The role of migrating myoelectric complexes in the regulation of digesta transport in the preruminant calf C. L. GIRARD'AND J. W. SISSBNS
Can. J. Physiol. Pharmacol. Downloaded from www.nrcresearchpress.com by YORK UNIV on 11/11/14 For personal use only.
Agriculture Canada Research Station, Lennoxville, QuL, Canada J I M HZ3 and AFRC Institute fir Grassland and Animal Producti~n,Shinfield, Reading, Berkshire WG2 9AQ, England Received December 16, 1991 GIRARD, C. L., and S r s s s ~ sJ., W* 1992. The role of migrating myoelectric complexes in the regulation of digesta transport in the premminant calf. Can. J. Physiol. Pharmacol. 70: 1142 - 1147. Four calves were equipped with an electromagnetic flow probe inside the tranverse duodenum and with electrodes at intervals of 2 cm on either side of the probe. Amounts of 0.5, 2.0, 3.5, and 5.0 kg of whole milk were given according to a latin square design. Recordings of digesta flow and myoelectric activity were made during a 5 . 6 4 period after feeding to quantifj the influence of migrating myoelectric complexes on digesta flow through the transverse duodenum of preruminant calf under different levels of milk intake. Immediately after feeding, a phase of irregular spiking activity appeared; its length increasing linearly ( p = 0.002) with the amount s f milk fed. Increasing milk intake led to linear increases in duration ( p = 0.001) and total electrical activity ( p = 0.QO2) of the irregular activity phases, quadratic shortening of the quiescent phases (g = 0.021), and linear decrease ( p = 0.006) in the numbers of migrating myoelectric complexes. Intermittent flows of digesta, each of them corresponding to a strong spike burst, appeared during irregular spiking activity phases. Augmentation of the milk ingested did not affect the volume of each gush sf digesta but caused a cubic increase in the number of gushes ( p = 0.023) and in the total volume of digesta ( p = 0.009). These cubic effects implied that with increased intake of milk, the duodenum endeavoured to accelerate the flow of digesta in an attempt to return to an "empty state" in about the same time for all levels of milk consumed. This was achieved mainly through adjustments in the duration and activity of the irregular spiking activity phase. Key words: calf, myoelectric complex, digesta transport, milk intake. GIRARD, C. L., et SISSQNS, J. W. 1992. The role of migrating myoelectric complexes in the regulation of digesta transport in the preruminant calf. Can. J. Physiol. Pharmacol. 70 : 1142 - 1147. Une sonde dkbitmttrique a Ctt placte 2i l'inttrieur du duodtnum transverse de quatre veaux et des Cleetrodes ont t t t placks B des intervalles de 2 cm de chaque c6tt de la sonde. L9activitCmystlectrique et le dtbit du digesta ont t t t enregistrts pendant une ptriode de 5,6 h aprks chaque repas afin de quantifier l'influence des complexes myotlectriques migrants sur le dtbit du digesta dans le dusdtnum transverse de veaux prtruminants ingtrant difftrents volumes de lait, soit 0,5, 2,0, 3,5 et 5,O kg de lait de vache donnts suivant un carrt latin. Une phase d'aetivitt irrtgulikre apparait immtdiatement aprks le repas; la d u r k de cette phase augrnente en fonctisn de la quantitt de lait ingCrCe (effet lintaire, p = 0,002), Une augmentation de la quantitt de lait ingtrt entraine aussi une augmentation de la durte et de l'activitt Clectrique totale des phases d'activitt irrtgulikre (effet lintaire, p I0,W2), une raccourcissement des phases de quiescence (effet quadratique, p = 0,821) et une diminution du nombre de complexes myoklectriques migrants (effet lintaire, p = 0,006). Des dtbits intermittents de digesta ont t t t enregistrts pendant la phase d'activitt irrkgulihre, chacun d'entre eux correspondant B un fort potentiel de pointe. Une augmentation du volume de lait ingtrC n'affecte pas le volume de chacun de ces dCbits mais augmente le nombre de dtbits et le volume total de digesta (effet cubique, p = 0,023 et 0,009). Ces effects cubiques semblent dtmontrer que, via un ajustement de la durte et de l'activitt des phases d'activitk irrtgulikre, le duodCnum "acctlkre" le dtbit du digesta tentant ainsi d'effectuer la vidange gastrique dans un laps de temps semblable, quelque soit le volume de lait ingtrt. Mots cle's : veau, complexes myotlectriques migrants, dtbit du digesta, volume de lait ingtrt.
Introduction It has previously been reported that digesta flow in proximal duodenum of premminant calf is associated with the recurring patterns of myoelectric complexes, more precisely with the irregular spiking activity phase. There is generally no Row during the quiescent and regular spiking activity phases (Dardillat 1977). Feeding increases abomasal emptying during the first hour post-feeding to a rate two or three times superior to the pre-feeding rate and temporarily interrupts the recurring patterns of intestinal myoelectric activity with a continuous irregular spiking activity (Dardillat 1977; Sissons 1983). The duration of this post-feeding activity increases with the amount of milk consumed (Sissons 1983). This experiment was conducted to examine and quantify the influence of migrating myoelectric complexes (MMC) on 'Correspondence may be sent to the author at the following address: Station de reeherches, Agriculture Canada, C.P. 90, Lennoxville (Qutbec), Canada J 1M 123. Contribution no. 384. Printed in Canada i Imprime au Canada
digesta transit through the small intestine of the milk-fed calf. Digests movement in the gut lumen and myoelectric activity of the muscle wall were measured at the transverse duodenum of animals equipped with an electromagnetic Row probe and wire recording electrodes.
Methods Animals and feeding Four Friesan bull calves were equipped with an electromagnetic flow probe ( i d . , 1.6 cm; Skalar Medican, Delft, Holland) placed inside the transverse duodenum approximately 10 em from the sigmoid flexure. Groups of wire electrodes for recording myoelectric activity were implanted as described by Ruckebusch (1970) at intervals of 2 cm oneither side of the three groups of electrodes before and two groups after the probe location. Each group of electrodes consisted of three multistrained stainless steel wires coated with Teflon (W = 102 Qlm) (Cooner Sales Company Inc., Chatsworth, Calif.). Surgical preparations were carried out when the calves were about 3 weeks of age and weighed 50 -55 kg. Anaesthe-
Can. J. Physiol. Pharmacol. Downloaded from www.nrcresearchpress.com by YORK UNIV on 11/11/14 For personal use only.
GIWARB AND SISSONS
sia was maintained during surgery by endotracheal intubation using a mixture of oxygen and halothane. Animals were cared for according to recommended codes of practices (Canadian Council on Animal Care 1988; Agriculture Canada 1990). Precise electrode sites were ascertained by post-mortem examination. Calves received colostrum up to 4 d of age and then whole milk, supplemented from 3 weeks with minerals and vitamins, in amounts calculated to give a growth rate of about 0.25 kg/d (Roy et al. 1958). The calves were maintained on this regimen except when experimental feeds were given. From about 2 weeks after surgery, experimental feeds of 0.5, 2.0, 3.5, and 5.0 kg whole milk were given to calves by bucket at intervals of 2 -3 d according to a 4 X 4 latin square design. Electromyographi6:and digesta flow recordings On the day of recordings, the calf was placed in a restraining crate at 88:30 h. The appropriate amount of milk was fed at about 09:00 h, which was about 16 h after a previous feed. Recordings of myoelectric activity and digesta flow were made shortly before and during a period of approximately 6 h after feeding using a chart speed of 0.6 m / s , Electrical activity was recorded from two sites before and one site after the electromagnetic flow probe. Electromyographic recordings were made with a Grass model 7 ink-writing polygraph (Grass Instruments, Quincy, Mass., U. S.A.). Frequency responses of the polygraph were set to record electrical events occurring between 10 and 35 Hz. Electrical potentials were integrated continuously using a summating integrator (Grass model 7P10). Recordings of digesta movement were obtained from the electromagnetic flow probe coupled via a SEM 275 flowmeter (SE Laboratories ktd., Feltham, Middlessex, U.K.) to a direct current (DC) pen driver amplifier (Grass model 9BA) set to record signals under 3.0 Hz. Signals at the DC pen driver amplifier were simultaneously recorded with a magnetic tape recorder. The tape was replayed later on the polygraph and the light drift of the baseline, observed during direct recording, was corrected manually. Flow responses were integrated using a sumating integrator; backward and forward movements were s u m a t e d separately using the &signalcross" facility on the integrator (Grass model 7P10). Calibration of the ekectromgnetie flowmeter Calibration of the electromagnetic flowmeter was made for each calf. At post-mortem examination, a segment of approximately 25 cm of transverse duodenum on which the flow probe was fixed was removed and immersed in a saline solution (0.9% NaC1). Known volumes of saline solution, in a range of 5- 100 mE, were injected in the duodenal segment. Results of calibration of the flowmeter with duodenal digesta from a cannulated calf were similar to those obtained with saline solution (0.9% NaC1). Flow responses were recorded as described in the previous section. The responses of the flowmeter varied linearly with the volumes injected; the equation, obtained for each calf, served to quantify the volume of gushes of digesta recorded in vivo during the experimental period. Statistical analj~sis Data from electromyographic recordings were analysed as a latin square design (Snedecor and Cochran 1957) using the general linear model of the Statistical Analysis System (1985). Recordings of digesta flow from one calf were not clear and were not used in the study. Consequently, data from digesta flow recordings were analysed as a Youden square design (Cochran and Cox 1950). The following model was used for electrical activity and digesta flow data:
where Y indicated the dependent variable. The overall mean was p; aiwas the effect of treatment; @, was the effect of calf; and -yk,the effect of the order of the treatments. Least square means were compared using orthogonal contrasts when appropriate (Snedecor and Cochran 1959). The effect of time on digesta flow was studied with the following model:
l 143
where Y indicated the dependent variable. The overall mean was p; aiwas the effect of treatment; 0, was the effect of calf; -yk was the effect of the order of the treatments; and ql, the effect of the time. The two error terms were euk and GUkl,where eijk was the random effect of the jth animal in the ikth treatment by order combination. The effect of the part of irregular spiking activity (ISA) on myoelectric activity, the number of gushes, the volume of gushes, and the digesta flow was tested by dividing each ISA into four equal parts and by using the previous model in which qi indicated the part of the ISA. Electrical activities recorded from one site before and one site after the electromagnetic flow probe were compared using the following model:
where Y indicated the dependent variable. The overall mean was p; aiwas the effect of treatment; @, was the effect of calf; -yk was the effect of the order of the treatment; and ql, the effect of the electrode site. The two error terms were eOkand 8jjkl,where eUkis the random effect of the jth animal in the ikth treatment by order combination. Correlations were made between digesta flow and myoelectric activity (Snedecor and Cochran 1957).
Results Pattern of myoelectrie activity In an attempt to evaluate the effect of the electromagnetic flow probe placed inside the duodenum on the transmission of the electrical activity in the muscle wall, recordings from one site before and one after the flow probe were compared. The total number of MMC was different between the two locations ( p = 0.0006) with approximately two supplementary MMC recorded after the flow probe. The statistical interaction "calf by location of the electrode' ' was also significant ( p = 0.01), meaning that the flow probe affected each animal differently. The number of MMC recorded before and after the flow probe were 6.3 and 10.5, 10.0 and 10.3, 6.8 and 4.5, and 6.8 and 9 .O, respectively, for the four calves used in this experiment. The only disturbance was the presence in some calves of supplementary regular spiking activity (RSA) phases after the flow probe during periods of high spiking activity of ISA phases before the probe. There was no quiescent phase after these RSA; the transmission of spike bursts between the two sites started again after these supplementary RSA phases. This pattern did not change with time after surgery. The difference between the two locations was not affected by the level of milk intake or the order of treatments. Moreover, there was no difference in the total electrical activity recorded at the two locations for the four calves ( p > 0.05). Immediately after feeding, a phase of ISA appeared; the duration and the total electrical activity of the first ISA phase increased linearly with the amount of milk fed ( p = 0.002 and 0.003, respectively: Fig. 1). Duration and total electrical activity of the first regular spiking activity (RSA) and quiescent phases were not affected by the level of milk intake. The amount of milk fed had no marked effect ( g > 0.05) on the second and the third MMC after feeding. Overall, during the 5.6-h recording period after feeding, increasing milk intake from 0.5 to 5.0 kg led to a linear decrease ( p = 0.006) in the number of MMC and linear increases in the duration ( p = 0.003) and total electrical activity ( g = 0.01) of MMC. The augmentation of milk fed led to linear increases in the duration ( p = 0.001) and total electrical activity ( p = 0.002) of ISA
CAN. J. PHYSIOL. PHARMACOL. VOL. 70, 1992
Can. J. Physiol. Pharmacol. Downloaded from www.nrcresearchpress.com by YORK UNIV on 11/11/14 For personal use only.
200
Duration (min)
4000
Total electrical activity
Milk intake (kg)
Milk intake (kg)
FIG. 1. Duration (a) and total electrical activity in arbitrary units (b) of the immediate post-feeding period of irregular spiking activity on the transverse duodenum of four calves according to milk intake. TABLE1. Effect of level of milk intake on the pattern of myoelectl-ic activity recorded at the transverse duodenum of four calves during the first 5.6 h post-feeding (mean +_ SEM) Level of milk intake (kg) 0.5 Number of MMC* Duration of MMC* (rnin) Electrical activity of (AU) Duration of Qt. (min) Electrical activity s f (AU) Duration of ISA* (miin) Electrical activity of (AU) Duration of RSA (mi@ Electrical activity of (AU)
2.0
3.5
5.0
the MMC*
Q
ISA*
RSA
NOTE:AU, arbitrary units; ISA, irregular spiking activity; MMC, migrating myoelectric complex; Q , quiescent phase; RSA, regular spiking activity. *Linear effect of treatments ( p 5 0.05). ?Quadratic effect of treatments ( p 5 0.05).
phases and a quadratic shortening of quiescent phases ( p = 0.02). There was no effect on the duration or total electrical activity of RSA phases ( p > 0.05) (Table 1). Time after surgery and age of calves had no effect on myoelectric activity. There was, however, a significant difference ( p < 0.05) between cdves in the total electrical activity of MMC and ISA phases. Measurements of digesta movement using an electromagnetic flow probe Digesta flow at the transverse duodenum of milk-fed cdves consisted of a series of intermittent gushes of digesta with no flow between these gushes. The mean volume of each gush of
digesta during the first 4 h after feeding was 6.6 mL (SE 0.13) and was not affected by the quantity s f milk ingested. The volume of a gush of digesta was relatively constant: 7.40 mL (SE 0.24), 6.35 mL (SE 0.26), 6.27 mb, (SE O X ) , and 6.28 mb, (SE 0.34) for each of the first 4 h, respectively. However, during the first 4 h post-feeding, there was a cubic increase in the number of gushes ( p = 0.02) and in the totd volume of digesta ( p = 0.089) according to the augmentation of the amount of milk fed (Fig. 2). The amount of digesta entering the transverse duodenum per hour varied during the 4 h after milk intake (quadratic effect, p = 0.04). The interaction treatment by hour being nearly significant ( p = O.OQ), data of digesta flow were analysed
GIBAWD AND SISSONS
(a)
(b)
Gushes of digesta (no.)
Total volume of digesta (mL)
7 I 0 6000
,
1
Can. J. Physiol. Pharmacol. Downloaded from www.nrcresearchpress.com by YORK UNIV on 11/11/14 For personal use only.
eoo 1
V
Y
0.5
3.5
2
6
0.6
2
3.6
6
Milk intake (kg)
Milk intake (kg)
FIG.2. Effect of milk intake on the number of gushes (a) and the total volume of digesta (b) at the transverse duodenum of three milk-fed calves.
0 L-1
L
2
I
3
4
Time after feeding (hours) FIG.3. Cumulative amounts of total digesta entering the transverse duodenum of three calves given 0.5 (a), 2.0 (01, 3.5 ( x), and 5.0 kg ( A ) of milk.
In all treatments there was a positive correlation between the total electrical activity of ISA phases and the number of gushes of digesta during the first 4 h post-feeding ( p = 0.004, "r 0.41). During the immediate post-feeding period of ISA, the volume of digesta was positively correlated to the duration of 0.98) and showed a tendency this period ( p = 0.0001, "r to be correlated to the total electrical activity ( p = 0.08, "r 0.52). The number of gushes of digesta was also positively correlated to the total electrical activity recorded during this period ( p = 0.02, "r 0.64). ISA phases were divided into four q u d parts to observe the effects of the proximity of a RSA on digesta flow and myoelectric activity. Myoelectric activity, the number of gushes, the mean volume of a gush, and the total volume of digesta were not different ( p > 0.05) between each part of an ISA. Similarly, myoelectric activity, the number of gushes, and the volume of digesta calculated per unit of time (min) did not differ ( p > 0.05) between each part of the ISA.
Discussion separately for each hour. During the first, third, and fourth hours after feeding, digesta flow increased (cubic effect, p = 0,004) with the amount of milk ingested (Table 2). However, there was no effect ( p > 0.05) of treatments on digesta flow during the second hour. Cumulative amounts of digesta entering the transverse duodenum increased linearly (p = 0.000 1) during the 4 h after milk intake. However, as shown in Fig. 3, the slopes differed slightly according to the level of milk ingested (interaction treatment by hour, p = 0.005). Relation between digesta flow and myoelectric activity in transverse duodenum wall There were intermittent flows of digesta during ISA phases. Little or no digesta flow was detected by the probe during quiescent phases. Some backward and forward flows were detected during RSA phases but summation of the flows were always near zero (Fig. 4). Each gush of digesta during ISA phases corresponded to a spike burst recorded on electrodes placed before the flow probe and generally transmitted on electrodes placed after the flow probe.
Methohlogy In previous experiments, electromagnetic flow probes were placed in reentrant cannulas (Poncet et al. 1977; Poncet and Ivan 1984) or around the intestine (Dardillat 1977; Sissons 1983; Poncet and Ivan 1984). In a study with sheep comparing the effects of different devices for measuring digesta flow in the ascending duodenum, Poncet and Ivan (1984) found that disturbances of myoelectric activity seem to be related to the length of duodenum occupied by the cannula or the electromagnetic flow probe. Electromagnetic flow probe placed around the ascending duodenum of sheep (Poncet and Ivan 1984) or the transverse duodenum of the preminant calf (Dardillat 1977) did not modify propagation of spike burst or migration of RSA phases. However, in a preliminary study, recordings from a flow probe placed around the intestine were not satisfactory. Some "fibrinous" tissues grew between the probe and the intestine, decreasing sensitivity of the probe and partially blocking the intestine. This obstruction increased with time and slowed down the digesta flow leading to an accumulation of digesta
Can. J. Physiol. Pharmacol. Downloaded from www.nrcresearchpress.com by YORK UNIV on 11/11/14 For personal use only.
CAN. J. PHYSIOL. PHARMACOL. VOL. 70, 1992
FIG. 4. Myoelectric activity and digesta flow during regular spiking activity, quiescent, and irregular spiking activity phases recorded in the transverse duodenum of a calf given 2.0 kg milk. Recordings show measurements of digesta flow (c) and myoelectric activity from electrodes implanted 5.0 cm (a) and 2.5 crn (6) before and 2.5 cm (d) after the flow probe. TABLE2. Rates of digesta flow (mLIh) in the transverse duodenum of three calves at different times after feeding 0.5 -5.0 kg milk (mean f SEM) Period after feeding (h)
Amount s f milk fed (kg)
8.5
2.0
3.5
5.0
*Cubic effect sf treatments ( p 5 0.004).
and a dilation of the intestine before the flow probe. At this time, large disturbances in the transmission of electricd activity before and after the flow probe appeared (C. L. Girard and J. W. Sissons, unpublished data). Subsequently, the flow probe was placed inside the transverse duodenum of milk-fed calves to avoid these problems. These surgical procedures maintained the integrity of the intestine. Moreover, in the present experiment, as the flow probe occupied only a short length of intestine, approximately 1 cm, disturbances of myoelectric activity were reduced as previously reported by Boncet and Ivan (1984). Myoelectric activity in the transverse duodenum As reported by many authors, the pattern of myoelectric activity at the transverse duodenum of milk-fed calf was an alternation of ISA, RSA, and quiescent phases, interrupted by an ISA phase provoked by anticipation of the meal and ingestion of milk (Ruckebusch et al. 1972; Dardillat 1977; Sissons 1983). The results of the present experiment are similar to those obtained from sheep in which augmentation of feed intake decreases the number of MMC per 24 h, and increases the duration of ISA at the expense of the duration of the quiescent phases while the RSA phases remain unchanged (Bubno 1977; BuCno et al. 1977). However, these results are different from those observed in the preruminant calf, in which an augmentation of the amount of milk ingested increases the duration of the immediate post-feeding period of ISA but decreases the duration of the first RSA phase (Sissons 1983). As previously reported by Sissons and Smith (1979) for
milk-fed calves aged 6-20 weeks, there was no effect of age on the pattern of MMC. Digesta flow in transverse duodenum The volume of gushes was constant and not affected by animal, age of animal, volume of meal, or time after feeding. This is in agreement with Dardillat (1977) who observed gushes of digesta varying from 4 to 10 mL in the transverse duodenum of the preruminant calf. Sissons and Smith (1979) also reported that milk intake ranging from 2 to $ kg had no effect on volume of gushes in the transverse duodenum. The cubic effects observed on the number of gushes and the total volume of digesta implied that digesta flow increased with the amount of liquid consumed. Moreover, gastric emptying was accelerated by an augmentation of milk intake, which agrees with results reported by Bell and Weber (1981) and Sissons (1983). Digesta flow at the transverse dudenum was accelerated during the first hour post-feeding and returned gradually to the pre-feeding value (quadratic effect) as reported by Mylrea (1966), Dardillat (1977), and Sissons (1983). Bre-feeding digesh flow in the duodenum varies between 280 mL/h (Mylrea 1966) and 280 mL/h (Sissons 1983). With a milk intake of 0.5 kg, the rate of digesta flow had already returned to similar values in the second hour post-feeding. Rates of digesta flow for the different milk intakes in this experiment were slightly inferior to those observed by Sissons (1983) but close to those calculated from Mylrea (1966). Calves at the end of the experimentd period were approxi-
GIRARD AND SISSONS
Can. J. Physiol. Pharmacol. Downloaded from www.nrcresearchpress.com by YORK UNIV on 11/11/14 For personal use only.
mtely 2 or 3 weeks older than at the beginning, as a result of the experimental design used. However, no effect of the order of treatment on the volume of digesta flow was observed, which confirms that volume of endogenous secretions does not change with age (Ternouth et d. 1976; Sissons and Smith 1982).
Relation befiveen digests flow and myoele~tr-i~ activity a? the transverse duodenum Digesta flow at the transverse duodenum was recorded only during ISA phases and was always related to the presence of a spike burst in the duodenal wd1 proximal to the flow probe, as reported by other authors for the premminant calf (Dardillat 1977; Sissons 1983), sheep (Poncet et al. 198I), dog (Summers and Dusdieker 1981), and pig (Rayner and Wenham 1986). Backward and forward flows observed during RSA phases were probably attributable to oscillations of digesta trapped inside the probe; the probe was a rigid area without contraction in a zone affected by strong contractions during the passage of the RSA phase. Digesta flow is related to the presence s f spike bursts during ISA phases; therefore, it is not surprising to obtain a correlation between total electrical activity during ISA phases, particularly the first one post-feeding, and the number of gushes and total volume of digesta. A similar relation between frequency of contractions and transit time was found in the jejunum s f dogs (Schemann and Erldein B 986). Dardillat (1977) observed that the rate of digesta flow in the duodenum increases progressively during the ISA phase. According to this author, this phenomenon is more evident in the jejunum where digesta flow increases markedly before RSA phase. This disagrees with the present results, in which there was no difference for myoelectric activity, digesta Wow, the number of gushes, and the mean volume of a gush between the different parts of an HSA phase. In conclusion, an augmentation in the amount of milk fed increased duration and total electrical activity of ISA phases at the expense of the duration s f the quiescent periods. This increased activity s f ISA phases led to an augmentation of digesta flow and an acceleration of abomasd emptying. This suggests that with an increased intake sf liquid feed, the duodenum, via a change in the myoelectric pattern, endeavoured to accelerate the flow of digesta in an attempt to return the abomasum to an 'empty statey9in about the same time for a11 levels of milk consumed. Agriculture Canada. 1998. Code de prratique pour le soin et la manipulation des bovins laitiers. Agriculture Canada publ. no. 1853/F. Ottawa. Bell, F. R., and Webber, B. E. 1981. The change in the volume of the periodic antral gush when the stomach is maintained at different constant volumes. S. Bhysiol. (London), 319: 47 -48. BuCno, L. 1977. Complexe myoklectrique de 19intestingrele et variations de l'apport alimentaire chez le mouton. C.R. SCances Soc. Biol, Toulouse, 171: 959 -964.
1147
BuCno, %. , Fioramonti, J ., and Ruckebusch, Y. 2 977. Mechanisms of propulsion in the small intestine. Ann. Rech. Vet. 8: 293 -301. Canadian Council on Animal Care. 1980. Guide to the care and use sf experimental animals. Vol. 1. Canadian Council on Animal Care. Ottawa, Canada. Cochran, W. G., and Cox, 6. M. 1950. Experimental designs. 2nd ed. John Wiley & Sons Hnc., New York. Dardillat, C. 1977. Analyse Clectromyographique et dtbitmktrique du transit alimentaire chez le veau nouveau-nC. J. Physiol. (Paris), 73: 925-944. Mylrea, P. J. 2966. Digestion of milk in young calves. 1. Flow and acidity of the contents of the small intestine. Res. Vet. Sci. 7: 333-341. Poncet, C., and Ivan. M. 1984. Effect of duodena1 cannulation in sheep on the pattern of gastroduodenal electrical activity and digestive flow. Reprod. Nutr. Dev. 24: 887 -902. Poncet, C., Dimova, E., UveillC, M., and Dardillat, C. 1977. Mise au point d'une mtthode d'enregistrement chronique du dCbit duodCnal chez 1e mouton: exemple d9application. Ann. Biol. Anim. Biochem. Biophys. 17: 5 15-522. Poncet, C., Ivan, M., and LkveillC, M. 1981. Electromagnetic measurements of duodena1 digesta flow in cannulated sheep. Reprod. Nutr. Dev. 22: 97-186. Rayner, V., and Wenham, G. 1986. Small intestinal motility and transit by electromyography and radiology in the fasted and fed pig. J. BhysioB. (London), 379: 245 -256. Roy, J. H. B., Shillam, K. W. G., Hawkins, G. M., and Eang, J. M. 1958. The milk requirements of the newborn calf. Br. J. Nutr. 12: 123-137. Ruckebusch, Y. 1970. The electrical activity of the digestive tract of the sheep as an indication of the mechanical events in various regions. J. Physiol. (London), 210: 857 - 882. Ruckebusch, Y., Dardillat, C., and Hatey , F. 1972. MotricitC intestinale chez le veau nouveau-nC: influence du repas. C.R. Seances SOC.Biol. Toulouse, 166: 1547- 1551. Schemann, M . , and Ehrlein, M. J. 1986. Postprandial patterns of canine jejunal motility and transit of luminal content. Gastroenterology, 90: 99 1- 1000. Sissons, I. W. 1983. Effect of feed intake on digesta flow and myselectric activity in the gastrointestinal tract of the premminant calf. J . Dairy Res. 50: 387 -395. Sissons, J. W., and Smith, R. H. 1979. Digesta movement and gut motility in the premminant calf- Ann. Rech. Vet. 10: 176- 178. Sissons, 9. W., and Smith, R. M. 1982. Effect of duodenal cannulation on abomasal emptying and secretion in the premminant calf. I. Physiol. (London), 322: 409 -4 17. Snedecor, G. W., and Cwhran, W. 6 . 1957. Methodes statistiques. 6th ed. Association de la coordination technique agricole, Paris. Statistical Analysis System. 1985. SAS User's Guide. Statistical Analysis System Institute Inc., C a q , NC. Summers, W. W., and Budieker, N. S. 1981. Patterns of spike burst spread and flow in the canine small intestine. ~ a s t r o e n t e r o l o ~ ~ , $1: 742-750. Ternouth, J. H., Roy, J. H. B., and Shotton, S. M. 1976. Concurrent studies of the flow of digesta in the duodenum and exocrine pancreatic secretion of calves. 4. The effect of age. Br. J. Nutr. 36: 523 -535.
Can. J. Physiol. Pharmacol. Downloaded from www.nrcresearchpress.com by YORK UNIV on 11/11/14 For personal use only.
Agriculture Canada Research Station, Lennoxville, QuL, Canada J I M HZ3 and AFRC Institute fir Grassland and Animal Producti~n,Shinfield, Reading, Berkshire WG2 9AQ, England Received December 16, 1991 GIRARD, C. L., and S r s s s ~ sJ., W* 1992. The role of migrating myoelectric complexes in the regulation of digesta transport in the premminant calf. Can. J. Physiol. Pharmacol. 70: 1142 - 1147. Four calves were equipped with an electromagnetic flow probe inside the tranverse duodenum and with electrodes at intervals of 2 cm on either side of the probe. Amounts of 0.5, 2.0, 3.5, and 5.0 kg of whole milk were given according to a latin square design. Recordings of digesta flow and myoelectric activity were made during a 5 . 6 4 period after feeding to quantifj the influence of migrating myoelectric complexes on digesta flow through the transverse duodenum of preruminant calf under different levels of milk intake. Immediately after feeding, a phase of irregular spiking activity appeared; its length increasing linearly ( p = 0.002) with the amount s f milk fed. Increasing milk intake led to linear increases in duration ( p = 0.001) and total electrical activity ( p = 0.QO2) of the irregular activity phases, quadratic shortening of the quiescent phases (g = 0.021), and linear decrease ( p = 0.006) in the numbers of migrating myoelectric complexes. Intermittent flows of digesta, each of them corresponding to a strong spike burst, appeared during irregular spiking activity phases. Augmentation of the milk ingested did not affect the volume of each gush sf digesta but caused a cubic increase in the number of gushes ( p = 0.023) and in the total volume of digesta ( p = 0.009). These cubic effects implied that with increased intake of milk, the duodenum endeavoured to accelerate the flow of digesta in an attempt to return to an "empty state" in about the same time for all levels of milk consumed. This was achieved mainly through adjustments in the duration and activity of the irregular spiking activity phase. Key words: calf, myoelectric complex, digesta transport, milk intake. GIRARD, C. L., et SISSQNS, J. W. 1992. The role of migrating myoelectric complexes in the regulation of digesta transport in the preruminant calf. Can. J. Physiol. Pharmacol. 70 : 1142 - 1147. Une sonde dkbitmttrique a Ctt placte 2i l'inttrieur du duodtnum transverse de quatre veaux et des Cleetrodes ont t t t placks B des intervalles de 2 cm de chaque c6tt de la sonde. L9activitCmystlectrique et le dtbit du digesta ont t t t enregistrts pendant une ptriode de 5,6 h aprks chaque repas afin de quantifier l'influence des complexes myotlectriques migrants sur le dtbit du digesta dans le dusdtnum transverse de veaux prtruminants ingtrant difftrents volumes de lait, soit 0,5, 2,0, 3,5 et 5,O kg de lait de vache donnts suivant un carrt latin. Une phase d'aetivitt irrtgulikre apparait immtdiatement aprks le repas; la d u r k de cette phase augrnente en fonctisn de la quantitt de lait ingCrCe (effet lintaire, p = 0,002), Une augmentation de la quantitt de lait ingtrt entraine aussi une augmentation de la durte et de l'activitt Clectrique totale des phases d'activitt irrtgulikre (effet lintaire, p I0,W2), une raccourcissement des phases de quiescence (effet quadratique, p = 0,821) et une diminution du nombre de complexes myoklectriques migrants (effet lintaire, p = 0,006). Des dtbits intermittents de digesta ont t t t enregistrts pendant la phase d'activitt irrkgulihre, chacun d'entre eux correspondant B un fort potentiel de pointe. Une augmentation du volume de lait ingtrC n'affecte pas le volume de chacun de ces dCbits mais augmente le nombre de dtbits et le volume total de digesta (effet cubique, p = 0,023 et 0,009). Ces effects cubiques semblent dtmontrer que, via un ajustement de la durte et de l'activitt des phases d'activitk irrtgulikre, le duodCnum "acctlkre" le dtbit du digesta tentant ainsi d'effectuer la vidange gastrique dans un laps de temps semblable, quelque soit le volume de lait ingtrt. Mots cle's : veau, complexes myotlectriques migrants, dtbit du digesta, volume de lait ingtrt.
Introduction It has previously been reported that digesta flow in proximal duodenum of premminant calf is associated with the recurring patterns of myoelectric complexes, more precisely with the irregular spiking activity phase. There is generally no Row during the quiescent and regular spiking activity phases (Dardillat 1977). Feeding increases abomasal emptying during the first hour post-feeding to a rate two or three times superior to the pre-feeding rate and temporarily interrupts the recurring patterns of intestinal myoelectric activity with a continuous irregular spiking activity (Dardillat 1977; Sissons 1983). The duration of this post-feeding activity increases with the amount of milk consumed (Sissons 1983). This experiment was conducted to examine and quantify the influence of migrating myoelectric complexes (MMC) on 'Correspondence may be sent to the author at the following address: Station de reeherches, Agriculture Canada, C.P. 90, Lennoxville (Qutbec), Canada J 1M 123. Contribution no. 384. Printed in Canada i Imprime au Canada
digesta transit through the small intestine of the milk-fed calf. Digests movement in the gut lumen and myoelectric activity of the muscle wall were measured at the transverse duodenum of animals equipped with an electromagnetic Row probe and wire recording electrodes.
Methods Animals and feeding Four Friesan bull calves were equipped with an electromagnetic flow probe ( i d . , 1.6 cm; Skalar Medican, Delft, Holland) placed inside the transverse duodenum approximately 10 em from the sigmoid flexure. Groups of wire electrodes for recording myoelectric activity were implanted as described by Ruckebusch (1970) at intervals of 2 cm oneither side of the three groups of electrodes before and two groups after the probe location. Each group of electrodes consisted of three multistrained stainless steel wires coated with Teflon (W = 102 Qlm) (Cooner Sales Company Inc., Chatsworth, Calif.). Surgical preparations were carried out when the calves were about 3 weeks of age and weighed 50 -55 kg. Anaesthe-
Can. J. Physiol. Pharmacol. Downloaded from www.nrcresearchpress.com by YORK UNIV on 11/11/14 For personal use only.
GIWARB AND SISSONS
sia was maintained during surgery by endotracheal intubation using a mixture of oxygen and halothane. Animals were cared for according to recommended codes of practices (Canadian Council on Animal Care 1988; Agriculture Canada 1990). Precise electrode sites were ascertained by post-mortem examination. Calves received colostrum up to 4 d of age and then whole milk, supplemented from 3 weeks with minerals and vitamins, in amounts calculated to give a growth rate of about 0.25 kg/d (Roy et al. 1958). The calves were maintained on this regimen except when experimental feeds were given. From about 2 weeks after surgery, experimental feeds of 0.5, 2.0, 3.5, and 5.0 kg whole milk were given to calves by bucket at intervals of 2 -3 d according to a 4 X 4 latin square design. Electromyographi6:and digesta flow recordings On the day of recordings, the calf was placed in a restraining crate at 88:30 h. The appropriate amount of milk was fed at about 09:00 h, which was about 16 h after a previous feed. Recordings of myoelectric activity and digesta flow were made shortly before and during a period of approximately 6 h after feeding using a chart speed of 0.6 m / s , Electrical activity was recorded from two sites before and one site after the electromagnetic flow probe. Electromyographic recordings were made with a Grass model 7 ink-writing polygraph (Grass Instruments, Quincy, Mass., U. S.A.). Frequency responses of the polygraph were set to record electrical events occurring between 10 and 35 Hz. Electrical potentials were integrated continuously using a summating integrator (Grass model 7P10). Recordings of digesta movement were obtained from the electromagnetic flow probe coupled via a SEM 275 flowmeter (SE Laboratories ktd., Feltham, Middlessex, U.K.) to a direct current (DC) pen driver amplifier (Grass model 9BA) set to record signals under 3.0 Hz. Signals at the DC pen driver amplifier were simultaneously recorded with a magnetic tape recorder. The tape was replayed later on the polygraph and the light drift of the baseline, observed during direct recording, was corrected manually. Flow responses were integrated using a sumating integrator; backward and forward movements were s u m a t e d separately using the &signalcross" facility on the integrator (Grass model 7P10). Calibration of the ekectromgnetie flowmeter Calibration of the electromagnetic flowmeter was made for each calf. At post-mortem examination, a segment of approximately 25 cm of transverse duodenum on which the flow probe was fixed was removed and immersed in a saline solution (0.9% NaC1). Known volumes of saline solution, in a range of 5- 100 mE, were injected in the duodenal segment. Results of calibration of the flowmeter with duodenal digesta from a cannulated calf were similar to those obtained with saline solution (0.9% NaC1). Flow responses were recorded as described in the previous section. The responses of the flowmeter varied linearly with the volumes injected; the equation, obtained for each calf, served to quantify the volume of gushes of digesta recorded in vivo during the experimental period. Statistical analj~sis Data from electromyographic recordings were analysed as a latin square design (Snedecor and Cochran 1957) using the general linear model of the Statistical Analysis System (1985). Recordings of digesta flow from one calf were not clear and were not used in the study. Consequently, data from digesta flow recordings were analysed as a Youden square design (Cochran and Cox 1950). The following model was used for electrical activity and digesta flow data:
where Y indicated the dependent variable. The overall mean was p; aiwas the effect of treatment; @, was the effect of calf; and -yk,the effect of the order of the treatments. Least square means were compared using orthogonal contrasts when appropriate (Snedecor and Cochran 1959). The effect of time on digesta flow was studied with the following model:
l 143
where Y indicated the dependent variable. The overall mean was p; aiwas the effect of treatment; 0, was the effect of calf; -yk was the effect of the order of the treatments; and ql, the effect of the time. The two error terms were euk and GUkl,where eijk was the random effect of the jth animal in the ikth treatment by order combination. The effect of the part of irregular spiking activity (ISA) on myoelectric activity, the number of gushes, the volume of gushes, and the digesta flow was tested by dividing each ISA into four equal parts and by using the previous model in which qi indicated the part of the ISA. Electrical activities recorded from one site before and one site after the electromagnetic flow probe were compared using the following model:
where Y indicated the dependent variable. The overall mean was p; aiwas the effect of treatment; @, was the effect of calf; -yk was the effect of the order of the treatment; and ql, the effect of the electrode site. The two error terms were eOkand 8jjkl,where eUkis the random effect of the jth animal in the ikth treatment by order combination. Correlations were made between digesta flow and myoelectric activity (Snedecor and Cochran 1957).
Results Pattern of myoelectrie activity In an attempt to evaluate the effect of the electromagnetic flow probe placed inside the duodenum on the transmission of the electrical activity in the muscle wall, recordings from one site before and one after the flow probe were compared. The total number of MMC was different between the two locations ( p = 0.0006) with approximately two supplementary MMC recorded after the flow probe. The statistical interaction "calf by location of the electrode' ' was also significant ( p = 0.01), meaning that the flow probe affected each animal differently. The number of MMC recorded before and after the flow probe were 6.3 and 10.5, 10.0 and 10.3, 6.8 and 4.5, and 6.8 and 9 .O, respectively, for the four calves used in this experiment. The only disturbance was the presence in some calves of supplementary regular spiking activity (RSA) phases after the flow probe during periods of high spiking activity of ISA phases before the probe. There was no quiescent phase after these RSA; the transmission of spike bursts between the two sites started again after these supplementary RSA phases. This pattern did not change with time after surgery. The difference between the two locations was not affected by the level of milk intake or the order of treatments. Moreover, there was no difference in the total electrical activity recorded at the two locations for the four calves ( p > 0.05). Immediately after feeding, a phase of ISA appeared; the duration and the total electrical activity of the first ISA phase increased linearly with the amount of milk fed ( p = 0.002 and 0.003, respectively: Fig. 1). Duration and total electrical activity of the first regular spiking activity (RSA) and quiescent phases were not affected by the level of milk intake. The amount of milk fed had no marked effect ( g > 0.05) on the second and the third MMC after feeding. Overall, during the 5.6-h recording period after feeding, increasing milk intake from 0.5 to 5.0 kg led to a linear decrease ( p = 0.006) in the number of MMC and linear increases in the duration ( p = 0.003) and total electrical activity ( g = 0.01) of MMC. The augmentation of milk fed led to linear increases in the duration ( p = 0.001) and total electrical activity ( p = 0.002) of ISA
CAN. J. PHYSIOL. PHARMACOL. VOL. 70, 1992
Can. J. Physiol. Pharmacol. Downloaded from www.nrcresearchpress.com by YORK UNIV on 11/11/14 For personal use only.
200
Duration (min)
4000
Total electrical activity
Milk intake (kg)
Milk intake (kg)
FIG. 1. Duration (a) and total electrical activity in arbitrary units (b) of the immediate post-feeding period of irregular spiking activity on the transverse duodenum of four calves according to milk intake. TABLE1. Effect of level of milk intake on the pattern of myoelectl-ic activity recorded at the transverse duodenum of four calves during the first 5.6 h post-feeding (mean +_ SEM) Level of milk intake (kg) 0.5 Number of MMC* Duration of MMC* (rnin) Electrical activity of (AU) Duration of Qt. (min) Electrical activity s f (AU) Duration of ISA* (miin) Electrical activity of (AU) Duration of RSA (mi@ Electrical activity of (AU)
2.0
3.5
5.0
the MMC*
Q
ISA*
RSA
NOTE:AU, arbitrary units; ISA, irregular spiking activity; MMC, migrating myoelectric complex; Q , quiescent phase; RSA, regular spiking activity. *Linear effect of treatments ( p 5 0.05). ?Quadratic effect of treatments ( p 5 0.05).
phases and a quadratic shortening of quiescent phases ( p = 0.02). There was no effect on the duration or total electrical activity of RSA phases ( p > 0.05) (Table 1). Time after surgery and age of calves had no effect on myoelectric activity. There was, however, a significant difference ( p < 0.05) between cdves in the total electrical activity of MMC and ISA phases. Measurements of digesta movement using an electromagnetic flow probe Digesta flow at the transverse duodenum of milk-fed cdves consisted of a series of intermittent gushes of digesta with no flow between these gushes. The mean volume of each gush of
digesta during the first 4 h after feeding was 6.6 mL (SE 0.13) and was not affected by the quantity s f milk ingested. The volume of a gush of digesta was relatively constant: 7.40 mL (SE 0.24), 6.35 mL (SE 0.26), 6.27 mb, (SE O X ) , and 6.28 mb, (SE 0.34) for each of the first 4 h, respectively. However, during the first 4 h post-feeding, there was a cubic increase in the number of gushes ( p = 0.02) and in the totd volume of digesta ( p = 0.089) according to the augmentation of the amount of milk fed (Fig. 2). The amount of digesta entering the transverse duodenum per hour varied during the 4 h after milk intake (quadratic effect, p = 0.04). The interaction treatment by hour being nearly significant ( p = O.OQ), data of digesta flow were analysed
GIBAWD AND SISSONS
(a)
(b)
Gushes of digesta (no.)
Total volume of digesta (mL)
7 I 0 6000
,
1
Can. J. Physiol. Pharmacol. Downloaded from www.nrcresearchpress.com by YORK UNIV on 11/11/14 For personal use only.
eoo 1
V
Y
0.5
3.5
2
6
0.6
2
3.6
6
Milk intake (kg)
Milk intake (kg)
FIG.2. Effect of milk intake on the number of gushes (a) and the total volume of digesta (b) at the transverse duodenum of three milk-fed calves.
0 L-1
L
2
I
3
4
Time after feeding (hours) FIG.3. Cumulative amounts of total digesta entering the transverse duodenum of three calves given 0.5 (a), 2.0 (01, 3.5 ( x), and 5.0 kg ( A ) of milk.
In all treatments there was a positive correlation between the total electrical activity of ISA phases and the number of gushes of digesta during the first 4 h post-feeding ( p = 0.004, "r 0.41). During the immediate post-feeding period of ISA, the volume of digesta was positively correlated to the duration of 0.98) and showed a tendency this period ( p = 0.0001, "r to be correlated to the total electrical activity ( p = 0.08, "r 0.52). The number of gushes of digesta was also positively correlated to the total electrical activity recorded during this period ( p = 0.02, "r 0.64). ISA phases were divided into four q u d parts to observe the effects of the proximity of a RSA on digesta flow and myoelectric activity. Myoelectric activity, the number of gushes, the mean volume of a gush, and the total volume of digesta were not different ( p > 0.05) between each part of an ISA. Similarly, myoelectric activity, the number of gushes, and the volume of digesta calculated per unit of time (min) did not differ ( p > 0.05) between each part of the ISA.
Discussion separately for each hour. During the first, third, and fourth hours after feeding, digesta flow increased (cubic effect, p = 0,004) with the amount of milk ingested (Table 2). However, there was no effect ( p > 0.05) of treatments on digesta flow during the second hour. Cumulative amounts of digesta entering the transverse duodenum increased linearly (p = 0.000 1) during the 4 h after milk intake. However, as shown in Fig. 3, the slopes differed slightly according to the level of milk ingested (interaction treatment by hour, p = 0.005). Relation between digesta flow and myoelectric activity in transverse duodenum wall There were intermittent flows of digesta during ISA phases. Little or no digesta flow was detected by the probe during quiescent phases. Some backward and forward flows were detected during RSA phases but summation of the flows were always near zero (Fig. 4). Each gush of digesta during ISA phases corresponded to a spike burst recorded on electrodes placed before the flow probe and generally transmitted on electrodes placed after the flow probe.
Methohlogy In previous experiments, electromagnetic flow probes were placed in reentrant cannulas (Poncet et al. 1977; Poncet and Ivan 1984) or around the intestine (Dardillat 1977; Sissons 1983; Poncet and Ivan 1984). In a study with sheep comparing the effects of different devices for measuring digesta flow in the ascending duodenum, Poncet and Ivan (1984) found that disturbances of myoelectric activity seem to be related to the length of duodenum occupied by the cannula or the electromagnetic flow probe. Electromagnetic flow probe placed around the ascending duodenum of sheep (Poncet and Ivan 1984) or the transverse duodenum of the preminant calf (Dardillat 1977) did not modify propagation of spike burst or migration of RSA phases. However, in a preliminary study, recordings from a flow probe placed around the intestine were not satisfactory. Some "fibrinous" tissues grew between the probe and the intestine, decreasing sensitivity of the probe and partially blocking the intestine. This obstruction increased with time and slowed down the digesta flow leading to an accumulation of digesta
Can. J. Physiol. Pharmacol. Downloaded from www.nrcresearchpress.com by YORK UNIV on 11/11/14 For personal use only.
CAN. J. PHYSIOL. PHARMACOL. VOL. 70, 1992
FIG. 4. Myoelectric activity and digesta flow during regular spiking activity, quiescent, and irregular spiking activity phases recorded in the transverse duodenum of a calf given 2.0 kg milk. Recordings show measurements of digesta flow (c) and myoelectric activity from electrodes implanted 5.0 cm (a) and 2.5 crn (6) before and 2.5 cm (d) after the flow probe. TABLE2. Rates of digesta flow (mLIh) in the transverse duodenum of three calves at different times after feeding 0.5 -5.0 kg milk (mean f SEM) Period after feeding (h)
Amount s f milk fed (kg)
8.5
2.0
3.5
5.0
*Cubic effect sf treatments ( p 5 0.004).
and a dilation of the intestine before the flow probe. At this time, large disturbances in the transmission of electricd activity before and after the flow probe appeared (C. L. Girard and J. W. Sissons, unpublished data). Subsequently, the flow probe was placed inside the transverse duodenum of milk-fed calves to avoid these problems. These surgical procedures maintained the integrity of the intestine. Moreover, in the present experiment, as the flow probe occupied only a short length of intestine, approximately 1 cm, disturbances of myoelectric activity were reduced as previously reported by Boncet and Ivan (1984). Myoelectric activity in the transverse duodenum As reported by many authors, the pattern of myoelectric activity at the transverse duodenum of milk-fed calf was an alternation of ISA, RSA, and quiescent phases, interrupted by an ISA phase provoked by anticipation of the meal and ingestion of milk (Ruckebusch et al. 1972; Dardillat 1977; Sissons 1983). The results of the present experiment are similar to those obtained from sheep in which augmentation of feed intake decreases the number of MMC per 24 h, and increases the duration of ISA at the expense of the duration of the quiescent phases while the RSA phases remain unchanged (Bubno 1977; BuCno et al. 1977). However, these results are different from those observed in the preruminant calf, in which an augmentation of the amount of milk ingested increases the duration of the immediate post-feeding period of ISA but decreases the duration of the first RSA phase (Sissons 1983). As previously reported by Sissons and Smith (1979) for
milk-fed calves aged 6-20 weeks, there was no effect of age on the pattern of MMC. Digesta flow in transverse duodenum The volume of gushes was constant and not affected by animal, age of animal, volume of meal, or time after feeding. This is in agreement with Dardillat (1977) who observed gushes of digesta varying from 4 to 10 mL in the transverse duodenum of the preruminant calf. Sissons and Smith (1979) also reported that milk intake ranging from 2 to $ kg had no effect on volume of gushes in the transverse duodenum. The cubic effects observed on the number of gushes and the total volume of digesta implied that digesta flow increased with the amount of liquid consumed. Moreover, gastric emptying was accelerated by an augmentation of milk intake, which agrees with results reported by Bell and Weber (1981) and Sissons (1983). Digesta flow at the transverse dudenum was accelerated during the first hour post-feeding and returned gradually to the pre-feeding value (quadratic effect) as reported by Mylrea (1966), Dardillat (1977), and Sissons (1983). Bre-feeding digesh flow in the duodenum varies between 280 mL/h (Mylrea 1966) and 280 mL/h (Sissons 1983). With a milk intake of 0.5 kg, the rate of digesta flow had already returned to similar values in the second hour post-feeding. Rates of digesta flow for the different milk intakes in this experiment were slightly inferior to those observed by Sissons (1983) but close to those calculated from Mylrea (1966). Calves at the end of the experimentd period were approxi-
GIRARD AND SISSONS
Can. J. Physiol. Pharmacol. Downloaded from www.nrcresearchpress.com by YORK UNIV on 11/11/14 For personal use only.
mtely 2 or 3 weeks older than at the beginning, as a result of the experimental design used. However, no effect of the order of treatment on the volume of digesta flow was observed, which confirms that volume of endogenous secretions does not change with age (Ternouth et d. 1976; Sissons and Smith 1982).
Relation befiveen digests flow and myoele~tr-i~ activity a? the transverse duodenum Digesta flow at the transverse duodenum was recorded only during ISA phases and was always related to the presence of a spike burst in the duodenal wd1 proximal to the flow probe, as reported by other authors for the premminant calf (Dardillat 1977; Sissons 1983), sheep (Poncet et al. 198I), dog (Summers and Dusdieker 1981), and pig (Rayner and Wenham 1986). Backward and forward flows observed during RSA phases were probably attributable to oscillations of digesta trapped inside the probe; the probe was a rigid area without contraction in a zone affected by strong contractions during the passage of the RSA phase. Digesta flow is related to the presence s f spike bursts during ISA phases; therefore, it is not surprising to obtain a correlation between total electrical activity during ISA phases, particularly the first one post-feeding, and the number of gushes and total volume of digesta. A similar relation between frequency of contractions and transit time was found in the jejunum s f dogs (Schemann and Erldein B 986). Dardillat (1977) observed that the rate of digesta flow in the duodenum increases progressively during the ISA phase. According to this author, this phenomenon is more evident in the jejunum where digesta flow increases markedly before RSA phase. This disagrees with the present results, in which there was no difference for myoelectric activity, digesta Wow, the number of gushes, and the mean volume of a gush between the different parts of an HSA phase. In conclusion, an augmentation in the amount of milk fed increased duration and total electrical activity of ISA phases at the expense of the duration s f the quiescent periods. This increased activity s f ISA phases led to an augmentation of digesta flow and an acceleration of abomasd emptying. This suggests that with an increased intake sf liquid feed, the duodenum, via a change in the myoelectric pattern, endeavoured to accelerate the flow of digesta in an attempt to return the abomasum to an 'empty statey9in about the same time for a11 levels of milk consumed. Agriculture Canada. 1998. Code de prratique pour le soin et la manipulation des bovins laitiers. Agriculture Canada publ. no. 1853/F. Ottawa. Bell, F. R., and Webber, B. E. 1981. The change in the volume of the periodic antral gush when the stomach is maintained at different constant volumes. S. Bhysiol. (London), 319: 47 -48. BuCno, L. 1977. Complexe myoklectrique de 19intestingrele et variations de l'apport alimentaire chez le mouton. C.R. SCances Soc. Biol, Toulouse, 171: 959 -964.
1147
BuCno, %. , Fioramonti, J ., and Ruckebusch, Y. 2 977. Mechanisms of propulsion in the small intestine. Ann. Rech. Vet. 8: 293 -301. Canadian Council on Animal Care. 1980. Guide to the care and use sf experimental animals. Vol. 1. Canadian Council on Animal Care. Ottawa, Canada. Cochran, W. G., and Cox, 6. M. 1950. Experimental designs. 2nd ed. John Wiley & Sons Hnc., New York. Dardillat, C. 1977. Analyse Clectromyographique et dtbitmktrique du transit alimentaire chez le veau nouveau-nC. J. Physiol. (Paris), 73: 925-944. Mylrea, P. J. 2966. Digestion of milk in young calves. 1. Flow and acidity of the contents of the small intestine. Res. Vet. Sci. 7: 333-341. Poncet, C., and Ivan. M. 1984. Effect of duodena1 cannulation in sheep on the pattern of gastroduodenal electrical activity and digestive flow. Reprod. Nutr. Dev. 24: 887 -902. Poncet, C., Dimova, E., UveillC, M., and Dardillat, C. 1977. Mise au point d'une mtthode d'enregistrement chronique du dCbit duodCnal chez 1e mouton: exemple d9application. Ann. Biol. Anim. Biochem. Biophys. 17: 5 15-522. Poncet, C., Ivan, M., and LkveillC, M. 1981. Electromagnetic measurements of duodena1 digesta flow in cannulated sheep. Reprod. Nutr. Dev. 22: 97-186. Rayner, V., and Wenham, G. 1986. Small intestinal motility and transit by electromyography and radiology in the fasted and fed pig. J. BhysioB. (London), 379: 245 -256. Roy, J. H. B., Shillam, K. W. G., Hawkins, G. M., and Eang, J. M. 1958. The milk requirements of the newborn calf. Br. J. Nutr. 12: 123-137. Ruckebusch, Y. 1970. The electrical activity of the digestive tract of the sheep as an indication of the mechanical events in various regions. J. Physiol. (London), 210: 857 - 882. Ruckebusch, Y., Dardillat, C., and Hatey , F. 1972. MotricitC intestinale chez le veau nouveau-nC: influence du repas. C.R. Seances SOC.Biol. Toulouse, 166: 1547- 1551. Schemann, M . , and Ehrlein, M. J. 1986. Postprandial patterns of canine jejunal motility and transit of luminal content. Gastroenterology, 90: 99 1- 1000. Sissons, I. W. 1983. Effect of feed intake on digesta flow and myselectric activity in the gastrointestinal tract of the premminant calf. J . Dairy Res. 50: 387 -395. Sissons, J. W., and Smith, R. H. 1979. Digesta movement and gut motility in the premminant calf- Ann. Rech. Vet. 10: 176- 178. Sissons, 9. W., and Smith, R. M. 1982. Effect of duodenal cannulation on abomasal emptying and secretion in the premminant calf. I. Physiol. (London), 322: 409 -4 17. Snedecor, G. W., and Cwhran, W. 6 . 1957. Methodes statistiques. 6th ed. Association de la coordination technique agricole, Paris. Statistical Analysis System. 1985. SAS User's Guide. Statistical Analysis System Institute Inc., C a q , NC. Summers, W. W., and Budieker, N. S. 1981. Patterns of spike burst spread and flow in the canine small intestine. ~ a s t r o e n t e r o l o ~ ~ , $1: 742-750. Ternouth, J. H., Roy, J. H. B., and Shotton, S. M. 1976. Concurrent studies of the flow of digesta in the duodenum and exocrine pancreatic secretion of calves. 4. The effect of age. Br. J. Nutr. 36: 523 -535.
