The stomach of artiodactyls consists of. What is the name of the first section of the complex stomach of ruminants?
Ruminant animals do not bother thoroughly chewing the food they eat in their mouths. The food is chewed only lightly. The main processing of the feed takes place in the rumen, where it remains until it reaches a fine consistency. This is facilitated by periodically repeated chewing of gum after belching food into the oral cavity. After thorough re-chewing, the feed bolus is re-swallowed.
Stomach ruminants complex and multi-chambered. It consists of four sections: rumen, mesh, book and abomasum. The first three are called proventriculi, the last - the fourth - abomasum is the true stomach. The rumen is the largest initial chamber of the ruminant stomach. Its capacity for cattle is 100-300 liters, for sheep and goats - 13-23 liters. It occupies almost the entire left half of the abdominal cavity. The inner shell does not have glands; it is keratinized on the surface, with many papillae, which creates a very rough surface.
The mesh is a small round bag. The inner surface has no glands. Its mucous membrane protrudes in the form of lamellar folds up to 12 mm in height, forming mesh cells. The mesh is connected to the scar, book and esophagus by a special formation - the esophageal groove in the form of a semi-closed tube. The mesh in the proventriculus is necessary for the ruminant body as a sorting organ. It creates conditions for the further passage of only sufficiently crushed, liquefied mass into the book. The book is an additional filter and shredder of retained large particles of feed. Active absorption of water also occurs in it.
The book lies in the right hypochondrium and has a round shape. On the one hand, it serves as a continuation of the mesh, on the other, it passes into the abomasum. Its mucous membrane forms various folds (leaflets), at the ends of which there are rough short papillae. The abomasum is a true stomach of an elongated shape in the form of a curved pear, thickened at the base. At the point of its connection with the book, the opposite narrow end passes into the duodenum. The mucous membrane of the abomasum has glands.
In the rumen of ruminants, the feed then lingers for a long time, where complex processes of its decomposition occur. First, the fiber is broken down, in which the microorganisms inhabiting the forestomach in the form of simple ciliates and bacteria play a huge role. The species composition of microorganisms depends on the composition of the feed in the diet, therefore, for ruminants, a gradual transition from one type of feed to another is important. It is the presence of these microorganisms that is associated with the ability to digest fiber and use it as a source of energy.
In addition, fiber promotes normal motility of the proventriculus, which ensures the movement of feed masses through the gastrointestinal tract. Here, in the rumen of ruminants, fermentation processes of food masses take place, aimed at the breakdown and absorption of starch and sugars. In the rumen, almost completely (60-80%) protein is broken down and microbial protein is produced from non-protein nitrogenous compounds, of which approximately 135 g is formed from 1 kg of digestible organic matter.
Owners of personal farmsteads who have ruminant animals, in order to receive the greatest amount of products from them and for the animals to be healthy, need to know the digestive characteristics of this group of animals.
In ruminants, of all farm animals, the stomach is the most complex - multi-chambered, divided into four sections: rumen, mesh, book, the first three sections are called forestomach, the last - abomasum - is the true stomach.
Scar– the largest section of the stomach of ruminants, its capacity in cattle, depending on age, ranges from 100 to 300 liters, in sheep and goats from 13 to 23 liters. In ruminants, it occupies the entire left half of the abdominal cavity. Its inner shell does not have any glands; on the surface it is keratinized and is represented by many papillae, which give its surface roughness.
Net- is a small round bag. The inner surface also does not have glands. The mucous membrane is represented by protruding lamellar folds up to 12 mm high, forming cells that resemble a honeycomb in appearance. The mesh is connected to the scar, book and esophagus by the esophageal groove in the form of a semi-closed pipe. The mesh in ruminants works on the principle of a sorting organ, allowing only sufficiently crushed and liquefied feed into the book.
Book- lies in the right hypochondrium, has a rounded shape, on one side it is a continuation of the mesh, on the other it passes into the stomach. The mucous membrane of the book is represented by folds (leaflets), at the ends of which there are short, rough papillae. The book is an additional filter and roughage chopper. The book absorbs abundant water.
Abomasum– is a true stomach, has an elongated shape in the form of a curved pear, at the base - a thickened narrow end of which passes into the duodenum. The mucous membrane of the abomasum has glands.
Food swallowed by animals will first enter the vestibule of the rumen, and then into the rumen, from which, after some time, it returns to the oral cavity for repeated chewing and thorough wetting with saliva. This process in animals is called chewing. Regurgitation of food mass from the rumen into the oral cavity is carried out according to the type of vomiting, in which the mesh and diaphragm sequentially contract, while the animal’s larynx closes and the cardiac sphincter of the esophagus opens.
Chewing gum in animals usually starts 30-70 minutes after eating and proceeds in a strictly defined rhythm for each animal species. The duration of mechanical processing of a food coma in the form of chewing gum in the mouth is about one minute. The next portion of food enters the mouth after 3-10 seconds.
The ruminant period in animals lasts for on average 45-50 minutes, then the animals begin a period of rest, which lasts for different times in different animals, then the period of chewing begins again. During the day, a cow chews about 60 kg nutritional contents of the rumen.
The chewed food is then re-swallowed and enters the rumen, where it is mixed with the entire mass of rumen contents. Thanks to strong contractions of the proventriculus muscles, food is mixed and moved from the vestibule of the rumen to the abomasum.
The multichamber stomach in ruminants performs a unique, complex digestive function. In the rumen, the animal's body uses 70-85% digestible dry matter diet and only 15-30% used the rest of the gastrointestinal tract animal.
A biological feature of ruminants is that they consume a lot of plant feed, including roughage, which contains a large amount of hard-to-digest fiber. Due to the presence of numerous microflora (bacteria, ciliates and fungi) in the rumen contents, plant foods are subject to very complex enzymatic and other processing. The number and species composition of microorganisms in the rumen of animals depends on a number of factors, of which feeding conditions play a primary role. At every By changing the feeding diet, the microflora in the rumen also changes Therefore, for ruminants, a gradual transition from one type of diet to another is of particular importance. The role of ciliates in the rumen is reduced to the mechanical processing of feed and the synthesis of their own proteins. They loosen and break down the fiber so that the fiber later becomes more accessible to enzymes and bacteria. Under the influence of cellulolytic bacteria in the forestomach, up to 70% of the digestible fiber is broken down, out of 75% of the dry matter of the feed digested here. In the rumen, under the influence of microbial fermentation, a large amount of volatile fatty acids - acetic, propionic and butyric, as well as gases - carbon dioxide, methane, etc. During the day, up to 4l volatile fatty acids, and their ratio directly depends on the composition of the diet. Volatile fatty acids are almost completely absorbed in the forestomach and are a source for the animal's body. energy, and are also used for the synthesis of fat and glucose. When microorganisms enter the abomasum, they die under the influence of hydrochloric acid. In the intestine, under the influence of amylolytic enzymes, they are digested to glucose. 40-80%
of protein supplied with food (protein) in the rumen is subjected to hydrolysis and other transformations, is broken down by microbes to peptides, amino acids and ammonia, amino acids and ammonia are also formed from non-protein nitrogen entering the rumen. Simultaneously with the processes of breakdown of plant protein in the rumen, synthesis occurs bacterial protein and protozoan protein. For this purpose, non-protein nitrogen (carbamide, etc.) is also used in practice. Can be synthesized in the rumen within 24 hours from 100 to 450 grams microbial protein. Subsequently, bacteria and ciliates with the contents of the rumen enter the abomasum and intestines, where they are digested to amino acids, fats are also digested here and conversion of carotene to vitamin A. Due to the protein of microorganisms, ruminants are able to satisfy up to 20-30% of the body's protein needs. In the rumen of animals, the microorganisms present there synthesize amino acids, incl. and irreplaceable.
Along with the breakdown and synthesis of protein in the rumen, ammonia absorption, which is converted in the liver into urea. In cases where a large amount of ammonia is formed in the rumen, the liver is not able to convert it all into urea, its concentration in the blood increases, which leads to the appearance of clinical signs in the animal toxicosis.
Lipolytic enzymes microorganisms in the rumen are hydrolyzed feed fats to glycerol and fatty acids, and then are synthesized again in the rumen wall.
The microflora present in the rumen synthesizes vitamins: thiamine, riboflavin, pantothenic acid, pyridoxine, nicotinic acid, biotin, folic acid, cobalamin, vitamin K in quantities that practically meet the basic needs of adult animals.
The activity of the rumen is closely interconnected with other organs and systems and is under the control of the central nervous system. The mechano- and baroreceptors present in the rumen are irritated by the stretching and contraction of the muscle layer, chemoreceptors are irritated by the environment of the rumen contents and together influence the tone of the muscle layer of the rumen. The movements of each section of the proventriculus affects other sections of the digestive tract. Thus, overflow of the abomasum slows down the motor activity of the book; overflow of the book weakens or stops the contraction of the mesh and scar. Irritation of the mechanoreceptors of the duodenum causes inhibition of contractions of the forestomach.
Diseases of the proventriculus are observed most often in cattle, less often in small cattle, leading to a sharp decrease in productivity, and sometimes case.
Most common causes of diseases forestomach are: untimely feeding, poor-quality feed, contamination of feed with metal objects, rapid transition from succulent feed to dry and vice versa.
One-sided heavy feeding of concentrates, brewer's grains and stillage or rough low-nutrient feeds leads to disruption of the function of the proventriculus and metabolism.
The leading factor in the occurrence of forestomach diseases is a violation of the motor and microbial functions of the forestomach. Under the influence of strong irritation of mechano-, thermo- and chemoreceptors, rumen contractions are inhibited, chewing gum is disrupted, digestion in the rumen is disrupted, the pH of the rumen contents changes to the acidic side, the contents are subject to microbial decay with the formation of toxins.
- the largest section of the stomach, and in newborns the second largest. At the posterior end of the scar, dorsal and ventral caudal blind sacs are separated.
The esophagus enters the anterior end of the dorsal hemi-sac.
The mucous membrane of the rumen is leathery, glandless, dark brown in color; papillae of various sizes and shapes up to 10 mm long rise on it. It has independent mobility, since they contain muscle fibers. The papillae give the scar a rough surface. They are absent on the cords, where the mucous membrane is also lighter.
The muscular layer of the scar is formed by two layers of bundles of smooth muscle fibers. In the outer layer, the bundles run in a spiral shape in the form of a figure eight. In a deep layer, the beams run circularly. They are also common to both scar bags. In the area of the cords, the muscle wall of the scar is thickened.
The serous membrane of the scar in the area of the longitudinal grooves passes into the greater omentum. The ventral scar sac is located in the cavity of the omental sac.
Net
The mesh is spherical in shape, smaller than a book and serves as a continuation of the vestibule of the scar. It lies in front of the scar, separated from it on the outside by a furrow, and inside by a cord of scar and mesh. It communicates with the scar through a large hole, and with the book through a slit-like hole.
The mucous membrane of the mesh is leathery, glandless, covered with small keratinized papillae and collected in non-distributing but movable folds that form the (4) - 5 - (6) coal cells of the mesh.
The muscular layer of the mesh consists of two layers: an external transverse layer and an internal longitudinal layer, running almost parallel to the esophageal groove. The bottom of the esophageal groove is formed internally by a transverse layer of smooth muscle of the mesh, and externally by a longitudinal layer originating from the striated muscle of the esophagus. The serous membrane passes onto the mesh from neighboring parts of the stomach.
The stomach of ruminants is multi-chambered: rumen, mesh, book and abomasum.
The first three sections are the proventriculus, and the abomasum is the true stomach. The food swallowed by the animal ends up in the rumen. After chewing gum, fiber is digested in the rumen under the influence of microorganisms without the participation of digestive enzymes. There is a huge number of anaerobic microorganisms: bacteria, ciliates and fungi. Ciliates crush food particles, as a result of which it becomes more accessible to the action of bacterial enzymes. Ciliates, digesting proteins, partially fiber, starch, accumulate complete proteins and glycogens in their bodies. Under the influence of cellulolytic bacteria in the proventriculus of ruminants, digestive fiber is broken down.
In the rumen of ruminants, with the help of proteolytic enzymes of microorganisms, plant proteins of the feed are broken down into peptides, amino acids and ammonia. Rumen microorganisms synthesize B vitamins and vitamin K. The proteins of microorganisms, when entering the abomasum and intestines, are used by the animal. During the life of microorganisms in the rumen, gases are formed: carbon dioxide, methane, nitrogen, hydrogen, hydrogen sulfide, which are converted into a number of valuable nutrients.
From the rumen, the feed enters the mesh, which passes the crushed liquefied mass through it. When the book is reduced, the feed particles are further crushed. The abomasum is a true stomach that secretes rennet juice. The secretion of rennet juice occurs continuously, since rumen contents constantly enter the abomasum.
The small intestine extends from the stomach to the cecum. Digestion of food occurs in it, which is provided by pancreatic and intestinal juices and bile. Pancreatic juice is produced by the pancreas and enters the duodenum through the duct; it contains enzymes that break down proteins, carbohydrates and lipids.
A liver secretion is released into the cavity of the duodenum - bile, which emulsifies fat, which facilitates the action of lipase on fat, amylase, and proteases. Bile helps neutralize the acidic contents entering the intestines from the stomach.
The mucous membrane of the small intestine secretes intestinal juice, which contains enzymes that digest undigested foods.
The large intestine secretes juice containing mainly mucus and a small amount of weakly active enzymes. Digestion here occurs mainly due to enzymes brought with chyme from the small intestines, as well as under the influence of bacteria. The thick section contains a huge number of bacteria that break down fiber, ferment carbohydrates, and decompose proteins and fat.
The digestive apparatus transfers various substances into the blood and lymph. Almost no absorption occurs in the oral cavity. Water, glucose, amino acids, and minerals are absorbed in the stomach in small quantities. In the forestomach there is intensive absorption of water, minerals, ammonia, and gases. The main site of absorption of all substances in animals is the small intestine.
Food moves through the digestive tract as a result of peristaltic muscle contraction. It is caused by mechanical irritants - coarse particles of food and chemical ones - bile, acids, alkalis, polypeptides. The central nervous system regulates intestinal contractions.
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The digestive system of a ruminant animal may surprise the uninitiated in agricultural affairs. Thus, the digestive system of cows is very voluminous, which is associated with the need to process a large amount of incoming food. A large supply of food is naturally necessary to produce a sufficient amount of dairy products. The quality of the food entering the stomach should also be taken into account, since it is usually coarse, hence the need for a large amount of time to completely break down the food.
The stomach of a cow, like that of other cattle, is structured in a very unique way. How many stomachs does a cow have, how is it structured in general? digestive system these animals? We will answer these and a number of related other questions below in this article. Each section of the stomach has its own functions. We will also focus on them.
Cows do not bother much about chewing their food, only slightly grinding the grass they eat. The main part of the feed is processed in the rumen to a fine pulp.
The cow’s digestive system, on the one hand, ideally and rationally distributes time during grazing, and on the other hand, allows for the maximum extraction of all nutrients from roughage. If there is a cow chew thoroughly Every blade of grass she picks, she will have to spend the whole day in the pasture eating grass. During rest, it is worth noting that the cow constantly chews the food that has collected in the rumen and is now being re-chewed.
Section of the stomach of ruminants
The cow's digestive system consists of several sections that differ in function, namely:
The mouth of these animals is especially interesting, since its main purpose is to pluck grass, hence the presence of exclusively the front row of lower teeth. Impressive saliva volumes, released every day, it reaches approximately 90 to 210 liters! Enzymatic gases accumulate in the esophagus.
How many stomachs does a cow have? One, two, three or even four? This will cause surprise, but there is only one, but consisting of four departments. The first and largest compartment is the scar, and the proventriculus contains a mesh and a book. No less interesting and not quite euphonious name The fourth chamber of the stomach is the abomasum. The entire digestive system of the cow requires detailed consideration. Learn more about each department.
Scar
The cow's rumen is the largest chamber and performs a number of very important digestive functions. Thick-walled tripe is not affected by rough food. Minute reduction of the rumen walls provides stirring the eaten grass, subsequently the enzymes distribute them evenly. Here, in addition, hard stems are crushed. What is a scar used for? Let us outline its main functions:
- enzymatic - intracellular bacteria launch the digestive system, thereby ensuring the initial fermentation process. The rumen actively produces carbon dioxide and methane, with the help of which all food entering the organ is broken down. If carbon dioxide does not regurgitate, the animal’s stomach swells, and as a result, the functioning of other organs malfunctions;
- function of mixing food - scar muscles contribute to mixing food and its further release for repeated chewing. Interestingly, the walls of the rumen are not smooth, but with small formations resembling warts, which facilitate the absorption of nutrients;
- transformation function - more than one hundred billion microorganisms present in the rumen contribute to the conversion of carbohydrates into fatty acids, which provides energy to the animal. Microorganisms are divided into bacteria and fungi. Protein and ammonia keto acids are converted thanks to these bacteria.
A cow's stomach can hold up to 150 kg of feed, a huge proportion of which is digested in the rumen. Up to 70 percent of the food eaten is found here. There are several bags in the rumen:
- cranial;
- dorsal;
- ventral.
Probably, each of us has noticed that a cow, some time after eating food, regurgitates it back to chew it again. A cow spends more than 7 hours every day on this process! Repeatedly regurgitation is called chewing gum. This mass is thoroughly chewed by the cow, and then ends up not in the rumen, but in another section - in the book. The rumen is located in the left half of the abdominal cavity of the ruminant.
Net
The next section in the cow's stomach is the mesh. This is the smallest compartment, with a volume not exceeding 10 liters. The mesh is like a sieve that stops large stems, since in other sections coarse food will immediately cause harm. Imagine: a cow chewed grass for the first time, then food got into the rumen, belched, chewed again, hit the net. If the cow has not chewed thoroughly and left behind large stems, they will be stored in a net for one to two days. What is this for? The food is decomposed and again offered to the cow for chewing. And only then does the food go into another section - the book.
The mesh has a special function - it separates large pieces of food from small ones. Thanks to the mesh, large pieces are returned back to the rumen for further processing. There are no glands in the mesh. Like a rumen, the mesh walls are covered with small structures. The grid consists of small cells that define food processing level the previous chamber, that is, the scar. There are no glands in the mesh. How is the mesh connected to other sections - the scar and the book? Very simple. There is an esophageal groove, shaped like a semi-closed tube. Simply put, the net sorts food. Only sufficiently crushed food can get into the book.
Book
The book is a small compartment that holds no more than 5 percent of the food consumed. The capacity of the book is about 20 liters. Only here the food repeatedly chewed by the cow is processed. This process is ensured by the presence of numerous bacteria and potent enzymes.
It is no coincidence that the third section of the stomach is called a book, which is due to the appearance of the section - continuous folds, divided into narrow chambers. Food is located in folds. The cow's digestive tract does not end there - the incoming saliva processes the food, and fermentation begins. How is food digested in a book? Feed distributed along the folds and then becomes dehydrated. Moisture absorption is carried out due to the peculiarities of the mesh structure of the book.
The book performs an important function in the entire digestion - it absorbs food. On my own the book is quite voluminous, but it holds a small amount of food. The book absorbs all moisture and mineral components. What is the book like? An elongated bag with numerous folds.
The book is like a filter and chopper of large stems. In addition, water is absorbed here. This department is located in the right hypochondrium. It is connected to both the mesh and the abomasum, that is, it continues the mesh, passing into the abomasum. Shell of the third section The stomach forms folds with small nipples at the ends. The abomasum is elongated in shape and resembles a pear, which is thickened at the base. Where the abomasum and book connect, one end connects to the duodenum.
Why does a cow chew her food twice? It's all about the fiber contained in plants. It is difficult and time-consuming to process, which is why double chewing is necessary. Otherwise the effect will be minimal.
Abomasum
The last section of the cow's stomach is the abomasum, similar in structure to the stomachs of other mammals. A large number of glands and constantly secreted gastric juice are features of abomasum. Longitudinal rings in abomasum form muscle tissue. The walls of the abomasum are covered with a special mucus, consisting of their epithelium, containing the pyloric and cardiac glands. The mucous membrane of the abomasum is formed from numerous elongated folds. The main digestive processes take place here.
Huge functions are assigned to the abomasum. Its capacity is about 15 liters. Here the food is prepared for final digestion. The book absorbs all the moisture from the food, therefore, it enters the abomasum already in a dried form.
Let's sum it up
Thus, the structure of the cow’s stomach is very unique, since the cow does not have 4 stomachs, but a four-chamber stomach, which ensures the processes of the cow’s digestive system. The first three chambers are an intermediate point, preparing and fermenting the incoming feed, and only in the rennet contains pancreatic juice, completely processing food. The digestive system of a cow includes rumen, mesh, book and abomasum. The enzymatic filling of the rumen ensures the process of breaking down food. The structure of this compartment resembles a similar human organ. The rumen of cattle is very capacious - 100 - 300 liters; that of goats and sheep is much smaller - only 10 - 25 liters.
Long-term retention of food in the rumen ensures its further processing and decomposition. First, fiber undergoes breakdown, and is involved in a huge number of microorganisms. Microorganisms change depending on the food, so there should not be a sharp transition from one type of food to another.
Fiber is very important for the body of the ruminant animal as a whole, since it provides good motor skills pregastric sections. Motility, in turn, ensures the passage of food through the gastrointestinal tract. In the rumen, the process of fermentation of feed masses occurs, the mass is broken down, and the body of the ruminant animal absorbs starch and sugar. Also in this section, protein is broken down and non-protein nitrogen compounds are produced.
The acidity of the environment in the abomasum is provided by numerous glands located on the walls of the abomasum. The food here is broken down into tiny particles, and then the nutritional elements are completely absorbed by the body, ready mass moves into the intestines, where the most intense absorption of all beneficial microelements occurs. Imagine: a cow eats a bunch of grass in the pasture, and the digestion process begins, which ultimately takes from 48 to 72 hours.
The digestive system of cows is very complex. These animals must eat continuously, as a break will cause big problems and will have a very negative impact on the health of the cow. Complex structure of the digestive system has negative qualities - indigestion is a common cause of cow mortality. Does a cow have 4 stomachs? No, just one, and the entire digestive system includes the oral cavity, pharynx, cow's esophagus and stomach.
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