Ruminant (ch ú) animals areArtiodactylaA suborder of.Rumination means that after eating for a period of time, the semi digested food in the stomach will return to the mouth and chew again. Ruminant animals are animals that have rumination.Usually someHerbivoresBecause plant fiber is difficult to digest.Ruminants generally take food in a hurry, especially coarse fodder. Most of them swallow it into the rumen without sufficient chewing. After a period of immersion and softening in the rumen, food returns to the mouth through retching, and after re chewing, it is mixed with saliva again and swallowed again into the rumen.Except for camels and camels, these animals do not have upper incisors, but have hard gums in corresponding positions to support the things to be torn by the lower incisors.When eating, ruminants swallow food (mainly plants and twigs) after roughly chewing, and then lie or sit to return the food to their mouths for chewing again.
The digestive physiology of ruminants is quite different from that of monogastric mammals, and much more complex than that of monogastric mammals.Single stomach mammals digest the three major nutrients - sugars, lipids and proteins - through digestive juice to decompose them into simpler forms and then absorb them, and then use these substances to maintain the energy required for their own physiological activities or synthesize various substances required for their own metabolism, growth, development and reproduction.In monogastric animals, sugars are usually broken down into monosaccharides by digestive juice（glucose、fructose、Galactose、mannoseAnd disaccharides（malt dust、sucroseandlactose）After being absorbed, these sugars are oxidized in the body to produce energy needed for metabolic activities or synthesized into fat reserves;Fat decomposes high lipids intoTriglycerideOr other low-grade lipids are absorbed as energy sources or reconstituted into autologous fat reserves;Protein is hydrolyzed into amino acids under the action of digestive juice, and amino acids are used as the building blocks for the re synthesis of autologous protein[1]。 In ruminants, they do not directly digest and absorb the nutrients in the feed through their own digestion and absorption. No matter what kind of nutrients, they must first pass through the rumenMicrobial fermentationThe organic acids and some primary fatty acids finally produced in the fermentation process can be absorbed by the rumen as their metabolic energy, while other nutrients come from the digestion of rumen microorganisms.It can be said that the rumen microbesThallus proteinQuality, sugar and lipid are the most important, direct and most effective nutrition sources for ruminants[1]。 Therefore, in the feeding of ruminants, we must pay attention to the nutritional requirements of rumen microorganisms, fully meet the nutritional requirements of microbial reproduction and mineral elements, maximize the proliferation of rumen microorganisms, and enable ruminants to obtain more bacterial nutrition.The proliferation of rumen microorganisms can also convert more non protein nitrogen into available bacterial protein for cattle and sheep, which is of great significance for improving the feed utilization rate and nutrition level of ruminants.Minerals play a dual role in the nutrition of ruminants. They are not only necessary for maintaining normal metabolism of animals, but also necessary for the reproduction of rumen microorganisms.It plays an important role in improving feed conversion rate to fully meet the needs of rumen microorganisms for minerals.
Any sugar entering the rumen is fermented by the microbiota to form microbial cellsVolatile fatty acids, carbon dioxide and methane, sugars in ruminant feed, generally cellulose, fructan, pentosan, hemicellulose and other polysaccharides, pectin substances and other polysaccharide uronic glycosides, as well as starch, sucrose and glucose and other sugars.rumenmicroorganismCellulose and other sugars are fermented and hydrolyzed into cellobiose and glucose or other monosaccharides as energy for self reproduction.During fermentation, microorganisms proliferate in large quantities, and the final product of fermentation iscarbon dioxideAnd volatile fatty acids such as methane, acetic acid, propionic acid, butyric acid and valeric acid, which are absorbed by the rumen.70%~80% of ruminant energy comes from these organic acids, which pass throughGluconeogenesisSynthesize glycogen or fat reserves.Acetic acid mainly produces heat in the intermediate metabolism process. If the proportion of acetic acid produced in the fermentation process is too high, and there is a lack of propionic acid or glucose, it is difficult for acetic acid to synthesize fat. As a result, the energy level is increased, and the rate of action used to synthesize body fat is low.Therefore, the diet of ruminants should be reasonably matched with feed to make the acetic acid and propionic acid produced during fermentation reach the appropriate proportion.The digestion and absorption of crude fiber in feed by ruminants are completely dependent on rumen microorganisms. If they cannot meet the nutritional requirements of normal reproduction of rumen microorganisms, they will causeNutritional deficiency。 On the contrary, cattle and sheep feed a large amount of grain at a time, and a large amount of organic acid produced by intense fermentation is absorbed, which will cause acidosis.Therefore, the ruminant diet should be roughage type.Feeding dairy cows with silage alone can reduce the rumen pH, which is not conducive to the reproduction of rumen microorganisms, and it will also lose the important source of microbial nutrition for ruminants, leading to malnutrition of animals,reproductionAnd congenital blindness of newborn calves.Therefore, high-quality green hay is essential for ruminants[2]。
2. Protein
proteinDigestion in rumen is almost carried out at a stable rate of hydrolysis. Hydrolysis is achieved by reducing the length of peptide chain tofree amino acid In the same way.Most amino acids are destroyed by fermentation deamination, accompanied by the production of carbon dioxide, ammonia and short chain fatty acids. Some peptides and fatty acids may enter bacterial cells directly, but many rumen bacteria can use ammonia as the main nitrogen source to synthesize the protein components of their cells.Microbes in the rumen enter the abomasum and small intestine and are digested by the digestive fluid. The protein in the cell is decomposed into amino acids, and the sugars and lipids in the cell are decomposed into glucose and fatty acids. Most of these nutrients are absorbed in the small intestine.so to speak,rumenMicrobes are the most direct source of nutrition for ruminants. As long as they can meet the normal reproduction conditions of rumen microorganisms, they will not cause nutrient deficiency.Non protein nitrogen has important nutritional value for ruminants because rumen microorganisms can use ammonia produced by feed protein hydrolysis and other non protein ammonia to synthesize bacterial protein.However, when the total nitrogen content in the rumen is too high and the available carbohydrate in the small intestine is too low, the fat synthesis will be affected. For ruminants, the total nitrogen supply andcarbohydrateThe proportion should be appropriate[3]。 For ruminants, the physiological value of protein is different from that of monogastric mammals.Ruminants can complete various life activities as long as they are given enough total food nitrogen (including non protein nitrogen).For cattle, the physiological value of protein changes with different intake levels. The physiological value of protein in diets containing 9%, 11%, 13% and 15% crude protein is 79, 70, 60 and 52 respectively. This shows that the crude protein content in the diet is too high, on the contrary, the physiological value of protein is reduced.Therefore, the development and utilization of non protein nitrogen as protein feed for ruminants not only conform to the digestive physiological characteristics of ruminants, but also can improve the nutritional level of animals, expand the feed sources for ruminants, save feed grain, which is of great significance for promoting the development of animal husbandry and providing high-quality meat for the market.
3. Lipids
The outcome of lipids in rumen is similar to that of carbohydrates.Lipids are hydrolyzed to glycerol and fatty acids by microorganisms in the rumen, and glycerol is finally hydrolyzed to propionic acid.Fatty acids undergo extensive hydrogenation in the rumen, and are converted into 18 carbon unsaturated fatty acids that are absorbed by the rumen and used as components for animals to build their own fat[2]。
Calcium and phosphorus are essential minerals for animal growth, development and maintenance of physiological functions, and play an important role in animal metabolism and reproductive activities.Calcium in bones mainly exists in the form of phosphate.In addition to forming compounds with calcium or carbonate to enhance the hardness of bones and teeth in animals, phosphorus is present in every cell of the body and participates in many metabolic processes, including its vital relationship as a buffer in body fluids.In fact, various forms of energy exchange in cells include the formation and breaking of "high-energy phosphate bonds"“High-energy phosphate bond”To associate phosphorus oxides with carbon or carbon nitrogen compounds.In the limestone soil in the vast area of northwest China, the content of calcium is very high and phosphorus is seriously deficient, which leads to the ineffective absorption and utilization of calcium, resulting in poor growth and development of livestock, and even pica. Therefore, phosphorus supplementation in livestock diets is extremely important.In the paddy field area in the south, both phosphorus and calcium are deficient, so calcium and phosphorus should be supplemented at the same time[4]。
(2) Sulfur
Thomas et al. (1951) had difficulty in maintaining animal health by feeding sheep with synthetic feed with urea as the only nitrogen source.Feed supplementsulfurThis problem has been solved.Sulfur is syntheticessential amino acid ——Methionine is essential.It has been proved that the rumen of lambs can synthesize 10 essential amino acids.When urea is the only nitrogen source and inorganic sulfur is available, rumen bacteria can synthesize methionine.On the contrary, urea nitrogen can not be effectively utilized when sulfur in feed is deficient.In the experiment, sulfur deficient lambs showed gradually decreased appetite, weight loss, weight loss and death.The growth of wool seems to have greater priority over the metabolism and accumulation of nutrients than tissue growth or even maintenance, but the growth rate of wool is slowed down due to sulfur deficiency.Sulfur has a dual nutritional effect on ruminants. It is a rumen microorganismSynthetic proteinAnd essential elements for animal hair growth[4]。
(3) Iron
ironIts function is realized through its oxidation-reduction activity and the ability to transport electrons during respiration, and its function is greatly enhanced when iron is combined with protein.In animals, iron mainly exists in complex forms by combining with proteins, such as hemoglobin or myoglobin, mitochondrial cytochrome and microsomal cytochrome, catalase and peroxidase, and Fe flavinase,transferrinAnd ferritin, etc.Only a small amount of free inorganic iron was found in animals.Heme can form some active compounds in mammalian respiration, such ashemoglobin, myoglobin, cytochromeCytochrome oxidase, peroxidase andcatalase。 The protein composition of these compounds determines their special functions, while heme is the functional group.The role of iron is the carrier of oxygen or electron transporter. The iron in hemoglobin accounts for about 60% of the total body iron content.Therefore, any factor that affects the hemoglobin level in the blood has a great impact on the overall iron status of the body.The iron content of myoglobin only accounts for about 3% of the total iron content. The interspecific difference of iron content in the whole body is relatively small in adult animals, but quite large in newborn animals.There is individual variation in iron content in the same animal. There may be great difference in iron storage organs, such as liver, spleen and kidney, while the body's organs are relatively small[4]。
Reducing substances in food, such asascorbic acidandCysteineIt helps to reduce trivalent iron into divalent iron and strengthen its absorption.Dietary composition can also interfere with iron absorption, and higher phosphate levels reduce iron absorption.The amount of iron absorption is controlled by the demand.When iron storage decreased or erythropoiesis increased, iron absorption increased;When the iron storage is sufficient and the erythropoiesis is normal, the absorption of iron decreases.The feed of ruminants should be supplemented with abundant iron, and iron deficiency can cause iron deficiency anemia.Low iron storage of newborn pigletsiron-deficiency anemiaMore sensitive than ruminants[4]。
(4) Selenium
seleniumyesGlutathione peroxidaseIt can reduce all peroxides into non-toxic hydroxyl compounds and protect cells from the toxicity of peroxides.Selenium is an important substance that can improve animal fertility and productivity. Under the condition of selenium deficiency, female animals are in irregular estrus or not at all, and the embryo rate is low;Some female animals can ovulate and conceive normally, but the fetus cannot develop normally in the mother.However, too much selenium has adverse effects on reproductive function.When selenium poisoning occurs, the pregnancy rate and litter size of female animals decrease, and the growth and development of offspring animals are slow, which can also lead to embryonic abnormalities.Therefore, only by maintaining a normal level of selenium in animals can the reproductive function of animals be normal.Supplementing proper selenium in diet in selenium deficient areas can effectively improve fertility and prevent congenital leukmyopathy.Selenium/vitamin E deficiency can damage the physiological function of uterine muscle, which can often lead to the retention of the placenta or hinder the transfer of sperm, thus reducing the fertilization rate.Recent studies have shown that the incidence of mastitis is affected by the levels of vitamin E and selenium in the peripheral plasma. Adding vitamin E and selenium to the diet can reduce the incidence of mastitis[5]。
(5) Zinc
An important function of zinc is in synthesisRibonucleic acidAmong the essential enzyme systems, zinc is essential for the growth of germ cells and somatic cells.There are more than 200 enzyme activities related to zinc, and the role of zinc in these enzymes is to maintainprotein structureThe integrity of or directly involved in the catalytic process of enzymes.Therefore, zinc is of great significance to the life activities of animals. In the absence of zinc, metabolic barriers and low reproductive capacity are mainly manifested in the reduction of conception rate in female animals.In male animals, zinc is directly involved in the process of spermatogenesis, maturation, activation and capacitation, and can delay the lipid oxidation of sperm membrane, maintain the permeability and stability of cell membrane structure, so as to maintain good sperm vitality.The role of zinc in sperm is mainly to protect sperm by inhibiting the activity of degrading enzymesDeoxynucleic acidEnzymes are not destroyed, thus improving the semen quality of male animals.Zinc deficiency can delay the development and maturity of male gonads, and adult animals can have gonadal atrophy and fibrosis, the second sexual characteristicHypoplasia[4]。
(6) Cobalt
cobaltIt is necessary for digestive tract microorganisms, mainly rumen microorganisms to produce vitamin B12.Cobalt deficiency in ruminants is characterized by anorexia and emaciation. If the disease progresses, there will be obvious anemia and appetite loss, decreased blood volume and protein concentration in plasma, and reduced oxygen delivery capacity to 30% or even lower of normal. It is characterized by significant megaloblastic anemia, which eventually leads to polychromaticity.The most common symptom of cobalt deficiency in female livestock is the low conception rate of female livestock.Anemic female animals can not have estrus, the first estrus period is delayed, ovarian function is lost, abortion, weak fetus.Supplying cobalt to the cattle with cobalt deficiency can reduce the rate of dark estrus and irregular estrus, thus improving the pregnancy rate.The disease usually occurs in areas of the world where the soil cobalt content is less than 2%.In addition to the very low soil concentration, there are other factors causing cobalt deficiency.Taking proper amount of cobalt orally to the sick animals with cobalt deficiency anemia can often improve the symptoms. Adding a certain amount of cobalt to the feed can prevent the occurrence of diseases.This is a good example, which shows that some trace elements are necessary for the proper growth of rumen microorganisms and the synthesis of vitamin B12. These two aspects are important to the health of animals[4]。
(7) Manganese
The content of manganese in animals is about one tenth of that of copper, which is distributed throughout the body, but the content in bones, liver, kidney and pancreas is higher than that in skeletal muscle.When manganese is deficient in ruminant feed, it can cause swollen legs of knee joints, damaged or decreased reproductive function of animals, often showing anoestrus, irregular oestrus or delayed oestrus.Manganese is also involved in the metabolism of luteal tissue. The incidence of abortion and ovarian cysts in cows fed low manganese diet is increased[4]。
(8) Copper
Copper is involved in enzyme synthesis.It exists in the form of copper protein complex in plasma.Plasma cuprin has no oxidation, while transferrin has oxidation, but its activity is proportional to copper content.Copper participates in the hematopoietic process. Copper deficiency can cause copper deficiency anemia, which is characterized by a decrease in the number of red blood cells, but no decrease in hemoglobin.It can also cause slight loosening of bones and other defects.When female animals lack copper, their reproductive function is disordered, their embryos die early, their ovaries function is low, their oestrus is delayed or blocked, their conception rate is low, their delivery is difficult, and their placenta is not lowered. The calves often show congenital rickets.The conception rate of cows with low blood copper level increased after copper supplementation.Some tests prove that copper can improveprostaglandinThe binding force with receptors can improve the effect of prostaglandins.Copper and cobalt have synergistic effect. After injection of copper, the pregnancy rate of dairy cows increases from 53% to 67%. If cobalt is supplemented at the same time, the pregnancy rate can reach 93%[6]。
(9) Molybdenum
Molybdenum is necessary for many metal enzymes, such as xanthine oxidase, alcohol dehydrogenase and sulfite oxidase.The molybdenum content in the normal diet can meet the nutritional needs of animals, so animals generally do not lack molybdenum.If there is too much molybdenum, it will reduce the reproductive function of animals, especially cows can not tolerate high molybdenum[4]。
(10) Iodine
iodineIt is the basic component of thyroxine, the symptom of animal iodine deficiency andThyroid dysfunctionofIodine in soil is lost with rain water, and iodine is generally deficient in pasture.Therefore, iodine deficiency is considered to be the most common type of mineral deficiency in herbivorous livestock.Iodine deficiency in cows often leads to abortion, prolonged pregnancy, difficult delivery, retained placenta or weak calves.When the bull is iodine deficient, its libido is reduced and the semen quality is poor.Iodine supplementation can effectively treat the infertility of cows, but excessive iodine supplementation can also cause abortion of cows and birth of deformed calves.Iodine deficiency exists to varying degrees in many regions of China.Therefore, attention should be paid to adding an appropriate amount of iodized salt to the feed of breeding animals[4]。
(11) Vitamins
Vitamins are a kind of trace organic substances necessary for animal growth and metabolism.Each vitamin has its own special function, and can not replace each other.So any kind of feedVitamin deficiencyWill cause changes in the physiological function of the body and lead to a lack of specificity.
Classification of vitamins
Vitamins are a kind of low molecular organic compounds, including alcohols, esters, amines, acids, phenolic aldehydes and other different structures, so there are differences in physical and chemical properties and physiological functions. Vitamins can be divided intoFat soluble vitaminandWater-soluble vitaminTwo categories.Fat soluble vitamins mainly include vitamins A, D, K and E;Water soluble vitamins include B vitamins (vitamin B1, vitamin B2, niacin and nicotinamide, vitamin B6, pantothenic acid, biotin, folic acid, vitamin B12, etc.) and vitamin C.Because of their different physical and chemical properties, their effects on animal bodies are also different.
The Source of Vitamins and Their Digestive Characteristics in Ruminants
Fat soluble vitamins are abundant in animal feed, such as fish meal, liver, cod liver oil, egg yolk, etc.In additionCarotene, can be used as a source of vitamin A.Green hay is an important source of vitamin D plant feed.Vitamin E is abundant in various vegetable oils.Cabbage leaf is a good feed source of vitamin K1.However, restricted by economic and other conditions, the proportion of animal raw materials in feed is small, and the single type of plant raw materials leads to insufficient vitamin intake in animals, which causes changes in physiological functions of animals.Ruminants can synthesize B vitamins due to their unique rumen microbial system.Studies have shown that riboflavin, vitamin B6, thiamine, pantothenic acid, biotin and folic acid can be synthesized in the rumen.Traditionally, it is believed that the B vitamins produced in ruminants can meet their own needs, so the vitamin supplement for ruminants mainly focuses on fat soluble vitamins.However, most uncoated fat soluble vitamins are digested and utilized by microorganisms in the rumen, and only a small amount of vitamins can be truly absorbed by animal body, so the utilization of fat soluble vitamins in ruminants has always been a major concern at home and abroad[7]。
Classification of stomach
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Grass, hay and leaves are the main food for grazing ruminants, while ruminants with economic value (goats and cows, etc.) not only need to feed on grass stem plants, but also need to feed on some artificial refined feed, so that they can grow more plump.Therefore, ruminants have more kinds of food than other animals, and their food composition is more complex. What's more, the high content of crude fiber in forage makes it difficult to digest. Therefore, most ruminants must rely on the division and cooperation of four stomachs to complete the second "chewing" of food[8]。
The first "dark room" where food enters the gastrointestinal tract of ruminants is also the "main battlefield" of food digestion.It is a closed living fermentation tank, in which there are many kinds of microorganisms, mainly including protozoa, bacteria and fungi.Usually, every milliliter of rumen fluid contains 160-40 billion bacteria, 200000 ciliates and a large number of fungi.Don't underestimate these microorganisms. They are the specific executors of the rumen's digestive physiological function.After the food arrives in the rumen, a large number of microorganisms immediately cling to the food surface and secrete cellulase, hemicellulase andβ-Glycosidase and other digestive enzymes, so the cellulose, hemicellulose, pectin and other polysaccharide substances in food will soon be "cut" into monosaccharides, and "transformed" into volatile fatty acids and CO2, the former can provide 60-70% energy sources for ruminants.And these polysaccharidesPhytonutrientsThe ruminant itself is indigestible, so it must rely on the powerful "force" of microorganisms, because although the rumen is large, its mucosa has no digestive gland, and it cannot secrete digestive juice, so it is estimated that it is inflated by a large amount of food.After the food is fully digested by microorganisms in the rumen, about 50% of the crude fiber can be digested in the rumen[9]。
2. Reticulum
A stomach chamber close to the rumen. Its mucous membrane looks like a beehive, so it is also commonly known as "Bee Leaving the Stomach".In fact, the reticulum and rumen are not completely separated in spatial structure, so food particles can freely shuttle back and forth between the two stomach chambers.So, what physiological function does the reticulum have?In fact, the food that ruminants eat in the wild often contains some foreign matters such as iron nails. At this time, the reticulum is like a sieve. Storing these foreign matters in it not only plays the role of filtering, but also prevents the damage of foreign matters to the internal surface of other intestines.In addition, the sensor on the reticulum mucosa can accept the mechanical stimulus signal from grass or hay, and start the rumination behavior by contracting the muscle on the stomach wall of the rumen reticulum[10]。
3. Omasum stomach
It passes through the reticulum in the front and connects with the abomasum in the rear. Because its mucosa faces inward and forms many leaf valves of different sizes, it is also called the heavy flap stomach.The digestion of food by this stomach is more like the "sequel" of rumen digestion. It is like a water pump. The rough part of the chyme from the rumen is concentrated here, and the water and electrolyte are removed and further refined. At the same time, the thinner chyme is pushed into the abomasum.20% cellulose in food can be digested in the omasum[11]。
4. Abomasum
The stomach chamber next to the small intestine is also the only stomach with secretory function. It has a real digestive function, so it is called the true stomach.The abomasum can secrete a large amount of gastric juice, including hydrochloric acid, pepsin, rennet and other digestive enzymes, as well as a large amount of mucus.These secretions mainly further chemically digest the primary metabolites of food digested by the first three stomachs.
In addition to the digestion of microorganisms and digestive enzymes, the digestion of ruminants also depends on the muscle contraction of these four stomach bodies.Just imagine that if food cannot flow between the stomach chambers, wouldn't the four stomachs of ruminants be broken?Their rhythmic contraction forms a directional pressure gradient, which causes the flow and emptying of chyme in each gastric compartment.Gastric wallThe muscle movement of the stomach mainly plays three roles: the function of storing food, the function of mixing food and gastric juice to form semi liquid chyme, and the function of emptying food.It can be seen from this that the four stomachs of ruminants have their own physiological digestion characteristics, but they are connected with each other to jointly complete the digestion function of food[8]。
Application of probiotics
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In recent years, it has been used in ruminant productionMicroecological preparationThere are more and more experiments, researches and applications to raise cattle and sheep, and the application effect is also very obvious.Many research data show that ruminant microecological agents affect the quantity and activity of rumen microorganisms through their metabolites, enhance rumen fermentation, improve feed digestion and utilization, and thus improve animal production performance[12]。
Feeding microecological agents to ruminants such as cattle and sheep can affect the rumen microflora, increase the number of rumen bacteria, improve the cell protein synthesis, and improve the composition of cell amino acids.It is reported that the number of cellulolytic bacteria in the rumen has nearly doubled by feeding yeast and other cultures.The increase of cellulolytic bacteria and the total amount of microorganisms in the rumen is conducive to the digestion of crude fiber and other nutrients, thus promoting the improvement of ruminant production performance[13]。
Secondly, feeding ruminants with probiotics can affect the fermentation of rumen nutrients.The addition of microecological agents to the high fiber diet of calves increased the volatile fatty acids (VFA) in the rumen from 111.5 mmol per liter to 124.6 mmol, indicating that the fermentation of rumen nutrients was enhanced.At the same time, supplementation of microecological agents can more effectively degrade rumen crude protein, reduce rumen ammonia nitrogen, and improve nitrogen digestion and utilization.Microecological preparation of ruminant can improve feed intake and digestibility and utilization of nutrients[14]。
Feeding ruminants with microecological agents can improve their production performance.It is reported that Sichuan Agricultural University fed dairy cows with 8701 microecological preparation by adding 50mg preparation per kilogram of body weight once a day for 30 consecutive days. As a result, the daily milk yield of dairy cows increased by 16.8%.The experiment of feeding meat goats with ruminant microecological preparation produced by Zhongye Science and Technology Development Co., Ltd. in Linli of our province showed that it could increase the daily weight gain of goats by 6%~10% and reduce feed consumption by 8%.Feed ruminants with microecological agents, which are generally mixed into concentrate supplements as additives.It is used to feed sheep, adding 50~70g to each sheep every day;It is used to feed cattle, adding 70-100g per head every day.If liquid microecological preparation is used, 1% of the daily drinking water volume of cattle (sheep) can be directly put into the drinking water and allowed to drink freely.In addition, in production practice, it can also be fed at 0.1%~0.3% of the dry matter mass of cattle (sheep) concentrate (coarse) feed.Different livestock breeds and different production stages can be increased or decreased as appropriate, and can be fed flexibly[15]。
