A review is made of the ruminant digestive system in its morphophysiological variations and adaptations relating to foraging behaviour, digestive physiology, to interactions between plants and ruminants and to geographic and climatic diversity of ruminants' ecological niches. Evidence is provided for evolutionary trends from an extreme selectivity mainly for plant cell contents and dependence upon a fractionated fore- and hindgut fermentation, to an unselective intake of bulk roughage subjected to an efficient plant cell wall fermentation, mainly in the forestomachs. The review is based on detailed comparative morphological studies of all portions of the digestive system of 65 ruminant species from four continents. Their results are related to physiological evidence and to the classification of all extant ruminants into a flexible system of three overlapping morphophysiological feeding types: concentrate selectors (40%), grass and roughage eaters (25%) and intermediate, opportunistic, mixed feeders (35%). Several examples are discussed how ruminants of different feeding types are gaining ecological advantage and it is concluded that ruminants have achieved high levels of digestive efficiency at each evolutionary stage, (including well-documented seasonal adaptations of the digestive system) and that ruminant evolution is still going on. Deductions made from the few domesticated ruminant species may have, in the past, biased scientific evaluation of the free-ranging species' ecology. The main threat to a continuous ruminant evolution and diversity appears to be man's neglect for essential ecological interactions between wild ruminants and their specific habitats, which he alters or destroys.

La forme de l'estomac des ruminants sauvages etudies en Afrique Orientale varie considerablement et apporte plus de precisions sur leur comportement alimcntaire que la classique division en « browser » (mangeur de feuillage) ct « grazer » (brouteur d'herbe). 31 especes sont ainsi passdes en revue. Par ailleurs les auteurs fournissent des donndes concernant la nourriture de ces ruminants d'apres des observations directes. Les r£sultats de ces deux fa$ons d'etudier le comportement alimentaire concordent remarquablement.

Problem statement: The Oryx antelope is a grazing ruminant of the Bovidae family. The macroscopic anatomy of the stomach in one adult Oryx dammah, an extinct species in the wild, was described. Approach: The stomach of the Oryx was composed of the four classic compartments of the ruminants. The weight of all the full stomach was 21.5 kg. The ruminal papillae were distributed unevenly in the rumen. Results: The maximum height of the cristae reticuli was 0.3 cm. The Cellulae reticuli were divided and contained secondary and tertiary crests. The Curvatura omasi measured 30.0 cm and the omasum had 15 primary, 9 secondary, 30 tertiary and 34 cuaternary Laminae omasi. The abomasum had about 17 Plicae spirales abomasi. Conclusion/Recommendations: We concluded that the stomach morphology of the Oryx had characteristics of the others grazing feeders ruminants. An important limitation of this study is the fact that we used only one animal, further studies of the digestive system of this species are necessary.

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Magnetic resonance imaging of the syndesmotic complex is a highly sensitive and specific tool for the pretherapeutic-evaluation of syndesmotic injury.

In the ongoing debate about divergent evolutionary morphophysiological adaptations of grazing and browsing ruminants, the size of the salivary glands has received special attention. Here, we report the most comprehensive dataset on ruminant salivary glands so far, with data on the Glandula parotis (n=62 species), Gl. mandibularis (n=61), Gl. buccalis ventralis (n=44), and Gl. sublingualis (n=30). All four salivary gland complexes showed allometric scaling with body mass (BM); in all cases, the 95% confidence interval for the allometric exponent included 0.75 but did not include 1.0 (linearity); therefore, like other parameters linked to the process of food intake, salivary gland mass appears to be correlated to metabolic body weight (BM0.75), and comparisons of relative salivary gland mass between species should rather be made on the basis of BM0.75 than as a percentage of BM. In the subsequent analyses, the percentage of grass (%grass) in the natural diet was used to characterize the feeding type; the phylogenetic tree used for a controlled statistical evaluation was entirely based on mitochondrial DNA information. Regardless of phylogenetic control in the statistical treatment, there was, for all four gland complexes, a significant positive correlation of BM and gland mass, and a significant negative correlation between %grass in the natural diet and gland mass. If the Gl. parotis was analyzed either for cervid or for bovid species only, the negative correlation of gland mass and %grass was still significant in either case; an inspection of certain ruminant subfamilies, however, suggested that a convergent evolutionary adaptation can only be demonstrated if a sufficient variety of ruminant subfamilies are included in a dataset. The results support the concept that ruminant species that ingest more grass have smaller salivary glands, possibly indicating a reduced requirement for the production of salivary tannin-binding proteins.

(2008Using cranioskeletal measurements, several studies generated evidence that grazing ruminants have a more pronounced mastication apparatus than browsing ruminants -in terms of muscle insertion areas and protuberances, with the resulting hypothesis that grazers should have larger, heavier chewing muscles than browsers. However, the only investigation so far [Axmacher and Hofmann 1988] did not find differences between ruminant feeding types in the masseter muscle mass of 22 species. Here, we expand the dataset to 48 ruminant species.Regardless of phylogenetic control in the statistical treatment, there was a significant positive correlation of body mass and masseter mass, and also a significant association between %grass in the natural diet and masseter mass. The results support the concept that ruminant species that ingest more grass have relatively larger masseter muscles, possibly indicating an increased requirement to overcome the resistance of grass forage. The comparative chewing resistance of different forage classes may represent a rewarding field of ecophysiologic research.

The activity and abundance of the Na+/glucose co-transporter (SGLT1) was assessed in brush-border-membrane vesicles (BBMV) isolated from the intestine of grass- and roughage- (GR) consuming ruminants (sheep and dairy cattle), during the transition from the pre-ruminant to the mature ruminant state. The abundance of SGLT1 messenger ribonucleic acid (mRNA) was also compared in the intestinal tissue of the same animals. The dramatic developmental decline in the activity and expression of SGLT1 appears to be typical of GR-consuming ruminants and is coincident with the significant decline in the levels of lumenal monosaccharides. Expression of the ovine SGLT1 complementary deoxyribonucleic acid (cDNA) in Xenopus laevis oocytes confirmed that the isolated cDNA encodes for a functional Na+/glucose co-transporter. Determination of a bovine intestinal SGLT1 protein sequence (amino acids 347-658) indicated 99% similarity to the ovine SGLT1 protein with differences in the carboxyl terminus. In contrast to GR-consuming ruminants, the abundance of SGLT1 protein and SGLT1 mRNA remained significantly high in the intestine of ruminants in both the intermediate-mixed (IM) feeding goat and fallow deer and the concentrate-selecting (CS) moose and roe deer, dietary groups correlating with the availability of monosaccharides in the intestinal lumen.