Features of the structure of the digestive system of ruminants. How does a cow's stomach work? The structure of the stomach of ruminants drawing

The stomach is a sac-like extension of the digestive tube, into which the esophagus enters on one side, and the intestines begin on the other. It serves as a container for more or less long-term storage of food masses and their partial chemical processing.

The expansion of the digestive tube can be in the form of a single chamber or a series of recumbent chambers. Accordingly, stomachs are single-chamber (dogs, horses, pigs) and multi-chamber (ruminant animals).

There are also glandular stomachs, or intestinal type, and mixed, or esophago-intestinal type. In glandular stomachs, the mucous membrane is covered with a single layer of prismatic epithelium and contains many glands that open into the stomach cavity. Glandular stomachs in dogs and cats. In the stomachs of the esophago-intestinal type, part of the mucous membrane is covered with a squamous stratified epithelium, and part is covered with a single-layer prismatic epithelium. Stomachs of the esophago-intestinal type are inherent in ruminants (cattle, sheep, goats), pigs, horses, reindeer, camels.

Single chamber stomachs

The single chamber stomach is a curved sac. It distinguishes: the entrance (cardia) - the place where the esophagus enters and the exit into the duodenum - the pylorus, or pylorus. The middle part, lying between the entrance and exit, is called the bottom, or fundus. In addition, there are large (convex) and small (concave) curvature, anterior (hepato-diaphragmatic) and posterior (intestinal, visceral) surfaces.

The wall of the stomach consists of three layers:

1) external - serous,

2) medium - muscular and

3) internal - mucosal.

In the mucous membrane of the stomach of the intestinal type, there are three types of glands: 1) cardiac, 2) fundic and 3) pyloric.

The muscular coat is formed by smooth muscle fibers that form the longitudinal, annular and oblique layers. The outer, longitudinal, layer of the muscular membrane is located mainly along the curvatures; the layer of circular fibers is located mainly in the right half of the stomach and forms the pyloric sphincter; the oblique layer is characteristic of the left side of the stomach, consists of the outer and inner layers and forms the cardiac sphincter.

The serous membrane is represented by the visceral sheet of the peritoneum.

Pig stomach- single-chamber, esophago-intestinal type, in the left dorsal part has a conical blind protrusion - a diverticulum of the stomach, directed, caudally apex. The lesser curvature is convex.

In the cardiac zone, a small part of the mucous membrane is covered with squamous stratified epithelium, in the rest - with prismatic epithelium and contains glands of all three types. The circular layer of the muscular membrane of the pylorus forms a kind of sphincter, which consists of a transverse roller on the side of the greater curvature and a button-shaped protrusion on the side of the lesser curvature. The stomach lies in the left and right hypochondrium and in the region of the xiphoid cartilage.

The horse's stomach is single-chamber, esophago-intestinal type. It is an elongated, relatively small curved sac, which has a clearly visible constriction to the left of the middle of the greater curvature, indicating the border between the glandular and non-glandular part. From the side of the mucous membrane, the glandless part is white, the glandular part is pink.

The left end of the stomach forms a round blind sac. In the cardial part, a powerful loop-shaped cardiac sphincter (compressor) is formed from the inner oblique muscle layer. This powerful sphincter, as well as the narrow lumen of the esophagus with thick muscular walls, together form a strong closing device. As a result, when the stomach is overflowing with food or gases, this device, as it were, automatically closes the opening of the esophagus, so the release of the stomach by vomiting in a horse is impossible.

The horse's stomach is located in the left hypochondrium, and only the pyloric part of it enters the right hypochondrium. The blind sac faces the vertebral ends of the left ribs, and the most ventral part of the stomach lies at half the height? abdominal cavity, on the dorsal transverse position of the large colon.

The dog's stomach is single-chamber, intestinal (glandular) type. The pyloric region is strongly narrowed and elongated like a gut. The stomach is located in the left and right hypochondria and in the region of the xiphoid cartilage.

The stomach of ruminants (Fig. 1) is of the esophago-intestinal type. It consists of four chambers: scar, mesh, book and abomasum. The first three chambers are the proventriculus, which make up the alimentary-water part of the stomach, the last chamber is the glandular stomach itself.

Rice. 1. Multichamber stomach of ruminants:

A - the stomach of a cow; B - esophageal trough; B - leaflets of the book; G - mucous membrane of the abomasum; 1 - blind protrusions (bags) of the scar and transverse grooves; 2 - half bags of the scar and the right longitudinal groove between them; h - esophagus; 4 - grid; about - book 6 - abomasum; 7 - the beginning of the duodenum; 8 - entry from the esophagus 9- esophageal trough; 10 - entrance from the grid to the book; 11 - leaflets of the book; 12 - sail-like folds of the book at the entrance to the abomasum; 13 - spiral folds in the abomasum, 14 - scar vestibule; 15 - mesh combs; 16 - lips of the esophageal trough.

The reason for the appearance of such a complex stomach in ruminants is the originality of their way of eating - coarse, indigestible plant food with a huge amount of fiber that requires careful processing. The feed is chewed by ruminants twice: the first time hastily, during the feeding itself, the second time more thoroughly, at rest (ruminant period). This method of feeding gave the wild ancestors of our ruminants certain advantages in the struggle for existence, as it helped to capture a large amount of food in a relatively short period of time, keep it in the stomach for a certain time, and then subject it to repeated thorough mechanical processing already in a state of rest, safe from predators. place.

Scar- the largest chamber of the stomach of ruminants. It fills the entire left half of the abdominal cavity and partly passes to the right half. The scar is flattened laterally; it distinguishes between the left, parietal, surface and the right, visceral, to which the intestines and other organs are adjacent; left, dorsal, and right, ventral, edges; thoracic end and pelvic end. Two longitudinal grooves, right and left, cranial and caudal scar grooves divide the scar into the upper half-sac and the lower half-sac. Transverse grooves at the pelvic end of the scar are delimited on each half bag along a blind ledge. At the thoracic end, the upper blind protrusion, called the vestibule of the scar, is separated from the upper half-pouch. The esophagus opens into the vestibule and continues into the esophagus.

On the inner surface of the scar, longitudinal and transverse grooves correspond to strands formed by folds of the mucous membrane and thickening of the muscular membrane.

The mucous membrane of the scar is lined with stratified squamous keratinized epithelium, does not contain glands and is covered with numerous papillae (in cattle up to 1 cm long), creating a roughness that promotes grinding and movement of food masses. In the region of the strands, the mucous membrane is smooth and lighter.

The muscular layer consists of longitudinal and transverse layers.

The grid looks like an almost rounded bag. On its inner surface, high ridges are developed, which, intersecting with each other, delimit cells that look like honeycomb cells. In the depths of these cells are smaller cells from the lower ridges. Muscle fibers are embedded in high and low ridges. This indicates that the ridges are able to contract. The mucous membrane of the mesh is covered with flat stratified keratinized epithelium and dotted with small keratinized papillae. The mesh is connected to the scar with the opening of the scar and the mesh, with the book - with the hole of the mesh and the book.

On the inner surface of the right wall of the vestibule of the scar and the mesh from the esophageal opening to the opening of the mesh and the book, the esophageal trough goes twisting in the form of a spiral. It is formed by two roll-like elevations of the mucous membrane, called lips; between them is the bottom of the gutter. At the base of the lips are bundles of longitudinal smooth muscle fibers. The musculature of the bottom of the esophageal trough consists of an inner, transverse, layer of smooth muscle fibers and an outer, longitudinal layer, which also contains striated muscle fibers. During fluid intake, the lips of the esophageal trough close almost into a tube and the fluid from the esophagus freely enters directly into the book, bypassing the scar and mesh.

The mesh is involved in the burping of the gum: with the help of its cells, a burping food lump is formed. It lies in the region of the xiphoid cartilage and in the right and left hypochondria.

Book in cattle it is spherical, somewhat flattened laterally, in small ruminants it is oval in shape. It distinguishes the right and left surfaces, large and small curvatures. The book got its name because its mucous membrane is collected in numerous folds called leaflets. In size, they are of four types: large, medium, small and the smallest (goats do not have). The leaflets have smooth muscle fibers embedded from the muscle layer of the book. The leaflets are covered with stratified epithelium that has become keratinized from the surface and are densely covered with horny papillae. There are no leaflets on the bottom wall of the book, called the bridge, or bottom, of the book. This bridge in the form of a trough is located between the holes from the mesh into the book and into the abomasum. From the sides, it is delimited by two roll-like folds of the mucous membrane. The muscular layer of the bridge forms the sphincter.

On the sides of the hole in the abomasum, two sail-like folds of the book rise, preventing the contents of the abomasum from returning to the book. The leaflets of the book are located radially in relation to the bridge. Between the free edges of the leaves and the gutter of the bridge, there remains a free space leading from the book to the abomasum - the channel of the book.

The food mass caught between the leaves is kneaded and rubbed, at the same time liquid is squeezed out of it.

The book lies in the right hypochondrium, dorsally from the mesh and abomasum, between the scar and the liver.

The abomasum is a real glandular stomach, it is an elongated pear-shaped sac. Thickened, front, its end opens into a book; narrowed, posterior, end passes into the duodenum. Dorsal, small, curvature facing the spine, ventral, large, to the abdominal wall.

The mucous membrane of the abomasum is covered with prismatic glandular epithelium and contains cardiac, fundal and pyloric glands. It forms 12-16 wide, long, permanent, non-spreading spiral folds.

The muscular coat of the abomasum consists of the outer - longitudinal and inner - annular layers.

The abomasum lies in the right half of the region of the xiphoid cartilage and in the right hypochondrium.

In cattle, the largest section of the stomach is the scar, followed by the book, then the rennet, and lastly the mesh. In sheep and goats, the first place in size is the scar, the second is the abomasum, the third is the net, and the fourth is the book.

The stomach of ruminants is multi-chamber: scar, mesh, book and abomasum.

The first three sections are the proventriculus, and the abomasum is the true stomach. The food swallowed by the animal enters 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. Infusoria crush food particles, as a result of which it becomes more accessible for the action of bacterial enzymes. Ciliates, digesting proteins, partially fiber, starch, accumulate complete proteins and glycogens in their body. Under the action of cellulolytic bacteria in the proventriculus of ruminants, digest - my fiber is broken down.

In the rumen of ruminants, with the help of proteolytic enzymes of microorganisms, vegetable feed proteins are broken down into peptides, amino acids and ammonia. Rumen microorganisms synthesize vitamins of group B and vitamin K. The proteins of microorganisms are used by animals when they enter the abomasum and intestines. During the vital activity of microorganisms in the rumen, gases are formed: carbon dioxide, methane, nitrogen, hydrogen, hydrogen sulfide, which turn into a number of valuable nutrients.

From the scar, the feed enters the mesh, which passes the crushed liquefied mass through itself. With the reduction of the book, further grinding of the feed particles occurs. The abomasum is a true stomach that secretes rennet juice. The secretion of rennet juice occurs continuously, since cicatricial contents constantly enter the abomasum.

The small intestine extends from the stomach to the caecum. Digestion of food occurs in it, which is provided by pancreatic, 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.

The secret of the liver is secreted into the cavity of the duodenum - bile, which emulsifies fat, which facilitates the action of lipase on fat, amylases, and proteases. Bile contributes to the neutralization of acidic contents entering the intestines from the stomach.

The mucous membrane of the small intestine secretes intestinal juice, which contains enzymes that digest underdigested products.

The large intestine secretes a 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. In the thick section there is a huge number of bacteria that break down fiber, ferment carbohydrates, decompose proteins and fat.

The digestive apparatus transfers various substances into the blood and lymph. Almost no absorption occurs in the oral cavity. Small amounts of water, glucose, amino acids, and minerals are absorbed in the stomach. In the proventriculus there is an intensive absorption of water, minerals, ammonia, gases. The main place 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 stimuli - coarse feed particles and chemical - bile, acids, alkalis, polypeptides. The central nervous system regulates intestinal contractions.

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Owners of personal farmsteads who have ruminants, 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: scar, mesh, book, the first three sections are called proventriculus, the last - abomasum is a true stomach.

Scar- the largest section of the stomach of ruminants, its capacity in cattle, depending on age, is 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, as such, does not have glands, it is keratinized from the surface and is represented by many papillae, which roughen its surface.

Grid- is a small rounded bag. The inner surface also has no glands. The mucous membrane is represented by protruding in the form of lamellar folds up to 12 mm high, forms cells that resemble honeycombs in appearance. With the scar, book and esophagus, the mesh communicates with the esophageal trough in the form of a semi-closed tube. The mesh in ruminants works on the principle of a sorting organ, passing only sufficiently crushed and liquefied feed into the book.

Book- lies in the right hypochondrium, has a rounded shape, on the one hand it is a continuation of the grid, on the other it passes into the stomach. The mucous membrane of the book is represented by folds (leaves), at the ends of which there are short, coarse papillae. The book is an additional filter and grinder for roughage. The book absorbs a lot of 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.

The food swallowed by animals will first fall into the vestibule of the scar, and then into the scar, from which, after some time, it returns to the oral cavity for re-chewing and thorough wetting with saliva. This process in animals is called chewing gum. The regurgitation of the food mass from the scar into the oral cavity is carried out according to the type of vomiting, in which the mesh and the diaphragm are successively reduced, while the larynx of the animal closes and the cardiac sphincter of the esophagus opens.

Gum animals usually starts 30-70 minutes after eating and proceeds in a rhythm strictly defined 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 goes into the mouth after 3-10 seconds.

The ruminant period in animals lasts for average 45-50 minutes, then the animals enter a period of rest, which lasts for different animals for different times, then the period of chewing begins again. During the day, the cow thus chews about 60 kg food content of the rumen.

The chewed food is then re-swallowed and enters the scar, where it is mixed with the entire mass of the cicatricial contents. Due to strong contractions of the muscles of the proventriculus, food is mixed and moves from the vestibule of the scar to the abomasum.

The multi-chambered stomach in ruminants performs a unique, complex digestive function. In the rumen, the animal's body uses 70-85% digestible dry matter diet but only 15-30% used the rest of the gastrointestinal tract animal.

The biological feature of ruminants is that they consume a lot of vegetable feed, including roughage, which contain a large amount of indigestible fiber. Due to the presence of numerous microflora (bacteria, ciliates and fungi) in the contents of the rumen, plant foods are subjected 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 each changing the diet of feeding in the rumen simultaneously changes the microflora Therefore, for ruminants, the 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 tear the fiber so that the fiber becomes more accessible to the action of enzymes and bacteria. Under the action of cellulolytic bacteria in the pancreas, up to 70% of 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. 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 proventriculus and are a source for the animal organism. energy, and are also used for the synthesis of fat and glucose. When entering the abomasum, microorganisms die under the influence of hydrochloric acid. In the intestine, under the influence of amylolytic enzymes, they are digested to glucose. 40-80% the protein (protein) received with the feed in the rumen undergoes hydrolysis and other transformations, is broken down by microbes to peptides, amino acids and ammonia, amino acids and ammonia are also formed from the non-protein nitrogen entering the rumen. Simultaneously with the processes of cleavage of vegetable protein in the rumen, the synthesis of bacterial protein and protozoan protein. For this purpose, non-protein nitrogen (urea, etc.) is also used in practice. Can be synthesized in the rumen per day from 100 to 450 grams microbial protein. In the future, bacteria and ciliates with the contents of the rumen enter the abomasum and intestines, where they are digested to amino acids, and fats and fats are digested here. 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 needs for protein. 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 in the wall of the scar are synthesized again.

The microflora present in the rumen synthesizes vitamins: thiamine, riboflavin, pantothenic acid, pyridoxine, nicotinic acid, biotin, folic acid, cobalamin, vitamin K in amounts that practically meet the basic needs of adult animals.

The activity of the scar 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 scar are irritated by stretching and contraction of the muscle layer, the chemoreceptors are irritated by the environment of the contents of the scar and all together affect the tone of the muscle layer of the scar. The movement of each of the sections of the proventriculus affects other sections of the digestive tract. So the overflow of the abomasum slows down the motor activity of the book, the overflow of the book weakens or stops the contraction of the mesh and scar. Irritation of the mechanoreceptors of the duodenum causes inhibition of the contractions of the proventriculus.

Diseases of the proventriculus are observed most often in cattle, less often in small cattle, leading to a sharp decline in productivity, and sometimes case.

The most frequent causes of disease of the proventriculus are: untimely feeding, poor-quality feed, contamination of feed with metal objects, a quick transition from succulent to dry feed and vice versa.

One-sided abundant feeding with concentrates, brewer's grains and stillage or coarse low-nutrient feeds leads to a violation of the function of the proventriculus and metabolism.

The leading factor in the occurrence of diseases of the proventriculus is a violation of the motor and microbial functions of the proventriculus. Under the influence of strong irritation of mechano-, thermo- and chemoreceptors, rumen contractions are inhibited, chewing gum is disturbed, digestion in the rumen is disturbed, the pH of the rumen contents changes to the acid side, the contents undergo microbial decay with the formation of toxins.

The digestive system of a ruminant animal can be surprising to a person uninitiated in agricultural affairs. So, 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 enough 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 for the complete breakdown of food.

The stomach of a cow, like that of other cattle, is arranged in a very peculiar way. How many stomachs does a cow have, how is it arranged in general digestive system these animals? These and other related questions will be answered later in this article. Each section of the stomach has its own functions. We will also focus on them.

Cows do not bother chewing food, only slightly crushing the grass they eat. The main part of the feed is processed in the rumen to the state of fine gruel.

The digestive system of the cow, on the one hand, ideally and rationally allocates time during grazing, on the other hand, allows you to extract all the nutrients from the roughage to the maximum. If the cow is chew thoroughly every blade of grass plucked, she will have to spend whole days in the pasture and eat grass. During rest, it is worth noting that the cow constantly chews the food that has collected in the rumen and is now fed for re-chewing.

Division of the stomach of ruminants

The cow's digestive system consists of several departments that differ in function, namely:

Of particular interest is the mouth of these animals, since its main purpose is to pluck grass, hence the presence of an exclusively front row of lower teeth. impress saliva volumes, which stands out for each day, it reaches approximately from 90 to 210 liters! Enzymatic gases accumulate in the esophagus.

How many stomachs does a cow have? One, two, three, or even four? It will be surprising, but only one, but consisting of four departments. The first and largest compartment is the scar, and the proventriculus contains the mesh and the book. No less interesting and not quite euphonious name the fourth chamber of the stomach is the abomasum. Detailed consideration requires the entire digestive system of a cow. More about each department.

Scar

The cow's rumen is the largest chamber that performs a number of very important digestive functions. A thick-walled scar is not affected by rough food. Every minute contraction of the scar walls provides mixing eaten grass, subsequently enzymes distribute them evenly. Here, too, hard stems are rubbed. What is the scar for? Let's designate its main functions:

• enzymatic - intracellular bacteria start the digestive system, thereby providing the initial fermentation process. In the rumen, carbon dioxide and methane are actively produced, with the help of which all the food that enters the body is broken down. In the case of non-regurgitation of carbon dioxide, the animal's stomach swells, and as a result, a malfunction in the work of other organs;
• the function of mixing food - cicatricial muscles contribute to mixing food and its further exit for re-chewing. Interestingly, the walls of the scar are not smooth, but with small formations resembling warts that contribute to the absorption of nutrients;
• transformation function - more than a 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 ammonium keto acids are converted thanks to these bacteria.

The stomach of a cow 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 located here. There are several sacs in the rumen:

• cranial;
• dorsal;
• ventral.

Probably, each of us noticed that a cow, some time after eating, burps it back for re-chewing. A cow spends more than 7 hours a day on this process! re regurgitated mass is called chewing gum. This mass is carefully chewed by the cow, and then it does not fall into the scar, but into another department - into the book. The scar is located in the left half of the abdominal cavity of the ruminant.

Grid

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 departments coarse food will immediately cause harm. Imagine: the cow chewed the grass for the first time, then the food got into the scar, belched, chewed again, hit the grid. If the cow chewed poorly and left large stems, then they will be stored in the net for one to two days. What is it for? The food is decomposed and again offered to the cow for chewing. And only then the food gets into another department - the book.

The grid has a special function - it separates large pieces of food from small ones. Large pieces thanks to the mesh are returned back to the scar for further processing. There are no glands in the grid. Like a scar, the mesh walls are covered with small formations. The grid consists of small cells that define food processing level the previous chamber, that is, a scar. There are no glands in the grid. How is the mesh connected with other departments - the scar and the book? Quite simply. There is an esophageal trough, resembling a semi-closed tube in shape. Simply put, the mesh sorts the food. Only enough crushed food can get into the book.

Book

Book - a small compartment containing no more than 5 percent of the consumed feed. The capacity of the book is about 20 liters. Only here the food that has been chewed many times by a 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 associated with the appearance of the section - continuous folds, divided into narrow chambers. Food is in folds. The digestive tract of the cow does not end there - the incoming saliva processes the food, fermentation begins. How is food digested in a book? Feed distributed in folds and then dehydrated. Moisture absorption is carried out due to the peculiarities of the grid structure of the book.

The book performs an important function in all digestion - it absorbs food. By her own the book is quite big, but it holds a small amount of food. All moisture and mineral components are absorbed in the book. What is the book like? On an elongated bag with numerous folds.

The book is like a filter and grinder of large stems. In addition, water is absorbed here. This department is located in the right hypochondrium. It is connected with both the mesh and the abomasum, that is, it continues the mesh, passing into the abomasum. The shell of the third department 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 food twice? It's all about the fiber found 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, constantly secreted gastric juice are features of the abomasum. Longitudinal rings in the abomasum form muscle tissue. The walls of the abomasum are covered with a special mucus, consisting of their epithelium, which contains 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 food, therefore, it enters the rennet already in a dried form.

Summing up

Thus, the structure of the cow's stomach is very peculiar, since the cow does not have 4 stomachs, but a four-chamber stomach, which provides 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 abomasum contains pancreatic juice, completely processing food. The digestive system of a cow includes tripe, mesh, booklet and abomasum. Enzymatic filling of the rumen provides the process of splitting food. The structure of this branch resembles a similar human organ. The tripe of cattle is very capacious - 100 - 300 liters, goats and sheep have much less - only 10 - 25 liters.

Long-term retention of food in the rumen ensures its further processing and decomposition. First, fiber undergoes cleavage, this involves a huge number of microorganisms. Microorganisms change depending on the food, so there should not be a sudden transition from one type of food to another.

Fiber is very important for the body of the ruminant as a whole, as it provides good motor skills pancreatic regions. Motility, in turn, ensures the passage of food through the gastrointestinal tract. In the rumen, the process of fermentation of feed masses takes place, the mass is split, and the body of the ruminant assimilates 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 split into tiny particles, further the nutrients are completely absorbed by the body, finished mass it moves into the intestines, where the most intensive absorption of all useful trace elements occurs. Imagine: a cow has eaten a bunch of grass in a pasture, and the digestion process starts, which in the end is from 48 to 72 hours.

The digestive system of cows is very complex. These animals must continuously eat, as a break will bring great problems and affect the health of the cow very negatively. complex structure of the digestive system has negative qualities - indigestion is a common cause of cow mortality. Does a cow have 4 stomachs? No, only one, but the entire digestive system includes the oral cavity, pharynx, cow's esophagus and stomach.

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Introduction

Clinical diagnostics is the science of methods and laboratory studies of animals, as well as the stages of disease recognition and assessment of the condition of a sick animal in order to plan and implement therapeutic and preventive measures. Clinical diagnostics includes 3 main sections:

1. observation of a sick animal and methods of its study: physical, which are carried out with the help of the senses (examination, palpation, percussion, auscultation), and laboratory and instrumental.

2. signs of the disease, their diagnostic significance, principles of diagnosis.

3. peculiarities of thinking of a veterinarian when recognizing a disease - a diagnostic technique.

Acquaintance with the methods of diagnosing animal diseases begins with this discipline. When studying clinical diagnostics, one can continue to study in depth other disciplines of the clinical profile: internal diseases, surgery, epizootology, obstetrics, etc. Without a deep knowledge of the methods of clinical diagnosis of internal non-contagious, infectious, parasitic diseases of animals, the professional activity of a veterinarian is impossible. The value of clinical diagnosis lies in the formation of clinical thinking. The basis for the knowledge of this discipline is physics, chemistry, anatomy, physiology and other general biological sciences.

In clinical diagnostics, it is necessary to know the plan for the clinical study of the animal and the procedure for examining individual body systems, the methodology for recognizing the disease process; rules for taking, preserving and sending blood, urine, other biological material for laboratory research; rules for maintaining basic clinical documentation; safety precautions and rules of personal hygiene in the study of animals and when working in the laboratory. When working with animals, it is necessary to learn the rules of professional ethics. It is necessary to take into account the totality of legal and moral norms of behavior of a veterinarian in the performance of his official and professional duties. Professional ethics include not only the norms of behavior of a specialist in the production sphere, but also in everyday life - attitudes towards team members, colleagues, and medical duty.

digestive cattle disease animal

The procedure for the study of individual systems of the animal body

The digestive system carries out the exchange of substances between the body and the environment. Through the digestive organs, all the substances it needs - proteins, fats, carbohydrates, mineral salts and vitamins - enter the body with food, and some of the metabolic products and undigested food residues are released into the external environment.

The digestive tract is a hollow tube, consisting of a mucous membrane and muscle fibers. It starts in the mouth and ends at the anus. Throughout its length, the digestive tract has specialized sections that are designed to move and assimilate ingested food.

Muscle fibers are capable of producing 2 different types of contraction: segmentation and peristalsis. Segmentation is the main type of contraction associated with the digestive tract, and includes individual contractions and relaxation of adjacent segments of the intestine, but is not associated with the movement of the food bolus through the digestive tube. Peristalsis is the contraction of muscle fibers behind the food bolus and their relaxation in front of it. This type of contraction is necessary to move the food bolus from one part of the digestive tract to another. The digestive tract consists of several sections: the oral cavity, pharynx, esophagus, stomach, small and large intestines, rectum and anus. Food passes through the digestive tract within 2-3 days, and fiber up to 12 days. The speed of passage of feed masses through the digestive tract is 17.7 centimeters per hour or 4.2 meters per day. During the day, cattle need to drink 25-40 liters of water when fed with green mass, and 50-80 liters when fed with dry feed. Normally, 15-45 kilograms of feces are excreted per day, they have a pasty consistency and a dark brown color. The percentage of water content in normal feces is 75-80%.

The oral cavity includes the upper and lower lips, cheeks, tongue, teeth, gums, hard and soft palate, salivary glands, tonsils, pharynx. With the exception of the crowns of the teeth, its entire inner surface is covered with a mucous membrane, which may be pigmented.

The upper lip merges with the nose, forming a nasolabial mirror. Normally, it is moist cool, at elevated temperatures it is put dry and warm. Lips and cheeks are designed to hold food in the oral cavity and serve as the vestibule of the oral cavity.

The tongue is a muscular movable organ located at the bottom of the oral cavity and has several functions: tasting food, participating in the process of swallowing, drinking, as well as in feeling objects, stripping soft tissues from the bone, caring for the body, hairline, and so on. for contact with other individuals. On the surface of the tongue there are a large number of horny papillae that perform mechanical functions (capturing and licking food).

Teeth are oblique enamel organs for capturing and grinding food. In cattle, they are divided into incisors, premolars, or primary molars, and molars, or molars. Calves are born with teeth. The so-called milk jaw consists of 20 teeth. There are no molars, the replacement of milk teeth with molars begins at 14 months. The jaw of an adult animal consists of 32 teeth. The shape of the chewing surface of the teeth changes with age, which is used to determine the age of animals.

The gums are folds of mucous membrane that cover the jaws and strengthen the teeth in bone cells.

The hard palate is the roof of the oral cavity and separates it from the nasal cavity, and the soft palate is a continuation of the mucous membrane of the hard palate. It is freely located on the border of the oral cavity and pharynx, separating them. The gums, tongue, and palate may be unevenly pigmented.

Directly in the oral cavity, several paired salivary glands open, the name of which corresponds to their localization: parotid, submandibular, sublingual, molars, and supraorbital (zygomatic). The secret of the glands contains enzymes that break down starch and maltose.

The tonsils are organs of the lymphatic system and perform a protective function in the body.

Ruminants swallow almost unchewed food, then they regurgitate it, digest it thoroughly and swallow it again. The totality of these reflexes is called the ruminant process, or chewing gum. Lack of chewing gum is a sign of an animal's disease. In calves, the ruminant process appears at 3 weeks of age. In cows, chewing gum occurs 30-70 minutes after the end of eating food and lasts 40-50 minutes, after which there is a pause. There are usually 6-8 ruminant periods per day. The process of swallowing begins in the mouth with the formation of a food bolus, which rises to the hard palate with the tongue and moves towards the pharynx. The entrance to the throat is called the pharynx.

The pharynx is a funnel-shaped cavity that is a complex structure. It connects the mouth to the esophagus and the nasal cavity to the lungs. The oropharynx, nasopharynx, two Eustachian tubes, the trachea, and the esophagus open into the pharynx. The pharynx is lined with mucous membrane and has powerful muscles.

The esophagus is a powerful tube through which food is transported in a circular way from the pharynx to the stomach and back to the oral cavity for chewing gum. The esophagus is almost entirely formed by skeletal muscles.

The stomach is a direct continuation of the esophagus. In cattle, the stomach is multi-chamber, consisting of a scar, mesh, book and abomasum. The scar, mesh and book are also called proventriculus, since they do not have glands that secrete digestive juice, and the abomasum is a true stomach. From the esophagus, mushy food and liquid in small quantities enter the net, and not crushed - into the rumen.

If a liquid, such as milk or medicine, needs to be introduced into the abomasum, bypassing the scar, it must be drunk in small portions.

In cattle, digestion processes begin in the pre-stomachs, where, with the help of an abundant in quantity and diverse in species composition of microflora (ciliates, bacteria, plant enzymes), the feed is fermented. As a result, various compounds are formed, some of which are absorbed into the blood through the wall of the scar, enters the blood, where it undergoes further transformations in the liver, and is also used by the mammary gland for the synthesis of milk components and as an energy source in the body. From the scar, food enters the mesh or is regurgitated into the oral cavity for additional chewing. In the grid, food is soaked and exposed to microorganisms, and due to the work of the muscles, the crushed mass is divided into large particles entering the book and coarse particles that go to the scar. In the book, the food swallowed by the animal for the second time after chewing the gum is finally ground and turns into gruel that enters the abomasum, where, under the influence of enzymes, hydrochloric acid and mucus, further food splitting occurs.

The absolute length of the entire intestine in cattle reaches 39-63 meters (average 51 meters). The ratio of the body length of the animal and the length of the intestine is 1:20. Distinguish between thin and large intestines.

The small intestine starts from the stomach and is divided into 3 main parts:

1 duodenum (the first and shortest part of the small intestine 90-120 centimeters long, the bile ducts and pancreatic ducts enter it)

2 jejunum (the longest part of the intestine is 35-38 meters, suspended in the form of many loops on an extensive mesentery)

3 ileum (is a continuation of the jejunum, its length is 1 meter).

The small intestine is located in the right hypochondrium and goes to the level of the 4th lumbar vertebra. The mucous membrane of the small intestine is more specialized for digestion and absorption of food: it is collected in folds called villi. They increase the absorptive surface of the intestine.

The pancreas also lies in the right hypochondrium and secretes several liters of pancreatic secretion into the duodenum in 1 day, containing enzymes that break down proteins, carbohydrates, fats, as well as the hormone insulin, which regulates blood sugar levels.

The liver with gallbladder in cattle is located in the right hypochondrium. Through it passes and filters the blood flowing through the portal vein from the stomach, spleen and intestines. The liver produces bile, which converts fats, which facilitates absorption into the blood vessels of the intestinal wall.

The weight of the liver ranges from 1.1 to 1.4% of the body weight of cattle. In the small intestine, the contents of the stomach are exposed to the action of bile, as well as intestinal and pancreatic juices, which contributes to the breakdown of nutrients into simple components and their absorption.

The large intestine is represented by the caecum, colon and rectum. The caecum is a short, blunt tube 30-40 centimeters long, lying in the upper right half of the abdominal cavity. The colon is a short intestine 6-9 meters long. The rectum lies at the level of the 4-5th sacral vertebra in the pelvic cavity, has a powerful muscular structure and ends in the anal canal with the anus. The diameter of the large intestine in cattle is several times greater than the diameter of the small intestines. There are no villi on the mucous membrane, but there are depressions - crypts, where the common intestinal glands are located, they have few cells that secrete enzymes. In this department, fecal masses are formed. In the large intestine, 15-20% of fiber is digested and absorbed. The mucous membrane secretes a small amount of juices containing a lot of mucus and few enzymes. Microbes of the intestinal contents cause the fermentation of carbohydrates, and putrefactive bacteria destroy the residual products of protein digestion, and such harmful compounds as indole, skatole, phenols are formed, which, being absorbed into the blood, can cause intoxication, which occurs, for example, with protein overfeeding, dysbacteriosis , lack of carbohydrates in the diet. These substances are neutralized in the liver. Mineral and some other substances are released through the walls of the large intestine. Due to strong peristaltic contractions, the remaining contents of the large intestine through the colon enter the rectum, where the accumulation of feces occurs. The excretion of feces into the environment occurs through the anal canal (anus).

In animals, body temperature is measured rectally for 10 minutes, introducing through the anus into the rectum to a depth of 7-10 centimeters, having previously lubricated the thermometer with vaseline. Shake the instrument before insertion. You can attach a rubber tube to the thermometer so that you can easily pull it out. The rubber tube can be attached to the tail.

The stomach of a ruminant animal morphologically and functionally consists of four sections: scar, mesh, book and abomasum. The first three sections do not have glands and together form the so-called proventriculus, where food is subjected to mechanical and bacterial processing. The abomasum is arranged as a typical single-chamber stomach, the mucous membrane of which contains glands that secrete gastric (rennet) juice. In cows with a mass of 550 ... 650 kg, the stomach weighs 75 ... 125 kg. In an adult cow, rumen accounts for 57%, books - 20, nets - 7, abomasum - 11% of the total volume.

The wall of the pancreas consists of three layers: serous, muscular and mucous. The proportion of the mucous membrane of the total mass of the body is approximately 51...75%. The mucous membrane of the scar (Fig. 1) is represented by a flat stratified epithelium, slightly keratinized and forming villi, which increase its surface by about 7 times. Cattle have about 520 thousand villi. Villi cover about 80-85% of the entire mucosal surface. There are villi of various shapes: ribbon-like, leaf-shaped, dome-shaped, in the form of tongues, warts, etc. Their sizes range from 2 x 1 to 9x3 mm. In different zones of the scar, due to the formation of villi, the active surface can increase by 14...21.6 times. Often in the rumen of cattle there are villi larger than 12 x 5 mm. The highest density of large villi in all studied animals was noted on the eve of the scar. There are both specific differences in the structure of the relief of the mucous membrane of the scar, and fundamentally similar structures that do not depend on the species, determined by the type of nutrition. The relief of the mucous membrane of the rumen in wild animals that feed on roughage corresponds to that of domestic ruminants. In animals that prefer soft food (giraffe, gazelle), in all areas of the scar, the mucosa is densely and evenly covered with villi. The largest villi appear to be found in the rumen of giraffes (22 x 7 mm).

Rice. 1. The structure of the scar wall:

Stratified epithelium with a thickness of 200...300 microns has 15...20 rows of cells divided into 4 layers: basal, spinous, transitional, horny. The basal layer (Str. basale) consists of a single row of cells in direct contact with the basement membrane that separates the epithelium and the lamina propria (Lamina propria). Cells are adjacent to the basement membrane either by their flattened base or by long cytoplasmic processes that extend both from the base of the cell and from its lateral surfaces. The cell nuclei are round or oval in shape, located in the lower third of the cell. There are many mitochondria in cells. The spinous layer (Str. spinosum) consists of 2...20 rows of cells of irregular polygonal shape, strongly elongated processes of which can reach the basement membrane. The spiny shape of the cells is due to the presence of numerous short processes, with the help of which neighboring cells come into contact with each other. The cell nuclei are rounded, and there are fewer mitochondria than in the cells of the basal layer. As it approaches the transitional layer (Str. transitionale), epithelial cells flatten and orient themselves parallel to the surface of the layer. This layer is morphologically heterogeneous and consists of 2...3 rows of strongly flattened cells with folded membranes. In the cell nuclei, compaction of the nuclear material and wrinkling are observed. Dense fibrillar material accumulates along the cell periphery. The cells contain both larger granules and fine fibrillar and lamellar structures.

The transition to the stratum corneum (Str. corneum) occurs suddenly, as a kind of "jump in keratinization." At the same time, nuclear derivatives containing DNA are preserved in many keratinized cells. There are three types of cells. In squamous horny cells, a maximum of one slit-like cavity can be found; these cells consist of a homogeneous or cellular horny substance. Spindle-shaped cells are characterized by the presence of a wide peripheral zone of keratin and an expanded intracellular space with amorphous and granular contents. The cell membranes of both cell types are highly folded. The squamous cells are particularly closely bonded to each other. Pear-shaped cells are also noted, which are characterized by the presence of a thick keratinized wall; fibrillar material is located in the center of a large cellular space. During desquamation (desquamation), interconnected horny scales or individual horny cells are separated. Desmosomes penetrated by tonofibrils are formed at the junctions of adjacent cells in the epithelium of the scar. Cells Str. basale are connected to the basement membrane by hemidesmosomes (hemidesmosomes). In Str. spinosum and Str. transitionale is formed by significantly more desmosomes than in Str. basale. The sizes of intercellular spaces decrease in process of transition from Str. base to Str. transitional. Already in Str. basale and Str. spinosum, fusions of the outer sheets of the cell membrane are found. These Macule occludentes are located in the desmosome region of two neighboring cells. On the border between Str. transitional and str. corneum, there are elongated membrane fusions, which, in the form of Zonulae occludentes, close the intercellular spaces. Intercellular gaps between squamous horny cells of Str. corneum are very narrow.

A detailed analysis of the ultrastructure of the epithelial layer lining the surface of the scar shows that the wall of the scar, and primarily the mucosa, has important physiological functions, primarily maintaining the constancy of the scar content. Thanks to the system of endplates (Zonulae occludentes), the internal contents of the scar are reliably fenced off from the internal environment of the body, primarily from the mucosal lamina propria (Lamina propria mucoae). A powerful capillary network of the scar mucosa is localized in it, the branches of which penetrate almost to the very epithelium.

The mucous membrane has bilateral permeability, which ensures the passive transport of water and ions into the blood and back according to the laws of osmosis and the active transport of substances by phago-, pino- and exocytosis. A special role is played by the basal layer, which carries out active transport of metabolites, primarily volatiles and ammonia. Due to the possibility of transport of metabolites from the blood into the cavity of the rumen, the host organism can influence the population of microorganisms.

The stratum corneum of the scar epithelium acts as a reliable bacterial filter. Bacteria can only be found in bursting pear-shaped horn cells or wide intercellular spaces between these cells. Surface layers determine the passage of water and soluble metabolites through the epithelium. If a hydrostatic pressure of the order of 20 ... 40 cm^ of water acts on the surface of the mucous membrane from the side of the scar cavity. Art., then the passage of water towards the serous membrane increases. Pressure from the serosa causes a gradual and strong increase in the flow of water towards the cavity. Under these conditions, there is an expansion of intercellular spaces and damage to the epithelium, which is expressed in the formation of vacuoles. This condition can contribute to the flow of water into the rumen and dilute its contents in acidosis.

The barrier functions of the surface layers are mainly associated with the area of ​​Zonulae occludentes. It is here that the passage of substances is difficult, if not completely impossible. It is possible that this region functions as a selective absorption filter, permeable to macromolecular substances with a particle size of 75 mm. The highly branched subsystem of tubules Zonulae occludentes, formed by slit-like intercellular spaces, creates favorable conditions for the transport of substances between cells. Intracellular transport is facilitated by numerous contacts between adjacent and even very distant cells. It is assumed that in the deep layers of the rumen epithelium there is another functional barrier that limits the flow of water through the rumen wall.

Absorption, accumulation and intracellular digestion of macromolecular substances, as well as their transport through the surface layers of the mucous membrane of the scar, are carried out by a system of phagosomes and heterolysosomes, which carry out controlled transport through the epithelium. Even horny cells retain the ability to form membrane vesicles, and therefore the cells can perform such important functions as phago- and exocytosis. Membrane vesicles can move inside the cells, bypassing the cells of the keratin skeleton of horny cells. Diffusely distributed in Str. corneum hydrolases (esterases, acid phosphatase) begin the digestion of substances resulting from phagocytosis in heterolysosomes.

The processes of diffusion through the epithelium of the scar are largely determined by the higher permeability for lipophilic metabolites than for hydrophilic ones. This is explained by the fact that lipids pass through the lipid regions of the membranes more easily, while hydrophilic substances must diffuse through the water-filled pores. Thus, diffusion depends not only on chemical or electrochemical gradients, but also on the physicochemical properties of the diffusing metabolite itself. Qualitative differences in the permeability of cytoplasmic membranes under conditions of unequal distribution of these parameters in the cell constitute a prerequisite for active targeted transport, which is especially important in cases where specific carriers are not involved. This position has received the following experimental confirmation. Inhibition of Na + transport by ouabain (a specific inhibitor of Na + -, K + -ATPase) is noted only if the inhibitor acts from the serous side of the mucous membrane. In relation to blood, the content of the rumen is electronegative, and this electrochemical potential is explained by Na+ transport. The transepithelial potential difference increases with increasing sodium concentration and disappears when transport is suppressed by ouabain or oxygen starvation. In experiments in vitro, a maximum potential of 15 mV was registered in the rumen of sheep, and 36 mV in calves; in vivo, the potential difference in sheep is about 30 mV. Thus, more than half of the sodium from feed and saliva (1200 g-eq in sheep) is actively transported through the rumen epithelium.

Along with the mechanism of the ion pump for strong electrolytes, a non-specifically acting pump for the active transport of weak electrolytes was also found in the scar epithelium. The driving force of such a pump is the constancy of the electrochemical potential difference of hydrogen ions between the tissue and the surrounding internal liquid media (blood, lymph). In this case, both dissociated and non-dissociated molecules can enter the epithelial cells, but only non-dissociated compounds enter the blood.

The metabolism of the cicatricial epithelium also affects passive transport by diffusion. This occurs, firstly, during the transport of dissociated substances under the action of the cicatricial potential, which stimulates diffusion from the rumen into the blood of anions and inhibits this process for cations. In accordance with the electrochemical potential difference, the diffusion of monovalent cations becomes possible at a threefold, and divalent cations - at a ninefold excess of the concentration of this ion in the blood. Secondly, the chemical gradient is influenced by the use of diffusible metabolites in the metabolism of the rumen epithelium. The potential gradient loses continuity and becomes stepped. In these cases, the absorption of metabolites by tissues is accelerated, and further transport within the tissue is slowed down. These conclusions are based on studies on the transport of volatile fatty acids. In experiments in vitro, the rate of absorption by the mucous membrane towards the cavity of the scar turned out to be directly proportional, and the rate of transport towards the serous membrane was inversely proportional to the rate of transformations of acetic, propionic and butyric acids. When metabolism is suppressed under conditions of anoxia, the differences in the direction of diffusion processes disappear.

Features of the structure of the stomach in ruminants. The stomach of ruminants consists of four chambers - rumen, mesh, book and abomasum. The scar, mesh and book are called proventriculus, and the abomasum is a true stomach, similar to the single-chamber stomach of animals of other species.

The mucous membrane of the scar forms papillae, nets - folds, similar to honeycombs, and in the book there are leaves of different sizes. The volume of the scar in cows is 90-100 liters, and in sheep - 12-15 liters.

In calves and lambs during the milk period of nutrition, an important role in digestion is played by the esophageal trough, which is a muscular fold with a recess on the wall of the mesh, connecting the vestibule of the scar with the hole from the mesh into the book. When the edges of the esophageal trough close, a tube is formed through which milk and water enter through the bottom of the book directly into the abomasum, bypassing the scar and mesh. With age, the gutter ceases to function.

The contents of the scar is a viscous mass of brown-yellow color.

In the proventriculus of ruminants, the conversion of feed substances occurs mainly under the action of bacterial and protozoan enzymes.

In the rumen, there is a large number of diverse microflora and microfauna that contribute to the digestion of fiber. In 1 ml of the contents of the rumen, there are up to 10 p bacteria, mainly cellulolytic and proteolytic.

In addition to digestion, processes of microbial synthesis and reproduction of microorganisms take place in the rumen, while amino acids, glycogen, proteins, vitamins and many biologically active substances are formed.

The fauna of the proventriculus is mainly represented by protozoa (10 5 -10 6 in 1 ml), which can break down fiber. They multiply rapidly in the rumen and give up to five generations per day. Ciliates use vegetable protein and amino acids to synthesize the protein structures of their cells. Therefore, protozoa increase the biological value of feed protein. The colonization of the proventriculus by microflora begins from the first days of animal life. During the milk period, lactic acid and proteolytic bacteria predominate in the rumen.

Transformation of nitrogenous substances in the pancreas. In the rumen, from 40 to 80% of the incoming protein substances undergo hydrolysis and other transformations. The breakdown of proteins occurs mainly as a result of the activity of microorganisms. Under the action of proteolytic enzymes of bacteria and ciliates, feed proteins are broken down into peptides and amino acids.

Most of the protein undergoes a deep breakdown with the release of ammonia, which is used by many rumen microorganisms for the synthesis of amino acids and protein.

An important feature of nitrogen metabolism in ruminants is the hepatic cicatricial circulation of urea. The ammonia formed in the rumen is absorbed in large quantities into the bloodstream and converted into urea in the liver. Urea in ruminants, unlike monogastric animals, is only partially excreted in the urine, and mostly returns to the rumen, entering with saliva or through the wall of the organ. Almost all of the urea that re-enters the rumen is hydrolyzed to ammonia by the urease enzyme secreted by the microflora and is again used in the form of nitrogen for biosynthesis by the rumen microorganisms.

Bacteria and protozoa serve as a source of biologically valuable protein for animals. Cows can receive up to 600 g of complete protein per day due to the digestion of microorganisms.

Digestion of carbohydrates in the stomach. The organic matter of plant feed consists of 50-80% carbohydrates, which are divided into easily soluble and sparingly soluble. Easily soluble include oligosaccharides: hexoses, pentoses, sucrose, starch, pectin, sparingly soluble polysaccharides.

Hydrolysis of cellulose occurs under the action of the bacterial enzyme cellulase. In this case, cellobiose is formed, which is cleaved by glucosidase to glucose.

Polysaccharides are hydrolyzed to monosaccharides - hexoses and pentoses. Starch is broken down by a-amylase to dextrins and maltose.

Simple disaccharides and monosaccharides are fermented in the rumen to low molecular weight volatile fatty acids (VFAs) - acetic, propionic and butyric. VFAs are used by the ruminant organism as the main energy material and for the synthesis of fat. Volatile fatty acids through the wall of the scar and books are absorbed into the blood.

The ratio of individual volatile acids in the body of ruminants depends on the diet and is normally: acetic 60-70%, propionic 15-20%, oily 10-15%.

Digestion of lipids in the pancreas. Vegetable foods contain a small amount of fat. The composition of crude fat includes: triglycerides, free fatty acids, phospholipids, esters of glycerol, wax.

Under the influence of lipolytic enzymes secreted by rumen bacteria, feed lipids are degraded into monoglycerides, fatty acids and glycerol. Some fatty acids are involved in the synthesis of lipids in microbial cells, while others are fixed on food particles and enter the intestine, where they are digested.

Formation of gases in the rumen. In the rumen, under the influence of the activity of microflora, intensive fermentation of carbohydrates and the breakdown of nitrogenous compounds occur. In this case, a large number of different gases are formed: methane, CO 2, hydrogen, nitrogen, hydrogen sulfide. Cows in the rumen can form up to 1000 liters of gases per day.

The intensity of gas formation in the rumen depends on the quality of the feed: its highest level is with an increased content of easily fermentable and succulent feed in the diet of animals, especially legumes. The share of CO 2 accounts for 60-70% of the total volume of gas, and methane - 20-40%.

Gases are removed from the rumen in various ways: most of it is removed by belching, some diffuses from the rumen into the blood, and the rest is removed through the lungs.

Motor function of the pancreas. The motor function of the proventriculus contributes to the constant mixing of the contents and its evacuation into the abomasum.

The contractions of the individual parts of the proventriculus are coordinated with each other and pass sequentially - mesh, book, scar. At the same time, each department decreases during contraction and partially squeezes the contents into neighboring departments, which at that moment are in a relaxed state.

The next cycle of contractions begins with the grid and the esophageal trough. During mesh contractions, the liquid mass enters the vestibule of the scar.

The motor activity of the proventriculus is regulated by the nerve center located in the medulla oblongata. In this case, the vagus nerve strengthens, and the sympathetic nerves inhibit the contraction of the proventriculus. Other structures of the brain also influence the contraction of the proventriculus: the hypothalamus, the hippocampus and the cerebral cortex. Somatostatin and pentagastrin can also affect the motility of the proventriculus.

In ruminants, periodically (6-14 times a day) occur ruminant periods, manifested by regurgitation of portions of food from the rumen, their repeated chewing and swallowing. In the ruminant period, 30-50 cycles are noted, and the duration of each is 45-70 s.

A cow burps and chews up to 60-70 kg of feed per day.

The regulation of the ruminant process is carried out reflexively from the receptor zones of the grid, the esophageal trough and the scar, in which mechanoreceptors are located. Belching begins with an inhalation movement with the larynx closed, the opening of the esophageal sphincter, followed by an additional contraction of the mesh and the vestibule of the scar, throwing a portion of food into the esophagus. Thanks to the anti-peristaltic contractions of the esophagus, food enters the oral cavity. The re-chewed portion is swallowed and mixed again with the contents of the rumen.

Digestion in the abomasum. Abomasum is the fourth, glandular, section of the complex stomach of ruminants. In cows, its volume is 10-15 liters, and in sheep - 2-3 liters. On the mucous membrane of the abomasum, there are: cardiac, fundal and pyloric zones. Rennet juice has an acidic reaction (pH 1.0-1.5), it is excreted continuously, since food mass from the fore-stomachs constantly enters the abomasum. In cows, 50-60 liters of rennet juice is secreted during the day, which contains the enzymes chymosin (in calves), pepsin and lipase.

In the abomasum, protein is mainly broken down. Hydrochloric acid of gastric juice causes swelling and denaturation of protein, converts inactive pepsinogen into active pepsin. The latter, by hydrolysis, breaks down the protein to peptides, albumose and peptones, and partially to amino acids. Chymosin in the period of milk nutrition acts on the milk protein caseinogen and turns it into casein. Gastric lipase breaks down emulsified fats into fatty acids and glycerol.