Comprehensive Physiology Wiley Online Library

Gastrointestinal motor functions in ruminants

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
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
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
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
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 .] 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 ] 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
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 .] 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
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
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
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
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
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 , ©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. and . 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 F (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
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
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
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
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. ). 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. ) 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
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
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.


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


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


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


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


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 .] 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 ] 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


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 .] 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


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


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


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


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


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 , ©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. and . 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 F (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


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


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


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


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. ). 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. ) 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


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


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.
References
 1. Adrian, T. E., S. R. Bloom, and A. V. Edwards. Neuroendocrine responses to stimulation of the vagus nerves in conscious calves. J. Physiol. Lond. 344: 25–35, 1983.
 2. Ammerman, C. B., and R. D. Goodrich. Advances in mineral nutrition in ruminants. J. Anim. Sci. 57, Suppl. 2: 519–533, 1983.
 3. Andersson, B., R. Kitchell, and N. Persson. A study of rumination induced bv milking in the goat. Acta Physiol. Scand. 44: 92–102, 1958.
 4. Annison, E. F., K. J. Hill, and D. Lewis. Studies on the portal blood of sheep. 2. Absorption of volatile fatty acids from the rumen of the sheep. Biochem. J. 66: 592–599, 1957.
 5. Asai, T. Developmental processes of reticulo‐rumen motility in calves. Jpn. J. Vet. Sci. 35: 239–252, 1973.
 6. Ash, R. W. Abomasal secretion and emptying in suckled calves. J. Physiol. Lond. 172: 425–438, 1964.
 7. Bae, D. H., J. G. Welch, and A. M. Smith. Forage intake and rumination by sheep. J. Anim. Sci. 49: 1292–1299, 1979.
 8. Barcroft, J., R. A. McAnally, and A. T. Phillipson. Absorption of volatile acids from the alimentary tract of the sheep and other animals. J. Exp. Biol. 20: 120–129, 1944.
 9. Bauchop, T. Foregut fermentation. In: Microbial Ecology of the Gut, edited by R. T. J. Clark and T. Bauchop. New York: Academic, 1977, p. 223–250.
 10. Bauchop, T. Rumen anaerobe fungi of cattle and sheep. Appl. Environ. Microbiol. 38: 148–158, 1979.
 11. Bauman, D. E., C. L. Davis, R. A. Frobisch, and D. S. Sachan. Evaluation of polyethylene glycol method in determining rumen fluid volume in dairy cows fed different diets. J. Dairy Sci. 54: 928–930, 1971.
 12. Beghelli, V., G. Borgatti, and P. L. Parmeggiani. On the role of the dorsal nucleus of the vagus in the reflex activity of the reticulum. Arch. Ital. Biol. 101: 365–384, 1963.
 13. Bell, F. R., A. R. Green, J. A. H. Wass, and D. E. Webber. Intestinal control of gastric function in the calf: the relationship of neural and endocrine factors. J. Physiol. Lond. 321: 603–610, 1981.
 14. Bell, F. R., and M. L. Grivel. The effect of duodenal infusion on the electromyogram of gastric muscle during activation and inhibition of gastric emptying. J. Physiol. Lond. 248: 377–391, 1975.
 15. Bell, F. R., S. H. Holbrooke, and D. A. Titchen. A radiological study of gastric (abomasal) emptying and acid secretion in the milk‐fed calf. J. Physiol. Lond. 282: 51–57, 1977.
 16. Boivin, R., J. Bost, and F. E. Peralta. Oesophageal stimulation of chewing movements in sheep. Ann. Rech. Vet. 16: 227–235, 1985.
 17. Borgatti, G., and R. Matscher. Voies et signification du réflexe oral du réseau. Arch. Ital. Biol. 96: 38–57, 1958.
 18. Bost, J., H. Verine, and B. Matrat. Particularités du transit réticulo‐omasal chez le mouton. C. R. Seances Soc. Biol. Fil. 159: 2410–2415, 1965.
 19. Bowen, J. M. Effects of insulin hypoglycemia on gastrointestinal motility in the sheep. Am. J. Vet. Res. 23: 948–954, 1962.
 20. Brownlee, A. The development of rumen papillae in cattle fed on different diets. Br. Vet. J. 112: 369–375, 1956.
 21. Bueno, L., and Y. Ruckebusch. The cyclic motility of the omasum and its control in sheep. J. Physiol. Lond. 238: 295–312, 1974.
 22. Bürgin, H. The role of calcium in the mechanical performance of cattle ruminal muscle. J. Vet. Pharm. Ther. 2: 305–311, 1979.
 23. Caple, I. W., and T. J. Heath. Regulation of output of electrolytes in bile and pancreatic juice in sheep. Aust. J. Biol. Sci. 25: 155–165, 1972.
 24. Carr, D. H., P. C. Scott, and D. A. Titchen. Manometric and electromyographic observations of the esophagus of sheep in eructation, regurgitation and swallowing. Q. J. Exp. Physiol. 68: 661–674, 1983.
 25. Church, D. C. The Ruminant Animal. Digestive Physiology and Nutrition. New York: Simon & Schuster, 1988, p. 14–201.
 26. Cirio, A., T. Boivin, and J. Bost. Stimulation prandiale de la motricité réticulaire chez le mouton: phase céphalique et réflexe oral. Ann. Rech. Vet. 12: 291–302, 1981.
 27. Clark, R., and K. E. Weiss. Reflex salivation in sheep and goats initiated by mechanical stimulation of the cardiac area of the fore stomachs. J. S. Afr. Vet. Med. Assoc. 23: 163–165, 1952.
 28. Colvin, H. W., P. T. Cupps, and H. H. Cole. Dietary influences on eructation and related phenomena in cattle. J. Dairy Sci. 41: 1565–1579, 1958.
 29. Comline, R. S., I. A. Silver, and D. H. Steven. Physiological anatomy of the ruminant stomach. In: Handbook of Physiology. Alimentary Canal. Bile; Digestion; Ruminal Physiology, edited by C. F. Code. Washington, DC: Am. Physiol. Soc., 1968, sect. 6, vol. V, p. 2647–2671.
 30. Comline, R. S., and D. A. Titchen. Reflex contractions of the oesophageal groove in young ruminants. J. Physiol. Land. 115: 210–226, 1951.
 31. Comline, R. S., and D. A. Titchen. Reflex contractions of the reticulum and rumen and parotid salivary secretion. J. Physiol. Lond. 139: 24P, 1957.
 32. Comline, R. S., and D. A. Titchen. Nervous control of the ruminant stomach. In: Digestive Physiology and Nutrition of the Ruminant, edited by D. Lewis London: Butterworths, 1961, p. 10–22.
 33. Coombe, J. B., and R. N. B. Kay. Passage of digesta through the large intestine of sheep: retention times in the small and large intestines. Br. J. Nutr. 19: 325–338, 1965.
 34. Connor, H. G., A. D. McGillard, and C. F. Huffman. Bovine re‐entrant duodenal fistula studies. J. Anim. Sci. 16: 692–697, 1957.
 35. Cottrell, D. F., and A. Iggo. Tension receptors with vagal afferent fibres in the proximal duodenum and pyloric sphincter of sheep. J. Physiol. Lond. 354: 454–475, 1984.
 36. Coulouma, P. La terminaison des Nerfs Pneumogastriques et ses Variations. Etude d'Anatomie Descriptive Comparée chez l'Homme et dans la Série des Vertébrés. Lille, France: Université de Lille, 1936 PhD thesis.
 37. Crichlow, E. C., and B. G. Leek. The importance of pH in relation to the acid‐excitation of epithelial receptors in the reticulorumen of sheep. J. Physiol. Lond. 310: 60P–61P, 1981.
 38. Daniel, R. C. W. Motility of the rumen and abomasum during hypocalcaemia. Can. J. Comp. Med. 47: 276–280, 1983.
 39. Dardillat, C. Analyse électromyographique et débitmétrique du transit alimentaire chez le veau nouveau‐né. J. Physiol. Paris 73: 925–944, 1977.
 40. Dardillat, C., and Y. Ruckebusch. Aspects fonctionnels de la jonction gastro‐duodénale chez le veau nouveau‐né. Ann. Rech. Vet. 4: 31–56, 1973.
 41. Dean, R. E., T. Thorne, and T. D. Moore. Passage of alfalfa through the digestive tract of elk. J. Wild. Manage. 44: 272–273, 1980.
 42. Dedashev, I. P. Conditioned reflexes of motor activity in the reticulum and rumen of sheep. Setchenov. J. Physiol. 45: 104–108, 1959.
 43. Dehority, B. A. Carbon dioxide requirement of various species of rumen bacteria. J. Bacterial. 105: 70–76, 1971.
 44. Della‐Fera, M. A., C. A. Baile, B. S. Shneider, and J. A. Grinker. Cholecystokinin antibody injected in cerebral ventricles stimulates feeding in sheep. Science Wash. DC 212: 687–689, 1981.
 45. Demeyer, D. I., and C. J. Nevel. Methanogenesis, an integrated part of carbohydrate fermentation, and its control. In: Digestion and Metabolism in the Ruminant, edited by I. W. McDonald and A. C. I. Warner. Armidale, Australia: Univ. New Engl. Publ. Unit, 1975, p. 366–382.
 46. Deswysen, A. G., and H. J. Ehrlein. Silage intake, rumination and pseudo‐rumination activity in sheep studied by radiography and jaw movement recordings. Br. J. Nutr. 46: 327–335, 1981.
 47. Dobson, A., and A. T. Phillipson. Absorption from the ruminant forestomach. In: Handbook of Physiology. Alimentary Canal. Bile; Digestion; Ruminal Physiology, edited by C. F. Code Washington, DC: Am. Physiol. Soc., 1968, sect. 6, vol. V, p. 2761–2774.
 48. Dougherty, R. W. Physiology of eructation in ruminants. In: Handbook of Physiology. Alimentary Canal. Bile; Digestion; Ruminal Physiology, edited by C. F. Code. Washington, DC: Am. Physiol. Soc., 1968, sect. 6, vol. V, p. 2695–2698.
 49. Dougherty, R. W. Experimental Surgery in Farm Animals. Ames: Iowa State Univ. Press, 1981.
 50. Dougherty, R. W., J. L. Riley, and H. M. Cook. Changes in motility and pH in the digestive tract of experimentally overfed sheep. Am. J. Vet. Res. 36: 827–829, 1975.
 51. Duckworth, J. E., and D. W. Shirlaw. A study of factors affecting feed intake and the eating behaviour of cattle. Anim. Behav. 6: 147–154, 1958.
 52. Dulphy, J. P., and G. Bechet. Influence du stade de végétation et de l'espèce végétale sur le comportement alimentaire et mérycique de moutons recevant des fourrages verts hachés. Ann. Zootech. Paris 25: 505–519, 1976.
 53. Dulphy, J. P., B. Michalet‐Doreau, and C. Demarquilly. Etude comparée des quantités ingérées et du comportement alimentaire et mérycique d'ovins et de bovins recevant des ensilages d'herbe réalisés selon différentes techniques. Ann. Zootech. Paris 33: 291–320, 1984.
 54. Duncan, D. L. The effects of vagotomy and splanchnotomy on gastric motility in the sheep. J. Physiol. Lond. 119: 157–169, 1953.
 55. Duncan, D. L., and A. T. Phillipson. The development of the motor responses in the stomach of the foetal sheep. J. Exp. Biol. 28: 32–40, 1951.
 56. Dussardier, M. Contrôle nerveux du rhythme gastrique des ruminants. J. Physiol. Paris 47: 170–173, 1955.
 57. Dussardier, M. Réinnervation d'un muscle strié par des fibres préganglionnaires parasympathiques. Application á l'enregistrement de l'activité des fibres efférentes vagales chez l'animal éveillé. Ann. Biol. Anim. Biochim. Biophys. 3: 405–425, 1963.
 58. Dussardier, M., J. Flinois, and J. P. Rousseau. Localisation des centres bulbaires qui commandent la motricité gastrique. J. Physiol. Paris 52: 90–91, 1960.
 59. Dyce, K. M. Some remarks upon the functional anatomy of the ruminant stomach. Tijdschr. Diergeneeskd. 93: 1334–1344, 1968.
 60. Dziuk, H. E. Eructation, regurgitation and reticuloruminal contraction in the American bison. Am. J. Physiol. 208: 343–346, 1965.
 61. Dziuk, H. E., B. A. Fashingbaer, and J. L. Idstrom. Ruminoreticular pressure patterns in fistulated white‐tailed deer. Am. J. Vet. Res. 24: 772–782, 1963.
 62. Ehrlein, H. J. Untersuchungen über die Motorik des Labmagens der Ziege unter besonderer Berücksichtigung des Pylorus. Zentralbl. Veterinaermed. Reihe A 17: 481–497, 1970.
 63. Eiler, H., W. A. Lyke, and R. Johnson. Internal vomiting in the ruminant: effect of apomorphine on ruminal pH In sheep. Am. J. Vet. Res. 42: 202–204, 1981.
 64. Engelhardt, W. V., and J. R. S. Hales. Partition of capillary blood flow in rumen, reticulum, and omasum of sheep. Am. J. Physiol. 232 (Endocrinol. Metab. Gastrointest. Physiol. 1): E53–E56, 1977.
 65. Engelhardt, W. V., and R. Hauffe. Role of the omasum in absorption and secretion of water and electrolytes in sheep and goats. In: Digestion and Metabolism in the Ruminant, edited by I. W. McDonald and A. C. I. Warner. Armidale, Australia: Univ. New Engl. Publ. Unit, 1975, p. 216–230.
 66. Evans, L., and F. A. Spurrell. Technique for the direct injection of materials into the ruminant abomasum. J. Appl. Physiol. 22: 1030–1037, 1967.
 67. Faichney, G. J. The use of markers to measure digesta flow from the stomach of sheep fed once daily. J. Agric. Sci. 94: 313–318, 1980.
 68. Faichney, G. J. Measurement in sheep of the quantity and composition of rumen digesta and of the fractional outflow rates of digesta constituents. Aust. J. Agric. Res. 31: 1129–1137, 1980.
 69. Faichney, G. J. Marker techniques for the study of gastrointestinal tract function in ruminants. In: Techniques in Digestive Physiology, edited by L. H. Heywood and D. A. Titchen. County Clare, Ireland: Elsevier, 1982, vol. 211, p. 33–36.
 70. Faichney, G. J., and T. N. Barry. Intravenous somatostatin infusion affects gastrointestinal tract function in sheep. Can. J. Anim. Sci. 64: 93–94, 1984.
 71. Falempin, M., N. Mei, and J. P. Rousseau. Vagal mechanoreceptors of the inferior thoracic oesophagus, the lower oesophageal sphincter and the stomach in sheep. Pfluegers Arch. 373: 25–30, 1978.
 72. Falempin, M., and J. P. Rousseau. Vagal digestive deafferentation in sheep. Ann. Rech. Vet. 10: 186–188, 1979.
 73. Fell, B. F., and T. E. C. Weekes. Food intake as a mediator of adaptation in the ruminal epithelium. In: Digestion and Metabolism in the Ruminant, edited by I. C. McDonald and A. C. I. Warner. Armidale, Australia: Univ. New Engl. Publ. Unit, 1975, p. 101–118.
 74. Flourens, P. Expériences sur le mécanisme de la rumination. C.R. Acad. Sci. Paris Mém. 12: 531–550, 1844.
 75. Forbes, J. M., J. A. Wright, and A. Bannister. A note on rate of eating in sheep. Anim. Prod. 15: 211–214, 1972.
 76. Freer, M., and R. C. Campling. Factors affecting the voluntary intake of food by cows. 7. The behaviour and reticular motility of cows given diets, dried grass, concentrates and ground pelleted hay. Br. J. Nutr. 19: 195–207, 1965.
 77. Geoffroy, F. Etude comparée du comportement alimentaire et mérycique de deux petits ruminants: la chèvre et le mouton. Ann. Zootech. Paris 23: 63–73, 1974.
 78. Grau, H. Zur Funktion der Vormägen, besonders des Netzmagens der Wiederkaüer. Berl. Muench. Tieraerztl. Wochenschr. 68: 271–275, 1955.
 79. Gregory, P. C. Forestomach motility in the chronically vagotomized sheep. J. Physiol. Lond. 328: 431–447, 1980.
 80. Gregory, P. C. Control of intrinsic reticulo‐ruminal motility in the vagotomized sheep. J. Physiol. Lond. 346: 379–393, 1984.
 81. Gregory, P. C., S. J. Miller, and A. C. Brewer. The relationship between food intake and abomasal emptying and small intestinal transit time in sheep. Br. J. Nutr. 53: 373–380, 1985.
 82. Gregory, P. C., D. V. Rayner, and C. Wenham. Initiation of migrating myoelectric complex in sheep by duodenal acidification and hyperosmolarity: role of vagus nerves. J. Physiol. Lond. 355: 509–521, 1984.
 83. Grenet, E. Taille et structure des particules végétales au niveau du feuillet et des fèces chez les bovins. Ann. Biol. Anim. Biochim. Biophys. 10: 643–657, 1970.
 84. Grovum, W. L. Factors affecting the voluntary intake of food by sheep. 2. The role of distension and tactile input from compartments of the stomach. Br. J. Nutr. 42: 425–436, 1979.
 85. Grovum, W. L. Factors affecting the voluntary intake of food by sheep. 3. The effect of intravenous infusions of gastrin, cholecystokinin and secretin on motility of the reticulo‐rumen and intake. Br. J. Nutr. 45: 183–201, 1981.
 86. Grovum, W. L. Integration of digestion and digesta kinetics with control of feed intake—a physiological framework for a model of rumen function. In: Proc. Symp. Herbivore Nutrition in Sub‐Tropics and Tropics, edited by F. M. C. Gilchrist and R. I. Mackie. Pretoria, South Africa: Science, 1984, p. 244–268.
 87. Grovum, W. L., and H. W. Chapman. Pentagastrin in the circulation acts directly on the brain to depress motility of the stomach in sheep. Regul. Pept. 5: 35–42, 1982.
 88. Grovum, W. L., and G. D. Phillips. Factors affecting the voluntary intake of food by sheep. 1. The role of distension, flow‐rate of digesta and propulsive motility in the intestine. Br. J. Nutr. 40: 323–336, 1978.
 89. Grovum, W. L., and V. J. Williams. Rate of passage of digesta in sheep. 6. The effect of level of food intake on mathematical predictions of the kinetics of digesta in the reticulorumen and intestines. Br. J. Nutr. 38: 425–436, 1977.
 90. Guilhermet, R., C. M. Mathieu, and R. Toullec. Transit des aliments liquides au niveau de la gouttière oesophagienne chez le veau préruminant et ruminant. Ann. Zootech. Paris 24: 69–79, 1975.
 91. Habel, R. E. A study of the innervation of the ruminant stomach. Cornell Vet. 46: 555–633, 1956.
 92. Hammond, P. B., H. E. Dziuk, E. A. Usenik, and C. E. Stevens. Experimental intestinal obstruction in calves. J. Comp. Pathol. Ther. 74: 210–222, 1964.
 93. Harding, R., and B. F. Leek. The locations and activities of medullary neurones associated with ruminant forestomach motility. J. Physiol. Lond. 219: 587–610, 1971.
 94. Harding, R., and B. F. Leek. The effect of peripheral and central nervous influences on gastric centre neuronal activity in sheep. J. Physiol. Lond. 225: 309–338, 1972.
 95. Harding, R., and D. A. Titchen. Oesophageal and diaphragmatic activity during sucking in lambs. J. Physiol. Lond. 321: 317–329, 1981.
 96. Harris, L. E., and A. T. Phillipson. The measurement of the flow of food to the duodenum of the sheep. Anim. Prod. 4: 97–116, 1962.
 97. Harrison, F. A. Bile secretion in the sheep. J. Physiol. Lond. 162: 212–224, 1962.
 98. Harrison, F. A. Advances in the application of experimental surgery in digestive physiology. In: Digestive Physiology and Metabolism in Ruminants, edited by Y. Ruckebusch and P. Thivend. Lancaster, UK: MTP, 1980, p. 829–840.
 99. Harrison, F. A., and K. J. Hill. Digestive secretions and the flow of digesta along the duodenum of the sheep. J. Physiol. Lond. 162: 225–243, 1962.
 100. Hartnell, G. F., and L. D. Satter. Determination of rumen fill, retention time and ruminal turnover rates of ingesta at different stages of lactation in dairy cows. J. Anim. Sci. 48: 381–392, 1979.
 101. Hecker, J. F. The Sheep as an Experimental Animal. London: Academic, 1983, p. 34–134.
 102. Heller, R., P. C. Gregory, and W. V. Engelhardt. Pattern of motility and flow of digesta in the forestomach of the Llama (Lama guanacoe f. glama). J. Comp. Physiol. Biochem. Syst. Environ. Physiol. 154: 529–533, 1984.
 103. Heywood, L. H., and A. K. W. Wood. Thoracic oesophageal motor activity during eructation in sheep. Q. J. Exp. Physiol. 70: 603–613, 1985.
 104. Hill, K. J. Continuous gastric secretion in the ruminant. Q. J. Exp. Physiol. 40: 32–39, 1955.
 105. Hill, K. J. Nervous structures in the reticulo‐ruminal epithelium of the lamb and kid. Q. J. Exp. Physiol. 44: 222–238, 1959.
 106. Hill, K. J. Abomasal secretory function in the sheep. In: Physiology of Digestion in the Ruminant, edited by R. W. Dougherty Washington, DC: Butterworth, 1965, p. 221–230.
 107. Hill, K. J. Abomasal function. In: Handbook of Physiology. Alimentary Canal. Bile; Digestion; Ruminal Physiology, edited by C. F. Code Washington, DC: Am. Physiol. Soc., 1968, sect. 6, Vol. V, p. 2747–2759.
 108. Hill, K. J., and R. A. Gregory. The preparation of gastric pouches in the ruminant. Vet. Rec. 63: 647–652, 1951.
 109. Hodgson, J. The development of solid food intake in calves. 5. The relationship between liquid and solid food intake. Anim. Prod. 13: 593–597, 1971.
 110. Hoffmann, R. R., and B. Schnoor. Die funktionelle Morphologie des Wiederkäuer‐Magens Stuttgart, FRG: Ferdinand Enke, 1982, p. 1–170.
 111. Hoffmann, R. R., and D. R. M. Stewart. Grazers or browsers: a classification based on the stomach structure and feeding habit of East African ruminants. Mammalia 36: 226–240, 1972.
 112. Hoflund, S. Untersuchungen über Störungen in den Funktionen der Wiederkäuermagen, durch Schädigungen des N. vagus Verursacht. Suensk. Vet. Dskrift. Suppl. 45: 1–59, 1940.
 113. Hofmeyer, C. F. B., and H. C. Voss. Oesophageal fistulation of sheep. J. S. Afr. Vet. Med. Assoc. 35: 579–582, 1964.
 114. Hogan, J. P., and A. T. Phillipson. The rate of flow of digesta and their removal along the digestive tract of the sheep. Br. J. Nutr. 14: 147–155, 1960.
 115. Hopcroft, S. C., and A. W. Banks. The production of an isolated loop of upper small intestine in the sheep. Exp. Med. Surg. 23: 203–206, 1965.
 116. Hungate, R. E. Ruminal fermentation. In: Handbook of Physiology. Alimentary Canal. Bile; Digestion; Ruminal Physiology, edited by C. F. Code Washington, DC: Am. Physiol. Soc., 1968, sect. 6, vol. V, chapt. 13, p. 2725–2745.
 117. Iggo, A. Central nervous control of gastric movements in sheep and goats. J. Physiol. Land. 131: 248–256, 1956.
 118. Iggo, A., and B. F. Leek. An electrophysiological study of vagal efferent units associated with gastric movements in sheep. J. Physiol. Lond. 191: 177–204, 1967.
 119. Itabisashi, T. Relations between periodic potential fluctuations and intragastric pressure in goats. Natl. Inst. Animal Health Qt. Yatb. 4: 115–124, 1964.
 120. Itabisashi, T. Potential changes that accompany movement of the ruminant stomach. In: Physiology of Digestion and Metabolism in the Ruminant, edited by A. T. Phillipson Newcastle upon Tyne, UK: Oriel, 1970, p. 42–51.
 121. Kay, R. N. B. Continuous and reflex secretion by the parotid gland in ruminants. J. Physiol. Lond. 144: 463–475, 1958.
 122. Kay, R. N. B. Rumination in sheep caused by injection of adrenaline. Nature Lond. 183: 552–553, 1959.
 123. Kay, R. N. B. The rate of flow and composition of various salivary secretions in sheep and calves. J. Physiol. Lond. 150: 515–537, 1960.
 124. Kay, R. N. B., W. V. Engelhardt, and R. G. White. The digestive physiology of wild ruminants. In: Digestive Physiology and Metabolism in Ruminants, edited by Y. Ruckebusch and P. Thivend. Lancaster, UK: MTP, 1980, p. 743–761.
 125. Kay, R. N. B., and E. D. Goodall. The intake, digestibility and retention time of roughage diets by red deer (Cervus elaphus) and sheep. Proc. Nutr. Soc. 35: 98A, 1976.
 126. Kay, R. N. B., and A. T. Phillipson. Response of the salivary glands to distension of the oesophagus and rumen. J. Physiol. Lond. 148: 507–523, 1959.
 127. Kay, R. N. B., and Y. Ruckebusch. Movements of the stomach compartments of a young bull during sucking. Br. J. Nutr. 26: 301–309, 1971.
 128. Komarek, R. J., and E. C. Leffel. Gas‐tight cannula for rumen fistula. J. Anim. Sci. 20: 782–784, 1961.
 129. Kondos, A. C. A new method for cannulation of the abomasum in sheep. Aust. Vet. J. 43: 149–151, 1967.
 130. Langer, P. Stomach evolution in the Artiodactyla. Mammalia 38: 295–314, 1974.
 131. Langer, P. Comparative anatomy of the stomach in mammalian herbivores. Q. J. Exp. Physiol. 69: 615–625, 1984.
 132. Laplace, J. P. Omaso‐abomasal motility and feeding behavior in sheep: a new concept. Physiol. Behav. 5: 61–65, 1970.
 133. Leek, B. F. Reticulo‐ruminal mechanoreceptors in sheep. J. Physiol. Lond. 202: 585–609, 1969.
 134. Leek, B. F., and R. Harding. Sensory nervous receptors in the ruminant stomach and the reflex control of reticulo‐ruminal motility. In: Digestion and Metabolism in the Ruminant, edited by I. W. McDonald and A. C. I. Warner. Armidale, Australia: Univ. of New Engl. Publ. Unit, 1975, p. 60–76.
 135. Lefebvre, R. A. Study on the possible neurotransmitter of the non‐adrenergic non‐cholinergic innervation of the rat gastric fundus. Arch. Int. Pharmacodyn. Ther. 280, Suppl. 2: 110–136, 1986.
 136. Leng, R. A. Formation and production of volatile fatty acids in the rumen. In: Physiology of Digestion and Metabolism in the Ruminant, edited by A. T. Phillipson Aberdeen, UK: Oriel, 1970, p. 406–421.
 137. Louvier, J. A., H. W. Colvin, Jr., G. Ishizaki, G. A. Iwamoto, and H. R. Parker. Effect of rumen insufflation on ruminal contraction rate in sheep. J. Anim. Sci. 48: 934–940, 1979.
 138. Lysons, R. J., and T. J. L. Alexander. The gnotobiotic ruminant and in vivo studies of defined bacterial populations. In: Digestion and Metabolism in the Ruminant, edited by I. W. McDonald and A. C. I. Warner. Armidale, Australia: Univ. of New Engl. Publ. Unit, 1975, p. 180–204.
 139. Maas, C. L. Opiate antagonists stimulate ruminal motility of conscious goats. Eur. J. Pharmacol. 77: 71–74, 1982.
 140. Maas, C. L., C. T. M. van Duin, and A. S. J. P. A. M. van Miert. Modification by domperidone of dopamine‐ and apomorphine‐induced inhibition of extrinsic ruminal contraction in goat. J. Vet. Pharm. Ther. 5: 191–194, 1982.
 141. Macrae, J. C., C. S. W. Reid, D. W. Dellow, and R. S. Wyburn. Caecal cannulation in the sheep. Res. Vet. Sci. 14: 78–85, 1973.
 142. Magee, D. F. An investigation into the internal secretion of the pancreas in sheep. J. Physiol. Lond. 158: 132–143, 1961.
 143. Maloiy, G. M. O., and R. N. B. Kay. A comparison of digestion in red deer and sheep under controlled conditions. Q. J. Exp. Physiol. 56: 257–266, 1971.
 144. Matscher, R., and V. Beghelli. L'influenza dell'attivita abomasale sui prestomaci. Inibizione dell'atrio e del sacco ventrale del rumine per stimulazione elletrica del N. abomasale. Arch. Sci. Biol. 42: 251–262, 1958.
 145. Mayer, E. A., G. van Deventer, J. Elashoff, S. Khawaja, and J. H. Walsh. Characterization of substance P effects on canine antral muscle. Am. J. Physiol. 251 (Gastrointest. Liver Physiol. 14): G140–G146, 1986.
 146. McBride, B. W., R. Berzins, L. P. Milligan, and B. V. Turner. Development of a technique for gastrointestinal endoscopy of domestic ruminants. Can. J. Anim. Sci. 63: 349–354, 1983.
 147. McLeay, L. M., and F. R. Bell. Effect of cholecystokinin, secretin, glucagon, and insulin on gastric emptying and acid secretion in the calf. Am. J. Vet. Res. 41: 1590–1594, 1981.
 148. McLeay, L. M., and D. A. Titchen. Abomasal secretory responses to teasing with food and feeding in the sheep. J. Physiol. Lond. 206: 605–628, 1970.
 149. McLeay, L. M., and D. A. Titchen. Effects of the amount and type of food eaten on secretion from fundic abomasal pouches of sheep. Br. J. Nutr. 32: 375–387, 1974.
 150. McLeay, L. M., and D. A. Titchen. Gastric, antral and fundic pouch secretion in sheep. J. Physiol. Lond. 248: 595–612, 1975.
 151. McLeay, L. M., and D. A. Titchen. Acid and pepsin secretion of separated gastric pouches during perfusion of antral pouches with cholinergic stimulating and blocking agents and lignocaine. J. Physiol. Lond. 264: 215–227, 1977.
 152. McLeay, L. M., and D. A. Titchen. Inhibition of hydrochloric acid and pepsin secretion from gastric pouches by antral pouch acidification in sheep. J. Physiol. Lond. 273: 707–716, 1977.
 153. McManus, W. R., G. W. Arnold, and F. J. Hamilton. Improved techniques in oesophageal fistulation of sheep. Aust. Vet. J. 38: 275–281, 1962.
 154. Mendel, V. E. Pneumatic and semipneumatic plugs for largediameter rumen fistulas in cattle. J. Dairy Sci. 44: 679–686, 1961.
 155. Milne, J. A. Comparative digestive physiology and metabolism of the red deer and the sheep. Proc. N. Z. Soc. Anim. Prod. 40: 151–157, 1980.
 156. Milne, J. A., J. C. Macrae, A. M. Spence, and S. Wilson. A comparison of the voluntary intake and digestion of a range of forages at different times of the year by the sheep and the red deer (Cervus elaphus). Br. J. Nutr. 40: 347–357, 1978.
 157. Moir, R. Ruminant digestion and evolution. In: Handbook of Physiology. Alimentary Canal. Bile; Digestion; Ruminal Physiology, edited by C. F. Code Washington, DC: Am. Physiol. Soc., 1968, sect. 6, vol. V, p. 2673–2694.
 158. Morgan, C. A., and R. C. Campling. Chewing behaviour of hay‐fed cows given supplements of whole barley and oat grains. J. Agric. Sci. Camb. 91: 415–418, 1978.
 159. Morrison, A. R., and R. E. Habel. A quantitative study of the distribution of vagal nerve endings in the myenteric plexus of the ruminant stomach. J. Comp. Neurol. 122: 297–309, 1964.
 160. Murphy, C. A., and J. M. Nicoletti. Potential reduction of forage and rumen digesta particle size by microbial action. J. Dairy Sci. 67: 1221–1226, 1984.
 161. Murray, R. M., H. Marsh, G. E. Heinsohn, and A. V. Spain. The role of the midgut caecum and large intestine in the digestion of sea grasses by the dugong (Mammalia: Sirenia). Comp. Biochem. Physiol. 56: 7–10, 1978.
 162. Newhook, J. D., and D. A. Titchen. Effects of stimulation of efferent fibres of the vagus on the reticulo‐omasal orifice of the sheep. J. Physiol. Load. 222: 407–418, 1972.
 163. Newhook, J. C., and D. A. Titchen. Effects of vagotomy, atropine, hexamethonium and adrenaline on the destination in the stomach of liquids sucked by milk‐fed lambs and calves. J. Physiol. Land. 237: 415–430, 1974.
 164. Nicholson, R., and S. A. Omer. The inhibitory effect of intestinal infusions of unsaturated long‐chain fatty acids on forestomach motility of sheep. Br. J. Nutr. 50: 141–149, 1983.
 165. Nordin, M. Voluntary food intake and digestion by the lesser mousedeer. J. Wild. Manage. 42: 185–187, 1978.
 166. Ogha, A., Y. Ota, and Y. Nakazato. The movement of the stomach of the sheep with special reference to the omasal movement. Jpn. J. Vet. Sci. 27: 151–160, 1965.
 167. Ooms, L., and W. Oyaert. Electromyographic study of the abomasal antrum and proximal duodenum in cattle. Zentralbl. Veterinaermed. Reihe A 25: 464–473, 1978.
 168. Orskov, E. R., and D. Benzie. Studies on the esophageal groove reflex in sheep and on the potential use of the groove to prevent the fermentation of food in the rumen. Br. J. Nutr. 23: 415–420, 1969.
 169. Orskov, E. R., D. Benzie, and R. N. B. Kay. The effect of feeding procedure on closure of the oesophageal groove in young sheep. Br. J. Nutr. 24: 785–795, 1970.
 170. Orskov, E. R., D. A. Grubb, G. Wenham, and W. Corrigall. The sustenance: of growing and fattening ruminants by intragastric infusion of volatile fatty acids and protein. Br. J. Nutr. 41: 533–558, 1979.
 171. Orskov, E. R., N. A. MacLeod, R. N. B. Kay, and P. C. Gregory. Method and validation of intragastric nutrition. Can. J. Anim. Sci. 64: 138–139, 1984.
 172. Oyaert, W., and J. H. Bouckaert. A study of the passage of fluid through the sheep's omasum. Res. Vet. Sci. 2: 41–52, 1961.
 173. Pairet, M., T. Bouyssou, and Y. Ruckebusch. Colonic formation of soft feces in rabbits: a role for endogenous prostaglandins. Am. J. Physiol. 250 (Gastrointest. Liver Physiol. 13): G302–G308, 1986.
 174. Patterson, J., P. Brightling, and D. A. Titchen. Beta‐adrenergic effects on composition of parotid salivary secretion of sheep on feeding. Q. J. Exp. Physiol. 67: 57–67, 1982.
 175. Phillipson, A. T. The movements of the pouches of the stomach of the sheep. Q. J. Exp. Physiol. 29: 395–415, 1939.
 176. Phillipson, A. T., and C. S. W. Reid. Distension of the rumen and salivary secretion. Nature Lond. 181: 1722–1723, 1958.
 177. Poncet, C., and M. Ivan. Effects of duodenal cannulation in sheep on the pattern of gastrointestinal motility and digestive flow. Nutr. Reprod. Dev. 24: 887–902, 1984.
 178. Poncet, C., M. Ivan, and M. Leveille. Electromagnetic measurements of duodenal digesta flow in cannulated sheep. Reprod. Nutr. Dev. 22: 651–660, 1982.
 179. Quin, J. I., and J. G. van der Wath. Studies on the alimentary tract of Merino sheep in South Africa. V. The motility of the rumen under various conditions. Onderstepoort J. Vet. Sci. Anim. Ind. 11: 361–382, 1938.
 180. Reid, C. S. W. Diet and motility of the forestomachs of the sheep. Proc. N. Z. Soc. Anim. Prod. 23: 169–188, 1963.
 181. Reid, C. S. W., and J. B. Cornwall. The mechanical activity of the reticulo‐rumen of cattle. Proc. N. Z. Soc. Anim. Prod. 19: 23–35, 1959.
 182. Reid, C. S. W., and D. A. Titchen. Reflex stimulation of movements of the rumen in decerebrate sheep. J. Physiol. Lond. 181: 432–448, 1965.
 183. Riek, R. F. The influence of sodium salts on the closure of the oesophageal groove in calves. Aust. Vet. J. 30: 29–37, 1954.
 184. Roman, C. Contrôle nerveux du péristaltisme oesophagien. J. Physiol. Paris 58: 79–108, 1966.
 185. Rousseau, J. P. Electrophysiological study of vagal afferent and efferent units in conscious sheep. Q. J. Exp. Physiol. 69: 627–637, 1984.
 186. Roy, J. H. B. Factors affecting susceptibility of calves to disease. J. Dairy Sci. 63: 650–664, 1980.
 187. Ruckebusch, Y. Liaisons réflexes conditionnelles chez les ruminants. II. Rumination. Bull. Acad. Vet. Fr. 36: 99–107, 1963.
 188. Ruckebusch, Y. The electrical activity of the digestive tract of the sheep as an indication of the mechanical events in various regions. J. Physiol. Lond. 210: 857–882, 1970.
 189. Ruckebusch, Y. Motility of the ruminant stomach associated with states of sleep. In: Digestion and Metabolism in the Ruminant, edited by I. W. McDonald and A. C. I. Warner. Armidale, Australia: Univ. New Engl. Publ. Unit, 1975, p. 77–90.
 190. Ruckebusch, Y. Enhancement of the cyclic motor activity of the ovine small intestine by lysergic acid derivatives. Gastroenterology 87: 1049–1055, 1984.
 191. Ruckebusch, Y. Development of digestive motor patterns during perinatal life: mechanism and significance. J. Pediatr. Gastroenterol. Nutr. 5: 523–536, 1986.
 192. Ruckebusch, Y., T. Bardon, and M. Pairet. Opioid control of the ruminant stomach motility: Functional importance of μ, and δ receptors. Life Sci. 35: 1731–1738, 1984.
 193. Ruckebusch, Y., and L. Bueno. Origin of migrating myoelectric complex in sheep. Am. J. Physiol. 233 (Endocrinol. Metab. Gastrointest. Physiol. 2): E484–E487, 1977.
 194. Ruckebusch, Y., C. Dardillat, and P. Guilloteau. Development of digestive function in the newborn ruminant. Ann. Rech. Vet. 14: 360–374, 1983.
 195. Ruckebusch, Y., and C. H. Malbert. Physiological characteristics of ovine pyloric sphincter. Am. J. Physiol. 251 (Gastrointest. Liver Physiol. 14): G804–G814, 1986.
 196. Ruckebusch, Y., and A. M. Merritt. Pharmacology of the ruminant gastroduodenal junction. J. Vet. Pharm. Ther. 8: 339–351, 1985.
 197. Ruckebusch, Y., and G. Soldani. Gallbladder motility in sheep: effects of cholecystokinin and related peptides. J. Vet. Pharm. Ther. 8: 263–269, 1985.
 198. Ruckebusch, Y., and T. Tomov. The sequential contractions of the rumen associated with eructation in sheep. J. Physiol. Lond. 235: 447–458, 1973.
 199. Ruckebusch, Y., C. H. Tsiamitas, and L. Bueno. The intrinsic electrical activity of the ruminant stomach. Life Sci. 11: 55–64, 1972.
 200. Sakata, T., and H. Tamate. Rumen epithelium cell proliferation accelerated by propionate and acetate. J. Dairy Sci. 62: 49–52, 1979.
 201. Scott, D. Factors influencing the secretion and absorption of calcium and magnesium in the small intestine of the sheep. Q. J. Exp. Physiol. 50: 312–318, 1965.
 202. Scott, D. The effects of sodium depletion and potassium supplements upon electrical potentials in the rumen of the sheep. Q. J. Exp. Physiol. 51: 60–69, 1966.
 203. Sellers, A. F., and A. Dobson. Studies on reticulo‐rumen sodium and potassium concentrations and electrical potentials in sheep. Res. Vet. Sci. 1: 95–102, 1960.
 204. Sellers, A. F., and C. E. Stevens. Motor functions of the ruminant forestomach. Physiol. Rev. 46: 634–661, 1966.
 205. Sellers, A. F., C. E. Stevens, A. Dobson, and F. D. McLeod. Arterial blood flow to the ruminant stomach. Am. J. Physiol. 207: 371–377, 1964.
 206. Singleton, A. G. The electromagnetic measurement of the flow of digesta through the duodenum of the goat and the sheep. J. Physiol. Lond. 155: 134–147, 1961.
 207. Sissons, J. W. Effect of feed intake on digesta flow and myoelectric activity in the gastrointestinal tract of the preruminant calf. J. Dairy Sci. 50: 387–395, 1983.
 208. Sissons, J. W., and R. H. Smith. Effect of duodenal cannulation, abomasal emptying and secretion in the pre‐ruminant calf. J. Physiol. Lond. 322: 409–417, 1982.
 209. Sissons, J. W., S. M. Thurston, and R. H. Smith. Reticular myoelectric activity and turnover of rumen digesta in the growing steer. Can. J. Anim. Sci. 64: 70–71, 1984.
 210. Sperber, I., S. Hyden, and J. Eckman. The use of polyethylene glycol as a reference substance in the study of ruminant digestion. K. Lantbrukshogsk. Ann. 20: 337–344, 1953.
 211. Stevens, C. E. Transport of sodium and chloride by the isolated rumen epithelium. Am. J. Physiol. 206: 1099–1105, 1964.
 212. Stevens, C. E., and A. F. Sellers. Studies of the reflex control of the ruminant stomach with special reference to the eructation reflex. Am. J. Vet. Res. 20: 461–482, 1959.
 213. Stevens, C. E., and A. F. Sellers. Rumination. In: Handbook of Physiology. Alimentary Canal. Bile; Digestion; Ruminal Physiology, edited by C. F. Code Washington, DC: Am. Physiol. Soc., 1968, sect. 6, vol. V, p. 2699–2704.
 214. Stevens, C. E., A. F. Sellers, and F. A. Spurrell. Function of the bovine omasum in ingesta transfer. Am. J. Physiol. 198: 449–455, 1960.
 215. Stewart, W. E., and D. G. Stewart. Technique for cannulation of parotid salivary duct of sheep. J. Appl. Physiol. 16: 203–209, 1961.
 216. Stoyanov, I. N., Y. B. Loukanov, P. V. Vassileva, and V. I. Vassilev. Comparative studies of the alpha and beta adrenergic receptors in the longitudinal and circular smooth muscle layers of the simple and complex stomach. Gen. Pharmacol. 7: 399–404, 1976.
 217. Sutton, J. D. Carbohydrate fermentation in the rumen—variations on a theme. Proc. Nutr. Soc. 38: 275–281, 1979.
 218. Svendsen, P. Experimental studies on gastrointestinal atony in ruminants. In: Digestion and Metabolism in the Ruminant, edited by I. W. McDonald and A. C. I. Warner. Armidale, Australia: Univ. New Engl. Publ. Unit, 1975, p. 563–575.
 219. Symons, L. E. A., and D. R. Hennessey. Cholecystokinin and anorexia in sheep infected by the intestinal nematode Trichostrongylus colubriformis. Int. J. Parasitol. 11: 55–58, 1981.
 220. Szabo, T., and M. Dussardier. Les noyaux d'origine du nerf vague chez le mouton. Z. Zellforsch. Mikrosk. Anat. 63: 247–276, 1964.
 221. Tadmor, A., and H. Newmark. An abdominal approach for producing permanent omasal fistulae in the ox and sheep. Aust. Vet. J. 48: 408–415, 1972.
 222. Tamate, H., A. D. McGillard, N. I. Jacobson, and R. Getty. Effect of various dietaries on the anatomical development of the stomach in the calf. J. Dairy Sci. 45: 408–420, 1962.
 223. Taneike, T. 5‐Hydroxytryptamine potentiates contraction mediated by the intramural cholinergic nerves in the longitudinal smooth muscle of the ruminant forestomach. J. Vet. Pharm. Ther. 2: 59–68, 1979.
 224. Tansy, M. F., J. S. Martin, W. E. Landin, and F. M. Kendall. Species difference in GI motor response to somatostatin. J. Pharm. Sci. 68: 1107–1113, 1979.
 225. Tindal, J. S., L. A. Blake, A. D. Simmonds, I. C. Hart, and H. Mizuno. Control of growth hormone release in goats: effects of vagal cooling, feeding and artificial distension of the rumen. Horm. Metab. Res. 14: 425–429, 1982.
 226. Titchen, D. A. The production of rumen and reticulum contractions in decerebrate preparations of sheep and goats. J. Physiol. Lond. 151: 139–153, 1960.
 227. Titchen, D. A. Nervous control of motility of the forestomach of ruminants. In: Handbook of Physiology. Alimentary Canal. Bile; Digestion; Ruminal Physiology, edited by C. F. Code. Washington, DC: Am. Physiol. Soc., 1968, sect. 6, vol. V, p. 2705–2724.
 228. Titchen, D. A. Diaphragmatic and oesophageal activity in regurgitation in sheep: an electromyographic study. J. Physiol. Lond. 292: 381–390, 1979.
 229. Titchen, D. A. Gastrointestinal peptide hormone distribution, release and action in ruminants. In: Control of Digestion and Metabolism in Ruminants, edited by L. P. Milligan, W. L. Grovum, and A. Dobson. Englewood Cliffs, NJ: Prentice‐Hall, 1986, p. 498–515.
 230. Titchen, D. A., C. S. W. Reid, and P. Vlieg. Effects of intraduodenal infusions of fat on the food intake of sheep. Proc. N. Z. Soc. Anim. Prod. 26: 36–51, 1966.
 231. Toutain, P. L., M. R. Zingoni, and Y. Ruckebusch. Assessment of alpha 2 adrenergic antagonists on the central nervous system using reticular contraction in sheep as a model. J. Pharmacol. Exp. Ther. 223: 215–218, 1982.
 232. Tsuda, T. Studies on absorption from the rumen. 2. Absorption of several organic substances from the miniature rumen of the goat. Tohoku J. Agric. Res. 7: 241–256, 1956.
 233. Ulyatt, M. J., D. W. Dellow, A. John, C. S. W. Reid, and G. C. Waghorn. Contribution of chewing during eating and rumination to the clearance of digesta from the ruminoreticulum. In: Control of Digestion and Metabolism in Ruminants, edited by L. P. Milligan, W. L. Grovum, and A. Dobson. Englewood Cliffs, NJ: Prentice‐Hall, 1986, p. 498–515.
 234. Ulyatt, M. J., D. W. Dellow, C. S. W. Reid, and T. Bauchop. Structure and function of the large intestine of ruminants. In: Digestion and Metabolism in the Ruminant, edited by I. W. McDonald and A. C. I. Warner. Armidale, Australia: Univ. New Engl. Publ. Unit, 1975, p. 119–133.
 235. Vallenas, A., J. F. Cummings, and J. F. Munnell. A gross study of the compartmentalized stomach of two new‐world camelids, the llama and guanaco. J. Morphol. 134: 399–423, 1971.
 236. Vallenas, A. P., and C. E. Stevens. Motility of the llama and guanaco stomach. Am. J. Physiol. 220: 275–282, 1971.
 237. Vandeplassche, G., W. Oyaert, and A. Houvenaghel. The influence of prostaglandins on in vitro motility of the fundus and the pyloric sphincter of the bovine abomasum. Arch. Int. Pharmacodyn. Ther. 260: 306–310, 1982.
 238. Vandermeerschen‐Doize, F., and R. Paquay. Effects of continuous long‐term intravenous infusion of long‐chain fatty acids on feeding behaviour and blood components of adult sheep. Appetite 5: 137–146, 1984.
 239. Van Lennep, E. W. The glands of the digestive system in the one‐humped camel, Camelus dromedarius L. Acta Morphol. Neerl. Scand. 1: 286–292, 1958.
 240. Van Miert, A. S. J. P. A. M., L. E. van der Wal‐Komproe, and C. T. M. Van Duin. Effects of antipyretic agents on fever and ruminal stasis induced by endotoxin in conscious goats. Arch. Int. Pharmacodyn. Ther. 225: 39–50, 1977.
 241. Van Miert, A. S. J. P. A. M., and F. Van Vugt. The effect of dopamine on gastric adrenergic receptors in the goat. Zentralbl. Veterinaermed. Reihe A 21: 96–104, 1974.
 242. Van Soest, P. J. Nutritional Ecology of the Ruminant. Corvallis, Oregon: O & B Books, 1982.
 243. Van't Klooster, A. T., A. Kemp, J. H. Geurink, and P. A. M. Rogers. Studies on the amount and composition of digesta flowing through the duodenum of dairy cows. 1. Rate of flow of digesta measured direct and estimated indirect by the indicator dilution technique. Neth. J. Agric. Sci. 20: 314–324, 1972.
 244. Veenendaal, G. H., F. M. A. Woutersen‐van Nijnanten, and A. S. J. P. A. M. van Miert. Responses of goat ruminal musculature to bradykinin and serotonin in vitro and in vivo. Am. J. Vet. Res. 41: 479–483, 1980.
 245. Veenendaal, G. H., F. M. A. Woutersen‐van Nijmanten, and A. S. J. P. A. M. van Miert. Responses of goat ruminal musculature to substance P in vitro and in vivo. Vet. Res. Commun. 5: 363–367, 1982.
 246. Vlaminck, K., C. van den Hende, W. Oyaert, and E. Muylle. Studies on abomasal emptying in cattle. 1. Correlation between abomasal emptying, electromyographic activity and pressure changes in the abomasum. Zentralbl. Veterinaermed. Reihe A 31: 661–566, 1984.
 247. Waghorn, G. C., and C. S. W. Reid. Rumen motility in sheep and cattle as affected by feeds and feeding. Proc. N. Z. Soc. Anim. Prod. 37: 176–181, 1977.
 248. Wardrop, I. D., and J. B. Coombe. The development of rumen function in the lamb. Aust. J. Agric. Res. 12: 661–680, 1961.
 249. Warner, E. D. The organogenesis and early histogenesis of the bovine stomach. Am. J. Anat. 102: 33–64, 1958.
 250. Warner, R. G., W. P. Flatt, and J. K. Loosli. Dietary factors influencing the development of the ruminant stomach. Agric. Food Chem. 4: 788–792, 1956.
 251. Watson, R. Studies on deglutition in sheep. 1. Observations on the course taken by liquids through the stomach of the sheep at various ages from birth to maturity. Bull. Council Sci. Industr. Res. 180: 1–94, 1944.
 252. Weiss, K. E. Physiological studies on eructation in ruminants. Onderstepoort J. Vet. Res. 26: 251–283, 1953.
 253. Westra, R., and R. J. Hudson. Digestive function of Wapiti calves. J. Wild. Manage. 45: 148–155, 1981.
 254. Weyns, A., L. A. Ooms, A. Vehhofstad, T. Peeters, L. Van Nassauw, and P. Krediet. Neurotransmitters/neuromodulators of the ruminant stomach: a histochemical, radioimmunological, immunocytochemical and functional approach. In: The Ruminant Stomach, edited by L. A. Ooms, A. Degryse, and R. Marsboom. Beerse, Belgium: Janssen Foundation, 1985, vol. 1, p. 53–117.
 255. Weyreter, H., and W. V. Engelhardt. Adaptation of Heidschnucken, Merino and Blackhead sheep to a fibrous roughage diet of poor quality. Can. J. Anim. Sci. 64, Suppl. 1: 152–153, 1984.
 256. Wilson, A. D. The influence of diet on the development of parotid salivation and the rumen of the lamb. Aust. J. Agr. Res. 14: 226–238, 1963.
 257. Winship, D. H., F. F. Zboralske, W. N. Webber, and K. H. Soergel. Esophagus in rumination. Am. J. Physiol. 207: 1189–1194, 1964.
 258. Wise, G. H., and G. W. Anderson. Factors affecting the passage of liquids into the rumen of the dairy calf. 1. Method of administering liquids: drinking from open pail versus sucking through a rubber nipple. J. Dairy Sci. 22: 697–705, 1939.
 259. Wyburn, R. S. The mixing and propulsion of the stomach contents of ruminants. In: Digestive Physiology and Metabolism of Ruminants, edited by Y. Ruckebusch and P. Thivend. Lancaster, UK: MTP, 1980, p. 35–51.

Contact Editor

Submit a note to the editor about this article by filling in the form below.

* Required Field

How to Cite

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