spaced pages and is due no later than the last day of class, April 29Th. Format should be “Times New Roman”, 12 point font with 1.25 inch margins. * Topic: Choose a vitamin or vitamin-like substance and develop a subtopic that addresses one of the following six subject areas: 1) 2) 3) 4) 5) 6) chemical structure, properties, and antagonists metabolism (digestion, absorption, and transport) analytical procedures functions in mammals and poultry requirements effects of deficiency * Grading will be based on both depth and breadth of the paper. The reference text will serve as a base to start the paper from, but should be greatly expanded in depth and breadth to provide a clear, detailed understanding. There will be no duplication of subtopics at a particular TTVN site since there are over 150 subtopics to choose from. Tentative Schedule DATE March TOPIC 4 Introduction; Classification; History 9 Fat Soluble Vitamins; Vitamin A 11 16 -18 April May Vitamin D; Vitamin E Spring Vacation 23 Vitamin K; Vitamin C 25 Antioxidant vitamins ; Water soluble vitamins 30 Review and discussion (20 minutes); First Exam 6 Thiamin; Riboflavin 8 Riboflavin; Niacin 13 Vitamin B6; Panothenic acid 15 No class (Plains Nutrition Council Spring Conference) 20 Biotin; Folacin 22 Vitamin B12; Choline 27 Vitamin-like substances 29 Term Paper Due 7 Second Exam. (7:30 – 10:00 a.m.) **Date and time for Texas Tech students, other locations to be arranged during final exam week. Main Cellul ar Roles of B Vitamins Involved in Metabolism of Carbohydrates, Proteins and Fats Diet Proteins Carbohydrates Fats Body Cells Free Fatty Acids B2 B1 Glucose Biotin B2 PA Niacin B6 Biotin Niacin Amino Acids B6 B12 Folacin B6 B1 B2 Pyruvic Acid Acetyl Co-Enzyme A Niacin Mitochondria Krebs Cycle B1 Folacin B2 PA Niacin B12 Electrons (H+’s) Excretion ATP, H2O C. R. Richardson, 1999 ANSC 5308 VITAMIN NUTRITION SECTION LECTURE 1 INTRODUCTION 1. Syllabus 2. Definitions of vitamins 3. Complex organic compounds required in small amounts Required for essential life processes Consist of a mixed group of compounds unrelated to each other Some vitamins may deviate from the above definition (Vitamin C, Niacin, Vitamin D) Making sense of the role of vitamins in biological processes Train yourself to visualize molecular events Everything that occurs in the observable world has its basis in the unobservable world of atoms and molecules Develop a logical approach to solving Apply the principles you learn to real-world situations Let yourself be amazed by what you learn and curious about all there is still left to learn Optimum vitamin allowances Vitamin controversies problems . . . CLASSIFICATION 1. Fat soluble 2. Vitamin A Vitamin D Vitamin E Vitamin K Associated with lipids in feedstuffs; absorbed along with dietary fats; storage Water soluble Vitamin C B complex – rapidly excreted Other VITAMIN SYNONYM Fat Soluble Vitamin A1 Vitamin A2 Retinol Dehydroretinol Vitamin D2 Vitamin D3 Vitamin E Vitamin K1 Vitamin K2 Vitamin K3 Ergocalciferol Cholecalciferol Tocopherol Phylloquione Menaquione Menadione Water Soluble Thiamin Riboflavin Niacin Vitamin B6 Pyridoxamine Pantothenic Acid Biotin Folacin Vitamin B12 Choline Vitamin C Vitamin B1 Vitamin B2 VitaminPP, Vitamin B3 Pyridoxol, Pyridoxal, Vitamin B5 Vitamin H Vitamin M, Vitamin BC Cobalamin Gossypine Ascorbic Acid 3. Vitamin Nomenclature Letters of the Alphabet Designation of groups – the “B” group System of suffixes – D2, etc. Describing function or its source 1) H (Biotin) – “Haut” German for “skin” 2) K – Danish for “koagulation” (coagulation) 3) Panothenic Acid – Greek for “pantos” Rules for nomenclature by the Committee of Nomenclature of the American Institute of Nutrition (CNAIN, 1981). VITAMIN REQUIREMENTS 1. Dietary needs differ widely among species 2. Some vitamins are metabolic essentials, but not dietary essentials 3. Ruminants usually satisfy their needs for B vitamins from feed and symbiotic microorganisms 4. Horses may meet most of their requirements for B vitamins from symbiotic microorganisms VITAMIN OCCURRENCE 1. Vitamins originate primarily in plant tissue 2. Vitamin B12 – occurs in plant tissue from microbial synthesis 3. Vitamins A and D occur in plants as a provitamin (precursor) 4. No precursors are known for any water soluble vitamins 5. B vitamins are universally distributed in all living tissue 6. Fat-soluble vitamins are completely absent from some tissue HISTORY 1. Late 1800’s and early 1900’s – chemically defined diets 2. 1860 Louis Pasteur / Justus Von Liebig – yeast studies 3. Vitamin hypothesis 4. 1912 Casimer Funk proposed the “vitamin theory” “vital amine” 5. Later the term vitamin was coined 6. 1915 rat required two growth factors 7. Fat-soluble A Water-soluble B 1919 – Vitamin A 1922 – Vitamin D 1923 – Vitamin E 1926 – Thiamin 1926 – Riboflavin 1928 – Bacterial synthesis of B vitamins 1928 – Vitamin C 1930 – Panothenic Acid 1932 – Choline 1934 – Vitamin B6 1934 – Vitamin K 1935 – Niacin 1936 – Biotin 1943 – Folacin 1948 – Vitamin B12 The only disease a vitamin will cure is the one caused by a deficiency of that vitamin. FACTORS THAT ADVERSELY AFFECT THE STABILITY OF VITAMINS 1. Moisture 2. Temperature 3. Light 4. Pressure 5. Friction 6. Trace minerals (Cu & Fe) 7. Oxidizing and reducing agents 8. pH 9. Chemicals 10. Feed composition VITAMIN DESIGN AND DELIVERY 1. Crosslinking process (beadlet, insoluble in H2O) 2. Coating 3. Mixing with stable carriers 4. Water flush into complete diet and rapid mixing and delivery HOW TO ADD TO FEEDS 1. Premix 2. Manual weighing and hand addition 3. Computer weighing and direct addition 4. Sequence of batching ingredients ANSC 5308 VITAMIN NUTRITION SECTION LECTURE 2 FAT SOLUBLE VITAMINS 1. A, D, E, and K 2. Have some properties in common, yet each has a distinct physiological role 3. Diversity of primary biological functions 4. Excretion 5. A – vision, and cellular differentiation D – calcium absorption E – antioxidant K – blood clotting Fat soluble – feces via the bile Water soluble – rapid in urine Excesses 6. Composition 7. Fat soluble – C, H, and O Water soluble – C, H, O and some have N, S or Co Absorption 8. Fat soluble – A and D are toxic Water soluble – relatively nontoxic Fat soluble – passive diffusion Water soluble – passive diffusion, but some by active process if low level in the diet Some deficiency signs of fat soluble may be related to function D – required for Ca metabolism and deficiency results in bone abnormalities Water soluble are much less specific and deficiency signs are difficult to relate to function 1) 2) Most result in – dermatitis, rough hair coat, poor growth, and reduced feed efficiency Several cause loss of pigment in hair; and anemia which is a deficiency of hemoglobin VITAMIN A 1. May be most important from a practical standpoint 2. Needed by all animals, including ruminants 3. Found in plants as carotenoids (precursors) 4. Higher in yellow and green plants Deficiency – blindness in children throughout the world CHEMICAL STRUCTURE AND PROPERTIES 1. Vitamin A1 – retinol (C20 H30 O) Replacement of alcohol group with aldehyde gives Retinal Replacement with an acid gives retionic acid 2. Vitamin A2 – (3, 4 –dehydroretinol) 3. Since Vitamin A contains double bonds, it can exist in isomeric forms all – trans 13 – cis 11 – cis 9 – cis 11, 13 – di-cis 9, 13 – di-cis Biological Activity, % Rats Chicks 100 100 75 50 47 ? 21 ? 15 ? 24 ? 4. Yellow carotenoids Source Relative Rat-Biopotency (All trans forms) Plants/ animals 100 Plants/ animals 25 Gamma carotene Less ubiquitous 14 Beta zeacarotene Yellow corn 25 Cryptoxanthin Yellow corn, some fruits & flowers 29 Beta carotene Alpha carotene Zeaxanthin Lutein (xanthophyll) 5. 6. Corn, egg yolk 0 Green leaves, egg yolk 0 The most active form of Vitamin A and that most usually found in mammalian tissues is all-trans Cis can arise from trans but a marked loss on Vitamin A potency results Pure Vitamin A has twice the potency of beta carotene Only one molecule of Vitamin A is formed from one molecule of beta carotene ANALYTICAL PROCEDURES 1. Biological methods Growth responses – rats or chicks 2. Physicochemical methods 3. Liver storage tests – various species Cell changes in vaginal smears – rats Color reactions 1) Carr-Price method (antimony trichloride) 2) Gas chromatography 3) Thin-layer chromatography 4) Spectrophotometric procedures 5) High-pressure liquid chromatography (HPLC) Activity expressed International units (IU) U.S. pharmacopoeia units (USP) 1) IU = USP IU defined as 1) 0.300 ug of Vitamin A alcohol (retinol), or 2) 0.550 ug of Vitamin A palmitate One IU of Vitamin A activity = 0.6 ug of beta carotene METABOLISM 1. A number of factors influence digestibility of carotene Type of forage (hay, silage, greenchop, or pasture) Month of forage harvest Species of plant Plant dry matter Season – higher in warmer months 2. Appreciable amounts of carotene or Vitamin A may be degraded in the rumen – 40 to 70 % 3. Absorption and transport Conversion of beta carotene to Vitamin A occurs in intestinal mucosa In most mammals the product absorbed is Vitamin A itself 1) 2) Some species have ability to absorb dietary carotenoids – humans, cattle, horses, and carp In case of cattle there is a strong breed difference – Holstein vs. Guernsey and Jersey a) Difference may be due to – suitable receptor proteins, or micellar solutions in intestinal lumen Some Vitamin A derivatives are reexcreted into intestinal lumen via the bile 1) Retionic acid 2) Some retinol 3) Vitamin A glucuronides Vitamin A alcohol (retinol) is transported in the blood by retinol binding protein (RBP) 1) RBP is secreted by hepatic parenchymal cells, mol. wt. of 20,000 and has one binding site for one molecule of retinol 2) 90% of plasma RBP is complexed to thyroxine-binding prealbumin 3) Storage and release of Vitamin A by the liver is under several forms of homeostatic control STORAGE 1. Liver normally contains 90% of total body Vitamin A, remainder mostly in kidneys, lungs, adrenals and blood 2. Exceptions 1) Stomach oils of certain seabirds 2) Intestinal wall of some fish 3) Eyes of certain shrimp Measurement of liver stores of Vitamin A at slaughter or in samples obtained by biopsy is useful in studying Vitamin A status FUNCTIONS 1. Necessary for support of growth, health, and life of higher animals In the absence of Vitamin A, animals cease to grow and eventually die 2. The metabolic function of Vitamin A, explained in biochemical terms, is still incompletely known 3. Deficiency causes four different and probably physiologically distinct problems Loss of vision 1) Due to failure of rhodopsin formation in the retina Defects in bone growth Defects in reproduction 1) Male – failure of spermatogensis 2) Female – resorption of the fetus Defects in growth and differentiation of epithelial cells REQUIREMENTS 1. Requirements can be expressed as IU per kilogram body wt. – on a daily basis A unit of the diet 1) General practice is per unit of diet Tables 2.1, 2.2, 2.3, 2.4, 2.7, and 2.8 DEFICIENCY SIGNS 1. Ruminants Reduced feed intake Rough hair coat Edema of joints and brisket Lacrimation Xerophthalmia (dry eye) Night blindness Slow growth Diarrhea Convulsive seizures Improper bone growth Blindness 2. Low conception rates Abortion Stillbirths Blind calves Abnormal semen Reduced libido Susceptibility to respiratory and other infections Swine Principally nervous signs 1) Unsteady gait 2) Incoordination 3) Trembling of legs 4) Spasms 5) Paralysis During reproduction and lactation 1) Failure of estrus 2) Resorption of young 3) 4) 5) 6) 7) 8) 9) 3. Poultry 4. Wobbly gait Weaving and crossing of hind legs while walking Dropping of the ears Curving with head down to one side Spasms Inability to stand Impaired vision Slower growth Lowered resistance to disease Eye Lesions Muscular incoordination Other Horses Night blindness 5. Lacrimation Keratinization of the cornea and respiratory system Reproductive difficulties Capricious appetite Progressive weakness Death Humans Occurs in endemic proportions in many developing countries Alcohol consumption results in liver Vitamin A depletion Drugs such as phenobarbital or food additives such as butylated hydroxytoluene (BHT), when combined with ethanol, results in greater depletion of liver Vitamin A Deficiency is nearly always associated with 1) Protein-energy malnutrition 2) Parasitic infections 3) Intercurrent infections VITAMIN D 4. Thought of as the “sunshine vitamin” 5. Two major natural sources: 6. Ergocalciferol (D2) – occurs in plants Cholecalciferol (D3) – occurs in animals Synthesized in various materials when exposed to sufficient sunlight Not needed in the diet with adequate sunlight exposure Total confinement of animals leads to limited or no exposure to sunlight – poultry, swine, other 7. Deficiency – rickets in young; osteomalacia in adults 8. Vitamin D functions as a hormone CHEMICAL STRUCTURE and PROPERTIES 1. Group of compounds that have antirachitic activity 2. All sterols with Vitamin D activity have the same steroid nucleus, they differ only in the side chain attached at carbon 17 UV light Plant steroids Ergosterol Vitamin D2 (Ergocalciferol) Cholesterol or Squalene 7-Dehydrocholesterol UV light Vitamin D3 (Cholecalciferol) Precursors have no antirachitic activity until the B-ring is opened between the 9-10 carbons by irradiation and a double bond formed between the 10 and 19 carbons 3. Colorless crystals insoluble in water, but soluble in alcohol and organic solvents 4. Destroyed by over-treatment with UV light and peroxidation (polyunsaturated fatty acids) 5. Vitamin D Activity: RAT – D2 and D3 are equally active BIRDS – D2 has only 1/10th the activity of D3 ANALYTICAL PROCEDURES 1. Vitamin D analysis is complex because of so many isomers 2. Standard method is biological assay Only vitamin in which biological method is still used Rats and chicks are assay animals of choice 1) Involves developing rickets 2) Then, adding Vitamin D for 7d, followed by a line test (deposition of calcium salts) with silver nitrate Physical and chemical methods include: Ultraviolet absorption Colorimetric procedures Fluoresence spectroscopy Gas chromatography Competitive binding assays High pressure liquid chromatography (HPLC) METABOLISM 1. Absorbed from the small intestine and requires bile salts Only about 50% of a dose of Vitamin D is absorbed D3 is produced by irradiation of 7-dehydrocholesterol with UV light from the sun or and artificial source 1) 2) 3) 4) 5) Once formed, 7-dehydrocholesterol is thermally isomerized to D3 over 2-3 days Only about 15% 7-dehydrocholesterol in human skin is converted to D3 11-45 min. daily sunshine prevents rickets in chicks (longer exposure does not increase D3 concentration) 90% of 7-dehydrocholesterol synthesis occurs in the epidermis Rickets can be successfully treated by rubbing cod liver oil on the skin 6) 2. Once D2 or D3 enters the blood, it circulates at relatively low concentrations 3. Some D3 formed on the skin ends up in the digestive tract because of licking of skin and hair Probably a result of rapid accumulation in the liver Liver hyroxylates the 25 carbon in the side chain to produce 25-OH Vitamin D 1) Major circulating form of Vitamin D 2) Conversion to 25-OHD3 takes place in the microsomes and the mitochondria of the liver Intestine and kidney also produce small amounts of 25-OHD3 25-OHD3 is transported to the kidney where it is converted to a variety of compounds of which 1,25-(OH)2D3 is the most important 1,25-(OH)2D3 formed in the kidney is transported to the intestine, bones, or elsewhere 1,25-(OH)2D3 is carefully regulated by parathyroid hormone in response to serum Ca and P concentrations Transport of 25–OHD3, and possibly 24,25–(OH)2D3 and 1,25-(OH)2D3 occurs on the same protein 4. This protein has a mol. wt. of 50,000 – 60,000 in humans 1) Single chain polypeptide 2) Called transcalciferin, or Vitamin D – binding protein (DBP) Land animals and humans do not store large amounts of D, in contrast to aquatic species which store much more Much less storage than Vitamin A Blood has the highest concentration; in pigs several-fold higher than in the liver During times of deprivation, Vitamin D in tissues is released slowly Transplacental movement of Ca increases dramatically during the last trimester of gestation A liberal intake of Vitamin D during gestation does provide a sufficient store in newborn to prevent early rickets FUNCTIONS 1. Enhancement of intestinal absorption and mobilization, retention, and bone deposition of calcium and phosphorus 2. Recently, evidence suggest a role in immune cell functions 3. Also, possible use of Vitamin D analogs in differentiation of myelocytic-type leukemias and in the treatment of psoriasis 4. 1,25-(OH)2D3 works in relationship with thyrocalcitonin (calcitonin) and parathyroid (PTH) hormones to control blood calcium and phosphorus levels Calcitonin regulates high serum Ca levels by 1) Depressing gut absorption 2) Halting bone demineralization 3) Reasorption in the kidney Vitamin D brings about an elevation of plasma Ca and P by stimulating pump mechanisms in 1) Intestine 2) 3) 5. In 1963 it was demonstrated that Vitamin D regulated P absorption and transport, as well as Ca 6. P is transported against an electrochemical potential gradient involving sodium in response to 1,25-(OH)2D3 Bone synthesis in young animals 7. Bone Kidney Minerals are deposited on the matrix by an invasion of blood vessels that give rise to trabecular bone 1) This process causes bones to elongate 2) During Vitamin D deficiency, this organic matrix fails to mineralize 3) 1,25-(OH)2D3 brings about mineralization Vitamin D is involved with PTH in mobilization of Ca from bone to the extracellular fluid compartment 8. Another role of Vitamin D is in the biosynthesis of collagen in preparation for mineralization 9. Deficiency of Vitamin D causes inadequate cross-linking of collagen as a result of low lysyl oxidase activity Vitamin D functions in the distal renal tubules to improve Ca reabsorption REQUIREMENTS 1. Animals and humans do not have a nutritional requirement for Vitamin D if sufficient sunlight is available 2. Factors influencing dietary Vitamin D requirements include Amount of Ca and P Ratio of Ca and P Availability of Ca and P Species 3. Sunlight radiation 4. Contains only a small part of the UV range for Vitamin D synthesis More potent in the tropics than in the arctic zones More potent in summer than in winter More potent at noon than in morning or evening More potent at high altitudes Provides most of its antirachitic powers during the 4 h around noon Clouds, mist, smoke and air pollution screen out many UV rays 5. Physiological effects Thus, rickets has been called the first air pollution disease Colors of hair coat and skin affect ultraviolet irradiation More effective on exposed skin than through a heavy coat of hair Less effective on dark-pigmented skin 1) White pigs resist Vitamin D deficiency twice as long as colored pigs 2) 6. White humans, 20-30% of UV radiation is transmitted through the epidermis; black humans, less than 5% is transmitted Aging effect on production of Vitamin D3 In humans older than 20 years 1) Skin thickness decreases linearly with time 2) Aging decreases more than 2-fold the capacity of the skin to produce previtamin D3 REQUIREMENTS 1. Major species difference exist 2. Humans are more like birds than like other mammals 3. Growth rates were greater in children given 400 IU per day, although 100 IU is enough to prevent rickets 4. Table 3.1 DEFICIENCY 1. All animals 2. Failure of calcium salt deposition in the cartilage matrix Failure of cartilage cells to mature, leading to accumulation rather than destruction Compression of proliferating cartilage cells Elongation, swelling, and degeneration of cartilage Abnormal invasion of cartilage by capillaries Outward signs of rickets Weak bones cause curving and bending of bones Enlarged hock and knee joints Tendency to drag hind legs Beaded ribs and deformed thorax 3. Ruminants – clinical signs of deficiency 4. Decreased appetite and growth rate Digestive disturbances Stiffness of gait Labored breathing Irritability Weakness Occasionally tetany and convulsions Swine – clinical signs of deficiency Poor growth Stiffness Lameness Stilted gait General tendency to “go down” Loss of use of limbs Frequent cases of fractures 5. Poultry – clinical signs of deficiency 6. Softness of bones Bone deformities Beading of the ribs Enlargement and erosion of joints Unthriftiness Retarded growth Rickets Rest frequently in a squatting position Disinclination to walk Lame, stiff-legged gait Horses – clinical signs of deficiency Reduced bone calcification Stiff and swollen joints Stiffness of gait Bone deformities Frequent cases of fractures Reduction in serum Ca and P ASSESSMENT OF STATUS 1. Poor production rates by animals 2. Bone abnormalities in animals 3. Diagnosis of rickets and osteomalacia Serum calcium levels – 5 to 7 mg/100 ml High serum alkaline phosphatase activity ANSC 5308 VITAMIN NUTRITION SECTION LECTURE 5 VITAMIN K 9. Vitamin K was the last fat-soluble vitamin to be discovered 10. In contrast to the other fat-soluble Vitamins A, D, and E, which have multiple functions and wide biological importance, Vitamin K appears to be limited in its function to: Normal blood clotting mechanism Suggested roles in identified Vitamin K dependent proteins 11. Because of the blood clotting function, Vitamin K was previously referred to as the “coagulation vitamin”, “antihemorrhagic vitamin”, and “prothrombin factor” 12. Vitamin K is required for maintaining the function of the blood coagulation system in humans and all investigated animals 13. Even though Vitamin K is synthesized by intestinal microorganisms, deficiency signs have been observed under field conditions 14. Poultry and pigs are susceptible to vitamin K deficiency 15. In ruminants, a deficiency can be caused by ingestion of spoiled sweet clover hay, which is a natural source of dicumarol (a Vitamin K antagonist) 16. Vitamin K is most required in human nutrition of infants because of insufficient intestinal synthesis, and in adults under conditions where fat absorption is impaired CHEMICAL STRUCTURE AND PROPERTIES 6. Vitamin K is used to describe a group of quinone compounds that have characteristic antihemorrhagic effects 7. Vitamin K is a generic term consisting of 2-menthyl-1,4-naphthoquinone derivatives, called menadione 8. Various isomers differ in the nature and length of the side chain There are three forms of Vitamin K K1 – plant source (phylloquinone) 9. K2 – animal (microbial) source (menaquinone) K3 – synthetic source (menadione) Vitamin K is a golden yellow viscous oil Stable to heat Labile to oxidation, alkali, strong acids, light, and irradiation 10. 5. A number of Vitamin K antagonists exist Dicumarol Sulfonamides Mycotoxins ANALYTICAL PROCEDURES 5. High Pressure liquid chromatography (HPLC) is highly suitable for Vitamin K analysis 6. A classic biological assay for amount of Vitamin K is blood clotting time in the chick METABOLISM 3. Vitamin K is absorbed in association with dietary fats and requires bile salts and pancreatic juice 4. Unlike phylloquinone (K1) and menaquinones (K2), menadione bisulfites and phosphates are relatively water soluble and are satisfactorily absorbed from low-fat diets 5. Absorption of different forms of Vitamin K may differ greatly Rats 1) 40% absorption of K1 2) 89% absorption of K3 Conclusion is K3 (menadione) is well absorbed and poorly retained while the opposite is true for K1 (phylloquinone) FUNCTIONS 10. Coagulation time is increased when Vitamin K is deficient Plasma clotting factors VII, IX and X are dependent on Vitamin K for synthesis 1) These four blood-clotting proteins are synthesized in the liver in inactive forms and then converted to biologically active forms by Vitamin K REQUIREMENTS 7. Vitamin K requirement in mammals is met by a combination of dietary intake and microbial biosynthesis in the guts which involve E coli, and ruminal microbes 8. Because of microbial synthesis a precise expression of Vitamin K requirements is not feasible 9. The adult human requirement for Vitamin K is extremely low, and a dietary deficiency is rare in the absence of complicating factors DEFICIENCY 5. 6. All animals Impairment of blood coagulation Clinical signs include low prothrombin levels, increased clotting time, and hemorrhaging Ruminants Deficiency is seen only in the presence of a metabolic antagonist, such as dicumarol from moldy sweet clover 1) 2) 3) 7. Swine Deficiency was produced by using a sulfa drug and an antibiotic, and minimizing coprophagy In late 1960’s and early 1970’s there were numerous reports of bleeding disease of young pigs on commercial diets 1) 8. Condition is referred to as “hemorrhagic sweet clover disease” Responsible for large animal losses Dicumarol passes through the placenta and newborn animals may become affected immediately after birth This was overcome by Vitamin K medication Poultry Very young chicks are readily affected Carryover from the parent hen to the chick has been demonstrated Borderline deficiencies of Vitamin K often cause small hemorrhagic blemishes on the breast, legs, wings, abdominal cavity, and intestine Chicks show an anemia in part from blood loss, but also due to the development of a hypoplastic bone marrow VITAMIN C 1. Scurvy, a potentially fatal condition resulting from inadequate Vitamin C (ascorbic acid), has been known and feared since ancient times 2. The prevention and cure of scurvy is associated with consumption of fresh fruits (especially citrus) 3. Vitamin C is synthesized by most species, exceptions being the primate (including humans), guinea pigs, fish, fruit eating bats, insects, and some birds 4. Animals that cannot synthesize this vitamin need a dietary source for their normal maintenance 5. The concept that the sole function of Vitamin C is to prevent scurvy has been revised in recent years Small quantities prevent scurvy; however, larger quantities may be needed to maintain good health during 1) Adverse environment 2) Physiological stress 3) Certain disease conditions CHEMICAL STRUCTURE and PROPERTIES 1. Vitamin C occurs in two forms 2. Reduced ascorbic acid Oxidized dehydroascorbic acid Only the L isomer of ascorbic acid has activity In foods the reduced form of Vitamin C may oxidize to the dehydro form which may further oxidize to an inactive form called diketogulonic acid This takes place readily and is accelerated by heat and light Ascorbic acid is so readily oxidized to dehydroascorbic acid that other compounds may be protected against oxidation Vitamin C is used in canning of certain fruits to prevent oxidation changes that cause darkening 3. Vitamin C is the least stable, and therefore most easily destroyed, of all vitamins 4. Reversible oxidation-reduction of ascorbic acid and dehydroascorbic acid is the most important chemical property of Vitamin C and is the basis for its physiological activities ANALYTICAL PROCEDURES 1. Analysis of Vitamin C include biological, chemical, and physical methods Biological test measures total amount of Vitamin C present in both forms 1) Guinea pigs are often used Chemical and physical methods require precautions to prevent oxidation 1) Homogenize under N2 and avoid copper and other metallic ions 2) 7. Dye methods are widely used Both gas-liquid chromatographic (GLC) and high-pressure liquid chromatographic (HPLC) methods have been developed for L- ascorbic acid determination METABOLISM 1. Vitamin C is absorbed similar to carbohydrates (monosaccharides) Intestinal absorption requires Na+- dependent active transport 2. Vitamin C is readily absorbed when quantities ingested are small, but limited intestinal absorption occurs when excess amounts are ingested 3. Absorbed Vitamin C readily equilibrates with the body pool of the vitamin 4. No specific binding proteins for Vitamin C have been reported Vitamin C may be retained by binding to subcellular structures 5. Highest levels of Vitamin C are found in the pituitary and adrenal glands, with high concentrations also in the liver, spleen, brain, and pancreas 6. Vitamin C tends to localize around healing wounds 7. Vitamin C is excreted in urine and sweat, with minimal losses in feces FUNCTIONS 1. The function of Vitamin C is related to its reversible oxidation and reduction characteristics 2. The exact role of this Vitamin in animals is not clearly known since a coenzyme form has not been reported 3. The most clearly established functional role for Vitamin C involves collagen biosynthesis Impairment of collagen synthesis in Vitamin C deficiency appears to be due to lowered ability to hydroxylate lysine and proline Proline is needed to form a stable extracellular matrix Lysine is needed for formation of cross-links in the fibers REQUIREMENTS 1. A wide variety of plant and animal species can synthesize Vitamin C from glucose and galactose 2. Species that cannot synthesize Vitamin C lack the enzyme L-gulonolactone DEFICIENCY 1. Under practical feeding situations only humans, nonhuman primates, guinea pigs, and fish will develop Vitamin C deficiency 2. Farm animals synthesize Vitamin C from glucose in the liver or kidney 3. Ruminants Synthesize Vitamin C; however, clinical cases of scurvy have developed Vitamin C stores are reduced in cold stress situations More prone to deficiency than non-ruminants because dietary sources are rapidly destroyed by ruminal microflora Low Vitamin C levels may occur in winter and spring and tends to reduce general resistance of the animal causing 1) 2) 3) 4) 4. Swine Infertility Retained placenta Low viability of progeny And other economic losses 5. Generally, Vitamin C is not formulated into diets (inconsistent data base showing need) If the need for Vitamin C exists in swine, the newly weaned pig would most likely be deficient first Poultry Like swine, poultry do not normally need Vitamin C supplementation However, the newly hatched chick may deficient because of 1) 2) 6. Slow rate of synthesis Stress Humans Deficiency causes scurvy, a disease characterized by multiple hemorrhages Scurvy is preceded by 1) Lassitude 2) Fatigue 3) Anorexia 4) Muscular pain 5) General susceptibility to infection and stress ANSC 5308 VITAMIN NUTRITION SECTION LECTURE 6 ANTIOXIDANT VITAMINS 17. Vitamin E, Vitamin C and beta carotene (pro-vitamin A) are antioxidants An antioxidant has the ability to stabilize highly reactive, potentially harmful molecules called free radicals 18. Free radicals are generated during: Cellular metabolism Exposure to ingested or inhaled environmental pollutants Metabolism of certain drugs 19. The generation of free radicals has been associated with damage to membranes, enzymes, and the cell’s nuclear material 20. The antioxidant’s ability to destroy these highly reactive free radicals serves to protect the structural integrity of cells and prevents the depletion of required nutrients or matabolites REFERENCES (ANTIOXIDANT VITAMINS) 11. The role of vitamins on animal performance and immune response. Symp. Proc. Hoffman-LaRoche Inc., Nutley, NJ, March 11, 1987. 12. Halliwell, B., and J.M.C. Gutteridge. 1985. Free radicals and toxicology. In: Free Radicals in Biology and Medicine. Basel:Karger, pp. 360-370. 13. Pryor, W.A. 1976. The role of free radical reactions in biological systems. In: Free Radicals in Biology. London:Acad. Press, pp. 1-49. WATER SOLUBLE VITAMINS 8. Main cellular roles of B vitamins involved in metabolism of carbohydrates, proteins and fats 9. Metabolism of glucose and pyruvic acid Metabolism of amino acids Metabolism of free fatty acids Production of acetyl co-enzyme A Production of ATP B vitamins are usually readily absorbed and excesses are excreted on a daily basis Thus, needs must be met on a daily basis from dietary sources in non-ruminants, and from a combination of dietary sources and microbial synthesis in ruminants and horses ANSC 5308 VITAMIN NUTRITION SECTION LECTURE 7 THIAMIN 21. Thiamin also called: thiamine, aneurin(e), and Vitamin B1. First water-soluble vitamin to be discovered 22. There is little chance of a thiamin deficiency for non-ruminant animals, including humans, when diets contain whole cereal grain or starch roots 23. Thiamin deficiency in humans has occurred mostly in Asian countries when highly milled (polished) rice is consumed 24. Intensification of ruminant feeding has resulted in nervous disorders that are responsive to thiamin supplementation High-concentrate diets Management system changes Increased levels of production 25. Thiamin deficiency disease beriberi is probably the earliest documented deficiency disorder in humans (2600 B.C.) 26. No cure of beriberi was found until the 1880’s, where the incidence of beriberi was 32% among sailors. CHEMICAL STRUCTURE AND PROPERTIES 14. Thiamin consists of molecule of pyrimidine and a molecule of thiazole linked by a methylene bridge Contains nitrogen and sulfur Isolated in pure form as thiamin hydrochloride Sulfurous odor and bitter taste Soluble in water, and insoluble in fat solvents Very sensitive to alkali 1) Thiazole ring opens at room temperature with pH above 7 In dry state, thiamin is stable at 100°C for several hours Moisture greatly accelerates destruction and thus it is much less stable to heat in fresh foods than in dry foods 15. Anti-thiamin activity is fairly common and includes structurally similar antagonists (competitive inhibition) Pyrithiamine 1) Blocks the esterification with phosphoric acid 2) Inhibits thiamin coenzyme cocarboxylase Oxythiamine 1) Likewise displaces cocarboxylase Amprolium (coccidiostate) 1) Inhibits absorption of thiamin from the intestine 2) Also blocks the phosphorylation of thiamin 16. Thiaminase (enzyme) activity destroys thiamin activity by altering the structure of the vitamin “Chastek paralysis” in animals results from feeding raw fish that has a thiaminase that splits the thiamin molecule into two components Certain bacteria and molds also produce thiaminases Bracken fern poisoning in horses results from antagonism to thiamin ANALYTICAL PROCEDURES 10. Thiamin activity can be analyzed by biological, microbiological and chemical methods Biological – based on curative ability for polyneuritis in pigeons, bradycardia in rats, or growth in the chick, pigeon or rat. Microbiological – fairly rapid but some organisms lack specificity for thiamin Chemical – conducted by oxidation to thiochrome 1) Shows blue fluorescence in ultraviolet light 2) Widely used in foodstuffs and feeds METABOLISM 6. Readily digested and released from natural sources 7. Must have sufficient production of hydrochloric acid in the stomach for digestion 8. Phosphoric acid esters of thiamin are split in the intestine 9. Free thiamin is easily absorbed in the duodenum 10. Ruminants absorb free thiamin from the rumen But the rumen wall is not permeable for bound thiamin or thiamin contained in rumen microorganisms 11. Horses can absorb thiamin from the cecum 12. Absorption Both active transport and simple diffusion are involved in intestinal absorption 1) Active sodium-dependent transport occurs at low concentrations 2) Whereas, it diffuses passively at high concentrations Absorption from the rumen is believed to be an active mechanism Absorbed thiamin is transported via the portal vein to the liver with a carrier plasma protein 13. Phosphorylation Thaimin phosphorylation can take place in most tissues but particularly in the liver Phosphorylation occurs under the action of adenosine triphosphate (ATP) to form thiamin pyrophosphate (TPP) TPP is the metabolically active form of thiamin Total body thiamin 1) 80% - TPP 2) 3) 10% - thiamin triphosphate (TTP) Remainder is thiamin monophosphate (TMP) and free thiamin 14. Animals need a regular supply of thiamin and unneeded intakes are excreted The pig is somewhat of an exception and its tissues contain several times as much thiamin as other species studied 1) Can meet needs from body stores for up to two months 15. Excretion of absorbed thiamin is in both the urine and feces, and small amounts in sweat FUNCTIONS 11. Coenzyme A principal function in all cells is as the coenzyme cocarboxylase (TPP) In the Krebs cycle, energy production from carbohydrates, fats and proteins result in products that require further breakdown and thiamin is involved 1) Thiamin is the coenzyme for all enzymatic decarboxylations of -keto acids 2) Thus, it functions in the oxidative decarboxylation of pyruvate to acetate which combines with coenzyme A and enters the TCA cycle. Two essential oxidative decarboxylation reactions in mammals 1) Pyruvate acetyl-CoA + CO2 2) -Ketoglutaric acid succinyl-CoA + CO2 TTP is required for the synthesis of: 1) Ribose from glucose – needed for nucleotide formation 2) NADPH from carbohydrates – essential to form fatty acids 12. Neurophysiology Evidence shows a specific role of thiamin in neurophysiology that is independent of its coenzyme function Fatty acids and cholesterol are the major constituents of cell membranes 1) Thiamin deficiency in cultured glial cells impairs their ability to synthesize fatty acids and cholesterol 1) Their synthesis would affect membrane integrity and function The defect is related to reduced formation of key lipogenic enzymes Possible mechanisms of action of thiamin in nervous tissue include: 1) 2) Synthesis of acetylcholine which transmits neural signals Participation in the passive transport of sodium of excitable membranes 3) Reduction in activity of pentose phosphate pathway which reduces the synthesis of fatty acids and metabolism of energy REQUIREMENTS 10. Requirements in some species are difficult to establish Synthesis by microflora in ruminants Synthesis too far down the intestinal tract in non-ruminants for absorption In horses only about 25% of free thiamin is absorbed from the cecum In humans and most species other than ruminants and horses, thiamin synthesis and absorption makes little contribution to body needs In ruminants, total feed thiamin and ruminal synthesis must be considered together, and the total need is yet to be defined. DEFICIENCY 9. The classic diseases, beriberi in humans and polyneuritis in birds represent a late stage of the deficiency Results from peripheral neuritis, perhaps from accumulation of carbohydrate metabolism intermediates Brain covers its energy requirements from glucose degradation In addition to neurological disorders, the other main group of disorders involves cardiovascular damage. Clinical signs include: 1) 2) 3) Slow heart beat (bradycardia) Enlargement of the heart Edema Of all the nutrients, a deficiency of thiamin has the most marked effect on appetite 1) Must force-feed or inject thiamin to induce animals to resume eating 10. Ruminants Because of extensive ruminal thiamin synthesis, the general conclusion is that ruminants possessing a normally functioning rumen have no dietary requirement Young calves and lambs have been shown to suffer from thiamin deficiency Polioencephalmalacia (PEM), a thiamin responsive disease, occurs sporadically in cattle, sheep, and goats 1) The incidence of PEM is reported to be between 1 and 10% and mortality may reach 100% 2) Biochemical changes in animals include reduced tissue thiamin, dramatic elevation in blood pyruvate, and lactate, and markedly reduced transketolase activity 11. Swine – Clinical signs of deficiency Reduced feed intake Vomiting Sharp reduction in weight gains 12. Poultry Most susceptible to neuromuscular effects of thiamin deficiency Clinical signs 1) 2) 3) 4) Loss of appetite Emaciation Frequent convulsions Other 13. Horses – Clinical signs Reproductive failure in both sexes Anorexia Incoordination of hind legs Other 14. Humans Beriberi, a state in which both cardiac and nervous functions are disturbed 1) Wet form – characterized by edema 2) Dry form – characterized by peripheral neuritis, paralysis, and muscular dystrophy RIBOFLAVIN 6. After the isolation of thiamin as the “Vitamin B” factor, riboflavin was the first growth factor to be characterized from the remaining B-complex vitamins 7. Riboflavin functions as a coenzyme in diverse enzymatic reactions as Flavin mononucleotide (FMN) Flavin adenine dinucleotide (FAD) 8. Riboflavin is required in metabolism of all plants and animals, and every plant and animal cell contains the vitamin 9. Adult ruminants do not require riboflavin. However, young ruminants require dietary sources 10. One of the vitamins most likely to be deficient in typical swine and poultry diets 11. Likewise, human diets low in milk and eggs and leafy vegetables are likely to be deficient in riboflavin CHEMICAL STRUCTURE and PROPERTIES 5. Riboflavin consists of a dimethylisoalloxazine nucleus combined with the alcohol of ribose as a side chain 6. Riboflavin exists in three forms: Free riboflavin Flavin mononucleotide (FMN) Flavin adenine dinucleotide (FAD) 7. Riboflavin is an odorless, bitter, orange-yellow compound that melts at 280°C 8. It is only slightly soluble in water but readily soluble in dilute basic or strong acidic conditions 9. When dry it is not affected appreciably by light, but in solution it is quickly destroyed Pasteurization of milk and exposure to light – 10 to 20% loss Bottled milk in bright sunlight for 2 hours – 50 to 70% loss FUNCTIONS 4. Essential to the utilization of carbohydrates, protein and fat 5. FMN and FAD combine with specific proteins to form active enzymes called flavoproteins Most flavoproteins contain FAD, and a few contain FMN Riboflavin in these coenzyme forms acts as an intermediary in the transfer of electrons in biological oxidation-reduction reactions The enzymes that function aerobically are called oxidases, and those that function anaerobically are called dehydrogenases Flavoproteins function by accepting and passing on hydrogen, undergoing alternate oxidation and reduction 6. Although riboflavin is present mostly as flavoprotein enzymes FAD and FMN, the retina of the eye contains free riboflavin in relatively large amounts. REQUIREMENTS 3. Riboflavin requirements decline with animal maturity and increase for reproductive activity 4. Microbial biosynthesis occurs in ruminants and thus affects requirements 5. The utilization of riboflavin depends on diet composition Slowly digested carbohydrates such as starch, cellulose or lactose increase synthesis Dextrose, fat and protein decrease intestinal production and increase dietary requirements DEFICIENCY 4. Animals and humans are unable to synthesize riboflavin within tissues, thus needs are met by dietary sources with some intestinal microbial synthesis 5. A decreased rate of growth and poorer feed efficiency are common signs in all species affected 6. Ruminants 4. Not a problem because ruminal microorganisms synthesize it in adequate amounts Swine – clinical signs of deficiency Impaired reproduction Anorexia Slow growth Light sensitivity Other 5. Poultry Curled-toe paralysis Retarded growth High mortality 10. Horses Generally felt that riboflavin synthesis in the cecum and colon provides some of the horse’s requirement Horses fed low-riboflavin diets have demonstrated anorexia, severe weight loss, general weakness and poor growth 11. Humans Clinically, riboflavin deficiency is usually observed in conjunction with deficiencies of other B vitamins Clinical features include dermatitis around the nose and mouth, soreness and burning of the mouth and tongue, glossitis (flattening followed by disappearance of the papilla of the tongue) ANSC 5308 VITAMIN NUTRITION SECTION LECTURE 8 NIACIN 27. Niacin exerts its major effects through its role in the enzyme system for cell respiration 28. Niacin deficiency results in the disease pellagra in humans, and black tongue in dogs 29. The requirement for niacin in non-ruminants has been established, however exact requirements are difficult to determine since it can be synthesized from the amino acid tryptophan 30. Supplemental niacin may provide substantial benefits under some feeding systems, even though it has been accepted that there is no dietary requirement in ruminants for B vitamins including niacin CHEMICAL STRUCTURE AND PROPERTIES 17. Chemically, niacin is one of the simplest vitamins 18. Nicotinic acid and nicotinamide correspond to 3-pyridine carboxylic acid and its amide, respectively 19. The term niacin is used as a generic descriptor of pyridine 3-carboxylic acid and derivatives exhibiting the same qualitative biological activity of nicotinamide 20. Nicotinic acid and nicotinamide (niacinamide) possess the same vitamin activity, the free form is converted to the amide in the body 21. Nicotinamide functions as a component of two coenzymes Nicotinamide adenine dinucleotide (NAD, formerly called DPN) Nicotinamide adenine dinucleotide phosphate (NADP, formerly called TPN) ANALYTICAL PROCEDURES 11. Microbiological determination is the most sensitive and is the preferred method Lactobacillus plantarum responds to both forms of the vitamin Whereas, leuconostoc mesenteroides measures only nicotinic acid METABOLISM 16. Effectively absorbed by diffusion at either low or high doses 17. By employing the gastrointestinal tube technique, niacin was shown to be equally absorbed from both the stomach and the upper small intestine in humans 18. Blood transport of niacin is associated mainly with the red blood cells 19. Niacin rapidly leaves the bloodstream and enters kidney, liver, and adipose tissues 20. Although niacin coenzymes are widely distributed in the body, no true storage occurs TRYPTOPHAN-NIACIN CONVERSION 1. 2. The amino acid tryptophan is a precursor for the synthesis of niacin Synthesis in the body, and evidence that synthesis takes place in the intestine Synthesis occurs in the developing chick embryo Metabolic requirement for niacin can be met from tryptophan in the diet if: 3. Sufficient quantity of tryptophan Efficient conversion of tryptophan Protein, energy, riboflavin and Vitamin B6 nutritional status and hormones affect conversion of tryptophan to niacin 4. It is suggested that pellagra is not simply a disease of niacin deficiency but a disease of tryptophan metabolism 5. Factors that affect efficiency of conversion Levels of tryptophan intake, low levels – high conversion Energy restriction, high conversion Pregnacy in women, increses conversion Amino acid imbalance due to excess leucine Animal species 1) Humans: 60 mg of tryptophan for 1 mg of niacin synthesis 2) Rats: 35 – 50 mg of tryptophan for 1 mg of niacin synthesis 3) Cats: no conversion 4) Ducks: no conversion Picolinic acid carboylase in livers of various species has a very close inverse relationship to dietary niacin requirement 1) Cat and duck have so much of the enzyme that they cannot convert any dietary tryptophan to niacin (excess tryptophan is catabolized to carbon dioxide and water) FUNCTIONS 13. The major function of niacin is in the coenzyme forms of nicotinamide, NAD and NADP 14. Enzyme containing NAD and NADP are important links in a series of reactions associated with carbohydrate, protein and lipid metabolism, especially energy metabolism 15. More than 40 biochemical reactions have been identified that have paramount importance, particularly for the: Skin Gastrointestinal tract Nervous system 16. NAD and NADP – containing enzymes play key roles in oxidation-reduction reactions by serving as hydrogen transfer agents in conjunction with a second hydrogen-carrying system, the riboflavin coenzymes The transfer of hydrogen is reversible and sterospecific NADP has an important role in the synthesis of fats and steroids Both NAD and NADP are involved in degradation and synthesis of amino acids REQUIREMENTS 11. There is a wide variation in niacin requirements generally due to the conversion of tryptophan to niacin 2. Factors that influence niacin requirements Genetics – meatier, faster-growing animals Increased production levels Ability to synthesize niacin from tryptophan Stress and subclinical disease level Exposure to feces (coprophagy) Handling and processing of feeds Amino acid imbalances Earlier weaning Molds and antimetabolites in feeds DEFICIENCY 15. All animals A deficiency of niacin is characterized by severe metabolic disorders in the skin and digestive organs 1) First sign to appear are loss of appetite, retarded growth, weakness, digestive disorders, and diarrhea Three D’s: diarrhea, dermatitis, death 16. Ruminants Dietary requirement for niacin does not exist as long as the level of tryptophan is near 0.2% of the diet For calves, a diet free of niacin and low in tryptophan resulted in deficiency signs of: 1) 2) 3) 4) Sudden anorexia Severe diarrhea Dehydration Sudden death 17. Swine Niacin is expected to be deficient in typical swine diets, particularly when corn, which is low in available niacin and tryptophan is fed Wide variation has been observed 1) Occasionally animals appear to thrive with no niacin, and others appear to vary in their requirement Niacin deficient pigs have inflammatory lesions of the gastrointestinal tract 18. Poultry Deficiency results in black tongue, a condition characterized by inflammation of the tongue and mouth cavity Clinical signs include: 1) 2) 3) Bowing of the legs Poor feathering Dermatitis on the feet and head 19. Horses No requirements for niacin have been established for the horse and a deficiency has not been reported 20. Humans The similarity of niacin deficiency signs between the dog and humans has been important because the dog is the laboratory animal to identify niacin deficiency Traditionally niacin deficiency in humans has been equated with pellagra 3) Skin changes 4) Lesions of the mucous membranes of the mouth, tongue, stomach, and intestinal tract 5) Changes in nervous origin Earliest symptoms of pellagra is inflammation and soreness of the mouth followed by bilateral symmetrical erythema on all parts of the body exposed to sunlight 1) Common sites are surfaces of the extremities, face and neck 2) Lesions are also found at sites of constant irritation such as under the breast, scrotum, axilla, and perineum 3) Tongue is swollen and beefy red ANSC 5308 VITAMIN NUTRITION SECTION LECTURE 9 VITAMIN B6 31. Vitamin B6 refers to a group of three compounds: Pyridoxol (Pyridoxine) Pyridoxal Pyridoxamine Their activity is equivalent in animals but not in various microorganisms 32. Vitamin B6 is involved in many enzymes during metabolism of proteins, fats, and carbohydrates. The vitamin is particularly involved in various aspects of protein metabolism. 33. It is generally considered that common feed ingredients for poultry and swine diets contain adequate amounts of Vitamin B6 34. There is evidence of low Vitamin B6 status in the human population, especially for young and pregnant, or lactating women CHEMICAL STRUCTURE AND PROPERTIES 22. Vitamin B6 is a relatively simple compound with three substituted pyridine derivatives that differ only in the functional group in the 4-position Alcohol (pyridoxine or pyridoxal) Aldehyde (pyridoxal Amine (pyridoxamine) 23. Pyridoxine is the predominant form in plants, whereas pyridoxal and pyridoxamine are generally found in animal products 24. Two additional Vitamin B6 forms found in foods are the coenzyme forms of pyridoxal phosphate (PLP) and pyridoxamine phosphate 25. Metabolically active Vitamin B6 is mainly as PLP and to a lesser degree pyridoxamine phosphate 26. Exposure to light, especially in neutral or alkaline media, is highly destructive 27. Forms of Vitamin B6 are colorless crystals soluble in water or alcohol, commercial preparation is the hydrochloride salt of the alcohol form, pyridoxine hydrochloride 28. Several Vitamin B6 antagonists exist Deoxypridoxine – used in experiments to accelerate deficiency Isonicontic acid hydrazide (isoniazid) – used in tuberculosis treatment 1) Used to clarify functions of enzymes dependent on PLP Thiosemicarbazide and hydralazine-antihypertensive drugs Penicillamine – used to remove body copper in copper poisoning and Wilson’s disease L-Dopa – antiparkinson drug Oral contraceptives Hydrazic acid – present in linseed oil meal from flax METABOLISM 21. Vitamin B6 forms are bound to feed proteins and must be split off through digestive processes for absorption to occur 22. Vitamin B6 compounds are first dephosphorylated in the small intestine and then absorbed 23. After absorption, B6 compounds rapidly appear in the liver, where they are mostly converted into pyridoxal phosphate 24. Both niacin (as an NADP-dependent enzyme) and riboflavin (as the flavoprotein pyridoxamine phosphate oxidase) are important for conversion of Vitamin B6 forms and phosphorylation reactions FUNCTIONS 17. Vitamin B6 in the form of PLP plays on essential role in the interaction of amino acid, carbohydrate, and fatty acid metabolism, and the energy producing citric acid cycle 18. Over 50 enzymes are already known to depend on Vitamin B6 coenzymes 19. Pyridoxal phosphate is involved in amino acid metabolism through: Transamination Decarboxylation Deamination Desulfhydration Clevage or synthesis of amino acids 20. Some other important reactions that Vitamin B6 is involved in include: Synthesis of niacin from tryptophan Conversion of linolenic to arachidonic acid (this function is controversial) Glycogen breakdown to glucose 1-phosphate Synthesis of epinephrine and norepinephrine Incorporation of iron in hemoglobin synthesis Synthesis of globulins, which carry antibodies REQUIREMENTS 12. Because of microbial synthesis, ruminants have no dietary requirement, with the exception of young animals that don’t have a fully developed rumen 13. The horse has considerable synthesis in the large intestine (cecum) but adequate absorption is controversial 14. Breed of animal and environmental temperature influence Vitamin B6 requirements Breed differences – chick research Temperature differences – rat research 15. Quantity of dietary protein affects requirement for B6 in both animals and humans Increased on high protein diets DEFICIENCY 21. Characteristics of Vitamin B6 deficiency are retarded growth, dermatitis, epileptic-like convulsions, anemia, and a partial alopecia 22. Because of the predominant function of Vitamin B6 in protein metabolism, the following may result: Fall in nitrogen retention Feed protein is not well utilized Nitrogen excretion is excessive Impaired tryptophan metabolism 23. Ruminants 4. No deficiency signs have yet been observed in mature ruminants Essential for young calves when selected experimental diets are used Swine – clinical signs of deficiency Poor appetite Microcytic hypochromic anemia Epileptic-like fits or convulsions Other 16. Poultry – clinical signs of deficiency Poor appetite and grow slowly Squat with wings slightly spread and head resting on the ground Abnormally excitable 17. Horses – no deficiency has been reported Some researchers believe that racehorses need Vitamin B6 supplementation 1) Intensive training 2) High proportion of protein in their diets 18. Humans High proportion of the human population receives inadequate dietary Vitamin B6, particularly young and pregnant, or lactating women Clinical signs of deficiency include 6) Hypochromic microcytic anemia 7) Loss of weight 8) Vomiting 9) Hyperirritability 10) Other PANTOTHENIC ACID 1. Pantothenic acid is found in two enzymes, coenzyme A and acyl carrier protein which are involved in many reactions in carbohydrate, fat, and protein metabolism 2. Although this vitamin occurs in practically all feedstuffs, the quantity present is generally insufficient for optimum performance of poultry and swine and other nonruminant species 3. There are no reports of deficiency in adult ruminants because of microbial synthesis 4. Pantothenic acid deficiency occurs rarely in humans CHEMICAL STRUCTURE AND PROPERTIES 1. Pantothenic acid is an amide consisting of pantoic acid joined to -alanine 2. The free acid of the vitamin is a viscous, pale yellow oil readily soluble in water and ethyl acetate The oil is extremely hygroscopic and is easily destroyed by acids, bases, and heat 3. Maximum heat stability occurs at pH 5.5-7.0 4. Calcium pantothenate is the pure form of the vitamin used in commerce 5. Pantothenic acid is optically active, and only the dextrorotatory form d-pantothenic acid is effective as a vitamin METABOLISM 1. Pantothenic acid is found in feeds in both bound (largely as coenzyme A) and free forms 2. Pantothenic acid is absorbed from the intestinal tract, probably by diffusion Little information is available on digestion, absorption, and transport of the vitamin 3. Within tissues pantothenic acid is converted to coenzyme A FUNCTIONS 1. The most important function of coenzyme A is to act as a carrier mechanism for carboxylic acids 2. Such acids when bound to coenzyme A have a high potential for transfer to other groups and are referred to as active The most important of the reactions is the combination of coenzyme A with acetate to form active acetate 1) It is used directly by combining with oxaloacetic acid to form citric acid, which enters the Krebs citric acid cycle 2) This enables two-carbon fragments from fats, carbohydrates, and certain amino acids to form acetyl coenzyme A and enter the citric acid cycle Coenzyme A also functions as a carrier of acyl groups in enzymatic reactions involved in synthesis of fatty acids, cholesterol, and sterols 3. In the form of active acetate, acetic acid can also combine with choline to form acetylcholine 4. Coenzyme A has an essential function in lipid metabolism Fatty acids are activated by formation of the coenzyme A derivative Degradation by removal of acetate fragments in beta oxidation 1) 5. These fragments may directly enter the citric acid cycle or combine to form ketone bodies When pantothenic acid is deficient, the incorporation of amino acids into the blood albumin fractions is inhibited, and there is a reduction in the titer of antibodies REQUIREMENTS 1. When energy density of diets is increased, intake is reduced so that higher dietary concentrations of pantothenic acid and other vitamins are required 2. 3. 4. Increasing energy in diets for broilers from 2870 to 3505 kcal/kg resulted in a 19.1% decrease in pantothenic acid Antibiotics have a sparing effect on the pantothenic acid requirement Aureomycin – weanling pigs Penicillin – turkey poults In ruminants, synthesis by ruminal microflora is: Reduced by diets high in cellulose Increased by diets high in easily soluble carbohydrates There are interrelationships with other vitamins on pantothenic acid requirements Vitamin B12 – sparing effect Vitamin C – sparing effect Biotin – related to utilization DEFICIENCY 1. 2. All animals Clinical signs take many forms and differ from one animal species to another Deficiency does occur under certain feeding programs for animals, however, clear cut deficiency symptoms in humans are rarely found in practice Ruminants Not required in the diet of adult ruminants Deficiency in the calf results in scaly dermatitis around the eyes and muzzle 3. 4. Swine Many swine diets are borderline in supplying pantothenic acid and many are deficient in the vitamin A characteristic sign of deficiency is a locomotor disorder in the hindquarters termed goose stepping Insufficient quantities pantothenic acid may result in complete reproductive failure in females 1) Sows become pregnant but do not farrow or show signs of pregnancy 2) Macerating feti in the uterine horns in all cases Poultry Reduced egg production Reduced hatchability In young chicks a deficiency of pantothenic acid is difficult to differentiate from a biotin deficiency – both cause severe dermatitis 5. Horses – no deficiency has been reported 6. Humans Deficiency does not occur under natural conditions except when associated with severe malnutrition Deficiency results in burning feet syndrome ANSC 5308 VITAMIN NUTRITION SECTION LECTURE 10 BIOTIN 35. For many years it was believed that supplemental biotin was not required in swine and poultry diets because of wide distribution in feedstuffs and synthesis by intestinal microflora However, in the mid 1970’s, field cases of deficiency were found under modern production systems On the basis of these findings nutritionists have had to reexamine the role of biotin 36. Humans and animals may become deficient after consumption of excessive quantities of raw eggs Raw eggs contain a biotin complexing factor (avidin) 37. Children may be biotin deficient due to inborn errors of metabolism Respond dramatically to high-level dietary supplementation CHEMICAL STRUCTURE AND PROPERTIES 29. Biotin has a sulfur atom in its ring (like thiamin) and a tranverse bond across the ring 30. Biotin has a rather unique structure with three asymmetric carbons and therefore eight different isomers are possible Only one isomer has vitamin activity, d-biotin 31. Biotin crystallizes from water solution as long, white needles 32. It is soluble in dilute alkali and hot water. Its melting point is 232-233 C 5. Biotin is inactivated by: Rancid fats Choline Formaldehyde Nitrous acid Ultraviolet radiation 6. Oxidation converts biotin to sulfoxide or sulfone 7. Strong agents result in sulfur replacement by oxygen to produce oxybiotin METABOLISM 25. Biotin exists in natural feedstuffs in both bound and free forms Bound form is about one-half biologically available Biotin is often bound to lysine in protein of animal tissues and plant seeds Free biotin occurs in fruit, milk, and vegetables 26. Biotin is absorbed as the intact molecule in the first half of the small intestine 27. Limited information is available on biotin transport, tissue deposition, and storage in animals and humans 28. Biotin is transported as a free water-soluble component of plasma, is taken up by cells via active transport, and is attached to its apoenzymes 29. All animal cells contain some biotin, with larger quantities in liver and kidneys Intracellular distribution is associated with biotin-dependent enzymes (carboxylases) 30. Biotin excretion in urine and feces together often exceeds total intake Biotin producing microorganisms in intestinal tract FUNCTIONS 21. Biotin is an essential coenzyme in carbohydrate, fat, and protein metabolism Conversion of carbohydrate to protein and vice versa Maintaining normal blood glucose levels when carbohydrate intake is low Transports carboxyl units Fixes carbon dioxide (as bicarbonate) in tissue Serves as a prosthetic group in enzymes 1) Linked covalently to -amino group of a lysyl residue of the biotin-dependent enzyme 22. Specific biotin-dependent reactions in carbohydrate metabolism Carboxylation of pyruvic acid to oxalascetic acid Conversion of malic acid to pyruvic acid Interconversion of succinic acid and propionic acid Conversion of oxalocuccinic acid to -kelogultaric acid 23. Role of biotin in protein metabolism Transcarboxylation in degradation of various amino acids Deficiency of biotin hinders the conversion of deaminated leucine to oxaloacetate Synthesis of citrulline from ornithine 24. Role of biotin in fat metabolism Catalyzes the addition of CO2 to acetyl-CoA to form malonyl-CoA 1) This is the first step in the synthesis of fatty acids Deficiency in rats inhibits arachidonic acid synthesis from linoleic acid REQUIREMENTS 19. Microorganisms contribute to the animal and human requirements Supply provided may be variable and undependable 20. In poultry, it has been shown that polyunsaturated fats, Vitamin C, and other B vitamins may influence the demand for biotin 21. Biotin is rapidly destroyed as feeds become rancid Pure biotin is inactivated by 96% in presence of linoleic acid In presence of Vitamin E, biotin destruction was only 40% DEFICIENCY 24. Most dramatic clinical sign of biotin deficiency is severe dermatitis 25. Biotin is also important for normal function of the thyroid and adrenal glands, the reproductive tract, and the nervous system 26. Ruminants No evidence for a biotin deficiency has been produced in animals with functional rumens In calves, hindquarters pralysis has been reported in calves 27. Swine – clinical signs of deficiency Alopecia (hair loss) Dermatitis Transverse cracking of the hooves Other 28. Poultry – clinical signs of deficiency Reduced growth rate and poorer feed efficiency Disturbed and broken feathering Dermatitis Leg and beak deformities 29. Horses Biotin is synthesized in the lower digestive tract of horses Hoof integrity for a number of cases has been reported to improve as a result of biotin supplementation 30. Humans Except in infants, there is no evidence of biotin deficiency in humans Intake through foods is good due to the ubiquitous nature of the vitamin and benefits from microbial synthesis FOLACIN 1. Folacin is a general term used to describe folic acid and related compounds that exhibit the biological activity of folic acid 2. High incidence of deficiency in pregnant women Affects 1/3 of all pregnant women in the world (both in developed and undeveloped countries) Causes megaloblastic anemia 3. 1) Large red blood cells that are poor in carrying oxygen 2) Associated with poor diet selection Common in women 16 to 40 years old In animals, folacin needs are met mostly by dietary sources and intestinal bacterial sysnthesis However, it is a feed additive of general use in poultry diets Being reevaluated for supplementation of young swine CHEMICAL STRUCTURE AND PROPERTIES 1. Pure folic acid is pteroylmono-glutamic acid Consists of glutamic acid, p-aminobenzoic acid (PABA), and a pteridine nucleus 2. PABA portion of folic acid was once thought to be a vitamin 3. If folacin requirement is met, there is no need to add PABA to the diet 4. Folacin in natural feedstuffs is conjugated with varying numbers of extra glutamic acid molecules Generally 1 to 9 glutamates long Poly glutamate forms (usually 3 to 7 glutamyl residues) are natural coenzymes abundant in every tissue 5. Synthetic folacin (folic acid) is in the monoglutamate form 6. There are more biologically active forms of folacin than any other vitamin About 100 different compounds No. 5 and 10 nitrogens are associated with a formyl or methyl group 7. Easily degraded by light and ultraviolet radiation 8. A wide variety of folacin analogs have been prepared, principally for anticancer and antimicrobial therapy METABOLISM 1. The enzyme for hydrolysis of pteroylpolyglutamate is -carboxypeptidase known as folate conjugase 2. The sequence of intestinal absorption of conjugated folate is mucosal or luminal uptake followed by hydrolysis to simple folate 3. Conjugase activity is inhibited by low pH Orange juice (citric acid) Drugs 4. Zinc Transport is significantly decreased when folacin is present in intestinal lumen and folacin transport is likewise decreased with the presence of zinc 5. Specific folate-binding proteins (FBPs) exist in many tissues and body fluids and affect bioavilability Serum Milk Leukemic granulocytes Other FUNCTIONS 1. Folacin is indispensable in the transfer of single-carbon units in various reactions A role analogous to that of pantothenic acid in the transfer of two-carbon units One-carbon units of formyl, forminino, and methyl groups One-carbon units: 1) Bound to folacin by tetrahydrofolic acid (THF) 2) Generated mostly during amino acid metabolism 3) Used in interconversions of amino acids (serine and glycine) 4) Used in purine and pyrimidine synthesis (cell division) 2. In folacin deficiency, histidine cannot be completely transformed to glutamate and a hydrofolic acid resulting in an intermediate (formiminoglutamic acid) being excreted in the urine 3. 4. Used for diagnosis of early deficiency Relationship of folacin and Vitamin B12 Vitamin B12 regulates the methyl trap theory Vitamin B12 deficiency decreases the formation of methionine from homocysteine and methyl-THF Folacin is needed to maintain the immune system Probably mediated through a reduction in DNA synthesis, resulting in impaired nuclear division REQUIREMENTS 1. Species differ markedly in their requirements 2. Poultry and humans (and other primates) develop deficiencies on low dietary folacin 3. Self-synthesis is dependent on dietary composition 4. Higher needs for high protein diets Higher needs when simple sugars are high in the diet Dietary fiber sources (xylan, wheat bran and beans) stimulate folacin synthesis Sulfa drugs in diets increase requirements Aflatoxins (moldy feed) inhibit microial intestinal synthesis The more rapid the growth or production rates, the greater is the need for folacin because of its role in DNA synthesis DEFICIENCY 1. Folacin deficiency has occurred in many animals species, with megalogblastic anemia and leukopenia (reduced number of white cells) being constant findings 2. In some animals (chick, guinea pig, and monkey) deficiency can be readily induced by low folacin diets 3. In other animals (dog, rat and pig) intestinal microflora meet requirements 4. Ruminants 5. Swine 6. Synthesis occurs in the rumen Until recently, deficiency occurred only when sulfa drugs were fed Poultry – clinical signs of deficiency 7. Poor feather development (folacin and lysine are required for feather pigmentation) Decreased egg production Horses Synthesis occurs in intestinal tract Deficiency has been reported in a diet lacking fresh grass for months 8. Humans Probably the most common vitamin deficiency in the world Adolescent girls have a greater nutritional requirement in relation to body size that adult women In older people, utilization of polyglutamate forms is lower compared to younger people Clinical signs include: 1) 2) 3) 4) 5) Pallor Weakness Forgetfulness Sleeplessness Bouts of euphoria Often associated with chronic alcoholism ANSC 5308 VITAMIN NUTRITION SECTION LECTURE 11 VITAMIN B12 38. Vitamin B12 was the last vitamin discovered (1948) and the most potent of the vitamins. 39. It is synthesized in nature only by microorganisms 40. Non-ruminant animals and humans that eat only plant foods are susceptible to Vitamin B12 deficiency 41. Discovery of this vitamin was dramatic and involved microbiologists, biochemists, nutrition scientists and physicians in various laboratories CHEMICAL STRUCTURE AND PROPERTIES 33. Vitamin B12 is a complex structure C63 H88 O14 N14 PCo. It is called cyanocobalamin It belongs to the corrinoid group of compounds that have a corrin nucleus However, numerous other corrinoids do not possess Vitamin B12 activity The name cobalamin is used for compounds that have the cobalt atom in the center of the corrin nucleus Cyanide is attached to the cobalt atom and thus the name cyanocobalamin 34. The cyanide can be replaced by other groups and are referred to as “pseudo” Vitamin B12 complexes or B12 – like factors OH (hydroxycobalamin) H20 (aquacobalamin) NO2 (nitrocobalamin) CH3 (methylcobalamin) 35. Vitamin B12 is a dark-red, hygroscopic substance, freely soluble in water and alcohol 36. It is the heaviest of all vitamins with a molecular weight of 1354 METABOLISM 31. Vitamin B12 in the diet is bound to food particles which are released by the combined effort of low pH and peptic digestion The released B12 is then bound to a nonintrinsic factor – cobalamin complex 32. The B12 remains bound to nonintrinsic protein until pancreatic proteases (i.e. trypsin) partially degrade the nonintrinsic factor protein and thus enables B12 to become bound exclusively to an intrinsic factor Patients with pancreatic insufficiency absorb B12 poorly Malabsorption is completely corrected by pancreatic enzymes or purified trypsin 33. Intrinsic factor is a glycoprotein (nucoprotein) synthesized by the parietal cells of the gastric mucosa Intrinsic factor concentrates from one animal do not always increase B12 absorption in other species Intrinsic factor has been identified in humans, monkey, cattle, swine, rat, rabbit, hamster, fox, lion, tiger and leopard Intrinsic factor has not yet been detected in dog, horse, sheep, chicken, guinea pig, and a number of other species 34. About 3% of ingested cobalt is converted to Vitamin B12 in the rumen. Only 1 –3% of Vitamin B12 produced in the rumen is absorbed. FUNCTIONS 25. Vitamin B12 is essential for reactions that involve transfer or synthesis of one-carbon units, such as methyl groups 26. A general function of B12 is to promote red blood cell synthesis and to maintain nervous system integrity 27. A deficiency of either folacin or B12 leads to impaired cell division and alterations of protein synthesis 28. A deficiency of B12 will induce a folacin deficiency by blocking utilization of folacin derivatives 29. Overall synthesis of protein is impaired in vitamin B12 deficient animals Affects methionine reformation from homocysteine Principal reason for the growth depression 30. Propionate metabolism Propionate is a three-carbon compound and must be converted to succinate to enter the TCA cycle 1) To add the one carbon unit requires methymalonyl-CoA isomerase (mutase) which is a B12 requiring enzyme 31. Another important function of Vitamin B12 is in maintaining glutathione and sulfhydryl groups of enzymes in the reduced state REQUIREMENTS 22. Excess protein increases the need for B12 as does performance levels 23. The B12 requirement seems to depend on the levels of choline, methionine and folacin in the diet and B12 is interrelated with Vitamin C metabolism 24. A reciprocal relationship occurs between B12 and pantothenic acid in chick nutrition, with pantothenic acid sparing the B12 requirement 25. Dietary need depends on intestinal synthesis and tissue reserves at birth 26. Requirement for Vitamin B12 in ruminant diets is closely related with their requirement for cobalt Dietary requirement: 0.07 to 0.20 ppm 27. A ruminant may require more Vitamin B12 than a non-ruminant animal of comparable size Propionic acid utilization DEFICIENCY 31. The result of Vitamin B12 deficiency in humans is a megalablastic anemia (pernicious anemia) and neurological lesions 32. In animals, anemia is not characteristic of a Vitamin B12 shortage B12 functions as a growth factor and reduced growth is observed when deficient 33. Ruminants – clinical signs of deficiency Poor appetite and growth Muscular weakness Poor general condition 34. Swine – clinical signs of deficiency Poor appetite and growth Variable feed intake Dramatic growth decline 35. Poultry – clinical signs of deficiency Reduced body weight gain, feed intake and feed conversion Perosis may occur when diet lacks choline, methionine, or betaine Reduced hatchability 36. Horses Not required for mature horses 37. Humans Pernicious anemia and degenerative changes in the nervous system 1) Either B12 or folacin will cure the anemia 2) Only B12 will prevent degenerative changes in the nervous system 3) Results in stiffness of limbs, progressive paralysis, mental disorders, diarrhea, and finally death CHOLINE 4. Choline is tentatively classified as one of the B-complex vitamins 5. However, it does not entirely satisfy the strict definition of a vitamin 1) Can be synthesized in the liver 2) Is required in the body in greater amounts 3) Functions as a structural constituent rather than as a coenzyme 4) Also existence of choline in essential body constituents was recognized long before the first vitamin was discovered Regardless of classification, choline is an essential nutrient for all animals and a required dietary supplement for swine and poultry CHEMICAL STRUCTURE AND PROPERTIES 9. Choline is widely distributed in nature as free choline, acetylcholine, and more complex phospholipids It is an integral part of lecithins and thus occurs in all plant and animal cells FUNCTIONS 5. Metabolic essential for building and maintaining cell structure 6. Plays an essential role in fat metabolism in the liver 7. Essential for the formation of acetylcholine 8. Source of labile methyl groups REQUIREMENTS 5. Choline requirements are influenced by dietary methionine, betaine, myo-inositol, folacin, and Vitamin B12 6. Choline and methionine are the two principal methyl donors functioning in animal metabolism Provide biologically labile methyl groups that can be transferred within the body 1) Transmethylation occurs between choline and methionine through intermediates Methyl (from methionine) + ethanolamine choline Methy (from choline) + homocystome methionine DEFICIENCY 9. Common signs include poor growth, fatty livers, perosis, hemorrhagic tissue, and hypertension 10. Ruminants Choline under certain conditions of high-concentrate feeding (feedlot cattle) may be limiting in the diet Choline may increase milk fat percentage in dairy cows 11. Swine Fatty infiltration of the liver Spraddled hindleg in young pigs 1) 2) Suggests a strong genetic component Started to appear as swine producers began to decrease feed allowances given sows during gestation 12. Poultry Growth retardation and perosis result from choline deficiency in young poultry 13. Horses No deficiencies have been reported 14. Humans Dietary choline may arrest cirrhosis of the liver and reverse the fatty infiltration 1) Inconclusive Choline supplements may be useful in preventing age related memory deficits and certain neurological diseases ANSC 5308 VITAMIN NUTRITION SECTION LECTURE 11 VITAMIN B12 42. Vitamin B12 was the last vitamin discovered (1948) and the most potent of the vitamins. 43. It is synthesized in nature only by microorganisms 44. Non-ruminant animals and humans that eat only plant foods are susceptible to Vitamin B12 deficiency 45. Discovery of this vitamin was dramatic and involved microbiologists, biochemists, nutrition scientists and physicians in various laboratories CHEMICAL STRUCTURE AND PROPERTIES 37. Vitamin B12 is a complex structure C63 H88 O14 N14 PCo. It is called cyanocobalamin It belongs to the corrinoid group of compounds that have a corrin nucleus However, numerous other corrinoids do not possess Vitamin B12 activity The name cobalamin is used for compounds that have the cobalt atom in the center of the corrin nucleus Cyanide is attached to the cobalt atom and thus the name cyanocobalamin 38. The cyanide can be replaced by other groups and are referred to as “pseudo” Vitamin B12 complexes or B12 – like factors OH (hydroxycobalamin) H20 (aquacobalamin) NO2 (nitrocobalamin) CH3 (methylcobalamin) 39. Vitamin B12 is a dark-red, hygroscopic substance, freely soluble in water and alcohol 40. It is the heaviest of all vitamins with a molecular weight of 1354 METABOLISM 35. Vitamin B12 in the diet is bound to food particles which are released by the combined effort of low pH and peptic digestion The released B12 is then bound to a nonintrinsic factor – cobalamin complex 36. The B12 remains bound to nonintrinsic protein until pancreatic proteases (i.e. trypsin) partially degrade the nonintrinsic factor protein and thus enables B12 to become bound exclusively to an intrinsic factor Patients with pancreatic insufficiency absorb B12 poorly Malabsorption is completely corrected by pancreatic enzymes or purified trypsin 37. Intrinsic factor is a glycoprotein (nucoprotein) synthesized by the parietal cells of the gastric mucosa Intrinsic factor concentrates from one animal do not always increase B12 absorption in other species Intrinsic factor has been identified in humans, monkey, cattle, swine, rat, rabbit, hamster, fox, lion, tiger and leopard Intrinsic factor has not yet been detected in dog, horse, sheep, chicken, guinea pig, and a number of other species 38. About 3% of ingested cobalt is converted to Vitamin B12 in the rumen. Only 1 –3% of Vitamin B12 produced in the rumen is absorbed. FUNCTIONS 32. Vitamin B12 is essential for reactions that involve transfer or synthesis of one-carbon units, such as methyl groups 33. A general function of B12 is to promote red blood cell synthesis and to maintain nervous system integrity 34. A deficiency of either folacin or B12 leads to impaired cell division and alterations of protein synthesis 35. A deficiency of B12 will induce a folacin deficiency by blocking utilization of folacin derivatives 36. Overall synthesis of protein is impaired in vitamin B12 deficient animals Affects methionine reformation from homocysteine Principal reason for the growth depression 37. Propionate metabolism Propionate is a three-carbon compound and must be converted to succinate to enter the TCA cycle 1) To add the one carbon unit requires methymalonyl-CoA isomerase (mutase) which is a B12 requiring enzyme 38. Another important function of Vitamin B12 is in maintaining glutathione and sulfhydryl groups of enzymes in the reduced state REQUIREMENTS 28. Excess protein increases the need for B12 as does performance levels 29. The B12 requirement seems to depend on the levels of choline, methionine and folacin in the diet and B12 is interrelated with Vitamin C metabolism 30. A reciprocal relationship occurs between B12 and pantothenic acid in chick nutrition, with pantothenic acid sparing the B12 requirement 31. Dietary need depends on intestinal synthesis and tissue reserves at birth 32. Requirement for Vitamin B12 in ruminant diets is closely related with their requirement for cobalt Dietary requirement: 0.07 to 0.20 ppm 33. A ruminant may require more Vitamin B12 than a non-ruminant animal of comparable size Propionic acid utilization DEFICIENCY 38. The result of Vitamin B12 deficiency in humans is a megalablastic anemia (pernicious anemia) and neurological lesions 39. In animals, anemia is not characteristic of a Vitamin B12 shortage B12 functions as a growth factor and reduced growth is observed when deficient 40. Ruminants – clinical signs of deficiency Poor appetite and growth Muscular weakness Poor general condition 41. Swine – clinical signs of deficiency Poor appetite and growth Variable feed intake Dramatic growth decline 42. Poultry – clinical signs of deficiency Reduced body weight gain, feed intake and feed conversion Perosis may occur when diet lacks choline, methionine, or betaine Reduced hatchability 43. Horses Not required for mature horses 44. Humans Pernicious anemia and degenerative changes in the nervous system 4) Either B12 or folacin will cure the anemia 5) Only B12 will prevent degenerative changes in the nervous system 6) Results in stiffness of limbs, progressive paralysis, mental disorders, diarrhea, and finally death CHOLINE 6. Choline is tentatively classified as one of the B-complex vitamins 7. However, it does not entirely satisfy the strict definition of a vitamin 5) Can be synthesized in the liver 6) Is required in the body in greater amounts 7) Functions as a structural constituent rather than as a coenzyme 8) Also existence of choline in essential body constituents was recognized long before the first vitamin was discovered Regardless of classification, choline is an essential nutrient for all animals and a required dietary supplement for swine and poultry CHEMICAL STRUCTURE AND PROPERTIES 10. Choline is widely distributed in nature as free choline, acetylcholine, and more complex phospholipids 9. It is an integral part of lecithins and thus occurs in all plant and animal cells FUNCTIONS Metabolic essential for building and maintaining cell structure 10. Plays an essential role in fat metabolism in the liver 11. Essential for the formation of acetylcholine 12. Source of labile methyl groups REQUIREMENTS 7. Choline requirements are influenced by dietary methionine, betaine, myo-inositol, folacin, and Vitamin B12 8. Choline and methionine are the two principal methyl donors functioning in animal metabolism Provide biologically labile methyl groups that can be transferred within the body 2) Transmethylation occurs between choline and methionine through intermediates Methyl (from methionine) + ethanolamine choline Methy (from choline) + homocystome methionine DEFICIENCY 15. Common signs include poor growth, fatty livers, perosis, hemorrhagic tissue, and hypertension 16. Ruminants Choline under certain conditions of high-concentrate feeding (feedlot cattle) may be limiting in the diet Choline may increase milk fat percentage in dairy cows 17. Swine Fatty infiltration of the liver Spraddled hindleg in young pigs 3) 4) Suggests a strong genetic component Started to appear as swine producers began to decrease feed allowances given sows during gestation 18. Poultry Growth retardation and perosis result from choline deficiency in young poultry 19. Horses No deficiencies have been reported 20. Humans Dietary choline may arrest cirrhosis of the liver and reverse the fatty infiltration 1) Inconclusive Choline supplements may be useful in preventing age related memory deficits and certain neurological diseases
