Feed Nutrients And Their Nutritional Functions

Email: [email protected] Whatsapp: +86 15054097656 Web: www.sdlachance.net

Carbohydrate and its nutritional function

Carbohydrate is composed ofcarbon, hydrogen and oxygen, including sugar, starch, cellulose, hemicellulose,lignin, etc. it is usually divided into crude fiber and soluble carbohydrate(or nitrogen-free extract). Crude fiber is composed of cellulose,hemicellulose, pentose and mosaic substances (lignin, keratin, etc.), which isthe main component of plant cell wall and the most difficult to digest in feed. Cellulose is true fiber. Its chemical property is very stable. Weak inorganicacid can't decompose it. 

Under the action of 80% sulfuric acid, the purpose ofhydrolysis can be achieved. Its nutritional value is similar to starch.Hemicelluloses are widely distributed in the plant kingdom and are easilyhydrolyzed by dilute acids.

Most of hemicelluloses are composed of the samecomponents as polysaccharides; Others are made up of different monosaccharides,and individual hemicelluloses are made up of molecules of non sugar substances.Lignin is the most stable and tough material. It is generally believed thatlignin contains methoxyacetyl group and aromatic ring. It is difficult forgeneral animals to use crude fiber, but it is essential for herbivorousanimals, especially for animals with complex stomach. In the feed of herbivoressuch as rabbits and guinea pigs, if the crude fiber content is insufficient, itcan cause digestive dysfunction and digestive tract diseases. In ruminants andequine animals, the volatile fatty acids (acetic acid, propionic acid, butyricacid) formed by fermentation of crude fiber in rumen and cecum participate incarbohydrate metabolism in the body, form high-energy phosphate compoundsthrough the tricarboxylic acid cycle, and produce heat energy, which is animportant energy source. Nitrogen free extract is a kind of soluble substance,including monosaccharide, disaccharide, polysaccharide and starch. It canprovide nutrition for monogastric animals, also known as effectivecarbohydrate, and is the main source of energy for animals. In addition to themain supply of animal heat, the excess can be converted into body fat andglycogen, stored in the body for use when necessary.

Minerals and their nutritional functions

The remaining substances after thefeed is fully burned are called minerals, or ash, mainly potassium, sodium,calcium, phosphorus, etc. Minerals are some of the indispensable metal andnon-metallic elements in animal growth, development and reproduction. Accordingto the content of minerals in animals, they are divided into constant elements(accounting for more than 0.01% of animal weight) and microelements (0.01% ofthe body weight). The major elements include calcium, phosphorus, sodium,chlorine, sulfur, magnesium, potassium, etc., and trace elements include iron,copper, zinc, manganese, iodine and other elements. Some of these elements areimportant components of animal body (such as calcium and phosphorus are themain components of skeleton), and some play an important role in variousphysiological processes of the body (such as iron participates in the bloodoxygen transport process), if the supply is insufficient, a series ofdeficiency will occur, and poisoning will occur when the supply is too much.Minerals have their unique characteristics on animal nutrition: they can notproduce heat in vivo, but they are closely related to the metabolism ofcarbohydrate, fat and protein that produce energy; In animals, it can not besynthesized or disappeared in metabolism, and can only be excreted in vitro;Although the content is small, it is very important for the life activities ofanimals.

(1) Nutrition of constant elements

a) Calcium and phosphorus These two elements are the most abundant mineral elements in animals,accounting for more than 70% of the total mineral content of animal body.Calcium and phosphorus are not only the main components of bone, but also playan important role in maintaining the normal function of nerve and muscle, andthe normal coagulation process. Phosphorus is an important part of someenzymes, and plays an important role in lipid metabolism, transportation andenergy metabolism. When calcium, phosphorus or vitamin D are deficient,chondropathy can be formed in the growing animals, and the adult animals causeexcessive resorption of bone and osteoporosis. In addition, the lack of calciumleads to low blood calcium, which can cause calcium spasm. When phosphorus islacking, the animal has poor appetite and has heterovoria. Too much calcium andphosphorus can also cause adverse effects. Excessive calcium can causeosteosclerosis, soft tissue calcification and influence the absorption of othermineral elements. Too much phosphorus can make calcium deficiency, causeserious bone resorption, and soften ribs, and affect normal respiration.Therefore, in animal feed, we should not only guarantee the amount of calciumand phosphorus but also keep the appropriate proportion of the two.

b) Potassium, sodium, chlorine All three elements are electrolytes, which play a synergistic role inmaintaining the osmotic pressure of the cell and the acid-base balance of thebody, and have their own special functions. Potassium promotes the absorptionof neutral amino acids and protein synthesis of cells, which is of great significanceto maintain the normal activities of heart, kidney and muscle. In addition, italso participates in the activation of pyruvate kinase and the phosphorylationof creatine, which affects the absorption of glucose by cells. Sodium is foundin muscle, which makes muscle excitability strengthen and regulate cardiacactivity. Chlorine is the main anion in gastric juice, forming hydrochloricacid to activate pepsin, and keep the acid in the stomach, and has bactericidaleffect. Under normal circumstances, animals can regulate the discharge ofpotassium, sodium and chlorine through the kidney. Potassium is more abundantin plants than sodium, so it is often added to animal feed. However, when thereis too much salt in diet, drinking water is limited or kidney function isabnormal, poisoning symptoms will also occur.

c) Magnesium and sulfur Magnesium is a component of bones and teeth, and the rest is distributed insoft tissue cells. Magnesium is an activator of pyrophosphatase,cholinesterase, adenosine triphosphate and other enzymes, which plays animportant role in the metabolism of sugar and protein. Sulfur is distributed inevery cell of the whole body, and exists in methionine, cystine and biotin,which mainly plays a role in the body through the above-mentioned organicmetabolites.

(2) Nutrition of trace elements

a) Iron Most of them arefound in hemoglobin and myoglobin, and some of them combine with proteins toform ferritin, which is found in liver, spleen and bone marrow, and a small amountin pigment and a variety of oxidase. Iron plays an important role in ensuringoxygen transport in tissues and is closely related to intracellular biologicaloxidation.

b) Copper It is mainlydistributed in the pigmented parts of liver, brain, kidney, heart and hair. Itis the component and activator of various enzymes. The formation of red bloodcells, the composition of bones, the pigmentation of hair and the quality ofbrain cells and spinal cord all need appropriate copper.

c) Selenium The highestcontent was found in liver, kidney and muscle. Selenium is the main componentof glutathione peroxidase, which plays an important role in protecting theintegrity of cell membrane, protecting the normal function of pancreatic cells,and helping the absorption and retention of vitamin E. 

d) Other trace elements Manganese, zinc, iodine, cobalt and chromium are also necessary for animals.Lack of these elements can cause some tissue and functional abnormalities.These trace elements actively participate in the growth and development ofanimal body, reproduction and other main functions and maintain the health ofthe body. When lacking or surplus, it will cause animal diseases.

Vitamin

Vitamins are essential nutrientsfor normal metabolic activities of animals. They are small molecular organiccompounds and participate in the enzyme system in the form of coenzymes orenzyme precursors. Although the demand of animals is very small, it has a greateffect on regulating metabolism. Except for a few vitamins, most of them cannotbe synthesized in animals and must be provided by feed or intestinal bacteria.Under normal circumstances, water-soluble vitamins and vitamin K will not bedeficient, but should be supplemented in high temperature sterilization. VitaminC cannot be synthesized in guinea pigs and primates and must be supplied infeed. There are many kinds of vitamins, which are traditionally divided intofat soluble vitamins and water-soluble vitamins according to their solubility.  

（1）Fat solublevitamins include vitamins A, D, e and K. they are soluble in fat and fatsolvent, but insoluble in water. Because it can be stored in the body afterabsorption, short-term supply shortage will not have adverse effects on growthand health.??

a) Vitamin A Naturalvitamins only exist in animal feed. Plants only contain vitamin A, which isabsorbed in the digestive tract and then transformed into vitamin A inintestinal cells and liver. Vitamin A is mainly stored in the liver of animals,and the rest is stored in fat and released into the blood when the body needsit. Vitamin A is an essential component of general cellular and subcellularstructure. It can promote growth and development, maintain the normal growth ofbone, repair, maintain the integrity of epithelial tissue, promote thesynthesis of mucopolysaccharide in connective tissue, enhance the resistance todiseases, maintain the integrity of cell membrane and organelle membranestructure, and maintain normal vision. In addition, vitamin A is also relatedto the normal reproductive function and immune function of animals. Vitamin Adeficiency will have a wide range of effects on the body: the body can notsynthesize rhodopsin, resulting in night blindness; Epithelial hyperplasia,keratinization and bacterial infection are the main causes of secondarydiseases, especially in eyes, respiratory tract, digestive tract, urinary andreproductive organs; It affects the growth of young animals and the normalgrowth and development of bones.

b) Vitamin D Vitamin D is asteroid derivative. Although there are more than ten compounds with vitamin Dactivity, only vitamin D2 and D3 play an important role in animals. Animals canget vitamin D in two ways, that is, in the skin or from feed. The most importantrole of vitamin D is to regulate the metabolism of calcium and phosphorus,maintain the normal development of bone and teeth, in addition, it alsoparticipates in the metabolism of citric acid, maintain the content of aminoacids in the blood. Vitamin D deficiency seriously affects calcium andphosphorus metabolism and bone growth and development. Rickets occurs in younganimals and osteoporosis occurs in adult animals, especially in pregnant,lactating and aged animals. In addition, the decrease of serum calcium andphosphorus also affects the normal function of muscle and nervous system.

c) Vitamin E Tocopherols,also known as tocopherols, are a group of bioactive phenolic compounds withsimilar chemical structure α、β、γ、δ Thereare four kinds, among which, the most are α－ Tocopherolis the most widely distributed and active. The basic function of vitamin E isto maintain the integrity of cells and their internal structure, and preventthe destruction of some enzymes and internal components. Vitamin E has a strongantioxidant effect, can resist the oxidation of polyunsaturated fatty acids intissue membrane, stabilize cell lipids, and ensure the integrity of red bloodcells. Vitamin E is also an essential factor for cell respiration, which is involvedin the synthesis of DNA, vitamin C and coenzyme Q. In addition, it is closelyrelated to the reproductive function and immune function of animals. Vitamin Edeficiency can cause muscular dystrophy in animals, which is characterized byacute myocardial degeneration and subacute skeletal muscle degeneration. Theformer often dies, while the latter has dyskinesia and can not stand when it isserious. Long term lack of vitamin E, can make erythrocyte membrane dissolved,life shortened, hemolytic anemia. Vitamin E deficiency seriously affects thereproductive function of animals, the formation of sperm cells in male animalsis blocked, the quality of semen is poor, and the number of sperm is reduced.The conception rate of female animals is decreased, even if the conception willproduce stillbirth or the fetus will be absorbed.

d) Vitamin K Vitamin K isactually the general term of a group of compounds, and many compounds have beenfound to have vitamin K activity. The most important are K1, K2 and K3. Thereare only two natural forms of vitamin K. vitamin K1 only exists in greenplants, while K2 is synthesized by microorganisms. Vitamin K can promote thesynthesis of thrombin in liver, so it can promote blood coagulation. Inaddition, it can enhance the function of gastrointestinal peristalsis andsecretion, and participate in the redox process in the body. Generally, animalbody will not produce vitamin K deficiency, because it widely exists in feed,and bacteria in large intestine can also synthesize it, but aseptic animals canproduce vitamin K deficiency.

(1) Water soluble vitamins

Water soluble vitamins mainlyinclude vitamin B and vitamin C. Due to little or almost no storage in thebody, the short-term lack or insufficiency of water-soluble vitamins will causethe change of some enzyme activities in the body, inhibit the correspondingmetabolic process, thus affecting the growth and development of animals anddisease resistance, but it may not be shown in clinic, and the deficiency willonly appear after a long time. Rumen microorganisms of ruminants can synthesizeenough B vitamins. In monogastric animals, although intestinal microorganismscan also synthesize, they can be used less, and most of them are excreted withfeces. Animals with faecalism, such as rabbits, can get vitamin B supplementfrom faeces.

a) Vitamin B1 (thiamine) Vitamin B1 is a kind of compound with pyrimidine ring and thiazole ring inmolecular composition. The storage capacity of animal organism is the leastamong all vitamins, so it should be supplied frequently. Its main function isto participate in carbohydrate metabolism, as a coenzyme in the process ofenergy metabolism and glucose into fat. In addition, it plays a certain role inmaintaining the normal function of nerve tissue and myocardium, maintainingnormal intestinal peristalsis and fat absorption in the digestive tract.Thiamine deficiency will affect the growth of animals, can cause anorexia,dyspepsia, stomach relaxation and other digestive disorders, but also damagethe nerve activity performance, continue to lack will cause neuritis, furtherdegradation of the nervous system, leading to paralysis and muscle atrophy.

b) Vitamin B2 Composed of ayellow pigment and a reduced form of ribose, also known as riboflavin, it iswidely distributed in plant and animal tissues. In animals, the liver andkidney contain high concentration of riboflavin, but the storage capacity ofthe body is limited. Riboflavin participates in energy metabolism and is anindispensable and important substance in the process of biological oxidation.It plays an important role in promoting growth, maintaining the integrity ofskin and mucous membrane, and in the process of eye sensitization and cornealrespiration of lens. Riboflavin deficiency usually has no obvious and specificpathological changes. Even in severe cases, riboflavin deficiency only showssome nonspecific symptoms, such as growth arrest, loss of appetite, rough anddisordered coat, and increased secretion of eye corner in young animals. 

c) Vitamin B3 (pantothenic acid) From the pan solution acid and β－Alanine is a component of coenzyme A, which exists in all tissues. It is anindispensable component of energy metabolism in the body. Pantothenic acidplays an important role in carbohydrate, fat and protein metabolism, especiallyin fat synthesis and metabolism. Pantothenic acid is also essential for theformation of acetylcholine. Lack of pantothenic acid can reduce the growth rateof animals, damage skin, nervous system disorders, antibody formation blocked.

d) Vitamin B4 (choline) Lecithin is a key part of lecithin structure, which has important physiologicalfunction in vivo. As a component of some phospholipids, it can prevent fattyliver through fat metabolism; As a component of acetylcholine, it plays a rolein nerve conduction; As a source of unstable methyl, it is used in theproduction of creatine and the synthesis of several hormones. Cholinedeficiency can cause slow growth and fat metabolism disorder in animals.

e) Vitamin B5 (nicotinic acid) It plays an important role in the process of biological oxidation,maintaining the normal function of nervous system, digestive system and skin,expanding peripheral blood vessels and reducing serum cholesterol level. Nicotinicacid deficiency can slow down the growth of animals, loss of appetite, squamousdermatitis, nerve reflex disorders, dyskinesia, skeletal dysplasia. f) VitaminB6 (pyridoxine) Pyridoxine, pyridoxal and pyridoxamine all have theactivity of B6, which is generally called vitamin B6. They play a particularlyimportant role in protein metabolism, as well as in carbohydrate and fatmetabolism. In addition, it is necessary for energy production, central nervoussystem activity, hemoglobin synthesis and glycogen metabolism. Vitamin B6deficiency is the most common disorder of the central nervous system, animalconvulsions, peripheral neuropathy, leading to dyskinesia, and ultimatelydeath.

f) Vitamin B7 (biotin) Under normal circumstances, the microorganism in animal intestines cansynthesize biotin, and the amount of synthesis can meet the nutritional needsof animals. Due to the lack of intestinal microorganisms, sterile animals maylack biotin, resulting in slow growth and poor appetite.

g) Vitamin B11 (folic acid) It is a group of compounds which are combined with L-glutamic acid andp-aminobenzoic acid. It is indispensable for the body to form one carboncompound. It is related to the synthesis of nucleic acid and participates inthe formation of cells. In the absence of folic acid, the growth of animals ishindered, appetite is decreased, hair is removed, megaloblastic anemia,leukopenia and thrombocytopenia are found. In general, microorganisms can besynthesized in animals, which is easy to be lacking in sterile animals orintestinal flora disorder.

 h) Vitamin B12 It is a kindof compound containing cobalt and has many forms. It generally refers tocyanocobalan. The only source in nature is microbial synthesis, which isnecessary for the normal function of hematopoietic organs. It maintains thenormal function of nervous system and participates in carbohydrate, fat andprotein metabolism. Generally, animals are not prone to vitamin B12 deficiency.

 i) Vitamin C It is aderivative of 6-carbon sugar. There are L-form and d-form isomers, but onlyL-form has physiological effect on animals. Vitamin C exists in all livingtissues, but cannot be synthesized in primates and guinea pigs. Vitamin C isnecessary for the formation of bone collagen in bone tissue and the maintenanceof normal function of these tissues. It also promotes the body's defensefunction, promotes the absorption of iron in the intestine, participates in themetabolism of folate, tyrosine and tryptophan, and regulates the metabolism offat, lipid and cholesterol. It has strong detoxification and antioxidanteffect.

 Vitamin C deficiency, animalgrowth block, loss of appetite, poor activity, subcutaneous and joint diffusebleeding, easy to fracture, anemia, diarrhea.

The relationship between various nutrients

In the process of metabolism,there are various and complex relationships among various nutrients. Theabsorption and utilization of one nutrient in the body is often closely relatedto other nutrients. The ratio of energy (carbohydrate and lipid) to protein(also known as egg energy ratio) in feed should be appropriate. Improperproportion will affect the utilization rate of nutrients, resulting in wasteand even nutritional disorders. Different stages of animal growth anddevelopment require different energy and protein. There are also greatdifferences among different animals, which should be supplied according todemand. The supply of protein is not the more the better, too much supply ofprotein will cause the body to convert excess protein into energy, resulting ina waste of protein, while increasing the cost of feed. There is a negativecorrelation between fiber and the utilization of other nutrients, that is,fiber is more, the digestibility of other nutrients is lower, but forherbivores, cellulose is an essential nutrient. For example, when the contentof cellulose in rabbit feed is too low, it will cause digestive disorders oreven death. The amount of protein supply also has a significant effect on theabsorption of some vitamins such as a, D, B2, etc. If the protein isinsufficient, the utilization rate of vitamin A in feed will be reduced. Thecontent of lipids is also related to the absorption of vitamins, especially fatsoluble vitamins. High fat diet can affect the absorption of calcium, whilehigh protein diet can improve the absorption of calcium and phosphorus. Thelack or excessive supply of various nutrients will lead to the destruction ofthe normal physiological state of the body, causing animal diseases, which areusually called metabolic diseases.