Function and Dysfunction of the Ruminant Forestomach

Walter Grünberg , Peter D. Constable , in Food Animal Do (Fifth Edition), 2009

OMASAL Motility

The omasum is a meaty spherical organ, comprising the omasal culvert and omasal body. Motility of the omasal culvert is coordinated with that of the reticulorumen, whereas omasal trunk contractions occur independently of and at a slower charge per unit than reticuloruminal contractions. The office of the omasum is incompletely understood; however, the omasum plays an important role in the transport of appropriately sized feed particles from the reticulorumen to the abomasum, esophageal groove closure, fermentation of ingesta, and assimilation of water, volatile fatty acids, and minerals. Sheep and goats have a relatively small omasum when compared with cattle.

Definitive evidence of an omasal disorder requires exploratory celiotomy or rumenotomy. Diseases particularly affecting the omasum are rare but include omasal impaction, omasal canal obstruction, and omasal erosions. Omasal canal obstructions usually result from ingestion of baling twine or plastic and are easily diagnosed during rumenotomy. Omasal erosions may be severe enough to pb to perforation of one or more omasal leaves. These erosions are usually seen in healthy cattle, and their etiopathogenesis is unknown, although inflammation resulting from Fusobacterium necrophorum infection is a likely cause. 19 Omasal lesions are too observed in cattle dying of diseases such as bovine virus diarrhea, infectious bovine rhinotracheitis, and rinderpest.

Omasal impaction is a clinical disease of controversial significance, primarily considering the normal bovine omasum varies markedly in size and consistency. The disorder is characterized by anorexia, an extremely firm and enlarged omasum that may be painful on palpation, the absence of other pathologic abdominal conditions, and clinical comeback following softening of the omasum. Handling consists of intraoperative kneading of the omasum until the contents go pliable. Four liters of mineral oil should be administered intraruminally for three-five days postoperatively to facilitate softening. Omasotomy is indicated in unresponsive cases. The omasum is exteriorized through a midline abdominal incision, opened forth the greater curvature, and flushed with water until information technology becomes soft and pliable. The omasum is airtight with a two-layer inverting blueprint, and the abdomen is routinely closed. 20

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Digestion

Thomas H. Herdt , in Cunningham'due south Textbook of Veterinarian Physiology (6th Edition), 2020

Passage of Material From the Reticulum to the Omasum Occurs During Reticular Contraction

The omasum is composed of a trunk and a canal. The body is filled with multiple muscular folds, or leaves, that project from the greater curvature into the lumen. The canal, which is located on the lesser curvature, connects the reticulum to the abomasum. Ingesta movement into the omasum during reticular contractions. The reticulo-omasal orifice usually remains open, only dilates during the second phase of the reticular contraction, during which ingesta menstruum quickly into the omasal canal. After the reticular contraction, the reticulo-omasal orifice closes briefly equally the canal contracts, forcing newly arrived ingesta up into the leaves. Intermittently, the trunk and leaves of the omasum contract, forcing the cloth from the body of the organ into the canal and on into the abomasum.

Proper functioning of the omasum and reticulum appears to be particularly important to the passage of ingesta out of the rumen. Occasionally, traumatic injury resulting from ingested foreign bodies causes severe adhesions of the reticulum and omasum to the body wall. In addition, damage to vagal fibers entering the organs may occur. In such cases, motility of the rumen proper may continue normally, but the power to move food out of the forestomachs and into the abomasum is severely impaired. The rumen becomes profoundly distended with finely comminuted feed, and the entire rumen becomes a slurry zone. Despite the distended rumen, little movement of ingesta occurs into the abomasum, and the animals somewhen suffer severe inanition. This condition is variably known equally omasal send failure and vagal indigestion; usually, little tin can be done to correct it.

The construction of the omasum, with its many leaves and large mucosal surface expanse, suggests that it has an absorptive function, just the exact nature of this function is still incompletely understood. 1 important possibility is that it exists to remove residual VFAs and bicarbonate from ingesta before material is transported to the abomasum. VFAs appear to cause unfavorable reactions in the abomasum, so it is important that a large portion of them be removed before abomasal entry. Also, it appears desirable to blot, before abomasal entry, whatever bicarbonate remaining in the ingesta. Bicarbonate remaining in ingesta and inbound the abomasum would just neutralize abomasal hydrochloric acid, increasing the piece of work load of the abomasal glands to maintain appropriate abomasal pH.

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Neoplasia

Beth A. Valentine , ... Emily E. Barrell , in Farm Animal Surgery (Second Edition), 2017

Forestomach

Tumors of the omasum, reticulum, and rumen occur well-nigh often in cattle merely are uncommon in most parts of the world. Papilloma, fibropapilloma, and fibroma are the most common tumors in the forestomach of cattle. Papillomavirus has been detected by immunohistochemical studies in some, just non all, cases of bovine forestomach papillomas. These tumors are less mutual in sheep, and only one report of forestomach neoplasia—rumen papilloma—was found in goats. Papillomas can occur at whatsoever age. Squamous prison cell carcinoma occurs in older cattle and sheep and oft results from malignant transformation of a papilloma. In cattle in Kenya and northern England, the interaction between bovine papillomavirus infection and the mutagens present in bracken fern is suspected to be the cause of a high incidence of forestomach papillomas and of cancerous transformation of papilloma to squamous cell carcinoma. Bracken fern ingestion is also suspected to explain a high incidence of rumen squamous prison cell carcinoma in cattle in Brazil. Lymphoma can involve the rumen and reticulum of older cattle every bit function of a more generalized neoplastic process associated with BLV infection. Fibrosarcoma of the rumen has been seen in an adult sheep.

Forestomach papilloma, fibropapilloma, and fibroma in cattle most often occur in the rumen near the ruminoreticular groove, causing recurrent bloat. Squamous cell carcinoma too occurs at these sites. In sheep, squamous cell carcinoma can likewise exist found in the reticulum and omasum. Abdominal pain, bloat, and excessive salivation oft accompany forestomach squamous cell carcinoma in cattle. Clinical signs have not been reported in sheep with forestomach neoplasia. Forestomach lymphoma is typically associated with concurrent abomasal interest, every bit well every bit other organs, and generalized ill-thrift. Involvement of the omasum by lymphoma is less mutual. Leiomyoma of the omasum has been seen as an incidental finding in a goat.

Fibroma, fibropapilloma, and papilloma of the forestomach are benign, localized tumors that form exophytic, nodular or multinodular to multilobular, smooth-surfaced, firm, tan masses (Effigy 8-sixteen). Tumors may be sessile or pedunculated. These tumors are readily excised via rumenotomy, merely they tin can be multiple, specially in areas with a high incidence. Histopathologic evaluation is necessary to differentiate those tumors that have epithelial proliferation (papilloma), both epithelial and fibroblastic proliferation (fibropapilloma), or only fibroblastic elements (fibroma). Histopathologic evaluation is besides needed to place bear witness of malignancy in the rare cases of forestomach fibrosarcoma. The fibrosarcoma seen in the rumen of a sheep had metastasized to the liver.

Squamous cell carcinoma is an invasive and destructive tumor. Mucosal ulceration acquired by squamous jail cell carcinoma is common. Histopathologic evaluation reveals nests of invasive squamous epithelial cells in dense collagenous stroma. Neoplastic squamous cells may be seen on cytologic preparations, only the caste of sclerosis often results in poor exfoliation of epithelial cells. Surgical excision of early and localized forestomach squamous cell carcinoma might be possible, but in most cases the extent of tumor at the fourth dimension of diagnosis precludes surgical intervention.

Lymphoma most often results in locally all-encompassing house and nonulcerated thickening of the forestomach wall by stake tan solid tissue. Rarely, forestomach lymphoma may involve simply the serosa. Sheets of relatively homogeneous lymphocytes are seen on cytologic and histopathologic preparations, and transmural involvement with obliteration of normal architecture is characteristic.

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Noninfectious Diseases of the Gastrointestinal Tract

Susan Fubini , Thomas J. Divers , in Rebhun's Diseases of Dairy Cattle (Second Edition), 2008

Displacement of the Omasum

In the past few years nosotros have seen several cows with displaced omasum into the upper correct abdomen, both just behind and in front end of the last rib. These cases were starting time brought to our attention by Dr. Chuck Guard and accept been confirmed on exploratory laparotomy and at necropsy. Cows oftentimes have a several-twenty-four hour period history of decreased appetite and product. A pocket-size ping can be heard over the surface area of the displacement, ofttimes high on the 13th rib. The omasum has been palpated rectally on a couple of the cows. An appropriate surgical repair method has not been determined at this time.

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Alimentary Organization and the Peritoneum, Omentum, Mesentery, and Peritoneal Cavity1

Howard B. Gelberg , in Pathologic Footing of Veterinarian Illness (Sixth Edition), 2017

Rumen, Reticulum, and Omasum

The three compartments of the ruminant forestomach are the reticulum, rumen, and omasum. Folds and compartments subdivide the forestomach. Normal forestomach motility, and thus innervation, is critical in maintaining digestive homeostasis. The ruminant forestomachs are aglandular. The resident flora and beast are responsible for digestion and fermentation of cellulose. In general, the rumen is a big fermentation vat where microorganisms suspension downward ingesta by mechanical and chemic action into short-chain fatty acids that are straight absorbed beyond the epithelial lining into the blood. These fat acids supply more than one-half of the energy from nutrients absorbed past the alimentary tract. The reticulum and omasum act mechanically to further reduce the ingesta to fine particles.

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Surgery of the Bovine Digestive Arrangement

Norm G. Ducharme , ... Ava 1000. Trent , in Subcontract Animal Surgery (2nd Edition), 2017

Anatomy and Physiology

The three nonglandular forestomach compartments in the cow are the rumen, reticulum, and omasum. The abomasum is the true "stomach" and has a glandular mucous membrane. The rumen occupies most of the belly's left side; its long axis extends from ribs seven to eight to the pelvis. The reticulum lies against the diaphragm left of midline opposite the sixth to eighth ribs, and the omasum is right of midline at the ventral aspect of ribs vii to eleven. The abomasum lies by and large right of midline and extends from the xiphoid expanse to the 9th or 10th intercostal space in the nonpregnant cow. The cardia opens dorsal to the fundus of the reticulum. The reticular groove is located on the right wall of the reticulum and joins the reticuloomasal orifice. The omasal groove is on the left wall of the omasum and joins the omasoabomasal orifice.

In the newborn dogie, the abomasum is twice as large as the rumen. The rumen becomes most 9 times as large as the abomasum over the first yr of life as a result of the mechanical stimulus of roughage in the diet and the chemical charges associated with fermentation.

The vagus nervus, which is made up of 90% sensory fibers, is the chief innervation of the forestomach compartments and abomasum. The dorsal vagal trunk innervates the rumen, caudal attribute of the reticulum, omasum, and visceral surface of the abomasum. The ventral vagal trunk supplies the reticulum, parietal side of the reticuloomasal junction, omasum, and abomasum.

The forestomach compartments, especially the rumen, are sites of microbial fermentation. The rumen or reticulum movement allows mixing of ingesta besides as regurgitation, eructation, and passage of ingesta into the omasum. The omasum acts equally a pump that aspirates ingesta and transfers it to the abomasum. The abomasum behaves similarly to the stomach of a nonruminant. Digestive enzymes in the abomasum are responsible for the next phase of digestion.

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Noninfectious Diseases of the Alimentary canal

Susan L. Fubini , ... Thomas J. Divers , in Rebhun's Diseases of Dairy Cattle (Tertiary Edition), 2018

Displacement of the Omasum

In the by few years, nosotros accept seen a few cows with displacement of the omasum into the upper right abdomen, either merely backside or merely in front of the last rib. These cases were first brought to our attention by Dr. Chuck Guard and were confirmed on exploratory laparotomy and at necropsy in at least 6 cases. Cows oftentimes take a several-24-hour interval history of decreased appetite and production and balmy abdominal distension just cranial to the right paralumbar fossa ( Fig. five.82). A small ping can exist heard in some of the cases over the area of the displacement, often loftier on the 13th rib, somewhat mimicking RDA. Ultrasound examination tin can help distinguish between the two weather, as can measurement of serum chloride. The omasum was palpated rectally on a couple of the cows. An appropriate surgical repair method has not been determined at this time, but one excellent moo-cow survived for more than 2 years after documentation of the disorder by laparotomy.

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Small Intestinal Beefcake, Physiology, and Digestion in Ruminants☆

Kendall C. Swanson , in Reference Module in Food Science, 2019

Beefcake and Physiology

The ruminant stomach has 4 compartments: 1) rumen, ii) reticulum, 3) omasum, and four) abomasum ( Van Soest, 1994). Pregastric fermentation and breakup of feeds occurs in the rumen, reticulum, and omasum, whereas the abomasum is the true stomach and is like in structure and function to the not-ruminant stomach. Considering of pregrastric fermentation, the composition of the digesta flowing to the modest intestine in ruminants is modified as compared to dietary intake, which differs from what occurs in non-ruminants.

The pocket-size intestine and associated organs in ruminants are similar in construction to non-ruminants (Fig. one). The small intestine functions in digestion and absorption of nutrients and equally an important barrier and allowed organ in the torso. The small intestine of ruminants is anatomically and functionally similar to non-ruminants and ranges in length between approximately 12 and 30 times the trunk length of the animal. Structurally, besides beingness of considerable length, the pocket-sized intestine has several folds and contains villi (finger-like projections composed columnar epithelial cells) and microvilli (finger-like projections from individual epithelial cells) which allows for increased surface area to let for the concluding stages of digestion and absorption of nutrients (Walton et al., 2016). Because of the workload associated with nutrient absorption and immune function, the epithelial cells of the pocket-sized intestine are replaced every 3 to five days with epithelial cells proliferating in the crypt and migrating to the tip of the villus where they get through apoptosis and are sloughed into the lumen of the pocket-sized intestine (Hellmich et al., 2006). Considering of the rapid proliferation rate and metabolic rate of the pocket-sized intestine, the small intestine uses a asymmetric amount of metabolizable energy compared to most other tissues (Ferrell and Jenkins, 1985). The small-scale intestine too responds to changes in diet (Burrin et al., 1990) or physiological state, such as lactation (Baldwin et al., 2004). The minor intestine has 3 regions (starting afterward the pylorus and ending at the ileal-cecal junction): duodenum, jejunum, and ileum.

Figure one. Position of the small-scale intestine within the abdominal cavity of the dairy cow. Note the position of the abomasum (12D), pylorus (13), duodenum (xiv), jejunum (15), ileum (18), cecum (20), and colon (19). Also shown are the liver (23), gallbladder (24), and pancreas (26).

 Reproduced from a 'Transart' anatomy booklet published by Cyanamid of Great U.k., London, UK (1966).

The pancreas and liver are important accompaniment organs to the small intestine and produce enzymes, buffers, and bile acids that are secreted into the small intestine to aid in digestion. The liver lays in the intestinal crenel on the correct of the median airplane (Sisson, 1975). The liver is a major site for metabolism of nutrients and also produces bile which is stored in the gall float and secreted into the duodenum through the bile duct. The pancreas is located in close proximity to the liver. The body of the pancreas is adherent dorsally to the liver and to the common bile duct and the duodenum. The pancreas secretes buffers and enzymes into the duodenum through the pancreatic duct.

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Tragulidae, Moschidae, and Cervidae

Nicholas J. Masters , Edmund Flach , in Fowler's Zoo and Wild Animal Medicine, Volume 8, 2015

Unique Anatomy

The chevrotains (Tragulidae) have many ruminant features such as a iv-chambered tummy (with a poorly developed omasum), no upper incisor teeth, and incisor-like lower canines, but they too resemble pigs and hippopotami in having four toes with supporting bones, equally well equally incomplete fusion of the 3rd and fourth metacarpals and metatarsals. 42,57 Members of this family unit lack antlers and have elongated upper canines as in musk deer and Chinese water deer (Hydropotes inermis) and, like musk deer, besides possess a gallbladder and lack preorbital odor glands. However, they exercise possess a chin gland.

Musk deer (Moschidae) lack antlers, have a gallbladder, and possess merely one pair of mammary glands. They have no facial glands just take caudal glands ventral to the tail and well-developed preputial or musk glands, from which the commercially valuable musk is obtained. Moschidae used to be included as a subfamily in Cervidae but has now been raised to family status. 26,72

The defining characteristic of the true deer (Cervidae) is the possession of antlers (Effigy 62-1). Males of all species, except the Chinese water deer, grow antlers each twelvemonth earlier the breeding season and lose them later. In the species that comprises the reindeer, or caribou (Rangifer tarandus), both sexes accept antlers. The size and complexity of antlers increases with distance from the equator, as climatic and nutritional conditions become more exacting. Hinds select males that can thrive best in the environment, and the pick of a female may exist the most of import factor for the evolution of large antlers. Antler growth occurs annually nether hormonal control. The antlers arise from the frontal bones and peel and, until fully grown, they are covered with a highly vascularized and sensitive skin known as velvet. Equally the mating season approaches, the testosterone level rises, the antlers harden, and the velvet dries. Stags may rub their antlers against objects to remove the flaking velvet. Afterwards the mating season, the testosterone level declines, and a layer of bone-dissolving cells invades the base of the antlers, causing them to fall off. Each twelvemonth, the size and, in some species, the complexity of antlers increase until full maturity. Antler growth has a less well-defined seasonality in tropical and subtropical zones.

Deer possess a range of specialized scent glands, most normally preorbital in location just also occurring on the limbs. Deer have no gallbladder, and female deer have two pairs of inguinal mammary glands. The skeleton has evolved for running and jumping, with reductions of the ulna and the fibula, loss of the first digit, reductions of digits II and V, and fusion of the 3rd and quaternary metacarpals and metatarsals to form cannon basic. The location of the vestigial metacarpal bones Two and V (splint bones) is the basis for differentiation of the subfamily Cervinae (proximal or plesiometacarpalian) from the Capreolinae (distal or telemetacarpalian). The Chinese h2o deer has been placed in the subfamily Capreolinae, as information technology is telemetacarpalian and is phylogenetically very close to the roe deer (Capreolus capreolus); this is based on mitochondrial cytochrome assay, 60 which suggests that the loss of antlers is a secondary feature.

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Thailand's Nutrient Policy on a Trans Fat-Gratis Country

Visith Chavasit , ... Juntima Photi , in Reference Module in Food Science, 2018

Biological Process

The biological procedure occurs naturally within the alimentary canal of a ruminant that has a four-role stomach, i.e., rumen, omasum, abomasum and reticulum. As the feed that naturally contains cis-course fatty acids enters the rumen part, information technology is anaerobically fermented past leaner, which transforms the natural cis-course fatty acids into the isomeric trans-form fat acids. This biological process results in trans fatty acid contamination in dairy products and meats, such as milk, butter, beefiness and lamb fats, which are natural sources of trans fatty. Ruminant fat usually contains 1%–3% of trans fat acids. The dominant trans fatty acrid found in these products is vaccenic acid (C18:one trans-eleven) (Alfaia et al., 2009; Bion et al., 2008; Goudjil et al., 2004; Kuhnt et al., 2011).

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