Aspectos morfológicos do rúmen, omaso e fígado de tourinhos alimentados com diferentes níveis de glicerina bruta / Morphological aspects of rumen, omasum and liver of bulls fed different levels of crude glycerin

The morphology of the ruminal and omasal mucosa and hepatic parenchyma of 44 young bulls submitted to four types of concentrates were evaluated by varying the inclusion level of crude Glycerin - CG (0, 6, 12 and 18%). The variables evaluated were number of ruminal papillae per cm² of wall; area of the papillae and total absorption surface per cm² of wall; Mitotic index - MI, height and area of ruminal and omasal papillae; and hepatic morphology. The samples processed for inclusion in paraffin and stained with Hematoxylin-Eosin. The different levels of inclusion of CG in the diet did not interfere either in the number of papillae per cm2 of rumen wall (P= 0,70) or in the ruminal absorptive surface area (P= 0,89). Animals that received diets with levels 12 and 18% had higher MI of the ruminal epithelium (P< 0.01), but higher cell proliferation wasn't reflected in height gain and papillary area (P= 0,82). The omasal mucosa wasn't influenced by the inclusion of CG (MI e height gain and papillary area, P= 0,43, P= 0,56 e P= 0,9, respectively). The inclusion of GB in up to 18% of diet dry matter didn't alter the morphology of the rumen and omaso mucosa; and the integrity hepatic parenchyma.(AU)

Comparative omasum anatomy in ruminants: Relationships with natural diet, digestive physiology, and general considerations on allometric investigations.

The omasum is the third forestomach compartment of pecoran ruminants. It is assumed that the re-absorption of fluid present in the forestomach digesta (that facilitates particle sorting, digestion, and harvest of microbes) is its main function, so that less diluted digesta is submitted to enzymatic digestion in the lower digestive tract. Here, we evaluate measures of omasum size (representing 84 ruminant species in the largest data set) against body mass and proxies of the natural diet (%grass) or forestomach physiology (fluid throughput), using phylogenetically controlled models. The origin of specimens (free-ranging or captive) did not have an effect in the data set. Models with the best support invariably either included %grass or a physiology proxy in addition to body mass. These effects were not necessarily additive (affecting the intercept of the allometric regression), but often indicated a change in the allometric body mass-exponent with diet or physiology. Only models that allowed an influence on the allometric exponent yielded basic exponents compatible with predictions derived from geometry. Species that include more grass in their natural diet, or that have a "cattle-type" physiology marked by a high forestomach fluid throughput, generally have larger omasa. However, the existence of outliers, as well as the overall data pattern, suggest that this is not an obligatory morphophysiological condition. Circumstantial evidence is presented leading to the hypothesis that the comparatively small and less complex omasa of "moose-type" species do not necessarily represent an "original" state, but may be derived from more complex states by ontogenetic reduction and fusion of omasal laminae.

Effect of increasing the proportion of dietary concentrate on gastrointestinal tract measurements and brush border enzyme activity in Holstein steers.

The aim of this study was to determine the time course for adaptation of the reticulo-rumen, omasum, abomasum, and small intestine in response to an abrupt increase in the proportion of grain in the diet. Adaptive responses include tissue and digesta mass, small intestinal length, and brush border enzyme activity in the duodenum, proximal jejunum, and ileum. Twenty-five Holstein steers (213 ± 23 kg; 5 to 7 mo of age) were blocked by body weight, and within block were randomly assigned to 1 of 5 treatments: the control diet (CTRL; 92% chopped grass hay and 8% mineral and vitamin supplement on a dry matter basis) or a moderate grain diet (MGD; 50% chopped grass hay, 42% rolled barley grain, and 8% mineral and vitamin supplement) that was fed for 3 (MGD3), 7 (MGD7), 14 (MGD14), or 21 d (MGD21). Dry matter intake was limited to 2.25% of body weight to ensure that changes in dry matter intake did not confound the results. On the last day of the dietary exposure, steers were slaughtered 2 h after feeding. Reticulo-rumen tissue mass and ruminal epithelium mass in the ventral sac of the rumen were not affected by the MGD. Wet reticulo-ruminal digesta mass decreased from CTRL to MGD7 and then increased, but reticulo-ruminal digesta dry matter mass did not differ between treatments. Omasal mass, omasal tissue mass, and omasum digesta mass decreased linearly with the number of days fed MGD, but abomasal tissue mass tended to increase linearly. Duodenal tissue mass tended to increase linearly, and ileal length increased linearly with the number of days fed MGD. Lactase activity in the proximal jejunum increased linearly and maltase activity in duodenum tended to increase linearly with days fed MGD. Aminopeptidase N activity in the proximal jejunum increased cubically with days fed MGD, and dipeptidylpeptidase IV activity in ileum tended to decrease from CTRL to MGD14 and then tended to increase. Adaptation to a diet with a greater proportion of concentrate involves changes in the mass and length of regions of the gastrointestinal tract and brush border enzyme activity. These changes take place gradually over at least 3 wk.

Gross Measurements of the Digestive Tract and Visceral Organs of Addax Antelope (Addax nasomaculatus) Following a Concentrate or Forage Feeding Regime.

Differences in macroscopic measurements of the gastrointestinal tract have been hypothesized to correlate with the browser-grazer continuum in the natural diet of ruminants. However, to what extent these characteristics represent species-specific traits, or respond to the actually ingested diet, remains to be investigated. Twelve surplus addax antelope (Addax nasomaculatus) were divided into two groups and fed, for 3 months, either their usual diet, consisting of a concentrate feed with a limited amount of hay, or a diet of unlimited hay only. After culling, macroscopic measurements were compared between groups. The macroscopic anatomy of the addax showed many characteristics considered typical for grazing or 'cattle-type' ruminants. While both diet groups had mesenteric, pericardial and perirenal adipose tissue, these depots were subjectively more pronounced in concentrate-fed animals. Hay-fed animals had significantly heavier filled forestomach compartments, with corresponding significantly longer linear measurements. Masseter muscles and the surface of first-order omasal leaves were significantly more prominent in hay-fed animals, reflecting possible adaptations to overcome resistance of grass forage and to reabsorb fluid from increased rumination, but differences were not as distinct as reported between 'cattle-type' and 'moose-type' ruminants. Some measurements such as reticular crests and empty foregut mass remained stable between groups, indicating possibly genetically pre-defined characteristics less prone to change in adult life. The results emphasize the adaptability of ruminant digestive tract anatomy in adult animals even after a short period of time, but also suggest limits to this adaptability that reveals a species-specific anatomy regardless of the diet actually consumed.

Macroscopic digestive tract anatomy of two small antelopes, the blackbuck (Antilope cervicapra) and the Arabian sand gazelle (Gazella subgutturosa marica).

The digestive tract anatomy of 14 blackbucks (Antilope cervicapra) and seven Arabian sand gazelles (Gazella subgutturosa marica) was quantified by dimensions, area and weight. Data from the two small-sized antilopinae were evaluated against a larger comparative data set from other ruminants classified as having either a 'cattle-type' or 'moose-type' digestive system. The digestive anatomy of the blackbuck resembled that of 'cattle-type' ruminants, which corresponds to their feeding ecology and previous studies of solute and particle retention time; however, a surprising exception was the remarkably small omasum in this species, which makes the blackbuck stand out from the general rule of a relatively large omasum in grazing ruminants. Sand gazelles had morphological features that corresponded more to the 'moose type' or an intermediate position, although previous studies of solute and particle retention time had led to the expectation of a more 'cattle-type' anatomy. The results show that outliers to general morphological trends exist, that findings on physiology and anatomy do not always match completely and that differences in the digestive morphology among ruminant species are more difficult to demonstrate at the lower end of the body mass range.

Anatomical study of the gastrointestinal tract in free-living axis deer (Axis axis).

The macroscopic anatomy of the stomach and intestines of adult axis deer (Axis axis), a cervid species considered intermediate/mixed feeder, was observed and recorded. Nine adult wild axis deers of both sexes were used and studied by simple dissection. The ruminal papillae were distributed unevenly in the overall area of the inner surface of rumen and primarily were more large and abundant within the atrium. The ruminal pillars had no papillae. There was an additional ruminal pillar located between the right longitudinal and right coronary ventral pillars connected to the caudal pillar. No dorsal coronary pillars were found, and the ventral coronary pillars are connected. The reticulum was the third compartment in size, and the maximum height of the reticular crests was 1.0 mm. The Cellulae reticuli were not divided and rarely contained secondary crests. There were no Papillae unguiculiformes. The omasum was the smallest gastric compartment. The abomasum had about twelve spiral plicae, and a small pyloric torus was present. The intraruminal papillation was similar to those species that are characterized by a higher proportion of grass in their natural diet. The finding of the small reticular crests is typical for browser ruminants and was coincident with data reported for other deer. The comparative ratio of the small intestine to the large intestine was 1.69, in terms of length measurements in axis deer and appears below of the 'browser range'. We concluded that the gastrointestinal system of axis deer reflected similar morphological characteristics of the both types of ruminants: browser and grazer, and we consider it as an intermediate feeder.

Histomorphometric characterization of forestomach of yak (Bos grunniens) in the Qinghai-Tibetan Plateau / Caracterización histomorfométrica del preestómago del yak (Bos grunniens) en la Meseta Qinghai-Tíbet

Six forestomachs of yaks (Bos grunniens) were studied with gross dissection and histological methods. It was found that the forestomach of yak consisted of the following three parts, rumen, reticulum and omasum, which were composed of the mucosa, submucosa, muscularis and serosa. In addition, the mucosal epithelium was covered with stratified squamous epithelium, with part of keratinized the shallow cells. Rumen, the mucosa of which formed ligulate papillae varying in size and shape, was no muscularis mucosa. Reticulum, consisted of a surface epithelium that invaginated to various extent into the lamina propria, formed various folds in shape, namely, grid-like small rooms. Furthermore, there are many secondary folds densely covered with keratinized papillae. The most striking feature of the omasum was to be formed the laminae omasi varying in length, with short and rough papillae distributing on both sides. Taken together, there was no glands within the mucosa and lamina propria of forestomach of yak, where diffuse lymphoid tissues can be observed clearly. It is, therefore, believed that the yak forestomach may have evolved those specific structural characteristics in response to the unique living environment and dietary habits impose on the Qinghai-Tibetan Plateau.

Seis preestómagos de yaks (Bos grunniens) fueron estudiados mediante disección macroscópica y métodos histológicos. Se encontró que el preestómago del yak constaba de tres partes: rumen, retículo y omaso, compuestas de mucosa, submucosa, muscular y serosa. Además, el epitelio de la mucosa se conformó con epitelio escamoso estratificado, con parte de células cornificadas superficiales. En el rumen, la mucosa formó papilas linguladas que variaron en tamaño y forma. El retículo, consistió en una superficie epitelial que se invaginó en distinta medida en la lámina propia, conformando varias formas de pliegues, es decir, cuadrículas como pequeños cubículos. Además, existían muchos pliegues secundarios densamente cubiertos con papilas cornificadas. La característica más llamativa del omaso, fue formar láminas que variaron en longitud, con papilas cortas y ásperas distribuidas en ambos lados. Tomados en conjunto, no hubo glándulas dentro de la mucosa y la lámina propia del preestómago del yak, donde los tejidos linfoides difusos se pueden observar claramente. Por lo tanto, creemos que esas características estructurales específicas del preestómago del yak pudieron haber evolucionado en respuesta a las condiciones de vida únicas y hábitos dietéticos que se presentan en la meseta de Qinghai-Tíbet.

Desenvolvimento do omaso de bovinos da raça Nelore (Bos taurus indicus) durante o período pré-natal / Development of the omasum of Nelore cattle (Bos taurus indicus) during the prenatal period

O desenvolvimento do estômago de mamíferos domésticos é um processo complexo, especialmente em ruminantes. Essa pesquisa analisou o desenvolvimento desse órgão durante o período pré-natal. Foram utilizadas amostras de omaso de fetos da raça Nelore (Bos taurus indicus) divididos em cinco grupos com seis amostras cada: 1º – fetos com 9 a 15 semanas (8 a 21cm) de gestação, 2º – fetos com 16 a 22 semanas (23 a 37cm), 3º – fetos com 23 a 29 semanas (40 a 58cm), 4º – fetos com 30 a 36 semanas (61 a 77cm) e 5º– fetos com 37 a 43 semanas (79 a 88cm). Os cortes histológicos foram corados com Hematoxilina e Eosina e Picrossirius e examinados ao microscópio de luz. No feto de 11 cm, foi observado mucosa com lâminas primárias, secundárias e terciárias uniformes e demais camadas presentes. No feto de 13,5 cm surgiram as lâminas quaternárias, papilas nas lâminas primárias e secundárias e a formação da muscular da mucosa. Aos 28 cm, as papilas estavam em pleno desenvolvimento, assim como as lâminas, principalmente as quaternárias. No feto de 42 cm houve início de queratinização epitelial e, no de 56 cm, estava totalmente queratinizado. No feto de 60 cm, as lâminas possuíam papilas grandes e afiladas no ápice e, aos 65 cm, houve diminuição do epitélio e aumento da camada muscular. O feto de 83 cm apresentou lâminas delgadas, muscular da mucosa discreta e papilas por toda a superfície. Concluiu-se que as lâminas e papilas foram as estruturas que mais apresentaram modificações durante o desenvolvimento fetal.

The development of the stomach of domestic mammals is a complex process, especially in ruminants. The aim of this study was to analyze this organ during prenatal period. Omasum samples of Nelore fetuses (Bos taurus indicus) were divided into five groups of six samples each: 1- fetuses from 9 to 15 weeks (8 to 21cm) of gestation, 2 - fetuses from 16 to 22 weeks (23 to 37cm), 3 - fetuses from 23 to 29 weeks (40 to 58cm), 4 - fetuses from 30 to 36 weeks (61 to 77cm) and 5 - fetuses from 37 to 43 weeks (79 to 88cm). The histological sections were stained with Hematoxylin and Eosin and Picrossirius and examined by light microscopy. In fetuses of 11 cm it was observed mucosa with uniform primary, secondary and tertiary blades and all layers present. The fetus with 13.5 cm presented quaternary blades emergence, papillae on primary and secondary blades and formation of the muscularis mucosae. At 28 cm it were observed papillae in development, as well as the blades, especially the quaternary. In 42 cm fetuses was early epithelial keratinization and at 56 cm it was fully keratinized. In 60 cm fetuses the blades presented large papillae with tapered apex and at 65 cm there was decreased epithelium and increase of the muscle layer. In the fetus of 83 cm it were observed thin sections, discrete muscularis mucosa and papillae over the entire organ surface. It was concluded that the blades and papillae were structures that presented more changes during fetal development.

Ontogenesis of the omasum: a comparative analysis of the Merino sheep and Iberian red deer.

The aim of this study is to describe differences in the ontogenesis of the omasum in sheep (domestic ruminant) and deer (wild ruminant). A total of 50 embryos and fetuses of Merino sheep and 50 Iberian deer were used, from the first stages of prenatal life until birth. For the study, the animals were divided into five experimental groups according to the most relevant histological characteristics. The appearance of the omasum from the primitive gastric tube was earlier in sheep (22% gestation, 33 days) than in deer (25% gestation, 66 days). In both cases it displayed a primitive epithelium of a stratified, cylindrical, non-ciliary type. The appearance of four laminae of different sizes was always earlier in sheep than deer. At around 36% gestation in sheep (53 days) and 36% (97 days) in deer, the omasum consisted of 4 clearly-differentiated layers: mucosa (with epithelial layer and lamina propria), submucosa, tunica muscularis and serosa. The temporal order of appearance of the four order laminae and omasal papillae was always earlier in sheep than deer. The tegumentary mucosa of the omasum was without secretion capability in the first embryonic phases. From 67 days (26% gestation) the neutral mucopolysaccharides appeared in deer and at 46 days (30% gestation) in sheep. In both cases they continued to decrease until birth, this decrease being more pronounced in deer. Finally, the presence of neuroendocrine and glial cells was detected in deer at earlier stages than in sheep.

Ultrasonography of the omasum in 30 Saanen goats.

BACKGROUND: Primary diseases of the omasum are uncommon in goats, although the omasum may be involved in various gastrointestinal disorders. Examination of the caprine omasum via ultrasonography requires a good understanding of the normal appearance of the organ. However, in contrast to cattle, there is a lack of reference information on this topic in goats. Thus, the goal of the present study was to describe the results of ultrasonography of the omasum in 30 healthy Saanen goats. RESULTS: Ultrasonography was carried out in standing, non-sedated goats using a 5.0 MHz linear transducer. The location and size of the omasum, thickness of the omasal wall and visualisation of the abomasal laminae, contents and contractions were assessed. The omasum was visible from the 9th intercostal space (ICS) in all the goats, and from the 8th and 10th ICSs in 29 and 24 goats, respectively. The omasum was seen medial to the liver, but only the omasal wall closest to the transducer was visible. The dorsal omasal limit formed a dorsally convex curve running from cranioventral to caudodorsal and was furthest from the dorsal midline in the 6th ICS. The ventral omasal limit formed a ventrally convex curve. The size of the omasum was largest (10.2 ± 3.1 cm) in the 9th ICS and decreased cranially and caudally from this position. Active omasal motility was recorded in 20 goats with 0.3 to 2.0 contractions per minute. CONCLUSIONS: The findings of this study provide reference ranges for the interpretation of the location and size of the omasum in goats with suspected omasal abnormalities. Ultrasonography is an ideal diagnostic tool for evaluation of the omasum, which is not accessible to conventional examination techniques, such as inspection, palpation, percussion and auscultation.

Structural, histochemical and immunocytochemical study of the forestomach mucosa in domestic ruminants.

The forestomach plays an important role in the digestion physiology of ruminants. The aim of this study is to clarify the morpho-functional role of the mucosa in each of the three compartments of the forestomach in three domestic ruminants species, viz cattle, buffalo and sheep, by means of structural, histochemical and immunocytochemical methods, including transmission electron microscopy, light microscopy and scanning electron microscopy. These methods were chosen to demonstrate the indirect evidence for the presence of nitric oxide (NO) employing NADPHd and nitric oxide synthase I (NOS I). The various cell layers of the forestomach epithelium are described and illustrated in detail. An intense NADPHd staining was observed in the granulosa, spinosa and basal layers of the epithelium, in particular in the cytoplasm over the nucleus. NOS I immunoreactivity was found in all specimens of the forestomach mucosa. The results of this study might reflect a possible role of NO in delaying the onset of cellular apoptosis in the forestomach mucosa of the domestic ruminants, by playing a role in the production of cell energy.

Effects of stage of gestation and nutrient restriction during early to mid-gestation on maternal and fetal visceral organ mass and indices of jejunal growth and vascularity in beef cows.

The objectives were to evaluate effects of maternal nutrient restriction and stage of gestation on maternal and fetal visceral organ mass and indices of jejunal growth and vascularity in beef cows. Thirty multiparous beef cows (BW = 571 +/- 63 kg; BCS = 5.4 +/- 0.7) carrying female fetuses (d 30 of gestation) were allocated to receive a diet of native grass hay (CON; 12.1% CP, 70.7% IVDMD, DM basis) to meet NRC recommendations for BW gain during early gestation or a nutrient-restricted diet of millet straw (NR; 9.9% CP, 54.5% IVDMD, DM basis) to provide 68.1% of NE(m) and 86.7% of MP estimated requirements. On d 125 of gestation, 10 CON and 10 NR cows were killed and necropsied. Five remaining CON cows received the CON diet, and 5 NR cows were realimented with a concentrate supplement (13.2% CP, 77.6% IVDMD, DM basis) and the CON hay to achieve a BCS similar to CON cows by d 220 of gestation. Remaining cows were necropsied on d 245 of gestation. Cow BW and eviscerated BW (EBW) were less (P < 0.01) for NR than CON at d 125 but did not differ (P > 0.63) at d 245. Cows fed the CON diet had greater (P < 0.09) total gastrointestinal (GI) tract, omasal, and pancreatic weights. Stomach complex, ruminal, and liver weights were greater for CON than NR cows (P < 0.09) on d 125. Total GI, stomach complex, and pancreatic weights increased (P < 0.001) with day of gestation. Restricted cows had decreased (P = 0.09) duodenal RNA:DNA compared with CON. Duodenal DNA was less (P = 0.01) and jejunal RNA:DNA (P = 0.09) was greater for cows at d 125 vs. 245. Cow jejunal capillary area density increased with day of gestation (P = 0.02). Fetal BW and EBW were unaffected by dietary treatment (P > or = 0.32). Total GI tract and all components increased in mass with day of gestation (P < 0.001). Fetuses from NR dams had greater (P = 0.003) reticular mass at d 245 than CON fetuses. Fetuses from NR cows had greater (P = 0.02) percent jejunal proliferation at d 125 and greater (P = 0.03) total intestinal vascularity (mL) at d 245. Fetal jejunal DNA decreased (P = 0.09), RNA:DNA increased (P = 0.05), and total jejunal proliferating cells increased (P < 0.001) with day of gestation. Jejunal capillary area density, number density, and surface density were greater (P < 0.008) during late gestation. Results indicate that maternal and fetal intestines undergo changes during gestation, which can be affected by nutrient restriction and may partially explain differences observed in fetal development and postnatal performance.

Functional morphology of unguiculiform papillae of the reticular groove in the ruminant stomach.

The arrangement of the ruminant stomach in four gastric compartments with specialized mucosal papillae along the gastric groove (GG) has been previously described. However, a debate remains about functional implications of these morphological pecularities. This study was aimed to elucidate the relation between the papillar morphology and its putative functions. The GG was obtained from adult bovine stomachs (n=10) and subdivided into (1) proximal, (2) middle, (3) distal portion of the reticular groove (RG) and (4) the area of the reticulo-omasal sphincter (ROS). The specimens were processed for scanning electron microscopy and stereomicroscopy to analyze the density, shape and location of the papillae. Whereas the proximal portion of the RG was characterized by small (1.5mm), conically shaped, smooth papillae, the middle portion exhibited larger papillae (4mm) with sharp borders covered by keratin. Towards the ROS the papillae further increased in size (3-11mm) and showed compound or single processes resembling the shape of arrows, twisted hooks or thorns (unguiculliform papillae). At the ROS the unguiculliform papillae were distributed in clusters groups and along the border of the sphincter. Due to their peculiar morphological features it is suggested that unguiculliform papillae functions as a filter barrier preventing the passage of large-sized food particles into the omasum and avoiding subsequent obstruction of both the RG and the ROS. The data give further evidence that unguiculliform papillae are actively involved in the complex mechanisms of food processing taking place within the ruminant pluricavity stomach.

Ultrasonographic evaluation of the omasum in cows and buffaloes.

The study was conducted to establish the ultrasonographic features of the healthy and impacted omasum in cows and buffaloes. Scanning was done using a 3.5 MHz microconvex transducer. In healthy buffaloes, the omasum could be scanned at the eighth to ninth intercostal space as a round or oval structure having thick echogenic wall with echogenic leaves. Gradual slow movements of omasal leaves could also be seen in real-time B-mode. The omasum appeared to be very clear, large, and close to the transducer at the start of the omasal contraction, and as the contraction progressed the omasum retracted away from the transducer and became very small. In healthy cows the omasum was seen as a crescent-shaped structure with an echogenic wall. The contents of the omasum or omasal leaves could not be visualized. Omasal contractility was not as prominent as in buffaloes. In buffaloes, the impacted omasum appeared amotile, the omasal leaves were not visible, and the omasum as a whole gave a prominent distal acoustic shadow. In cows, the impaction could be diagnosed based on amotile omasum covering a large area on the right side. Ultrasonography was found to be helpful in subjective assessment of omasal impaction but could not aid in diagnosing the severity of impaction.

Ultrasonography of the omasum in cows with various gastrointestinal diseases.

The omasums of 30 healthy cows and 55 cows with various gastrointestinal disorders (10 with left displacement and eight with right displacement of the abomasum, 10 with abomasal volvulus, 10 with traumatic reticuloperitonitis, nine with ileus of the small intestines and eight with reticulo-omasal stenosis) were examined ultrasonographically on the right side of the body with a 3.5 MHz linear transducer. The dorsal and ventral margins of the omasum and its size in the fifth to 11th intercostal spaces were determined. Generally, the ultrasonographic appearance of the omasum did not differ between the healthy and abnormal cows. The omasum appeared as a semicircle, and the omasal wall closest to the transducer was visible as a thick echogenic line. In a few of the abnormal cows, the omasal laminae were visible and the omasum appeared to have motility. In the cows with left and right displacement of the abomasum and abomasal volvulus, the dorsal margin of the omasum was significantly further from the dorsal midline in some intercostal spaces than in the healthy cows. In the cows with left displacement of the abomasum, the ventral margin of the omasum was significantly further from the dorsal midline in the 7th intercostal space than in the healthy cows. In the cows with reticulo-omasal stenosis, traumatic reticuloperitonitis and ileus of the small intestine, the ventral margin of the omasum was significantly closer to the dorsal midline in some intercostal spaces than in the healthy cows. The mean (sd) size of the omasum in the healthy cows varied from 16.3 (1.5) cm to 56.9 (10.0) cm, depending on the intercostal space, and the omasum was significantly smaller in some intercostal spaces in the cows with reticulo-omasal stenosis, right displacement of the omasum, abomasal volvulus and ileus of the small intestine.

Ultrasonographic examination of the omasum in 30 healthy cows.

A 3.5 MHz linear transducer was used to scan the intercostal spaces of 30 healthy cows from dorsal to ventral on the right side, and the appearance, dorsal and ventral limits and size of the omasum were determined in each intercostal space. The size of the omasum determined ultrasonographically was compared with that determined postmortem. The distance between the omasum and the peritoneum of the lateral body wall was also determined electronically in each intercostal space by means of the two cursors. In the sixth to 11th intercostal spaces, the omasum had a crescent shape, with only the wall closest to the transducer visible as a thick echogenic line. The dorsal limit of the omasum appeared from cranial to caudal as the upper part of a circle, whereas the ventral omasal limit appeared as the lower part of a circle. The mean (sd) size of the omasum varied with the intercostal spaces from 16.3 (1.5) cm to 56.9 (10.0) cm; it was greatest in the ninth intercostal space and decreased cranially and caudally. The omasum was closest to the right abdominal wall in the eighth and ninth intercostal spaces, and was immediately adjacent to these spaces in 22 and 20 cows, respectively. There were significant correlations between the size of the omasum determined ultrasonographically in the ninth intercostal space and the weight, volume and largest and smallest diameters of the omasum determined postmortem, with correlation coefficients (r) between 0.38 and 0.55.

Immunohistochemical evaluation of the muscularis mucosae in the ruminant forestomach.

The muscularis mucosae and condensed fibrous layer of the ruminant forestomach were studied by immunohistochemistry using specific antibodies against alpha-smooth muscle actin (alphaSMA) and gamma-smooth muscle actin (gammaSMA). The specimens were collected from the rumen, reticulum and omasum of cattle, water buffalo, sheep, goat, Barbary sheep, Japanese serow, sika deer and mouse deer. The muscularis mucosae showed immunoreactivity for both alphaSMA and gammaSMA. On the other hand, the condensed fibrous layer appearing between the propria mucosa and tela submucosa was immunoreactive only for alphaSMA except for that in the goat and Barbary sheep reticulum which is intermingled with gammaSMA immunoreactivity. The distribution of muscularis mucosae and/or condensed fibrous layer varied among the compartments of forestomach and ruminant species. In the rumen, only the condensed fibrous layer was detected. On the other hand, the omasum contained only the muscularis mucosae. In the reticulum, both were detected. The amount of the condensed fibrous layer in the reticulum varied among different species in the following order of abundance: goat > Barbary sheep > sika deer> sheep > water buffalo > cattle and Japanese serow. Smooth muscle cells of external muscle layer were immunoreactive for alphaSMA and gammaSMA whereas those of blood vessels and pericytes were immunoreactive only for alphaSMA. The present findings on the actin immunoreactivity and distribution profile of muscularis mucosae and the condensed fibrous layer provide additional knowledge to further understand the histophysiological specialization of the different compartments of the ruminant forestomach.

Functional anatomy of the omasum in high Arctic Svalbard reindeer (Rangifer tarandus platyrhynchus) and Norwegian reindeer (Rangifer tarandus tarandus).

The structure and fill of the omasum was investigated in summer and in winter in adult female reindeer living on the polar desert and tundra of the high Arctic archipelago of Svalbard and in sub-Arctic mountain habitats in northern Norway. The mean total mass of the omasum in non-lactating adult female Svalbard reindeer was 467 g (0.65 g per 100 g live body mass (BM)) in September and 477 g (1.03 g per 100 g BM) in April. By contrast, the mean mass of the omasum in non-lactating adult reindeer in northern Norway was 534 g (0.83 g per 100 g BM) in September but only 205 g (0.35 g per 100 g BM p < 0.05) in late March, owing to a decrease in both tissue mass and the wet mass of the contents of the organ. The mean absorptive surface of the omasum in Svalbard reindeer was 2300 cm2 in September and 2023 cm2 in April. In Norwegian reindeer, by contrast, the absorptive surface area decreased from 2201 cm2 in September to 1181 cm2 (p < 0.05) in late March. The marked seasonal decline of omasal tissue and contents in Norwegian reindeer probably results from intake of highly digestible forage plants, including lichens, in winter. Svalbard reindeer, a non-migratory sub-species, survive eating poor quality fibrous vascular plants in winter. The absence of any marked seasonal change in the mass, total absorptive surface area or filling of the omasum in Svalbard reindeer in winter despite a substantial decline in body mass presumably reflects their need to maintain maximum absorption of nutrients, including volatile fatty acids, when feeding on such poorly fermentable forage.

Omasal anatomy in New Zealand red and fallow deer: an exploratory multivariate analysis.

We measured the weight and volume of omasae, and the number, weight and area of omasal laminae from wild fallow (Cervus dama), and wild and farmed red deer (Cervus elaphus) whose diet, as indicated by rumen content, was known. A multivariate analysis yielded two principal components, interpreted as indices of overall omasal size and laminar leafiness. The second component showed significantly greater variance in wild red deer than in farmed red or wild fallow deer. Deer feeding on a mixed diet of browse and grasses may have greater variability of omasal from than those feeding on grass alone. A relationship is derived by which the laminar area can be estimated from counts of laminae in different size classes.