ANSCI 102 Animal Nutrition Chapter 6 - Vitamins PDF

ANSCI 102 ANIMAL NUTRITION Celso S. Sto. Domingo, DVM Assistant Professor IV, College of Agriculture Bulacan Agricultural State College  Chapter 6. VITAMINS I. What are Vitamins? II. Functions III. Vitamin Classifications IV. Fat Soluble Vitamins V. Water Soluble Vitamins...

ANSCI 102 ANIMAL NUTRITION Celso S. Sto. Domingo, DVM Assistant Professor IV, College of Agriculture Bulacan Agricultural State College  Chapter 6. VITAMINS I. What are Vitamins? II. Functions III. Vitamin Classifications IV. Fat Soluble Vitamins V. Water Soluble Vitamins  What are Vitamins? Vitamins are a group of chemically unrelated organic molecules that are needed in minute amounts for different physiological functions. The name “vitamin” originated from the term vital amine and refers to a group of compounds having specific roles in metabolism.  What are Vitamins? Vitamins, although organic compounds, do not provide energy like other macronutrients and are not used for the synthesis of structural compounds. However, they function as enzyme precursors, or coenzymes, in different metabolic processes.  What are Vitamins? Most vitamins need to be provided to the animal through diet, while some of vitamins can be synthesized by the rumen and hindgut microbes or by exposure to sunlight. Deficiency of vitamins in a diet leads to disease conditions, reduced productivity and animal welfare, and reduced immunity in food producing animals.  Vitamin Classifications 1. Fat-soluble vitamins Vitamins A, D, E, K Associated with fat during digestion and absorption Storage in liver, adipose tissue, and excess storage can be toxic for some vitamins (e.g., A and D) No daily need Deficiency is very slow  Vitamin Classifications 2. Water-soluble vitamins Total nine, all B vitamins and vitamin C Soluble in water and excess excreted through urine No storage and less toxic Daily requirement (except vitamin B12) Serve as cofactor in biochemical reactions Deficiency is fast Mnemonic for Vitamin B Vitamins – The Romans Never Painted Pyramids BeFore College  Fat-soluble vitamins Vitamin A discovered by M. Mori in 1922 as a “fat-soluble factor” present in butter and fish oil retinol (alcohol), retinal (aldehyde), and retinoic acid (acid form) Retinol is the biologically active form of vitamin A. required in the diet of all animals can be provided as a vitamin or through its precursor carotenoids present in plants.  Vitamin A Carotenoids are pigments present in plant cells that provide the deep orange/yellow color of plant foods. Two types: 1. Carotenes - these are a subgroup of carotenoids that can be converted into vitamin A in animals, which is crucial for vision, immune function, and skin health. E.g. Beta-carotene in carrots 1. Xanthophylls - these carotenoids do not convert into vitamin A but instead are responsible for the coloring properties. E.g. Lutein and zeaxanthin, which are found in leafy greens and yellow vegetables, contribute to plant pigmentation and are beneficial for eye health in animals and humans.  Vitamin A Uses of Carotenoids in Animal Diets: 1. Plumage Color Enrichment - for exotic birds (like parrots or flamingos) kept in captivity, carotenoids in their diet enhance the brightness and richness of their feathers. The pigments from carotenoids are deposited in their feathers, giving them vibrant, attractive colors. 2. Egg Yolk Pigmentation - in poultry diets, carotenoids, especially xanthophylls, are added to give egg yolks a rich yellow or orange color. This is often seen as a sign of a healthy, nutrient-rich egg. 3. Aquaculture Feeds - In fish farming (especially in salmon and shrimp), carotenoids are added to feeds to enhance the pink/red color of the flesh. The pigment astaxanthin, a type of carotenoid, is crucial for giving farmed salmon and shrimp their characteristic color, which is appealing to consumers.  Vitamin A FUNCTIONS For vision, bone growth, reproduction, and maintenance of epithelial cells, which cover the body surface (e.g., skin) and mucous membranes of body cavities (e.g., respiratory, urogenital, digestive tract).  Vitamin A FUNCTIONS 1. Night Vision Vitamin A, in the form of retinal, plays a crucial role in the visual process, particularly for night vision. In the rods of the retina (responsible for seeing in low-light conditions), retinal combines with a protein called opsin to form a light-sensitive pigment known as rhodopsin (also called visual purple). When exposed to light, rhodopsin breaks down into retinal and opsin, and the energy released in this reaction triggers a signal to the brain via the optic nerve, leading to vision.  Vitamin A FUNCTIONS 1. Night Vision Once retinal is used in vision, it needs to be recycled for rhodopsin formation to occur again. Without sufficient vitamin A, the recycling process becomes inefficient, making the rod cells in the retina less sensitive to changes in light. This leads to night blindness, where animals and humans struggle to see in dim lighting or darkness.  Vitamin A FUNCTIONS 2. Cellular Proliferation and Differentiation Vitamin A is essential for the growth and development of cells. It plays a role in cellular proliferation (the increase in cell number) and differentiation (the process by which cells develop into specialized types). In animals, vitamin A helps ensure that epithelial cells (cells that line body surfaces) develop properly, maintaining the integrity of skin, respiratory, urinary, and digestive tracts. This is why vitamin A deficiency can lead to issues in wound healing and overall tissue health, increasing susceptibility to infections.  Vitamin A FUNCTIONS 3. Xerophthalmia Xerophthalmia is a severe condition resulting from vitamin A deficiency. It affects the eyes, causing dryness and irritation of the cornea and conjunctiva. The deficiency results in cloudiness of the eye and may lead to infections due to reduced moisture and tear production. If untreated, xerophthalmia can progress to corneal ulceration and blindness in severe cases.  Vitamin A FUNCTIONS 4. Skeletal and Tooth Development Vitamin A is needed for bone growth and tooth development. It helps regulate the growth and differentiation of bone cells and maintains the balance between bone formation and resorption. Deficiency can lead to abnormal bone growth, reduced bone strength, and dental issues due to improper development of teeth and supporting structures.  Vitamin A FUNCTIONS 5. Reproductive Health Vitamin A is essential for reproduction in both males and females. It is needed for: Spermatogenesis Estrus cycles Without adequate vitamin A, animals may experience infertility, irregular estrous cycles, or even reproductive failure.  Vitamin A FUNCTIONS 6. Antioxidant Function Although vitamin A is not directly an antioxidant, its precursor compounds, such as carotenoids, act as antioxidants. Carotenoids neutralize free radicals and protect the body from oxidative stress, which is associated with aging, inflammation, and chronic diseases. This function is particularly important in supporting overall health and longevity in animals.  Vitamin A METABOLISM Vitamin A in the diet is digested and absorbed along with fat. In the diet, vitamin A is present as esters, is hydrolyzed by pancreatic lipase, and is incorporated into lipid micelles. Upon reaching the microvilli, they are transferred to mucosal cells, where they are re- esterified and are incorporated into the chylomicrons and transported to the lymph for storage in the liver as retinyl esters.  Vitamin A METABOLISM Carotenoid Conversion in Intestinal Mucosal Cells Carotenoids, especially β-carotene, are precursors to vitamin A. In most animals, they are metabolized into retinal within the intestinal mucosal cells. This process involves the splitting of carotenoids into two molecules of retinal. Retinal is then reduced to form retinol, the active form of vitamin A that can be used by the body for various functions, including vision, growth, and reproduction. The amount of vitamin A derived from β-carotene is measured in International Units (IU), where 1 IU of vitamin A is equivalent to 0.6 µg of β-carotene. This gives an estimate of the vitamin A activity provided by carotenoids in the diet.  Vitamin A METABOLISM Species Differences in Conversion Ability Some animals, such as cats, cannot convert β-carotene to vitamin A due to the lack of a key enzyme, β-carotene splitting dioxygenase. This enzyme is required to cleave β- carotene into retinal. As a result, cats need preformed vitamin A (retinol) directly from animal-based sources, such as liver, rather than relying on plant sources like carrots or sweet potatoes, which contain β-carotene. Other animals that can convert β-carotene to vitamin A can utilize both plant and animal sources to meet their vitamin A needs.  Vitamin A Vitamin A Toxicity (Hypervitaminosis A) Vitamin A is a fat-soluble vitamin, meaning that excess amounts are stored in the liver and fat tissues, rather than being easily excreted in urine (like water-soluble vitamins). Because of this, long-term excessive consumption of vitamin A can lead to toxic accumulation in the body, a condition known as hypervitaminosis A.  Vitamin A Vitamin A Toxicity (Hypervitaminosis A) Symptoms: Skeletal abnormalities - excessive vitamin A can interfere with normal bone metabolism, leading to: Bone fragility or thickening due to abnormal growth and remodeling. Joint pain or stiffness. Skeletal deformities, particularly in growing animals. Chronic vitamin A toxicity can cause hyperkeratosis, where the skin becomes thickened, dry, and rough due to overproduction of keratin. Since the liver stores vitamin A, it can become overwhelmed, leading to hepatotoxicity (liver damage), which can impact liver function.  Vitamin A Vitamin A Toxicity (Hypervitaminosis A) Factors Influencing Toxicity Certain species are more sensitive to vitamin A toxicity than others. For example, cats and dogs can develop toxicity from consuming excessive amounts of vitamin A from supplements or liver-rich diets. Young animals are more susceptible to vitamin A toxicity as they are in their growth phase, and excessive vitamin A can interfere with normal bone and cartilage development. Animals with specific health conditions, such as liver or kidney disease, may be more prone to vitamin A toxicity due to impaired storage or excretion mechanisms.  Vitamin A Toxicity  Vitamin D Vitamin D includes a group sterol compound that regulates calcium and phosphorus metabolism in the body. Vitamin D is formed by the irradiation of sterols in plants and in the skin of animals and can be called a “sunshine” vitamin. The two major forms of vitamin D are ergocalciferol (vitamin D2, activated plant form) and cholecalciferol (D3, activated animal form)  Vitamin D Ergocalciferol (vitamin D2) in plants is formed upon exposure to sunlight after harvest and not in living plant cells. Sun-cured forages and hay are good sources of vitamin D in grazing ruminant animals. Animals kept in confinement, as in modern pig and poultry commercial operations, without exposure to sunlight will require vitamin D.  Vitamin D The activated animal form of vitamin D3 (cholecalciferol) is the form that is of importance in other omnivores and carnivores. In most animals, vitamin D2 can be converted to vitamin D3. The efficiency of conversion is very low in poultry.  Vitamin D In the body, vitamin D3 is synthesized from cholesterol when it is converted to 7-dehydrocholesterol in the skin upon exposure to ultraviolet irradiation. To become active, it is transported from the skin to the liver, where it is hydroxylated to form 25- hydroxycholecalciferol. This compound is transported through the blood to the kidneys, where it is further hydroxylated to form 1,25- hydroxycholecalciferol, also called calcitriol, which is the most metabolically active form of vitamin D  Vitamin D Functions 1. Hormone-Like Role of Vitamin D Vitamin D acts like a hormone in the body, regulating various physiological processes, especially related to calcium and phosphorus metabolism. It works in close coordination with the gastrointestinal tract, kidneys, bones, and parathyroid hormone (PTH) to maintain blood calcium levels and promote bone calcification.  Vitamin D Functions 2. Blood Calcium Homeostasis Calcium homeostasis refers to maintaining normal calcium levels in the blood, which is critical for muscle function, nerve transmission, and bone strength. Vitamin D helps regulate blood calcium by adjusting: Calcium absorption from the gastrointestinal tract. Calcium release from bones when blood levels are low.  Vitamin D Functions 3. Calcium-Binding Proteins Calcium-binding proteins are required to efficiently absorb calcium and phosphorus from the digestive system. Vitamin D stimulates the production of these proteins in the intestinal lining, enhancing the body’s ability to absorb these essential minerals from food.  Vitamin D Functions  Vitamin E Tocopherols and tocotrienols. α-tocopherol is the most active biological form of vitamin E and is the one that is added to animal diets Most commercially available vitamin E is DL-α- tocopheryl acetate. One IU of vitamin E is defined as 1 mg of all-rac-α- tocopherol acetate. The only stereoisomer of α-tocopherol found in nature is RRR-α-tocopherol, which is the most biologically effective form of vitamin E in animals.  Vitamin E FUNCTIONS Lipid Peroxidation Prevention - lipid peroxidation refers to the process where free radicals attack and damage unsaturated lipids in cell membranes. This damage compromises cell membranes and can disrupt cell function. Vitamin E helps prevent this damage, maintaining the integrity and structure of cell membranes. Free Radical Scavenger - When free radicals form in the body, they can initiate harmful reactions, especially in lipids that make up cell membranes. Vitamin E scavenges (neutralizes) these free radicals by donating an electron from its hydroxyl group, stopping the chain reaction of lipid oxidation. Vitamin E  Vitamin E Deficiency Vitamin E deficiency can produce white muscle disease, exudative diathesis, and encephalomalacia. White muscle disease is caused by the degeneration of skeletal and heart muscle fiber, which leads to rapid death due to heart failure. Exudative diathesis in chickens is caused by leaky capillaries in the breast muscle. Treatment with either vitamin E or selenium will be successful in both cases. However, Encephalomalacia (crazy chick disease) can only respond to vitamin E treatment.  Vitamin E Toxicity Vitamin E is the least toxic of the fat-soluble vitamins and high levels are added in the diets of animals (beef cow, poultry) to enhance food nutritional and aesthetic value and lipid stability.  Vitamin E Toxicity  Vitamin K group of compounds called the quinones. Vitamin K1 is found in green plants (phylloquinones) and vitamin K2 (menaquinones) is synthesized by hindgut bacteria. Vitamin K’s are absorbed readily with fat in the gastrointestinal (GI) tract. The liver converts vitamin K1 and K3 to K2 before it is used. The metabolically active form of vitamin K is menaquinones. Menadione (vitamin K3, synthetic form) is the most common version of vitamin K that is included in animal diets.  Vitamin K Functions Vitamin K is needed for the synthesis of prothrombin, a blood-clotting protein. The blood-clotting process needs several proteins such as. thromboplastin, prothrombin, fibrinogen, and fibrin The enzymes needed for these processes are vitamin K dependent, and hence deficiency of vitamin K leads to failure in fibrin clot formation, hemorrhages, and/ or prolonged bleeding time.  Vitamin K Functions Often, subcutaneous hemorrhages appear over the body surface, giving a blotchy, bluish appearance to the skin. This can also be of economic importance in food- producing animals leading to a reduction in carcass quality or condemnation. Vitamin K is routinely administered in rodenticide poisoning in pets because the active ingredient (Warfarin) in these rodenticides are anticoagulants, causing bleeding and hemorrhaging.  Vitamin K Phylloquinone and menaquinone derivatives are nontoxic even at higher levels. However, menadione given in prolonged high doses produces anemia and other abnormalities in animals.  Water-Soluble Vitamins (B and C) What Are B Vitamins? The B vitamins (also called B complex vitamins) are originally grouped together because of their similar metabolic functions. The nine chemically unrelated organic molecules function as metabolic catalysts (coenzymes) for energy metabolism pathways, for cellular maintenance, or for blood cell formation in the animal body.  Water-Soluble Vitamins (B and C) What Are B Vitamins? The B vitamins discussed in this section include thiamine, riboflavin, niacin, pantothenic acid, pyridoxine, biotin, folic acid and cobalamin In ruminant animals and in herbivores, microbial synthesis meets the requirements, while in monogastric animals, such as pigs and poultry, daily supplementation is essential. B complex vitamins are also prone to loss during feed processing.  B1 - Thiamine Thiamin is also referred to as vitamin B1, as it is the first vitamin identified. Thiamine consists of one molecule of pyrimidine joined with one of thiazole. Thiamine is a component of the enzyme thiamin pyrophosphate (TPP), which is involved in several key reactions in energy-producing pathways. Dietary thiamine is converted into TPP inside cells to participate in the energy-producing pathway.  B1 - Thiamine Oxidation decarboxylation reactions, such as pyruvate dehydrogenase and α-ketoglutarate dehydrogenase, require TPP. Cereal grains are good sources of thiamine. However, since thiamine is heat labile, feed processing can destroy thiamine content. Thiamin requirement is linked to the energy content of the diet (0.5 mg/1,000 kcal diet)  B1 - Thiamine Deficiency Thiamin also plays a specific role in neurophysiology because a typical thiamin deficiency is beriberi, a dysfunction in the nervous system. Polyneuritis is another typical symptom of thiamin deficiency in chicks. Amprolium (coccidiostat) blocks activation of TPP and can cause a thiamine deficiency.  B1 - Thiamine Deficiency Raw fish and bracken ferns (a perennial) contain an enzyme, thiaminase, which destroys thiamin, causing a deficiency that causes a neurological disorder called Chastek paralysis, named after a farmer who observed similar condition in silver foxes. Heat treatment denatures thiaminase and prevents the problem.  B2 - Riboflavin named for its yellow color (flavin) and sugar (ribose). relatively heat stable but easily destroyed by light. Functions in the body as a component of two different coenzymes: Flavin mononucleotide (FMN) and flavin adenine dinucleotide (FAD). Both of these enzymes are involved in dehydrogenation/oxidation reactions that function in the release of energy from carbohydrates, fats, and proteins (the tricarboxylic acid [TCA] cycle, oxidation, electron transport chain).  B2 - Riboflavin Deficiency As with most B vitamins, deficiency leads to a reduction in growth in young animals. Diets low in riboflavin can cause lesions in the corners of the mouth and anorexia and can cause loss of hair and diarrhea in young animals.  B3 - Niacin generic description for pyridine 3-carboxylic acid and its derivatives Niacin functions as a constituent of two important coenzymes: nicotinamide adenine dinucleotide (NAD) and NADPH. These coenzymes serve as hydrogen carriers in several important metabolic processes involving carbohydrate metabolism (glycolysis) and other energy deriving pathways involving carbohydrates, fats, and proteins, such as the TCA cycle and oxidative phosphorylation.  B3 - Niacin In animal diets, niacin present in cereal grains is in a bound form and is not biologically available to the animal In addition to dietary sources, most animals (except cats) are capable of synthesizing niacin from the essential amino acid tryptophan Cats should receive the entire supply of niacin from their diet.  B3 - Niacin Deficiency This causes a condition called black tongue disease in dogs, and in chickens, it causes poor feathering around the eyes, also called spectacled eyes. The requirement is a 10–90 mg/kg diet. Pellagra (thick skin, dermatitis) is a typical deficiency symptom of niacin in humans associated with poor diet (high grain, no meat) and poverty.  B5 - Pantothenic Acid occurs in all tissues of the body. derived from the Greek term pan meaning “all,” or “everywhere.” Pantothenic acid was identified as a constituent of coenzyme A, the coenzyme required for acetylation of numerous compounds in energy metabolism. CoA is required in the formation of two-C fragments from fats, amino acids, and carbohydrates for entry into the citric acid cycle and for the synthesis of steroids  B5 - Pantothenic Acid Deficiency of this vitamin is extremely rare, and in extreme cases, in addition to the reduced growth rate, in pigs, it leads to a condition called goose- stepping, an abnormal gait, due to nerve degeneration. Other signs of deficiency include a rough coat, anorexia, and impaired productivity. The Ca salt (calcium pantothenate) is the most common form in which the vitamin is added to diets.  B6 - Pyridoxine Three different forms: pyridoxine (plant), pyridoxal (animal), and pyridoxamine (animal). Pyridoxal, which is a component of the coenzyme pyridoxal 5-phosphate is the biologically active form. Pyridoxal phosphate is also required for the synthesis of hemoglobin and the conversion of tryptophan to niacin. Vitamin B6 deficiency can precipitate niacin deficiency. Therefore, deficiency symptoms are similar for these two vitamins.  B6 - Pyridoxine Deficiency Symptoms include convulsions and reduced immune response. The requirement is a 1–3 mg/kg diet and is linked to the protein level in the diet.  B7 - Biotin Feeding raw egg whites to rats causes skin lesions and loss of hair and were cured by a protective factor found in the liver. The original name given to this compound was vitamin H because it protected haut, a German word for “skin.” Biotin was isolated from egg yolk in 1936, a growth factor for yeast. Biotin acts as a carbon dioxide carrier (carbon fixation) in reactions in which carbon chains are lengthened.  B7 - Biotin Deficiency Biotin deficiency is rare. It causes dermatitis and hair loss. This is usually caused not by lack of biotin in the diet but instead, the antivitamin avidin binds biotin and makes it unavailable for digestion and absorption. Eggs are a rich source of biotin. But egg whites contain avidin. However, cooking denatures avidin, making the biotin available for absorption.  B7 - Biotin Deficiency symptoms may be found in swine kept in pens with slotted floors with limited or no access to fecal matter as hindgut bacteria produce biotin. Requirements of biotin are a 0.1–0.3 mg/kg diet (dry basis). Animals subjected to antibiotic therapy that causes a decrease in bacterial population may need an extra supply of biotin.  B9 - Folic Acid Folacin is a generic term used to describe folic acid and related compounds. The active form of folacin in the body is called tetrahydrofolic acid. Dietary sources of folacin are converted mainly in the liver to tetrahydrofolic acid. Vitamin B12 enhances the conversion of folacin to tetrahydrofolic acid.  B9 - Folic Acid The function of tetrahydrofolic acid is as a transport vehicle for single carbon units. Tetrahydrofolic acid is required for purine, pyrimidine, glycine, serine, and creatine synthesis. Both purine and pyrimidine synthesis is required for DNA synthesis and thus cell replication.  B9 - Folic Acid Deficiency Lack of folic acid leads to less DNA and cell multiplication and affects all mitotically active cells. These include hematopoietic cells and all epithelial cells. Since rapidly dividing cells are most affected, it causes a condition called megaloblastic anemia.  B9 - Folic Acid Deficiency Folic acid deficiency is the most prominent human vitamin deficiency. Up to one-third of all pregnant women in the world may experience a folic acid deficiency during pregnancy. Folic acid and vitamin B12 have a close relationship—vitamin B12 deficiency will precipitate folic acid deficiency. Requirements of folic acid are a 0.25 mg/kg diet.  B12 - Cobalamin discovered in 1948. Cyanocobalamin is the vitamin and deoxyadenosyl cobalamin is the coenzyme form. Vitamin B12 is unique in that it has a trace element mineral (cobalt) as its active site. It is also the only vitamin that is synthesized only by microorganisms.  B12 - Cobalamin Similar to folic acid, cobalamin is involved in the transfer of single carbon units during various biochemical reactions. Folic acid serves as a coenzyme for several enzyme systems involving methyl transfer in fat and carbohydrate metabolism and for myelin synthesis. Cobalamin is required for the oxidation of propionic acid in ruminant animals.  B12 - Cobalamin The stomach plays an important role in the absorption of vitamin B12. The stomach provides the acidity and pepsin to release the tightly bound vitamin B12 from the dietary source. The stomach also secretes an intrinsic factor, a specific binding glycoprotein. The vitamin B12-intrinsic factor complex travels to the ileum and is absorbed into a portal vein.  B12 - Cobalamin Calcium is required for B12 absorption in the ileum. The absence of glycoprotein can lead to vitamin B12 deficiency. The requirement is extremely low: 5–50 µg/kg diet for nonruminants. Cobalt is required only for ruminants; the rumen microbes will synthesize cobalamin.  B12 - Cobalamin Deficiency This is very similar to folic acid deficiency, causing anemia and neural disorders. In livestock species, loss of appetite and reduced growth are observed. In ruminants, rumen microbes can synthesize all B vitamins; therefore, there is no requirement.  Vitamin C discovered in 1747 that scurvy can be prevented by the ingestion of lemon juice. Ascorbic acid (Vitamin C) was recognized as a vitamin in 1933. Ascorbic acid has a structure closely related to monosaccharide sugars. It is synthesized from glucose by plants and most animal species.  Vitamin C No coenzyme form is identified. Ascorbic acid is required for hydroxylation reactions of the amino acids proline and lysine in the formation of collagen, elastin synthesis, and neurotransmitter (norepinephrine, epinephrine) synthesis. It also functions as an antioxidant, reducing oxidative stress.  Vitamin C Ascorbic acid can be synthesized from glucose by all mammals except primates and guinea pigs. Therefore, there is no requirement for livestock species. Proline and OH-proline are required for collagen synthesis. Collagen is important for normal bone formation.  Vitamin C Deficiency This results in scurvy, a disease affecting humans with impaired wound healing, capillary bleeding, faulty bone formation, and anemia; it was first reported in sailors at sea. Water-soluble vitamins, coenzymes/cofactors, and functions End of Chapter 6