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Gastrointestinal motor functions in ruminants

Yves Ruckebusch

10.1002/cphy.cp060134

Source: Supplement 16: Handbook of Physiology, The Gastrointestinal System, Motility and Circulation

Originally published: 1989

Published online: January 2011

Full Article on Wiley Online Library



Abstract

The sections in this article are:

1 Mammalian Herbivore Stomach
1.1 Morphological Adaptation to Bulky Food
1.2 Functional Adaptation to Fermentation
1.3 Functional Adaptation to Absorption
1.4 Retention Time and Food Propulsion
2 Forestomach Motility
2.1 Cyclical Contractions of Reticulorumen
2.2 Events Associated With Rumination
2.3 Events Associated With Eructation
2.4 Cyclical Activity of Omasum
2.5 Reticular Groove Mechanisms
2.6 Nervous Control of Forestomach Motility
3 Stomach Motility
3.1 Motor Patterns of Activity
3.2 Duodenal Brake Mechanism
3.3 Control of Gastric Emptying
4 Small Intestine Motility
4.1 Periodic Activity
4.2 Mixing Versus Propelling Activity
4.3 Motor Function of Duodenal Bulb
4.4 Pancreaticobiliary Secretions
4.5 Nervous Control
4.6 5‐Hydroxy tryptamine
5 Large Intestine Motility
5.1 Functional Organization
5.2 Cecal Motility Patterns
5.3 Pelleted Feces Formation
5.4 Neural Influences
6 Pharmacological Considerations
6.1 Drugs Affecting Forestomach Motility
6.2 Drugs Affecting Gastroduodenal Junction
6.3 Perspectives
Figure 1. Figure 1.

Expansion of simple stomach into multichambered stomach in ruminant herbivore (associated with specialized motor function, fermentation, and absorption). Esophageal groove (1) directs sucked liquid from cardia toward abomasum. Groove is bound by 2 fleshy lips that run spirally; the one that lies caudally at upper right end of groove passes left to gain cranial aspect about reticuloo‐masal orifice (2). Relative infrequency with which the abomasal contents reflux through wide omaso‐abomasal opening (3) depends on development of abomasal plicae, which rise abruptly around margin of opening and act like a ball valve to close orifice when pressure within abomasum rises. Re, reticulum; Ru, rumen; Om, omasum; Ab, abomasum.

From Dyce 59
Figure 2. Figure 2.

Arrangement of smooth muscle bundles in adult ruminant stomach. Reticulum and rumen, which together are known as reticulorumen, hold on average 84% of total capacity. Nonglandular mucosa covers dorsal sac and ventral sac of rumen, reticulum, and omasum (cross‐hatching). Cardiac gland region (open areas) is near omaso‐abomasal opening. Fundic glands (vertical lines) and pyloric glands (horizontal lines) involve whole abomasum.
Figure 3. Figure 3.

Gastric form and relative volumes indicated as percentages of stomach regions in herbivores [Artiodactyla (A)] and others (B). Gastric groove is represented schematically (horizontal filled bar) and apertures between gastric regions are also represented. Dotted structures, semilunar folds. Esophagus comes in from top right, and duodenum points to left. Hatched areas correspond to HCl‐producing fundic glands and pyloric glands.

Adapted from Langer 131
Figure 4. Figure 4.

The illustration by Flourens of the esophageal (reticular) groove in sheep, which he claimed to close on food lying within and to force it into thoracic esophagus. Colin disproved its role in regurgitation after tying the lips together with a wire in a steer, and Wester showed the opening and closing to be in relation with biphasic or triphasic contraction of reticulum.

From Flourens 74
Figure 5. Figure 5.

Topography of thoracic and abdominal organs of a goat. Left lung has been removed and reticulum and rumen have been opened. Reticulum lies against costal part of the diaphragm. Its ventral relations are sternal part of diaphragm, caudal end of sternum, and xiphoid cartilage. Rumen is divided into dorsal and ventral sacs, a, Rumen dorsal sac; b, rumen ventral sac; c, ventral blind sac; d, dorsal blind sac; e, atrium; f, reticulum; g, cardia; h, esophageal groove; i, cranial pillar; k, caudal pillar of rumen; l, reticuloruminal fold; m, esophagus; n, vena cava caudalis; o, aorta; p, diaphragm; 1, level of solid material; 2, gas pouch; 3, sediment (small particles).

From Grau 78
Figure 6. Figure 6.

Typical record showing pressure registered simultaneously in reticulum (Re) and dorsal rumen sac (DRu) in a sheep fasted 18 h and while receiving oats for 10 min. Lightly inflated balloons, inserted through a rumen fistula, are connected to tambours writing on kymograph. Bottom: electromyogram showing normal biphasic reticulum contractions spread backward over anterior sac of rumen with a lag of ∼5 s. Regular small group discharges correspond to intrinsic motility.
Figure 7. Figure 7.

Left, diagram of bovine reticulorumen showing 4 recording points and typical pressure patterns. 1, Reticulum; 2, anterior rumen sac; 3, dorsal rumen; 4, ventral rumen sac. AP, anterior pillar; F, fistula; E, esophagus; PP, posterior pillar; RF, reticuloruminal fold. Note belching contractions (b) of rumen and hydrostatic pressure changes in anterior rumen sac. [From Reid and Cornwall 181.] Right, drawing summarizing movement of digesta in ovine reticulorumen as seen radiographically in horizontal and vertical planes. Arrows indicate direction of movement [From Waghorn and Reid 247] and main contraction sequences as indicated by radiography. Time in seconds indicates interval after reticular movement, and contracting region of reticulorumen wall is indicated by a heavy line. Gas bubble (stippled), is brought over cardiac orifice at 13 s and during eructation sequence at 38 s.

From Wyburn 259
Figure 8. Figure 8.

Intrinsic electrical activity of ovine rumen during impaction. Slow‐wave‐like activity at frequency of 18–20/min is superimposed with clustered burst spike potentials (bars) at time of contractions.
Figure 9. Figure 9.

Stimulation by distension of local intrinsic activity and ruminal contractions. Top: normal biphasic reticular contraction (1) spreading over the rumen (2, 3, 4), and followed within 18 s by a backward contraction of the rumen starting on the posterior ventral sac (5). Local intrinsic activity as group discharges at 3‐s intervals on the dorsal sac of the rumen (3). Bottom: distension by air at mean pressure of 10 mmHg is accompanied by a backward contraction of rumen starting within 6 s on the posterior ventral sac (5) and followed by to‐and‐fro contractions of rumen (arrows). Intrinsic activity is increased at both reticular (1) and ruminal levels (3).
Figure 10. Figure 10.

In sheep, electromyogram (A) of reticulum (R) and posterior dorsal sac (Dp) of rumen in conjunction with recording (B) of intraruminal pressure. 1–8, Primary cycle movements. Secondary contraction of rumen (↓) may occur immediately after a primary contraction (3) or much later (4) [From Ruckebusch and Tomov 198.] In cattle, measurement of volume of eructated gas passing into trachea cannula, inserted into trachea near larynx and connected to a spirometer. Transient blockade of primary reticulorumen cycles is obtained by an α2‐adrenergic receptor agonist xylazine. Each secondary contraction of rumen (Ru) is accompanied by elimination of 200–500 ml of gas.
Figure 11. Figure 11.

Goat fitted with esophageal cannula. Illustration of force at which digesta are propelled by antiperistalsis from rumen during rumination. Cannula was open within 1 s after visible inspiratory effort that signals a regurgitation. Average volume (∼200 ml) was ejected in toto through cannula within 2 s.
Figure 12. Figure 12.

Events on esophagus, reticulum, jaw, and chest associated with regurgitation. A: inspiratory effort occurs (arrows) toward end of extracontraction of reticulum and is followed in less than 1 s by chewing. B: esophageal electromyograms are recorded from electrodes placed at equal distance on esophagus, near glottis (1), at the entry of chest (2) and close to cardia (3) and reticulum. Regurgitation of digesta (AP) is followed by swallowing first the excess liquid on 2 occasions (P1 and P2) and then the bolus (P3).
Figure 13. Figure 13.

Conditioned regurgitation in a goat. Top: inspiratory efforts followed by regurgitation occurred 15 s after emission of conditioned stimulus (CS) after 39 associations. Bottom: latency becomes very short and regurgitation was seen immediately after 87 associations.

From Ruckebusch 187
Figure 14. Figure 14.

Effects of intravenous administration (bolus) of dopamine before (A) and within 5 min after (B) injection of naloxone on reticular (Ret) contractions in sheep. Lower jaw movements are recorded by balloon fixed on halter. Injection of dopamine induces transient inhibition of reticular contractions but increases salivary flow, resulting in frequent swallowing movements. Dopamine at same dosage after naloxone pretreatment was able to induce rumination.
Figure 15. Figure 15.

Top, electromyographic responses of ruminal wall for primary cycle of movement (A) and for primary cycle followed by secondary cycle of movement (B and C). Bottom, diagrammatic representation of strength of each contraction and orderly sequence of 2 primary cycles followed more or less rapidly by secondary cycle. Top, A, single cycle involves dorsal (D) and posterior dorsal sac (Dp) of rumen followed by ventral (V) and posterior ventral sac (Vp). B, double cycle with short time interval between primary and secondary eructative (↓) ruminal contractions. C, time interval between primary (1) and secondary (2) contractions of rumen is longer because of an additional contraction of posterior ventral sac ( split into and ). Bottom: eructation (↑) occurs ∼28 s after reticular (R) contraction in A but much later (42 s) in B because of sustained weak contraction of Vp. Some contractions of ventral sac of rumen are missing and indicated by .

From Ruckebusch and Tomov 198
Figure 16. Figure 16.

Tracing showing that cyclical contractions of omasal body (Om) occurred at same rate as reticulorumen (Ret‐Rum) contractions in sheep. This is not the case in cattle during slower rate of reticulorumen contractions during deep sleep (∼7 min).
Figure 17. Figure 17.

Motility of omasum (Om) and reticulum (Re) in cattle. Pressure changes recorded from small balloon inserted near middle part of greater curvature of bovine omasum, reticulum, and rumen (Rm). Arrow, intravenous injection of pentagastrin (1 μg/kg), which transiently blocks reticulorumen contractions and increases omasal pressure.
Figure 18. Figure 18.

Electrical activity of omasal wall (right and left sides, omasal groove, and greater curvature) in relation to contraction of reticulum (A) and reticulo‐omasal orifice (B).

From Ruckebusch 188
Figure 19. Figure 19.

Motility of reticulum and omasal body under local anesthesia of vagus nerves (top) and general anesthesia (bottom). Omasal contractions persist in both cases despite arrest of reticular contractions. Arrest of activity of reticulum during 20 min first increases frequency then strength of omasal contractions without changing mean level of activity.

(From Bueno and Ruckebusch 21
Figure 20. Figure 20.

Responses of an adult bull to the introduction of 2 liters of warm milk into abomasum by a tube inserted through reticulo‐omasal orifice (top) and the sucking of 2 liters of milk (bottom). Bars indicate duration of these procedures.
Figure 21. Figure 21.

Termination of dorsal and ventral trunks in the goat, showing their origin from right and left vagus nerves. After section of dorsal vagal trunk, which has 3 branches A, B, and C, reticular cyclical activity persists, whereas dorsal sac of the rumen shows small group discharges later grouped in regular series. Section of ventral vagal trunk (branches 1, 2,3,4) alters activity of reticulum.

Adapted from Coulouma 36
Figure 22. Figure 22.

Extrinsic (top traces) versus intrinsic (bottom traces) motor activity of reticulum (intraluminal pressure and electrical activity) and dorsal sac and ventral sac of rumen as seen 12 days after cervical vagotomy.

From Ruckebusch and Tomov 198, ©1972, with permission from Pergamon Press, Ltd
Figure 23. Figure 23.

Intrinsic motor activity of rumen (intraluminal pressure) recorded 6 wk after thoracic vagotomy in a sheep maintained at constant body weight by intragastric infusion of complete liquid diet (see refs. 170 and 171. From top to bottom, increased frequency of intrinsic contractions after progressive or sudden distension during 2 min and cholinergic, serotonergic, or prostaglandin stimulation obtained by intravenous injection of pilocarpine, 5‐hydroxytryptophan (5‐HTP), or prostaglandin F2α (PGF2α).

From Y. Ruckebusch and C. H. Malbert, unpublished observations
Figure 24. Figure 24.

Gastric centers in medulla. On each side, region relative to obex extends laterally from 1 to 3 mm, caudally 2 mm, and rostrally 4 mm. Black dots, retrograde cellular degeneration 16 days after rumenectomy in lamb.

Adapted from Szabo and Dussardier 220
Figure 25. Figure 25.

Functional organization of gastric centers. Neuronal network with type B and C interneurons may constitute rate circuit responsible for chronotropic regulation of extrinsic movements. Another network with type A interneurons is involved in inotropic (amplitude) regulation of cyclic movements of reticulum through early vagal discharges and of rumen through later vagal discharges. Rate and amplitude circuits are inhibited by abomasal distension. Amplitude circuit and vagal motoneurons are stimulated by reticular distension. Strong net excitatory drive on rate and amplitude circuits arises from central nervous system.

Adapted from Leek and Harding 134
Figure 26. Figure 26.

Responses of mechanoreceptors. Tension receptor gives a steady (slowly adapting) discharge throughout period of distension (horizontal bar). Discharges occur only at times of inflation and of deflation for epithelial receptors. (From E. C. Crichlow, unpublished observations).
Figure 27. Figure 27.

Mechanical activity of pyloric antrum in sheep recorded from curved strain‐gauge force transducers fixed on the antrum at 7 and 2 cm before pylorus and duodenal bulb and 2 and 3 cm beyond pylorus.
Figure 28. Figure 28.

Electrical activity recorded from pairs of electrodes fixed at 10‐mm intervals on gastroduodenal junction in sheep showing propulsive waves (*) and continuous spiking activity (**) commencing at pylorus (PYL) or duodenal bulb (Bulb). Ant, pyloric antrum.
Figure 29. Figure 29.

Percentages of propulsive (peristaltic) and aboral or oral locally propagated activity along duodenum in cattle.

From Ooms and Oyaert 167
Figure 30. Figure 30.

Electromyography of ovine gastroduodenal area from electrodes fixed 2 cm apart on pylorus, antrum (−7 cm), and duodenum (3 cm). Tracings are consecutive. Top: irregular spiking activity showing spike bursts of antrum at frequency of 6.5/min. Magnitude of spike bursts waxes and wanes with activity on duodenum. Bottom: cyclical period of regular spiking activity followed by quiescence.
Figure 31. Figure 31.

Changes in intraduodenal pH over time in sheep as measured by pH electrode inserted through cannula placed ∼7 cm from pylorus. Prolonged periods of relatively high, stable pH indicating myoelectrical quiescence follows cyclical phase of regular spiking activity (RSA) indicated as a bar. Trace A is suggestive of fairly high delivery rate of acid from abomasum to duodenum with mean pH of 4.1. Trace B was obtained by obstructing transpyloric outflow with a balloon of a Foley catheter inserted via duodenal cannula. Rise of 2.5 pH units within 6 min occurred that remained stable until cessation of occlusion. Bottom: changes in abomasal outflow as measured by electromagnetic probe at 7 cm from pylorus in cattle. Note absence of flow at the time of RSA phase.
Figure 32. Figure 32.

Duodenal myoelectrical activity from 8 electrode sites placed 2 cm orad to pylorus (E1) and along duodenum, indicative of postprandial propulsive waves in the calf. Flow probe was fixed around duodenum 65 cm aborad to pylorus. Four propulsive waves are seen propagating away from pylorus where their corresponding spike bursts differed by a higher amplitude and longer duration from the others at sites 45 and 65 cm from pylorus.

Adapted from Dardillat 39
Figure 33. Figure 33.

Relationship between antroduodenal myoelectrical activity and fluid propulsion in a 60‐kg sheep. Top traces show end of a phase of irregular spiking activity with propulsive waves at 2‐min intervals and regular spiking activity (RSA) followed by quiescence on both antrum and duodenum in a fully fed sheep. Middle traces are from a dehydrated animal without access to water for 72 h. Drinking increases antral spike activity and triggers occurrence of an RSA‐like activity phase with propulsive waves at less than 1‐min intervals corresponding to propulsion of water along upper part of small intestine. Bottom traces show persistence of these patterns 6 to 18 min after drinking.
Figure 34. Figure 34.

Relationship between the velocity of propagation of myoelectric complexes (regular spiking activity phases) and length of small intestine. Median daily number of jejunal complexes is high in ruminants and low in carnivores because of obliterating effect of feeding in latter species.
Figure 35. Figure 35.

Effect of digestive bulk on pattern of mitigating myoelectric complexes in a sheep fitted with 2 cannulas at an interval of 4 m on jejunum. Electrode sites were 2 m orad and aborad to each cannula. Flow bypass of segment of 4 m markedly reduced duration of phase of irregular spiking activity (ISA) at site 2 and to a much lesser extent at site 3. Duration of ISA was doubled at both sites 2 and 3 after infusion of 150 ml/h of contents. RSA, regular spiking activity.
Figure 36. Figure 36.

Integrated record of electrical spiking activity during 48 h in sheep fed a normal diet of hay. Electrode sites at 2, 7, 17, and 22 m from pylorus. Number of mitigating myoelectric complexes is 36.8% less in ileum than in duodenum (12 vs. 19).
Figure 37. Figure 37.

Radiographic anatomy of proximal duodenum in vertical position until hepatic flexure (A), transverse duodenum (B), and jejunum (C). Insert shows position of flow probe inserted in a T‐shaped cannula on duodenal bulb and the catheter required to infuse a protein solution at a fixed rate of 240 ml/h. Duodenal spiking activity associated with propulsion of fluids as gushes is characterized by bursts of spike potentials propagated along duodenal bulb. In hay‐fed sheep (control) and during gastric infusion, no flow was recorded when bursts of spike potentials remained localized to duodenal bulb (asterisks).
Figure 38. Figure 38.

Changes in flow of digesta along proximal duodenum induced by cholinergic stimulation of antroduodenal junction in a sheep under continuous abomasal infusion of a casein solution at a fixed rate of 240 ml/h. Note high rate of flow associated with duodenal bulb stimulation. Duod. bulb, duodenal bulb.
Figure 39. Figure 39.

A: diagram of ovine gallbladder with strain‐gauge force transducers sewn on fundus and corpus at 8 cm from short cystic duct and common bile duct. Note cyclical changes in smooth muscle tone. B: nichrome wires were fixed on reticulum and transverse duodenum 20 cm beyond bile duct. Changes in fundus and corpus tone (direct record) occurred during phases of irregular and regular spiking activity of transverse duodenum (integrated record) and ceased during phase of quiescence.
Figure 40. Figure 40.

Influence of splanchnic nerve section and additional bilateral vagotomy of phases of irregular spiking activity (ISA) and regular spiking activity (RSA) of cyclic motor events of ovine jejunum. Note reduced ISA after total denervation due to a functional stenosis of pylorus. Tracings are integrated records of electrical activity at 2 and 3 m from pylorus.
Figure 41. Figure 41.

Increment of frequency of migrating myoelectric complexes on ovine proximal small intestine after intraduodenal administration of methysergide. Tracings are integrated records of electrical spike activity from 1 electrode on pyloric antrum 4 cm proximal to pylorus, 1 electrode on duodenal bulb 4 cm distal to pylorus, and 3 electrodes on the jejunum at 1 m‐intervals. Dots correspond to expected pattern of migrating myoelectric complexes without treatment. Effect is more pronounced at site of administration (duodenal bulb) where 11 more regular spiking activity phases are recorded than at antrum and jejunum (7–9 phase III).
Figure 42. Figure 42.

Top, schematic representation of bovine gastrointestinal tract showing spiral colon, which is the equivalent of human transverse colon, and relatively large cecum. Fermentation of ingested cellulose that has passed intraruminal degradation occurs in both organs. Bottom, propagation at low velocity (2.1 ± 0.4 cm/min) of a period of spiking activity lasting 6 min along 5 electrode sites at 15‐cm intervals on spiral colon of the cow. First electrode was 150 cm from the ileocecal valve. Such a migrating spike burst pattern occurs from 8 to 10 times/day.
Figure 43. Figure 43.

Electrical activity of ovine large intestine. Top, direct record of propagated contractions from cecum toward proximal colon (filled circles) occurring ∼5 min before presence of a phase of regular spiking activity on terminal ileum. Trains of 2–5 strong contractions faded out at level of spiral colon. Bottom, integrated record showing pattern of activity of migrating myoelectric complexes on ileum and continuous spiking activity of spiral colon involved in pellet formation in small ruminants.
Figure 44. Figure 44.

Electrical activity of bovine large intestine. Top, direct record of contractions propagated from cecum through spiral colon. Bottom, integrated record snowing ileal pattern of activity of migrating myoelectric complexes and high values of activity on cecum (filled circles) corresponding to phases of regular spiking activity of ileum. Arrow, aboral migration of a 6‐min period of hyperactivity that slowly propagated from 8 to 10 times/day from spiral colon to distal colon.
Figure 45. Figure 45.

Blockade within 6–7 min of primary ruminal contractions after intramuscular injection of xylazine (0.08 mg/kg) in cattle (see Fig. 14). Contractions that persisted after xylazine correspond to secondary contractions of dorsal sac rumen (D. S. rumen). Primary contractions reappear after injection of the α2‐adrenoceptor antagonist tolazoline at a dosage ratio of 5:1.
Figure 46. Figure 46.

Inhibition of rate and amplitude of reticular contractions measured by strain gauges in sheep after subcutaneous administration of pentagastrin at 2 different dosages. Effects of central origin (see Fig. 25) but outside blood‐brain barrier are prevented by intravenous methylnaloxone.
Figure 47. Figure 47.

Blockade of motor effects of substance P (SP) on electrical and mechanical activities of ovine gastroduodenal junction 2 cm from pylorus. Stimulation induced by intravenous SP was equipotent on antrum and duodenal bulb. Atropine pretreatment prevented SP‐induced stimulation of antrum (and pylorus, not shown) but not of bulb.

From Ruckebusch and Merritt 196
Figure 48. Figure 48.

Integrated record of electrical activity of ovine gastroduodenal junction 5 cm proximal and 2 cm distal to the pylorus, the proximal duodenum (20 cm), and reticulum. Top. Stimulation of duodenum by the synthetic opiate loperamide and morphine or nalorphine was accompanied by inhibition of antral activity. Bottom. Nalorphine did not inhibit amplitude and/or frequency of reticular contractions, and its stimulatory effects on duodenum were not followed by inhibition as for morphine. D. Bulb, duodenal bulb; S.C., subcutaneous; I.V., intravenous.

From Ruckebusch and Merritt 196
Figure 49. Figure 49.

Comparative effects of 5‐hydroxytryptophan (5‐HTP) on ovine myoelectrical activity of gastroduodenal junction (integrated record). Occurrence of the regular spiking activity‐like phases at short intervals (top) is partly prevented by propranolol administration (bottom). S.C., subcutaneous; I.V., intravenous.
Figure 50. Figure 50.

Presence of hydroxytfyptamine (5‐HT) and acetylcholinesterase (ACHE) in different parts of ovine forestomach and stomach. Difference in height of the blocks and the numbers 1–3 are directly related to content in vasoactive intestinal peptide (VIP) and in substance P of the different layers determined by radioimmunoassays (blocks) and by immunochemistry (numbers). OG, oesophageal groove; RET, reticulum; RDS, rumen dorsal sac; RVS, rumen ventral sac; OMA, omasum; ABO, abomasum; AP, pyloric antrum; PYL, pylorus.

From Weyns et al. 254


Figure 1.

Expansion of simple stomach into multichambered stomach in ruminant herbivore (associated with specialized motor function, fermentation, and absorption). Esophageal groove (1) directs sucked liquid from cardia toward abomasum. Groove is bound by 2 fleshy lips that run spirally; the one that lies caudally at upper right end of groove passes left to gain cranial aspect about reticuloo‐masal orifice (2). Relative infrequency with which the abomasal contents reflux through wide omaso‐abomasal opening (3) depends on development of abomasal plicae, which rise abruptly around margin of opening and act like a ball valve to close orifice when pressure within abomasum rises. Re, reticulum; Ru, rumen; Om, omasum; Ab, abomasum.

From Dyce 59


Figure 2.

Arrangement of smooth muscle bundles in adult ruminant stomach. Reticulum and rumen, which together are known as reticulorumen, hold on average 84% of total capacity. Nonglandular mucosa covers dorsal sac and ventral sac of rumen, reticulum, and omasum (cross‐hatching). Cardiac gland region (open areas) is near omaso‐abomasal opening. Fundic glands (vertical lines) and pyloric glands (horizontal lines) involve whole abomasum.



Figure 3.

Gastric form and relative volumes indicated as percentages of stomach regions in herbivores [Artiodactyla (A)] and others (B). Gastric groove is represented schematically (horizontal filled bar) and apertures between gastric regions are also represented. Dotted structures, semilunar folds. Esophagus comes in from top right, and duodenum points to left. Hatched areas correspond to HCl‐producing fundic glands and pyloric glands.

Adapted from Langer 131


Figure 4.

The illustration by Flourens of the esophageal (reticular) groove in sheep, which he claimed to close on food lying within and to force it into thoracic esophagus. Colin disproved its role in regurgitation after tying the lips together with a wire in a steer, and Wester showed the opening and closing to be in relation with biphasic or triphasic contraction of reticulum.

From Flourens 74


Figure 5.

Topography of thoracic and abdominal organs of a goat. Left lung has been removed and reticulum and rumen have been opened. Reticulum lies against costal part of the diaphragm. Its ventral relations are sternal part of diaphragm, caudal end of sternum, and xiphoid cartilage. Rumen is divided into dorsal and ventral sacs, a, Rumen dorsal sac; b, rumen ventral sac; c, ventral blind sac; d, dorsal blind sac; e, atrium; f, reticulum; g, cardia; h, esophageal groove; i, cranial pillar; k, caudal pillar of rumen; l, reticuloruminal fold; m, esophagus; n, vena cava caudalis; o, aorta; p, diaphragm; 1, level of solid material; 2, gas pouch; 3, sediment (small particles).

From Grau 78


Figure 6.

Typical record showing pressure registered simultaneously in reticulum (Re) and dorsal rumen sac (DRu) in a sheep fasted 18 h and while receiving oats for 10 min. Lightly inflated balloons, inserted through a rumen fistula, are connected to tambours writing on kymograph. Bottom: electromyogram showing normal biphasic reticulum contractions spread backward over anterior sac of rumen with a lag of ∼5 s. Regular small group discharges correspond to intrinsic motility.



Figure 7.

Left, diagram of bovine reticulorumen showing 4 recording points and typical pressure patterns. 1, Reticulum; 2, anterior rumen sac; 3, dorsal rumen; 4, ventral rumen sac. AP, anterior pillar; F, fistula; E, esophagus; PP, posterior pillar; RF, reticuloruminal fold. Note belching contractions (b) of rumen and hydrostatic pressure changes in anterior rumen sac. [From Reid and Cornwall 181.] Right, drawing summarizing movement of digesta in ovine reticulorumen as seen radiographically in horizontal and vertical planes. Arrows indicate direction of movement [From Waghorn and Reid 247] and main contraction sequences as indicated by radiography. Time in seconds indicates interval after reticular movement, and contracting region of reticulorumen wall is indicated by a heavy line. Gas bubble (stippled), is brought over cardiac orifice at 13 s and during eructation sequence at 38 s.

From Wyburn 259


Figure 8.

Intrinsic electrical activity of ovine rumen during impaction. Slow‐wave‐like activity at frequency of 18–20/min is superimposed with clustered burst spike potentials (bars) at time of contractions.



Figure 9.

Stimulation by distension of local intrinsic activity and ruminal contractions. Top: normal biphasic reticular contraction (1) spreading over the rumen (2, 3, 4), and followed within 18 s by a backward contraction of the rumen starting on the posterior ventral sac (5). Local intrinsic activity as group discharges at 3‐s intervals on the dorsal sac of the rumen (3). Bottom: distension by air at mean pressure of 10 mmHg is accompanied by a backward contraction of rumen starting within 6 s on the posterior ventral sac (5) and followed by to‐and‐fro contractions of rumen (arrows). Intrinsic activity is increased at both reticular (1) and ruminal levels (3).



Figure 10.

In sheep, electromyogram (A) of reticulum (R) and posterior dorsal sac (Dp) of rumen in conjunction with recording (B) of intraruminal pressure. 1–8, Primary cycle movements. Secondary contraction of rumen (↓) may occur immediately after a primary contraction (3) or much later (4) [From Ruckebusch and Tomov 198.] In cattle, measurement of volume of eructated gas passing into trachea cannula, inserted into trachea near larynx and connected to a spirometer. Transient blockade of primary reticulorumen cycles is obtained by an α2‐adrenergic receptor agonist xylazine. Each secondary contraction of rumen (Ru) is accompanied by elimination of 200–500 ml of gas.



Figure 11.

Goat fitted with esophageal cannula. Illustration of force at which digesta are propelled by antiperistalsis from rumen during rumination. Cannula was open within 1 s after visible inspiratory effort that signals a regurgitation. Average volume (∼200 ml) was ejected in toto through cannula within 2 s.



Figure 12.

Events on esophagus, reticulum, jaw, and chest associated with regurgitation. A: inspiratory effort occurs (arrows) toward end of extracontraction of reticulum and is followed in less than 1 s by chewing. B: esophageal electromyograms are recorded from electrodes placed at equal distance on esophagus, near glottis (1), at the entry of chest (2) and close to cardia (3) and reticulum. Regurgitation of digesta (AP) is followed by swallowing first the excess liquid on 2 occasions (P1 and P2) and then the bolus (P3).



Figure 13.

Conditioned regurgitation in a goat. Top: inspiratory efforts followed by regurgitation occurred 15 s after emission of conditioned stimulus (CS) after 39 associations. Bottom: latency becomes very short and regurgitation was seen immediately after 87 associations.

From Ruckebusch 187


Figure 14.

Effects of intravenous administration (bolus) of dopamine before (A) and within 5 min after (B) injection of naloxone on reticular (Ret) contractions in sheep. Lower jaw movements are recorded by balloon fixed on halter. Injection of dopamine induces transient inhibition of reticular contractions but increases salivary flow, resulting in frequent swallowing movements. Dopamine at same dosage after naloxone pretreatment was able to induce rumination.



Figure 15.

Top, electromyographic responses of ruminal wall for primary cycle of movement (A) and for primary cycle followed by secondary cycle of movement (B and C). Bottom, diagrammatic representation of strength of each contraction and orderly sequence of 2 primary cycles followed more or less rapidly by secondary cycle. Top, A, single cycle involves dorsal (D) and posterior dorsal sac (Dp) of rumen followed by ventral (V) and posterior ventral sac (Vp). B, double cycle with short time interval between primary and secondary eructative (↓) ruminal contractions. C, time interval between primary (1) and secondary (2) contractions of rumen is longer because of an additional contraction of posterior ventral sac ( split into and ). Bottom: eructation (↑) occurs ∼28 s after reticular (R) contraction in A but much later (42 s) in B because of sustained weak contraction of Vp. Some contractions of ventral sac of rumen are missing and indicated by .

From Ruckebusch and Tomov 198


Figure 16.

Tracing showing that cyclical contractions of omasal body (Om) occurred at same rate as reticulorumen (Ret‐Rum) contractions in sheep. This is not the case in cattle during slower rate of reticulorumen contractions during deep sleep (∼7 min).



Figure 17.

Motility of omasum (Om) and reticulum (Re) in cattle. Pressure changes recorded from small balloon inserted near middle part of greater curvature of bovine omasum, reticulum, and rumen (Rm). Arrow, intravenous injection of pentagastrin (1 μg/kg), which transiently blocks reticulorumen contractions and increases omasal pressure.



Figure 18.

Electrical activity of omasal wall (right and left sides, omasal groove, and greater curvature) in relation to contraction of reticulum (A) and reticulo‐omasal orifice (B).

From Ruckebusch 188


Figure 19.

Motility of reticulum and omasal body under local anesthesia of vagus nerves (top) and general anesthesia (bottom). Omasal contractions persist in both cases despite arrest of reticular contractions. Arrest of activity of reticulum during 20 min first increases frequency then strength of omasal contractions without changing mean level of activity.

(From Bueno and Ruckebusch 21


Figure 20.

Responses of an adult bull to the introduction of 2 liters of warm milk into abomasum by a tube inserted through reticulo‐omasal orifice (top) and the sucking of 2 liters of milk (bottom). Bars indicate duration of these procedures.



Figure 21.

Termination of dorsal and ventral trunks in the goat, showing their origin from right and left vagus nerves. After section of dorsal vagal trunk, which has 3 branches A, B, and C, reticular cyclical activity persists, whereas dorsal sac of the rumen shows small group discharges later grouped in regular series. Section of ventral vagal trunk (branches 1, 2,3,4) alters activity of reticulum.

Adapted from Coulouma 36


Figure 22.

Extrinsic (top traces) versus intrinsic (bottom traces) motor activity of reticulum (intraluminal pressure and electrical activity) and dorsal sac and ventral sac of rumen as seen 12 days after cervical vagotomy.

From Ruckebusch and Tomov 198, ©1972, with permission from Pergamon Press, Ltd


Figure 23.

Intrinsic motor activity of rumen (intraluminal pressure) recorded 6 wk after thoracic vagotomy in a sheep maintained at constant body weight by intragastric infusion of complete liquid diet (see refs. 170 and 171. From top to bottom, increased frequency of intrinsic contractions after progressive or sudden distension during 2 min and cholinergic, serotonergic, or prostaglandin stimulation obtained by intravenous injection of pilocarpine, 5‐hydroxytryptophan (5‐HTP), or prostaglandin F2α (PGF2α).

From Y. Ruckebusch and C. H. Malbert, unpublished observations


Figure 24.

Gastric centers in medulla. On each side, region relative to obex extends laterally from 1 to 3 mm, caudally 2 mm, and rostrally 4 mm. Black dots, retrograde cellular degeneration 16 days after rumenectomy in lamb.

Adapted from Szabo and Dussardier 220


Figure 25.

Functional organization of gastric centers. Neuronal network with type B and C interneurons may constitute rate circuit responsible for chronotropic regulation of extrinsic movements. Another network with type A interneurons is involved in inotropic (amplitude) regulation of cyclic movements of reticulum through early vagal discharges and of rumen through later vagal discharges. Rate and amplitude circuits are inhibited by abomasal distension. Amplitude circuit and vagal motoneurons are stimulated by reticular distension. Strong net excitatory drive on rate and amplitude circuits arises from central nervous system.

Adapted from Leek and Harding 134


Figure 26.

Responses of mechanoreceptors. Tension receptor gives a steady (slowly adapting) discharge throughout period of distension (horizontal bar). Discharges occur only at times of inflation and of deflation for epithelial receptors. (From E. C. Crichlow, unpublished observations).



Figure 27.

Mechanical activity of pyloric antrum in sheep recorded from curved strain‐gauge force transducers fixed on the antrum at 7 and 2 cm before pylorus and duodenal bulb and 2 and 3 cm beyond pylorus.



Figure 28.

Electrical activity recorded from pairs of electrodes fixed at 10‐mm intervals on gastroduodenal junction in sheep showing propulsive waves (*) and continuous spiking activity (**) commencing at pylorus (PYL) or duodenal bulb (Bulb). Ant, pyloric antrum.



Figure 29.

Percentages of propulsive (peristaltic) and aboral or oral locally propagated activity along duodenum in cattle.

From Ooms and Oyaert 167


Figure 30.

Electromyography of ovine gastroduodenal area from electrodes fixed 2 cm apart on pylorus, antrum (−7 cm), and duodenum (3 cm). Tracings are consecutive. Top: irregular spiking activity showing spike bursts of antrum at frequency of 6.5/min. Magnitude of spike bursts waxes and wanes with activity on duodenum. Bottom: cyclical period of regular spiking activity followed by quiescence.



Figure 31.

Changes in intraduodenal pH over time in sheep as measured by pH electrode inserted through cannula placed ∼7 cm from pylorus. Prolonged periods of relatively high, stable pH indicating myoelectrical quiescence follows cyclical phase of regular spiking activity (RSA) indicated as a bar. Trace A is suggestive of fairly high delivery rate of acid from abomasum to duodenum with mean pH of 4.1. Trace B was obtained by obstructing transpyloric outflow with a balloon of a Foley catheter inserted via duodenal cannula. Rise of 2.5 pH units within 6 min occurred that remained stable until cessation of occlusion. Bottom: changes in abomasal outflow as measured by electromagnetic probe at 7 cm from pylorus in cattle. Note absence of flow at the time of RSA phase.



Figure 32.

Duodenal myoelectrical activity from 8 electrode sites placed 2 cm orad to pylorus (E1) and along duodenum, indicative of postprandial propulsive waves in the calf. Flow probe was fixed around duodenum 65 cm aborad to pylorus. Four propulsive waves are seen propagating away from pylorus where their corresponding spike bursts differed by a higher amplitude and longer duration from the others at sites 45 and 65 cm from pylorus.

Adapted from Dardillat 39


Figure 33.

Relationship between antroduodenal myoelectrical activity and fluid propulsion in a 60‐kg sheep. Top traces show end of a phase of irregular spiking activity with propulsive waves at 2‐min intervals and regular spiking activity (RSA) followed by quiescence on both antrum and duodenum in a fully fed sheep. Middle traces are from a dehydrated animal without access to water for 72 h. Drinking increases antral spike activity and triggers occurrence of an RSA‐like activity phase with propulsive waves at less than 1‐min intervals corresponding to propulsion of water along upper part of small intestine. Bottom traces show persistence of these patterns 6 to 18 min after drinking.



Figure 34.

Relationship between the velocity of propagation of myoelectric complexes (regular spiking activity phases) and length of small intestine. Median daily number of jejunal complexes is high in ruminants and low in carnivores because of obliterating effect of feeding in latter species.



Figure 35.

Effect of digestive bulk on pattern of mitigating myoelectric complexes in a sheep fitted with 2 cannulas at an interval of 4 m on jejunum. Electrode sites were 2 m orad and aborad to each cannula. Flow bypass of segment of 4 m markedly reduced duration of phase of irregular spiking activity (ISA) at site 2 and to a much lesser extent at site 3. Duration of ISA was doubled at both sites 2 and 3 after infusion of 150 ml/h of contents. RSA, regular spiking activity.



Figure 36.

Integrated record of electrical spiking activity during 48 h in sheep fed a normal diet of hay. Electrode sites at 2, 7, 17, and 22 m from pylorus. Number of mitigating myoelectric complexes is 36.8% less in ileum than in duodenum (12 vs. 19).



Figure 37.

Radiographic anatomy of proximal duodenum in vertical position until hepatic flexure (A), transverse duodenum (B), and jejunum (C). Insert shows position of flow probe inserted in a T‐shaped cannula on duodenal bulb and the catheter required to infuse a protein solution at a fixed rate of 240 ml/h. Duodenal spiking activity associated with propulsion of fluids as gushes is characterized by bursts of spike potentials propagated along duodenal bulb. In hay‐fed sheep (control) and during gastric infusion, no flow was recorded when bursts of spike potentials remained localized to duodenal bulb (asterisks).



Figure 38.

Changes in flow of digesta along proximal duodenum induced by cholinergic stimulation of antroduodenal junction in a sheep under continuous abomasal infusion of a casein solution at a fixed rate of 240 ml/h. Note high rate of flow associated with duodenal bulb stimulation. Duod. bulb, duodenal bulb.



Figure 39.

A: diagram of ovine gallbladder with strain‐gauge force transducers sewn on fundus and corpus at 8 cm from short cystic duct and common bile duct. Note cyclical changes in smooth muscle tone. B: nichrome wires were fixed on reticulum and transverse duodenum 20 cm beyond bile duct. Changes in fundus and corpus tone (direct record) occurred during phases of irregular and regular spiking activity of transverse duodenum (integrated record) and ceased during phase of quiescence.



Figure 40.

Influence of splanchnic nerve section and additional bilateral vagotomy of phases of irregular spiking activity (ISA) and regular spiking activity (RSA) of cyclic motor events of ovine jejunum. Note reduced ISA after total denervation due to a functional stenosis of pylorus. Tracings are integrated records of electrical activity at 2 and 3 m from pylorus.



Figure 41.

Increment of frequency of migrating myoelectric complexes on ovine proximal small intestine after intraduodenal administration of methysergide. Tracings are integrated records of electrical spike activity from 1 electrode on pyloric antrum 4 cm proximal to pylorus, 1 electrode on duodenal bulb 4 cm distal to pylorus, and 3 electrodes on the jejunum at 1 m‐intervals. Dots correspond to expected pattern of migrating myoelectric complexes without treatment. Effect is more pronounced at site of administration (duodenal bulb) where 11 more regular spiking activity phases are recorded than at antrum and jejunum (7–9 phase III).



Figure 42.

Top, schematic representation of bovine gastrointestinal tract showing spiral colon, which is the equivalent of human transverse colon, and relatively large cecum. Fermentation of ingested cellulose that has passed intraruminal degradation occurs in both organs. Bottom, propagation at low velocity (2.1 ± 0.4 cm/min) of a period of spiking activity lasting 6 min along 5 electrode sites at 15‐cm intervals on spiral colon of the cow. First electrode was 150 cm from the ileocecal valve. Such a migrating spike burst pattern occurs from 8 to 10 times/day.



Figure 43.

Electrical activity of ovine large intestine. Top, direct record of propagated contractions from cecum toward proximal colon (filled circles) occurring ∼5 min before presence of a phase of regular spiking activity on terminal ileum. Trains of 2–5 strong contractions faded out at level of spiral colon. Bottom, integrated record showing pattern of activity of migrating myoelectric complexes on ileum and continuous spiking activity of spiral colon involved in pellet formation in small ruminants.



Figure 44.

Electrical activity of bovine large intestine. Top, direct record of contractions propagated from cecum through spiral colon. Bottom, integrated record snowing ileal pattern of activity of migrating myoelectric complexes and high values of activity on cecum (filled circles) corresponding to phases of regular spiking activity of ileum. Arrow, aboral migration of a 6‐min period of hyperactivity that slowly propagated from 8 to 10 times/day from spiral colon to distal colon.



Figure 45.

Blockade within 6–7 min of primary ruminal contractions after intramuscular injection of xylazine (0.08 mg/kg) in cattle (see Fig. 14). Contractions that persisted after xylazine correspond to secondary contractions of dorsal sac rumen (D. S. rumen). Primary contractions reappear after injection of the α2‐adrenoceptor antagonist tolazoline at a dosage ratio of 5:1.



Figure 46.

Inhibition of rate and amplitude of reticular contractions measured by strain gauges in sheep after subcutaneous administration of pentagastrin at 2 different dosages. Effects of central origin (see Fig. 25) but outside blood‐brain barrier are prevented by intravenous methylnaloxone.



Figure 47.

Blockade of motor effects of substance P (SP) on electrical and mechanical activities of ovine gastroduodenal junction 2 cm from pylorus. Stimulation induced by intravenous SP was equipotent on antrum and duodenal bulb. Atropine pretreatment prevented SP‐induced stimulation of antrum (and pylorus, not shown) but not of bulb.

From Ruckebusch and Merritt 196


Figure 48.

Integrated record of electrical activity of ovine gastroduodenal junction 5 cm proximal and 2 cm distal to the pylorus, the proximal duodenum (20 cm), and reticulum. Top. Stimulation of duodenum by the synthetic opiate loperamide and morphine or nalorphine was accompanied by inhibition of antral activity. Bottom. Nalorphine did not inhibit amplitude and/or frequency of reticular contractions, and its stimulatory effects on duodenum were not followed by inhibition as for morphine. D. Bulb, duodenal bulb; S.C., subcutaneous; I.V., intravenous.

From Ruckebusch and Merritt 196


Figure 49.

Comparative effects of 5‐hydroxytryptophan (5‐HTP) on ovine myoelectrical activity of gastroduodenal junction (integrated record). Occurrence of the regular spiking activity‐like phases at short intervals (top) is partly prevented by propranolol administration (bottom). S.C., subcutaneous; I.V., intravenous.



Figure 50.

Presence of hydroxytfyptamine (5‐HT) and acetylcholinesterase (ACHE) in different parts of ovine forestomach and stomach. Difference in height of the blocks and the numbers 1–3 are directly related to content in vasoactive intestinal peptide (VIP) and in substance P of the different layers determined by radioimmunoassays (blocks) and by immunochemistry (numbers). OG, oesophageal groove; RET, reticulum; RDS, rumen dorsal sac; RVS, rumen ventral sac; OMA, omasum; ABO, abomasum; AP, pyloric antrum; PYL, pylorus.

From Weyns et al. 254
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Article Title: Gastrointestinal motor functions in ruminants
 

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Yves Ruckebusch. Gastrointestinal motor functions in ruminants. Compr Physiol 2011, Supplement 16: Handbook of Physiology, The Gastrointestinal System, Motility and Circulation: 1225-1282. First published in print 1989. doi: 10.1002/cphy.cp060134