It is best to supplement vitamin A according to your own physical needs. Vitamin A is essential for maintaining the integrity of epithelial cells, maintaining normal vision, gene regulation, animal reproduction and immune function. Recent studies also found that vitamin A can enhance the body's anti-infection ability, participate in the synthesis of protein, and maintain the normal growth and metabolism of bones. Further research shows that vitamin A also plays an important role in embryonic development. Insufficient intake of vitamin A will lead to malnutrition, decreased dark adaptation ability, and further development can form night blindness. Hyperplasia and hyperkeratosis of skin basal cells, especially the transformation of hair follicles into hair follicle papules (mostly occurring on the extensor surface of limbs, shoulders, neck and back and around hair follicles in buttocks); Sweat glands and sebaceous glands atrophy, dry skin and dry hair; Corneal keratosis and lacrimal gland secretion decrease, leading to dry eye, and further development may lead to corneal ulcer, perforation, blindness, conjunctival folds and pockmarks; Skeletal development is hindered, and immune and reproductive functions are reduced. Because vitamin A is fat-soluble, it is stored in the liver. If it is ingested too much, it will be toxic to the body, leading to nausea, headache, rash, diarrhea and other symptoms, or even chronic poisoning and even death. Vitamin B6 is an essential substance for energy production, amino acid and fat metabolism and central nervous system activities. (1) Vitamin B6 mainly acts as a coenzyme, usually in the form of pyridoxal phosphate and sometimes in the form of pyridoxamine phosphate, and participates in many metabolic reactions, including protein, fat and carbohydrate metabolism. One of the most important is protein's metabolism. In protein metabolism, different enzymes with pyridoxal phosphate as coenzyme catalyze different reactions of amino acids, including transamination, decarboxylation, deamination, dehydration of β-hydroxy amino acids, racemization of α-D- amino acids, desulfurization of cysteine and conversion of tryptophan to nicotinic acid. (2) Vitamin B6 is also involved in the biosynthesis of coenzyme A, the formation of antibodies and the synthesis of messenger RNA, and is related to nucleic acid metabolism and endocrine glands. At the same time, vitamin B6 also plays a role in the metabolism of the central nervous system, which is considered to be helpful to the energy transformation in the brain and nerve tissue, and is related to the function of the central nervous system. (3) Vitamin B6 cooperates with vitamin B 1 and vitamin B2 to complete the digestion and decomposition of food and help the skin; Combined with iron to treat anemia; Can promote the body to synthesize insulin and so on. Vitamin B6 deficiency can cause abnormal metabolism of amino acids and protein, and its clinical symptoms are anemia, convulsion, skin injury, antibody reduction and abnormal development. Long-term lack of vitamin B6 can also lead to dizziness, nausea, vomiting and kidney calculi. Lack of vitamin B6 can also cause peripheral neuritis, accompanied by swelling and tenderness of bursa of fabricius. Vitamin B6 is relatively nontoxic. But taking it in large doses will cause drowsiness, and taking it for a long time will be addictive. (1) participates in various hydroxylation reactions in vivo: proline and lysine are converted into light proline and hydroxylysine by collagen proline hydroxylase and collagen lysine photolyase, respectively. VC is an auxiliary factor to maintain the activity of these two enzymes. Hydroxyproline and hydroxylysine are unique to collagen. Hydroxyproline is the key substance to maintain the quaternary structure of collagen, which is an important component of connective tissue, bones and capillaries. VC is involved in the conversion of cholesterol. Liver cells can hydroxylate cholesterol through VC to produce 7-α- hydroxycholesterol, which is an important intermediate metabolite of bile acids. In addition, the adrenal cortex is rich in VC, especially during stress, vitamins in the body are mostly concentrated in the adrenal gland, and VC participates in the hydroxylation reaction in corticosteroid synthesis. The reaction of hydroxylation of phenylalanine to tyrosine, hydroxylation and translocation of tyrosine to p-hydroxyphenylpyruvate, and conversion to tyrosine all require VC's participation. VC also participates in many hydroxylation reactions in the process of liver biotransformation. As an auxiliary factor of hydroxylase, VC can affect the activity of 25(OH) 2D-α- hydroxylase. Adding VC can stimulate the synthesis of 25(OH) 2D3 and calcium-binding protein, so it can improve bone strength and eggshell quality and prevent tibial chondrodysplasia. (2) Participation in biological oxidation reactions in vivo: VC can exist in two forms: oxidation and reduction. As a acceptor and donor of hydrogen, VC participates in many biological oxidation-reduction reactions in vivo. Vc ⅰ。 VC can keep the -SH in mercaptoenzyme molecules in a reduced state, thus maintaining the activity of the enzyme. Heavy metal ions can combine with -SH of thiolase in the body, making it inactive, leading to metabolic disorder and poisoning. VC can reduce G-S-S-G to G-SH, and G-SH can combine with metal ions and be excreted to play a detoxification role. Two. VC plays an important role in the balance process of free radical generation and elimination in the body. VC also restores the antioxidant effect of VE by reducing VE free radicals, which indirectly acts as an antioxidant. At the same time, VC itself was reduced by nicotinamide purine dinucleotidase (NADH). VC can reduce ferric iron (Fe3+), which is difficult to absorb, to ferrous iron (Fe2+), which plays an important role in the process of iron (Fe2+) entering plasma ferritin, promoting the transformation of folic acid into tetrahydrofolic acid with physiological activity and promoting hematopoiesis. Therefore, when VC is deficient, the development and maturity of red blood cells are affected and anemia occurs. VC can also reduce methemoglobin in red blood cells to hemoglobin and restore its ability to transport oxygen. ⅲ. Antibody (immunoglobulin) contains many disulfide bonds, which are composed of two semi-deaminase molecules, and cysteine is produced by cystine reduction. This reaction also needs the participation of VC. At the same time, during the reduction reaction, VC is oxidized to dehydroVC, and the sulfhydryl group (-SH) on the newly synthesized immunoglobulin peptide chain becomes disulfide bond (-S-S), which promotes the formation of antibodies. (3) There is interaction between immune systems: there is obvious interaction between VC and immune system. VC maintains and strengthens the function of thymocytes, and neutrophils also need VC to play a role. VC is directly involved in humoral immune response. (4) Participate in other metabolic reactions in vivo: lysine and methionine in intracellular amino acids generate carnitine through the action of VC, which is closely related to fat metabolism. In addition, VC is also related to sugar metabolism. (5) Relationship with other vitamins and trace elements: VC can relieve symptoms caused by deficiency of VA, VE, VB, VB2, VB 12 and pantothenic acid, and enhance the storage capacity of VB 1 in vivo. When VB6 is deficient, the blood VC level drops, and when VB6 is supplemented, it returns to normal level. There is a certain relationship between VB6 and VC, but the mechanism is not clear. Insufficient VA and VE will affect the synthesis of VC in vivo. There are many relationships between the physiological functions of VE and VC, but at present, the research on the relationship between them is not very deep, and many conclusions are contradictory. Metabolism and excretion interact with these elements. VC can promote intestinal absorption of iron and increase blood iron content, and VC can promote the absorption of selenium, thus saving the need for selenium. Supplementing VC can eliminate the adverse reaction of excessive copper in feed and prevent copper poisoning. By adding VC to the diet, the adverse effects caused by toxic and sub-toxic doses of cadmium can be eliminated to some extent. Adding VC can effectively prevent the effect of vanadium on the quality decline of protein eggs. If VC can't meet the needs of the body, it will lead to insufficient or lack of VC, which is called scurvy. The early symptoms of scurvy are burnout, fatigue, impatience, shortness of breath, gum pain and bleeding, poor wound healing, transient joint muscle pain and easy fracture. Typical symptoms are gingival swelling and bleeding, gingival ulcer, tooth loosening and increased capillary fragility. Severe cases can lead to subcutaneous, muscle and joint bleeding and hematoma formation. Risk of anemia, decreased muscle fiber (including myocardium), heart failure, severe internal bleeding and sudden death. When domestic animals and poultry lack vitamin C, domestic animals will have symptoms such as growth stagnation, poor appetite, loss of mobility, subcutaneous and joint diffuse bleeding, dull fur, anemia, diarrhea and scurvy. Poultry is nervous at high temperature, and the hardness of eggshell decreases. Excessive intake of VC may cause the formation of oxalic acid and uric acid stones (daily intake of calcium, VB6 and drinking water can be adjusted). Long-term high-dose intake of VC can promote iron absorption and cause ferrate anemia: sudden withdrawal after long-term high-dose intake can cause rebound scurvy; The worst can be fatal. A large amount of vitamin C can reduce the absorption of vitamin B 12 in intestine and accelerate the deterioration of megaloblastic anemia. High dose VC can also cause hypercalcemia and hyponatremia, and reduce the phagocytosis of blood cells; A large amount of vitamin C will slow down the transmission of neuromuscular impulses and cause muscle fatigue. Excessive vitamin c will also destroy the coordination of visual response and motor response; Excessive vitamin c can delay the course of some infectious and allergic diseases, including rheumatism; Lavren Tszky, a former Soviet medical scientist, pointed out that taking too much vitamin C will increase blood coagulation and increase the chance of thrombosis. Because vitamin C can increase gastric acid, excessive intake often aggravates gastritis and gastrointestinal ulcer. Vitamin D regulates many biological functions of animals through the mechanism similar to steroid hormones, including cell growth and differentiation, immune function, reproduction and reproduction, mineral metabolism and other functions. 1 regulation of calcium and phosphorus): The important physiological function of vitamin D is to regulate the metabolism of calcium and phosphorus in the body, especially to promote the formation of calcium-binding protein in intestinal mucosal epithelial cells, promote the absorption of calcium and phosphorus in the intestine and calcification of bones and teeth. (2) Regulation of immune system function: Most cells related to immune system contain 1, 25-(OH) 2-D3 receptor (VDR), such as normal human monocytes, activated T lymphocytes and B lymphocytes, and malignant leukemia cells. These cells are also 1, 25-(OH) 2-D3. 1, 25-(OH) 2-D3 may affect immune system function through receptors in immunocompetent cells. (3) Effect on the function of the central nervous system: The central nervous system contains 1, 25-(OH) 2-D3 receptors (VDR), which are mainly distributed in the central amygdala and the bed nucleus of the stria terminalis in the forebrain, the periventricular nucleus, the parafascicular nucleus and the rhomboid nucleus in the front of the thalamus, and the posterior margin of the medulla oblongata and the nucleus of the solitary tract. It is speculated that 1, 25-(OH) 2-D3 plays an important role in maintaining the internal stability of calcium ions in the central nervous system by regulating the expression of calcium-binding protein. In addition, 1, 25-(OH) 2-D3 can also affect the activities of neurotransmitter-related enzymes. 3. The deficiency and excess of vitamin D are the main regulatory factors of calcium balance and bone metabolism. Vitamin D deficiency leads to the disorder of absorption and metabolism of calcium and phosphorus, which leads to incomplete calcification of bones. The typical symptoms of vitamin D deficiency are rickets in young animals and rickets in adult animals. Usually, the clinical symptoms of vitamin D deficiency in strawberries only exist in young animals. Growth inhibition, weight loss, loss of appetite or emaciation often occur before the symptoms related to the skeletal system appear. When vitamin D is seriously deficient, bone formation will be hindered, mainly as follows: calcium salt can not be deposited on cartilage matrix; Chondrocytes cannot mature, leading to the accumulation of bone cells; The proliferation of chondrocytes decreased; Proliferative cartilage is elongated, swollen and degenerated; Abnormal capillaries invade bones. The main effect of high-dose intake of vitamin D is extensive calcification of soft tissue. The affected tissues and organs include joints, synovium, heart, myocardium, alveoli, parathyroid gland, pancreas, lymph nodes, arteries, conjunctiva and cornea. If it lasts too long, it will interfere with cartilage growth. Inflammation, cell degeneration and calcification mainly occur in the above tissues. Other symptoms include anorexia, rapid weight loss, increased blood calcium, decreased blood phosphorus, and symptoms such as renal failure and hypertension may occur. Vitamin E is considered as an essential nutrient, which can protect fatty acids (PuAF) from oxidation, increase the utilization rate of vitamin A, and inhibit the production of prostaglandin, which may have a certain effect on delaying the aging process. (1) free radical scavenger: The main physiological function of vitamin E is to act as a free radical scavenger to prevent free radicals or oxidants from damaging polyunsaturated fatty acids, sulfhydryl-rich protein components in cell membranes, cytoskeleton and nucleic acids. Free radical is an active group widely existing in various chemical reactions and plays an important role in normal physiological metabolism of human body. If excessive free radicals lead to free radical chain reaction, it will lead to lipid peroxidation of unsaturated fatty acids in cell membrane, and a large number of newly produced lipid peroxides will damage protein and nucleic acids in cell membrane and cells, thus causing damage to the body. The anti-free radical effect of vitamin E is due to the fact that its structure is a derivative of benzopyran, and its benzene ring has an active hydroxyl group, which is reductive, followed by a saturated side chain on the five-carbon ring, which determines that vitamin E is reductive and lipophilic. When free radicals enter the lipid phase and have a chain reaction, vitamin E plays a role in capturing free radicals. Vitamin e has a highly effective anti-free radical lipid peroxidation effect. Vitamin book (2) as a biological antioxidant: α -tocopherol or vitamin E is the most important and effective biological antioxidant, which can prevent the oxidation of unsaturated fatty acids in the body. Without the protection of antioxidants, fat will be oxidized into peroxide. In vivo, hydrogen peroxide can cause tissue damage and destroy the integrity of cell structure, thus interfering with cell metabolism. As a biological antioxidant, α -tocopherol plays an important role in preventing the oxidation of inner membrane and intercellular membrane. (3) Maintaining the stability of biofilm: the functions of all parts of the biological system are coordinated with each other. In biological systems, organs are composed of cell structures separated by various biomembranes. Each cell has a special biofilm, which wraps various cell structures such as nucleus and mitochondria. The nucleus is the control center of cell activities, while mitochondria generate energy for biological activities. Vitamin E plays an important role in maintaining the stability of biofilm. Vitamin e can prevent the oxidation of lipid layer of biofilm by neutralizing free radicals, so it can also prevent the formation of lipid in membrane. Fat must flow into highly active cells to provide energy for cell activities, so it is easy to be oxidized. Vitamin A and carotene are also stored in tissues, so vitamin E can also protect them from oxidation. (4) Effect on fertility: It was found that the concentration of vitamin E in male and female reproductive organs was high, which affected fertility by directly acting on these organs. Vitamin E can also directly protect sperm by preventing them from being oxidized. In addition, vitamin E can also affect animal reproduction through pituitary gland and other reproductive control hormones. (5) Detoxification: α-tocopherol can reduce the poisoning caused by heavy metals such as arsenic and lead. In practice, vitamin E helps to reduce the immunosuppression of mycotoxins. (6) Other functions: Vitamin E is also necessary for many other biochemical reactions, such as the synthesis of ascorbic acid in phosphorylation and the metabolism of coenzyme Q, sulfur-containing amino acids and vitamin B 12. Vitamin complex 3. Vitamin E deficiency and excessive deficiency generally lead to enteritis, and may damage a series of body functions, including reproductive system, nervous system and muscle tissue function. The symptoms of vitamin E deficiency are: loss of appetite and slow action, which is the lack of antioxidants such as vitamin E, which has caused great damage to cerebellum and brain stem; Anemia, which is due to vitamin E deficiency, the erythrocyte membrane is destroyed by oxidation, resulting in shortened life span of red blood cells; Gastrointestinal discomfort, for example, frequent nausea, visual impairment, such as retinitis; When the reproductive system is destroyed, female animals lose their normal fertility without vitamin E; Without vitamin e, unsaturated fatty acids in adipose tissue in the body are easily oxidized and polymerized by peroxide. On the one hand, this kind of peroxide polymer increases the melting point of subcutaneous fat, stimulates tissue to cause lesions and forms scleroderma; On the other hand, it also has harmful effects on nerves, muscles, blood vessels and other tissues. Without vitamin e, the striated muscles of animals will atrophy or paralysis, and muscle fibers will even die. Vitamin e is relatively non-toxic at a certain dose. Long-term large intake can cause nausea, vomiting, headache, blurred vision, chapped skin, cheilitis, angular stomatitis, gastrointestinal dysfunction, diarrhea, breast enlargement, insufficient intake of vitamin E and the possibility of inducing cancer. (1) Function of cofactor: The main function of vitamin K is to play the role of cofactor in some special γ-carboxylation of preformed proteins. Vitamin K plays a role in the transformation of these protein into their bioactive forms. The main K- dependent proteins are the second coagulation factor (prothrombin), the seventh coagulation factor, the ninth coagulation factor and the tenth coagulation factor, and the main bone proteins such as osteocalcin and bone matrix protein. Mechanism of prothrombin participating in blood coagulation. Osteocalcin plays an important role in calcium metabolism because it exists in bones, eggshell glands and eggs. Osteocalcin was also found in chicken embryo bone before calcification. (2) Promoting blood coagulation: When blood vessels are damaged and lead to bleeding, there must be enough prothrombin in the body to promote blood coagulation and hemostasis. Prothrombin is produced in the liver and is constantly used by the body. Therefore, the supply of vitamin K must be uninterrupted and sufficient, and fruits rich in vitamins can support the biological activity of prothrombin. (3) Vitamin K can also increase intestinal peristalsis and secretion function, and participate in redox process in vivo. 3. Lack and excessive lack of vitamin K will reduce the synthesis of prothrombin in the body, which will lead to prolonged bleeding time. It will lead to prolonged coagulation time, bleeding, and even minor trauma or contusion may lead to blood vessel rupture. Subcutaneous hemorrhage, hemorrhage or hematuria, anemia and even the death of organs or tissues such as muscle, brain, gastrointestinal tract, abdominal cavity and urogenital system. Excessive intake of vitamin K can cause hemolysis, hemoglobinuria and porphyria.