1738 Effects of Intrruminl Sliv Flow on Feed Intke in Gots Fed on Alflf Hy Cues Ktsunori Sungw*, Yoshifumi Nktsu, Yoriko Nishikuo, Tkeshi Ooshiro, Kout Nitou nd Itsuki Ngmine Fculty of Agriculture, University of the Ryukyus, 1 Senru, Nishihr-cho, Okinw 903-0213, Jpn ABSTRACT : Reserch ws crried out to scertin whether or not the volume of sliv flowing into the rumen regultes dry forge intke in ruminnts. Gots with protid fistul were fed roughly crushed lflf hy cues, concentrted eef cttle feed nd NHCO 3 twice dily (10:00-12:00, 16:00-18:00). Except for the dys on which experiments were conducted, the nimls were free ccess to drinking wter. The nimls were intrruminlly infused every dy prior to the morning feeding period with protid sliv collected from the protid fistul over 24 h period. The present experiment consisted of three tretments, non-infusion (NI), intrruminl infusion of protid sliv (RSI), nd intrruminl infusion of wrm wter (RWI). In the RSI tretment, pproximtely 4-5 kg of protid sliv (280-290 mosm/l) collected over 24 h period ws intrruminlly infused 1 h prior to the commencement of morning feeding. In the RWI tretment, protid sliv ws sustituted for wrm wter (36 C). After infusions, the nimls were fed on roughly crushed lflf hy cues for 2 h. During feeding, eting nd sliv secretion rtes were mesured. Blood smples were lso periodiclly collected from the jugulr vein. After 2 h feeding, wter intke ws mesured for 30 min. These mesurements were used to define thirst levels. On the dy of the experiment, the nimls were not ccess to drinking wter during the morning feeding. It is thought tht rumen fill in RSI nd RWI tretments ws higher thn the NI tretment. In comprison with the NI tretment however, cumultive feed intke incresed y 39.3% with RSI tretment nd y 45.9% with RWI tretment fter completion of the 2 h feeding period. After 2 h feeding, thirst level in the RSI tretment showed only 10% decrese compred to the NI tretment, ut thirst level in the RWI tretment decresed 49.8%. Despite the significnt differences in thirst levels etween RSI nd RWI tretments, the cumultive feed intke in oth tretments ws similr. When compring ccumulted sliv secretion volumes 2 h fter feeding, volumes in the RSI tretment were significntly 35.9% lower thn the NI tretment while volumes in the RWI tretment were unchnged. However, the volumes of sliv nd fluid flowing into the rumen were greter in oth RSI nd RWI tretments when compred to the NI tretment. The results indicte tht the mount of sliv flowing into the rumen is fctor regulting feed intke in ruminnts fed on dry forge. (Asin-Aust. J. Anim. Sci. 2002. Vol 15, No. 12 : 1738-1746) Key Words : Intrruminl Sliv Flow, Dry Forge Intke, Gots INTRODUCTION In countries such s Jpn, ruminnts re frequently offered dry feed to rise productivity. Sliv in sheep is secreted in lrge volumes during the first hour fter the commencement of dry forge feeding (Sto, 1975). Sliv cts s luricnt in the mouth nd esophgus, nd ssists in the mstiction, remstiction, swllowing nd reswllowing of dry forge. Sliv lso cts s n lkline nd serves to uffer the decrese in the ph of ruminl fluid due to the voltile ftty cid production of microil fermenttion in the rumen. In this wy, sliv plys n importnt role in eting nd homeosttic regultion of the cid-se lnce in ruminl fluid. In sheep fed on dry forge, lrge volumes of sliv re secreted in the erly stges of feeding. However, secretion volumes shrply declined following these erly stges irrespective of continued feeding. Prsetiyono et l. (2000) nd Sungw et l. (2001) reported tht feed intke rtes in gots fed lflf hy cues once nd twice dy * Corresponding Author: Ktsunori Sungw. Tel: +81-98-895-8798, Fx: +81-98-895-8734, E-mil: 986094@gr.u-ryukyu. c.jp Received Mrch 22, 2002; Accepted August 20, 2002 respectively decresed shrply 30 min following the strt of feeding. Silnikove nd Tdmor (1989) reported tht in cows deprived of wter for long periods of time there ws positive reltionship etween sliv secretion rtes nd whet hy intke. Sungw et l. (2002) reported tht despite eing free ccess to wter nd slt vi pedl press system, sheep with protid fistul consumed sustntilly less lflf chff thn sheep without protid fistul. It is therefore thought tht sliv secretion volume is regulting fctor in dry forge intke. Until now, experiments investigting the physiologicl reltionship etween sliv secretion volume nd dry forge intke hve not een conducted. In the present experiment, the nimls were prepred with protid fistul. Sliv from the fistul ws collected nd infused into the rumen once ech dy prior to morning feeding. This experiment ws conducted to clrify whether dry forge intke is regulted y the mount of sliv flowing into the rumen. MATERIALS AND METHODS Animls Five gots (1 Jpnese Snen got, ged 4 yers,
INTRARUMINAL SALIVA FLOW AND FEED INTAKE 1739 weighing 72.5 kg; 4 crossred Jpnese Snen/Nuin gots, ged 3-5 yers, weighing 72, 83, 90, 97 kg) were used in this experiment. In order to collect protid sliv, the pertur of one of the protid ducts ws surgiclly prepred to exteriorize it vi the cheek of the niml more thn 6 months prior to experimenttion. An Atom Disposle Multiple Purposes Tue (o.d. 2.75 mm, 8 Fr, Atom, Tokyo) pproximtely 10 cm in length or depending on the niml, fluid infusion tue (o.d. 4.00 mm, Terumo, Tokyo) ws inserted into the protid duct nd fixed to the cheek. Furthermore, to enle the return of sliv collected from the protid fistul, n extension tue (X3-25, Top, Tokyo) ws inserted into the dorsl sc of the rumen. The other end of the tue ws fixed to the skin. Protid sliv flowing from the protid fistul ws collected in plstic ucket. The sheep were mintined in metolism cges tht llowed for the seprte collection of urine, feces nd sliv. The nimls were fed twice dy t 10:00 m nd gin t 4:00 pm for 2 h ech time. Prior to the morning feeding, the collected sliv (3-5 kg) ws infused into the rumen vi the extension tue using th tu pump (Minipondy, KP- 30F, Koshin, Tokyo). Following this, 2-3 kg of roughly crushed lflf hy cues, 20 g of NHCO 3 nd 200 g of commercil eef cttle concentrte feed were fed to the nimls for 2 h. Animls were free ccess to wter throughout the dy. The lflf hy cues (84.3% dry mtter) contined, on dry mtter sis, 18.7% crude protein, 2.4% crude ft, 29.7% crude fier, 39.7% nitrogen free extrcts (NFE), 45.9% NDF nd 36.6% ADF. The concentrted eef cttle feed (86.9% dry mtter) contined, on dry mtter sis, 13.4 % crude protein, 3.6% crude ft, 71.0% nitrogen free extrcts (NFE), 14.6% NDF nd 5.4% ADF. Experiment The experiment ws crried out in lortory with room temperture of 24-26 C nd reltive humidity of 74-84%. This experiment investigted the effect of intrruminl infusion of protid sliv or wrm wter (36 C) on cumultive feed intke nd eting rtes. The control tretment monitored cumultive feed intke nd eting rtes in the sence of infusion. Animls were deprived of wter during feeding on the dy of the experiment. Tretments in this experiment were crried out in order, eginning with the no infusion control (NI) followed y the protid sliv infusion tretment (RSI) nd concluding with the wrm wter infusion tretment (RWI). The tretments were crried out on 2-3 nimls t one week intervls to ensure tht nimls recovered nd to minimize the compounding effects of the previous tretments. Respirtion frequency, hert rte nd rectl temperture were mesured everydy prior to the morning feeding period. The vlues of these physiologicl prmeters indicted whether n individul ws in good helth nd hd no mesurle crry-over effects from the previous tretments. In order to tke lood smples during the course of the experiment, polyethylene tue (o.d. 1.5 mm, No. 5, Immur Gomu, Tokyo) ws inserted into the jugulr vein of the nimls on the dy prior to the commencement of experimenttion. This tue ws fixed in plce nd filled with heprin-sline solution (50 i.u./ml) to prevent cogultion of the lood. On the dy of the experiment, depending on the niml either n extension tue (o.d. 2.0 mm, X-1, Top, Tokyo) or polyethylene tue (o.d. 2.2 mm, No. 7, Immur Gomu, Tokyo) ws connected to the tue inserted into the protid fistul. From the open end of the tue, protid sliv ws collected in grduted mesuring cylinder (100 ml). On the dys of oth the RSI tretment nd the RWI tretment, 4.0-5.0 kg of sliv or wrm wter (36 C) respectively ws infused into the rumen using th tu pump (Minipondy, KP-30F, Koshinsh) 1 h prior to the commencement of the morning feeding period. The infusion volume for nimls weighing 72.5, 83.0, 90.0 nd 97.0 kg ws 5.0 kg, while the niml weighing 72.0 kg ws infused with 4.0 kg. Feeding ws egun t 10:30 m nd the nimls were fed roughly crushed lflf hy cues for 2 h. Eting rtes were determined using mesuring scle. The lflf hy cues (2.0-3.0 kg) were plced in feed ox ttched to 6 kg mesuring scle. The weight of the remining feed ws mesured every 10 min for the durtion of the 2 h feeding period. The rte of sliv secretion ws mesured in grduted cylinder. Mesurements egn 10 min prior to feeding commencement, continued every 10 min during the durtion of the feeding period nd concluded with the lst mesurement eing tken t the end of the 2 h feeding period. To mesure the osmollity of sliv, smple of the collected protid sliv ws tken. This smple ws plced in test tue nd refrigerted until mesuring. Thirst level (g/30 min) in this experiment ws defined s the wter intke for 30 min upon completion of 2 h of feeding. A totl of 10 lood smples were tken, 2 ech prior to nd fter the feeding period, nd 6 during feeding fter 10, 30, 45, 60, 90, 120 min hd elpsed. Blood smples (5 ml ech) were tken from the jugulr vein. Smples were collected in heprinized tues to prevent cogultion nd were susequently refrigerted. Blood plsm ws otined y centrifugtion (16,260 g, 10 min, 5 C). Biochemicl nlysis Sliv osmollity ws mesured ccording to the principle of freezing-point method using n osmometer (Model OM-6010, Kyoto Diichi Kgku, Kyoto). Blood smples were plced in hemtocrit cpillry tues nd centrifuged using hemtocrit centrifuge (HC-12 A, Tomy
1740 SUNAGAWA ET AL. Seiko, Tokyo, 16,260 g 5 min) to seprte plsm nd red lood corpuscle. Hemtocrit ws determined y hemtocrit reder. Plsm protein nd osmollity were mesured y refrctometer (Atgo, Tokyo) nd y n osmometer, respectively. Sttisticl nlysis The experiments in this reserch were conducted ccording to switchck design. A two-wy nlysis (niml, tretment) of vrince ws performed. Following tht Duncn's Multiple Rnge Tests were used to compre tretments. For sttisticl nlysis, GLM procedures (SAS, 1990) were dopted. Dt re presented s men±sd of five sheep. RESULT Physiologicl responses The men vlues of respirtion frequency, hert rte nd rectl temperture efore infusion in the three tretments were 26±3.9 reths/min, 83±9.5 ets/min nd 38.8±0.18 C respectively. The rte of eting nd cumultive feed intke Figure 1 shows the effect of intrruminl infusion of protid sliv or wrm wter on rte of eting nd cumultive feed intke. Eting rtes in the NI tretment rpidly decresed in the first 40 min of feeding (0 to 10 min 435 g/10 min, 30 to 40 min 79 g/10 min). However, eting rtes in the RSI nd RWI tretments slowly decresed for the first 60 min. Eting rtes in the RSI nd RWI tretments during the first 60 min of feeding were lrger thn those in the NI tretment. Eting rtes etween the RSI nd RWI tretments were not different ech other. After 60 min of the feeding period hd elpsed, there were no significnt differences mong three tretments. In comprison with the NI tretment (1,100± 544.1 g/2 h), cumultive feed intkes in RSI nd RWI tretments were 39.3% (1,532±648.5 g/2 h) nd 45.9 % (1,605 621.7 g/2 h) lrger upon conclusion of the 2 h feeding period. Thirst level Figure 2 shows the effect of intrruminl infusion of protid sliv or wrm wter on thirst level. Thirst level in the RSI tretment (5,760±1,553 g/30 min) showed only 10 % decrese nd ws not significntly different from the level in the NI tretment (6,400±2,618 g/30 min). Thirst level (3,210±1,111 g/30 min) in the RWI tretment ws, on the other hnd, significnt 49.8% lower thn the NI tretment level. Plsm osmollity, plsm totl protein concentrtion nd hemtocrit Figure 3 shows the effect of intrruminl infusion of protid sliv or wrm wter on plsm osmollity, plsm totl protein concentrtion nd hemtocrit in the lood smpled t 60 min efore feeding nd 0, 15, 30, 45, 60, 90, 120, 150, nd 165 min fter feeding ws commenced. Plsm osmollity grdully incresed in ll three tretments over the course of the 2 h feeding period. In comprison with the NI tretment, plsm osmollity in the RSI tretment ws significntly (p<0.05) higher throughout the entire period. On the other hnd, plsm osmollity in the RWI tretment ws not significntly different from the NI tretment during the 2 h feeding period. In ll three tretments, plsm totl protein concentrtions prior to feeding (NI: 6.9±0.52, RSI: 7.0±0.52, RWI: 7.7±1.15 g/dl) hd incresed 15 mins fter the commencement of feeding (NI: 7.8±0.58, RSI: 7.7±0.74, RWI: 8.1±1.12 g/dl). However, plsm totl protein concentrtions grdully decresed in ll tretments for the reminder of the feeding period. Plsm totl protein concentrtion in the NI tretment 1 h prior to the commencement of feeding (6.9±0.52 g/dl), nd immeditely prior to feeding (7.0±0.47 g/dl), were not significntly different. On the other hnd, due to infusion, plsm totl protein concentrtions in RSI nd RWI tretments decresed over the sme period from 7.0±0.52, 7.7±1.15 g/dl to 6.8±0.56, 7.3±1.01 g/dl respectively. Plsm totl protein concentrtions in the RSI tretment were lower thn oth NI nd RWI tretments 30 min fter feeding. There were no significnt differences etween the NI nd RWI tretments during feeding. In ll three tretments, hemtocrit immeditely prior to feeding (NI: 27.1±1.55, RSI: 26.9±1.14, RWI: 29.4±3.91%) hd incresed 15 min fter the commencement of feeding (NI: 32.2±3.44, RSI: 32.0±1.58, RWI: 35.6±4.39%). However, hemocrit grdully decresed in ll three tretments for the reminder of the feeding period. Hemtocrit in the RSI tretment were lower thn oth NI nd RWI tretments 60 min fter feeding. There were no significnt differences etween the NI nd RWI tretments during feeding. Rte of sliv secretion nd cumultive sliv secretion Figure 4 shows the effect of intrruminl infusion of protid sliv or wrm wter on the rte of sliv secretion nd cumultive sliv secretion. The rtes of sliv secretion in ll three tretments peked for the first 10 min fter feeding ws commenced (NI: 135±33.1, RSI: 133±13.6, RWI: 150±20.7 ml/10 min). In comprison with the NI tretment, the rtes of protid sliv secretion in the RSI tretment were significntly (p<0.05) lower throughout
INTRARUMINAL SALIVA FLOW AND FEED INTAKE 1741 Rte of eting (g DM/10 min) 600 500 400 300 200 100 NI RSI RWI 0 10 20 30 40 50 60 70 80 90 100 110 120 Cumultive feed intke (gdm) 1,800 1,600 1,400 1,200 1,000 800 600 400 200 0 10 20 30 40 50 60 70 80 90 100 110 120 Time fter feeding (min) Figure 1. The effect of intrruminl infusion of protid sliv (RSI) or wrm wter (RWI) on rte of eting nd cumultive feed intke., Mens with different superscripts re from no infusion tretment (NI, p<0.05). the entire period of feeding. On the other hnd, the rtes of sliv secretion in the RWI tretment were significntly (p<0.05) lower thn those in the NI tretment during the erly stge of feeding. Cumultive sliv secretion volumes upon conclusion of the 2 h feeding period were 828±131.7, 531±73.9, 811±86.4 ml/2 h in NI, RSI nd RWI tretments, respectively. Cumultive sliv secretion volume in the RSI tretment showed significnt 35.9% decrese when compred to the NI tretment. However, there ws no significnt difference etween the RWI nd NI tretments. Sliv osmollity Figure 5 shows the effect of intrruminl infusion of protid sliv or wrm wter on sliv osmollity. Protid sliv osmollity incresed fter feeding in ll three tretments. Sliv osmollity in the RSI tretment ws significntly higher thn tht in the NI tretment t 20, 100, 110 nd 120 min fter feeding. On the other hnd, sliv osmollity in the RWI tretment prior to, during nd fter feeding ws not significntly different from tht in the NI tretment.
1742 SUNAGAWA ET AL. Thirstlevel (g/30 min) 10,000 9,000 8,000 7,000 6,000 5,000 4,000 3,000 2,000 NI RSI RWI Figure 2. The effect of intrruminl infusion of protid sliv (RSI) or wrm wter (RWI) on thirst level., Mens with different superscripts re from no infusion tretment (NI, p<0.05). DISCUSSION Preliminry experiments were conducted 2 months prior to the present experiment. In the preliminry experiments, nimls were rised using two methods. The first method sw the infusion of protid sliv collected from the protid fistul into the rumen. In the second method, collected sliv ws not infused. Under these conditions, numer of different prmeters were mesured. The results were tht sliv secretion from the unilterl protid fistul nd feed intke during the morning 2 h feeding period in the infusion tretment (828±131.7 ml/2 h; 1,100±544.1 g/2 h) were significntly greter compred to the non infusion tretment wherey sliv secretion ws 399±50.7 ml/2 h nd feed intke ws 489 185.0 g/2 h. The feed intke in gots with protid fistul tht were intrruminlly infused with sliv,ws similr to pre-fistultion vlues (929 81.8 g/ 2 h) (Sungw et l., 2002). Sungw et l. (2002) reported tht in n experiment using pedl press system for the delivery of wter nd slt, feed intke of lflf chff in non-fistulted sheep ws significntly greter thn nonintrruminlly infused fistulted sheep. Therefore, it is thought tht the internl environment of nimls mintined with dily infusion of protid sliv in the present experiment ws similr to non-fistulted nimls. In the period 30-60 min fter feeding, sliv secretion rtes in the NI tretment declined mrkedly. During this sme period of time, eting rtes lso showed significnt decrese (Figure 1, 4). During ctul eting nd rumintion, sliv secretion rtes incresed significntly. Sliv secretion rtes in the NI tretment peked immeditely following the strt of feeding, ut then susequently declined reching prefeeding levels 60 min fter feeding hd commenced. This return to pre-feeding secretion rtes t the 60 min mrk of the feeding period coincided with the lowest eting rtes. These results suggest the existence of physiologicl control mechnism etween feed intke of hy nd sliv secretion volumes. When protid fistulted sheep, fed once dy with pproximtely 2 kg of lflf hy cues nd 50 g of NHCO 3, were intrruminlly infused with pproximtely 3 l of wrm wter, plsm osmollity did not incese with feeding (Sto, 1975). Additionlly, the mrked suppression of sliv secretion tht occurs with norml feeding conditions ws not induced. From this result, it is thought tht post-feeding sliv secretion suppression is cused y n increse in plsm osmollity with feeding. When n mount of wrm wter, equl to tht of the volume of sliv collected from the protid fistul in the course of one dy, ws infused into the rumen, similr to the NI tretment, little or no chnge ws oserved in plsm osmollity up until the 45 min mrk. Sliv secretion rtes tht coincided with feeding slowly decresed in oth NI nd RWI tretments. In the RWI tretment, despite there eing no significnt difference in plsm osmollity, sliv secretion rtes from 10-40 min fter feeding were significntly lower (Figure 3, 4). It is thought tht protid sliv secretion rtes were suppressed s the degree of ruminl fill incresed. In this experiment, when protid sliv collected from the unilterl protid fistul 1 h prior to the morning feeding period (280-290 mosm/l) ws infused into the rumen, s ws the cse with norml feeding, plsm osmollity incresed with feeding (Sungw et l., 2001). Except for the 10 min following the strt of the feeding period, sliv secretion rtes in RSI were suppressed continuously for 2 h of feeding. Sto (1975), Wrner nd Stcy (1977) reported tht there is negtive correltion etween sliv secretion rtes, ruminl fluid osmollity nd plsm osmollity. From these reports, it is thought tht the significnt decrese in protid sliv secretion tht occurred fter 20 min of the feeding period hd elpsed in the RSI tretment ws, in ddition to ruminl fill increses, due to increses in plsm osmollity during feeding tht were rought out y intrruminl infusion of sliv. It ws reported tht the feed intke of lflf pellets ws regulted y chnges in ruminl fluid osmollity (Bile et l., 1969; Kto et l., 1979; Grovum, 1995). The sme sized dose of hyperosmotic NCl, polyethylene glycol-400 (PEG), sodium cette or sodium propionte produced the sme increses in rumen fluid osmollity when intrruminlly infused. These increses in rumen fluid osmollity resulted in the sme sized decrese in feed intke (Grovum, 1995). On the other hnd, when the rumen fluid osmollity ws
INTRARUMINAL SALIVA FLOW AND FEED INTAKE 1743 Plsmosmollity (mosm/l) Plsm totl protein (g/dl) 325 320 315 310 305 300 295 290 285 280 275 270 9 8 7 6 NI RSI RWI -60 0 15 30 45 60 90 120 150 165 Hemtocrit (%) 5 38 36 34 32 30 28 26 24 22 20-60 0 15 30 45 60 90 120 150 165-60 0 15 30 45 60 90 120 150 165 Time fter feeding (min) Infusion Feeding Drinking Figure 3. The effect of intrruminl infusion of protid sliv (RSI) or wrm wter (RWI) on plsm osmollity, plsm totl protein concentrtion nd hemtocrit., Mens with different superscripts re from no infusion tretment (NI, p<0.05). decresed y the intrruminl infusion of n excessive mount of wrm wter (39.8 C) in sheep fed on concentrted feed, feed intke incresed y pproximtely 30% (Kto et l., 1979). It hs een thought tht the chnges in ruminl fluid osmollity were sensed y the osmoreceptors in the rumen wll nd these signls were then trnsported into the centrl nervous system (Leek nd Hrding, 1975). However, the effect of internl humorl fctors on the intke of grss hs not een investigted under these experimentl conditions. Kto (1977) compred feeding times nd feed intke in sheep with n esophgus fistul under norml feeding nd shrm feeding conditions. The nimls were fed fresh grss, hy nd concentrted feed. The result of this comprtive
1744 SUNAGAWA ET AL. 160 140 NI RSI RWI Rte of sliv secretion (ml/10 min) 120 100 80 60 40 20 0-10 10 20 30 40 50 60 70 80 90 100 110 120 Cumultive sliv secretion (ml) 900 800 700 600 500 400 300 200 100 0-10 10 20 30 40 50 60 70 80 90 100 110 120 Time fter feeding (min) Figure 4. The effect of intrruminl infusion of protid sliv (RSI) or wrm wter (RWI) on rte of sliv secretion nd cumultive sliv secretion., Mens with different superscripts re from no infusion tretment (NI, p<0.05). reserch ws tendency for oth feeding times nd feed intke to increse when fed fresh grss nd hy. This difference however, ws not significnt. This result suggests tht despite the consumed feed not entering the rumen, some extrruminl mechnism exists to suppress the feeding ehvior. In the present experiment, in comprison with the NI tretment, plsm osmollity in the RWI nd RSI tretments ws unchnged nd higher respectively. In the first hlf of the 2 h feeding period, eting rtes nd cumultive feed intke in oth tretments were significntly greter thn those oserved in the NI tretment. In the first hour of feeding, the RSI nd NI vlues for plsm totl protein concentrtion nd hemtocrit were pproximtely equl. However, thirst level in the RSI tretment t the conclusion of feeding ws 10.0% lower thn tht recorded in the NI tretment. Thirst level in the RWI tretment ws
INTRARUMINAL SALIVA FLOW AND FEED INTAKE 1745 Sliv osmollity (mosmol/l) 305 300 295 290 285 280 275 NI RSI RWI 270 265-10 10 20 30 40 50 60 70 80 90 100 110 120 oserved to e 49.8% lower (Figure 2, 3). These results were induced y increses in the volume of fluid flowing into the rumen. It is thought tht rumen fill in RSI nd RWI tretments ws higher thn NI tretment. In comprison with NI tretment however, cumultive feeding mounts were 39.3, 45.9% higher in RSI nd RWI tretments respectively. Sungw et l. (2001) intrvenously infused gots fed lflf hy cues twice dy with mixed rtificil sliv, hypo-osmotic mnnitol solution, nd n iso-osmotic mnnitol solution on different dys. The infusions were conducted from 1 h prior to feeding nd continued until 1 h of the 2 h feeding period hd elpsed. This infusion supplements the fluids in the lood lost through ccelerted sliv secretion during the erly stges of dry forge feeding. It ws reported tht thirst levels decresed pproximtely 13% while ccumulted feed intke incresed with infusions of mixed sliv (41%), hypo-osmotic mnnitol solution (45%) nd iso-osmotic mnnitol solution (43%). From these results, it is thought tht the suppression of feed intke of dry forge in gots is not simply result of rumen fill ut lso the thirst tht is rought out y the ccelerted secretion of sliv in the initil stges of feeding. Moreover, despite the significnt differences in thirst levels etween RSI nd RWI tretments, the feed intke in oth tretments ws similr. The reson for this is thought to e tht sliv consists of not only wter ut lso ppetite enhncing sustnces. The results of this experiment indicted tht dry forge intke is regulted y the mount of sliv flowing into the rumen. Time fter feeding (min) Figure 5. The effect of intrruminl infusion of protid sliv (RSI) or wrm wter (RWI) on sliv osmollity., Mens with different superscripts re from no infusion tretment (NI, p<0.05). ACKNOWLEDGMENT We thnk G. McIlvride for help in prepring the mnuscript. REFFERENCES Bile, C. A., J. Myer nd C. L. McLughlin. 1969. Feeding ehvior of gots: ruminl distension, ingest dilution nd cette concentrtion. Amer. J. Physiol. 217:397-402. Grovum, W. L. 1995. Mechnisms explining the effects of short chin ftty cids on feed intke in ruminnts-osmotic pressure, insulin nd glucgons. In: Ruminnt Physiology: Digestion, Metolism, Growth nd Reproduction. Proceedings of the Eighth Interntionl Syposium on Ruminnt Physiology (Ed. W.V. Engelhrdt, S. Leonhrd-Mrek, G. Breves nd D. Giesecke). Ferdinnd Enke Verlg. Stuttgrt. pp. 173-197. Kto, S., Y. Sski nd T. Tsud. 1979. Food intke nd rumen osmollity in the sheep. Annles de Recherches Veterinire. 10:229-230. Kto, S. 1977. Experimentl studies with regrd to fctors controlling feed intke in sheep. Ph.D. Thesis. Tohoku University, Sendi, Jpn. Leek, B. F. nd R. H. Hrding. 1975. Sensory nervous receptors in the ruminnt stomch nd the reflex control of reticulo-ruminl motility. In: Digestion nd Metolism in the Ruminnt Stomch (Ed. I. W. McDonld nd A. C. I. Wrner). University of New Englnd Pulishing Unit. Armidle. Austrli. pp. 60-76. Prsetiyono, B. W. H. E., K. Sungw, A. Shinjo nd S. Shirom. 2000. Physiologicl reltionship etween thirst level nd feed intke in gots fed on lflf hy cues. Asin-Aus. J. Anim. Sci. 13:1536-1541. SAS. 1990. SAS/STAT User's Guide. Volume 2, Version 6, Fourth
1746 SUNAGAWA ET AL. Edition. SAS Institute Inc., SAS Cmpus Drive, Cry, NC 27513. Sto, Y. 1975. The reltionship etween sliv secretion nd ody fluid lnce during feeding. Ph.D. Thesis. Tohoku University, Sendi, Jpn. Silnikove, N. nd A. Tdmor. 1989. Rumen volume, sliv flow rte nd systemic fluid homeostsis in dehydrted cttle. Am. J. Physiol. 256:R809-R815. Sungw, K., B. W. H. E. Prsetiyono nd A. Shinjo. 2001. Significnce of hypovolemi in feed intke control of gots fed on dry feed. Asin-Aust. J. Anim. Sci. 14:1267-1271. Sungw, K., B. W. H. E. Prsetiyono nd I. Ngmine. 2002. Significnce of feeding induced hypovolemi in feed intke control of gots fed on lflf hy. Asin-Aust. J. Anim. Sci. 15:366-370. Sungw, K., M. J. McKinley, B. S. Purcell, C. Thomson nd P. L. Burns. 2002. Effect of intrcereroventriculr infusion of urocortin on feed nd slt intke in protid fustulted sheep. Anim. Sci. J. 73:35-40. Wrner, A. C. nd B. D. Stcy. 1977. Influence of ruminl nd plsm osmotic pressure on slivry secretion in sheep. Q. J. Exp. Physiol. 62:133-142.
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