Pcrtanika 5(1), 34-38 (1982)

The Gross Morphology of the Stomach of the Malaysian LesserMousedeer (Tragulus javanicus)

M.K. VIDYADARAN, M. HILMI and ROY A. SIRlMANE1

Department of Animal Sciences, Faculty of Veterinary Medicine and Animal Sciences,Universiti Pertanian Malaysia, Serdang, Selangor.

Key words: Stomach; anatomy; lesser mousedeer; Tragulus javanicus.

RINGKASAN

Morfologi kasar perus pelanduk telah dihuraikan. Ciri rumen pelanduk adalah berbentuk S, belingkarsedikit dan mempunyai pundi-pundi ventral dan kaudo ventral yang besar. Omasumnya adalah vestigial danmerupakan kawasan seluas 2-3 cm 3. fsipadu reticulo-rumen adalah lebih besar dari yang pada lembu ataubiri-biri.

SUMMARY

The gross morphology of the stomach of the lesser mouse deer is described. Characteristically, therumen is S-shaped spirally twisted and has large ventral and caudoventral sacs. The omasum is vestigealand is represented by an area of about (2-3 cm'). Reticulo rumen volume is largPr than for ox and sheep.

INTRODUCTION

Simpson (1945) estimated 180 genera ofextinct and 68 genera of living ruminants andclaimed that of the primitive ruminants only thefamily Tragulidae have survived to the presenttime. The Malaysian lesser mousedeer is includedin the family Traguilidae in the Infra orderTragulina.

The anatomy of the domesticated ruminantsis well described for the ox (Sisson and Grossman,1975; Nickel et al., 1973), the sheep (May, 1970)and the goat (Sisson and Grossman, 1975). How­ever complete detailed information is lackingin the literature for most wild ruminants especiallyin the family Traguilidae. Available literaturedeals only with very general descriptions of theruminant stomach (Webbetal., 1972).

The present study ,vas undertaken firstly todescribe the detailed morphology of the stomachof the Malaysian lesser mousedeer. Secondly, itwas hoped that the study would aid in establishingits relationship with other ruminants and whetherfeeding strategies have evolved in response toselection of different foods producing adaptationsin the gastro-in testinal tract.

MATERIALS AND METHODS

AnimalsSix adult T. javanicus, three males and three

females aged between 2 to 3'h years (second

generation offsprings bred in captivity) werehOllsed at the Animal House Facilities at theFaculty of Veterinary Science. Two animals wereplaced in each cage measuring 2' X 4' X 8'. Theywere fed ad libitum on a diet consisting of Ipomoealeaves, long beans, raw peanu ts and commercialrabbit pellets (Zuellig Feed Mill). The weights ofthe slaughtered animals ranged from 1.362 kg ­I. 779 kg.Dissection

The animals were killed by exsanguinationof the neck. A midline incision was made on theskin extending from the base of the neck to thepubis. The skin was deflected and the sternumremoved after disarticulating the costochondraljoints of both sides. The abdominal muscles wereincised and the gastro-intestinal tract exposed.The location of the various parts of the stomachwas studied before ligatures were placed on theabdominal part of the oesophagus and at theproximal end of the duodenum. The stomachwas then removed after cutting above and belowthe ligatures respectively.

Measurements

1. WezghtThe live weight of the animals were taken

prior to slaughter. The weights of the stomach andcontents were also recorded. Each of the threecompartments (rumen, reticulum, abomasum) wasseparated after placing ligatures and cutting at therumino-reticulo and reticulo-abomosal junctions.The empty weights of the rumen, reticulum and

1 Animal House, Institute of Medical Research, Kuala Lumpur, Malaysia.

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M.K. VIDYADARAN, M. HILMI AND ROY A. SIRIMANE

Fig. 2. External morphology of the Stomachs ofthe "'Malaysian lesser mouse-deer and the"''''goa t (left view).Abo, Abomasum; Cbs, Cranial sac; Cvs,Caudo ventral sac; Ds, Dorsal sac; Llg,Left longitudinal groove; Ret, Reticulum;Vcg, Ventral coronary groove; Vs, Ventralsac.

a. Malaysian lesser mouse-deer (air driedspecimen)

b. Goat (air dried specimen)

... actual size reduced by half....... drawn to same scale as above.

Fig. 1. Left view of the stomach of the Lessermouse-deer.Abo, Abomasum; Cbs, Cranial sac; Cvs,Caudo ventral sac; Ds, Dorsal sac; Llg,Left Longitudinal groove, Ret, Reticulum;Ru, Rumen; Vcg, Ventral coronary groove;Vs, Ventral sac.

Compound StomachThe stomach consists of only three compart­

ments (Fig. I) namely the rumen, reticulum andabomasum. The omasum is absent for all purposesbut a rudimentary area is represented. The stomachoccupies almost the whole of the abdominal cavityand extends from the diaphragm to the pelvic inlet.Considerable portions of the rumen, reticulum andabomasum extend to the right of the medianplane.

abomasum respectively were obtained afteremptying the stomach contents, washing anddrying with tissue paper.

Dorsally the rumen extends from the seventhor eight intercostal space to the last lumbarvertebraand ventrally from the eleventh intercostal spaceto the pelvic inlet. Considerable portions of thedorsal sac lies to the left of the median planewhilst most of the ventral sac and caudo-ventralblind sac lie to the right of the median plane. Therumen resem bles a three quarter-S-shape anddiffers markedly in shape from that of ox, sheepand goat (Figs. 2 and 3). The dorsal sac overliesthe ventral sac which is pushed more caudally.The caudoventral blind sac is extensive (Fig. 2)and is placed caudodorsal to the ventral sac. Boththe right and left longitudinal grooves are presentand they correspond to pillars internally. The left

RESULTS AND DISCUSSIONS

3. Surface AreaThe rumen, reticulum and abomasum were

incised so that it flattened and spread out. Eachcompartment was placed on a polyethelene sheetand the circumference traced out. The tracedpolyethelene sheet was then placed on a graphpaper and the area calculated. Four specimens(2 males and 2 females) were used in this study.

2. VolumeThe volume of the three compartments were

obtained by filling each compartment, to the brimwith water and then emptying it into a measuringcylinder. Three readings were taken for eachcompartment.

4. Air-Dried Stomach SpecimenThe two air dried stomach specimens (I male

and I female) were prepared by the method ofChurch (1973). The fresh stomach was trimmed offat and the stomach flushed out with water. It wassoaked in 95% ethanol to dehydrate the tissuesand further ex tract some of the lipids. Finally, itwas dried by passing air through the iriflatedstomach.

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GROSS MORPHOLOGY OF STOMACH OF MALAYSIAN LESSER MOUSEDEER

Fig. 3. ["terMI morphology of the stomachs of the -Malaysian lesser mouse-deer and the --goat (Dorsalview). . . ,. .Cp, Cranial pillar; Vcp, Ventral caudal pjIlar; Up, Left 10ngi1;udinal pillar; Rrf, Rumino-reticulo fold;Rig, Rumino-reticulo groove. .

a. Malaysian lesser mouse-deer (air dried spuimeri{' '

b. Goat (air dried specimen).

* size reduced by one-sixth.** drawn to same scale as above.

longitudinal groove is prominent and extends fromthe cranial groove of the rumen, inclines dorsally,then ventrally and finally terminates caudally justanterior to the ventral coronary groove. No leftaccessory longitudinal groove is present. The rightlongitudinal groove is less distinct and extendsfrom the cranial groove and fades out caudally. Aright accessory groove is present dorsally. Theventral coronary groove is distinct, spiral in sh;\peand very prominent on the left dorsal and ventral

36

sides but less so on the right side. A dorsal coronarygroove is not present.

At the cranial end of the cavity of the rumenis "the rumino-reticular orifice, bounded by theRJrnino-reticular fold. Th~"longitudinal and trans­verse diameters are 2-3 em and 1-1.5 em respec­tively. The ruminoreticuiaifold is very large andextensive. It ex tends from. near the cranial pillaron the right side, passes dorsally, then to the le'it

M.K. VIDYADARAN, M. HILMI AND ROY A. SIRIMANE

and ventrally, and finally curves dorsally and endsnear the ventral lip of the reticular groove on theright dorsolateral wall of the reticulum. The foldis smallest at its end and biggest ventrally. Boththe reticular and ruminal sides of the fold arecovered with short, flat papillae.

The left longitudinal pillar is large (Fig. 3), itextends from the cranial pillar to the caudal pillar.The right longitudinal pillar is very small but aright accessory longitudinal pillar is present. Theventral coronary pillar does not meet the caudalpillar. It originates near the caudal pillar (on thedorsolateral part of right side) and ends caudally(on the ventro lateral part of the right side). Theventral coronary pillar separates the ventral sacfrom the caudo ventral blind sac. The dorsalcoronary pillar is absent. The gastric groove is welldefined bu t short. It lies on the dorsolateral partof the right side of the reticulum. The reticulargroove is more obliquely directed rather thandorso-ventral (in ox, goat, sheep) so it is moreappropriate to consider the lips as the dorsal lip(right) and the ventral lip (left). The dorsal lip ismore extensive and more thickened near itstermination. The groove is wide and the lips arecovered with thick-globose type of papillae.

The mucous membrane is pale brown toalmost yellow in colour. Large papillae are foundon the dorsal, ventral and caudoventral blind sacs.Smaller papillae are distributed on the rumino­reticular fold, right and left longitudinal pillarsand the regions surrounding it. The papillae areleaf like in shape and are variable in size even inthe same area. The larger ones measure 0.3 mm inheight and 0.1 mm in breadth.

The mean volume of the rumen is about380 ml or 88~ of the volume of the stomach.Ruminal contents averaged 51.8 ml or 76% of thestomach contents. Mean rumen surface area is139.8 em' or 78.3% of the surface area of thestomach.

ReticulumThe reticulum is large and its ventral relations

ex tend from the diaphragm. Laterally it ex tendsfrom the 8th to the 10th rib and although centrallylocated, considerable portions of the reticulumis on the right of the median plane.

The internal structure is honey-com b like andthe mucosa is raised into folds. The honey-combcells are four, five and six sided with the largestcells found ventrally. Unlike ox and goat, onlyprimary crest are found. The cells are not su b­divided into smaller compartments and so secon-

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dary crests are absent (Fig. 4). Long pointedpapillae are found on the walls and at the centerof the crests.

Fig. 4. Internal morphology of the 'honey comb'cells of the reticulum.Pr, Papillae of the ridges; Pc, Papillae of thecenter.

The mean volume is 35 ml or 8.1% of thetotal stomach volume. Mean reticular surface areais 20 em' or 11.27% of total stomach surface area.

OmasumA small area (2-3 em') lying between the

reticulum and abomasum represents the vestigealomasum. The mucosa is covered by irregular foldsbut no lamellae are seen. The omasal groove liesventrally and leads directly into the abomasum.

AbomasumThe abomasum lies almost entirely on the

right of the median plane and contacts the ventralsac of the rumen and liver. Internally, six longitu­dinal folds are present, and these extend to thepyloric region. Transverse folds connect thelongitudinal folds.

The mean volume . of abomasum is 17 mlor 3.9% of the total stomach volume. Meanabomasal surface area is 18.5 em' or 10.42%of the total stomach surface area.

The domestic artiodactyl ruminants have acomplex stomach consiting of four compartmentsalthough dietary habits or food preferences varytremendously. How the variations in proportionof different parts of the stomach with certainstructural pecularities can be related to differentaspects of diet is not so easily understood.

Grossly, the stomach is S-shaped with largeventral and caudo ventral sacs. The sacs are spirallytwisted, have large papillae and could be areaswhere food is not only stored but fermentativedigestion and absorption occurs. The prominent

GROSS MORPHOLOGY OF STOMACH OF MALAYSIAN LESSER MOUSEDEER

caudoventral sac may playa more prominent rolein ruminant contraction.

Reticulo rumen volume (96.1%) was greaterthan that reported for adult ox and sheep (yI arnerand Flatt, 1965). Many of the structural andfunctional variations in the digestive tract can oftenbe related to diet and feeding. The natural food isbelieved to consists of succulent grasses, fallenfruits and tubers. Vidydaran and Hilmi, (1981)studied teeth characteristics and reported thatteeth types were not particularly suited forgrinding. As for the physical reduction of food,Nordin (1978) reported that both in wild andcaptive animals food in the rumino-reticuloregion was physically reduced well. The relativelylarge reticulo rumen volume provides increasedstorage capacity and with a longer retention timeenables the animal to reduce the food well.

All true ruminants have a distinct omasum.It is not well developed in deer and antelope butreaches its full expression in the Girafidae andin the Bovidae (Moir, 1968). A functional omasumis absent. in the mouse-deer. The reticulum andomasum are important structures for the me­chanical separation of food (Hungate 1966 andBecker et aZ., 1963) before passage into theobomasum. One can only speculate that thereticulum and possibly the reticulo abomasalopening in some way control the passage of fineparticles into the abomasum.

ACKNOWLEDGEMENT

The au thors wish to thank Encik Ganesamurthy,Encik Abdullah Fakri bin Ahmad and EncikShuhaimi bin Abdullah for technical assistancerendered. This work was supported by a researchgrant from the Faculty of Veterinary Medicine,Universiti Pertanian Malaysia.

Special thanks are due to Dr. Kassim binHamid for valuable suggestions.

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(Received 31 July 1981)