Effect of State of Hydration on Body Weight, Blood Constituents and Urine Excretion in Nubian Goats (Capra hircus)

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1 World Journl of Agriculturl Sciences 6 (2): , 2010 ISSN IDOSI Pulictions, 2010 Effect of Stte of Hydrtion on Body Weight, Blood Constituents nd Urine Excretion in Nuin Gots (Cpr hircus) Adll M. Adeltif, Slw A. Elsyed nd Yhi M. Hssn 1 Deprtment of Physiology, Fculty of Veterinry Medicine, University of Khrtoum 2 Fculty of Medicine, University of Shendi Astrct: The ojective of this study ws to evlute the physiologicl responses to stte of hydrtion in femle Nuin gots. The effects of 3 dys of dehydrtion nd 2 dys of rehydrtion on ody weight (BW), lood constituents nd urine excretion were monitored. The dily feed intke ws significntly decresed y wter deprivtion. The feed intke returned to control level within 2 dys fter rehydrtion. The men (BW) decresed significntly (20.2%) in dehydrted nimls. The loss in (BW) ws recovered immeditely fter drinking. Wter deprivtion resulted in significnt increse in rectl temperture (Tr), it returned to norml level fter drinking. There ws mrked significnt increse in pcked cell volume (PCV) in dehydrted nimls, the (PCV) returned to norml level fter rehydrtion. Wter deprivtion ws ssocited with significnt increses in serum concentrtions of totl protein, lumin, ure nd cretinine, fter rehydrtion, these prmeters returned to the control level, except lumin. Wter deprivtion nd rehydrtion hd no significnt effect on plsm glucose nd serum sodium (N) nd potssium (K) levels. Serum osmollity incresed progressively nd significntly during wter deprivtion nd returned to norml level on the second dy of rehydrtion. The glomerulr filtrtion rte (GFR) nd urine volume decresed significntly during dehydrtion nd returned to norml level in the second dy of rehydrtion. Dehydrtion ws ssocited with significnt increse in urine ure concentrtion; following rehydrtion the ure level decresed to control level in the second dy. Key words: Dehydrtion Rehydrtion Body weight Blood constituents Urine excretion Gots INTRODUCTION points. Under semi-rid conditions in Sudn, gots my e exposed to stressful conditions nd constrints which The got popultion in Sudn is estimted t out include prolonged het nd periodic droughts, fctors 42 million hed [1] distriuted minly in rid nd semi-rid which influence criticlly their wter nd energy zones. The gots ply vitl role in rurl economy nd in metolism. Furthermore, gots hve to wlk long trditionl griculturl production. Gots fulfil multiple distnces in pursuit of feed nd wter. Derngements roles in the household nutrition nd food security; they in wter nd energy metolism influence the helth provide fmilies with proteins of high iologicl vlue s nd productivity of gots. However, physiologicl milk nd met; lso they provide skin, fire nd mnure. mechnisms evolved y nimls inhiting rid lnds my Gots re considered to e dpted to wter scrcity enle them to survive nd reproduce in the mrginl nd feed shortge. They hve the ility to utilize vrious res [3]. types of forges nd tolerte hrsh environments in The mintennce of wter homeostsis y controlling mrginl nd semi-rid regions, considered unfvourle the osmollity nd lood volume is essentil for survivl for other domestic ruminnts [2]. Low rinfll ffects wter of nimls. The ody wter is tightly controlled y nd feed vilility nd drinking wter is often limiting regulting oth wter intke nd urinry wter excretion fctor for gots grzing semi-rid zone. The endurnce of [4]. During dehydrtion, n increse in plsm osmollity long periods of wtering in semi-rid zones llows the cts on osmoreceptors in the hypothlmus to stimulte nimls to grze t long distnces from dispersed wtering thirst nd increse the relese of the ntidiuretic hormone Corresponding Author: Dr. Adll M. Adeltif, Deprtment of Physiology, Fcutly of Vterinry Medicine, Shmt, Sudn 178

2 rginine vsopressin (AVP) from the posterior pituitry Experimentl Procedure: The experimentl nimls were [5]. The hormone (AVP) increses the wter permeility rndomly ssigned to two groups of 4 ech, control nd of the collecting ducts in kidneys [6]. The kidneys re treted. The experimentl protocol comprised 3 phses: responsile for mintining the totl ody wter nd its phse I: (euhydrton) where wter nd feed were ville distriution, electrolyte composition of ody fluids nd d liitum for oth control nd treted group of nimls. cid-se lnce [7]. In phse 2: (dehydrtion) the treted group nimls were Wter deprivtion my hve detrimentl effects on deprived of drinking wter for 3 consecutive dys, food, the physiologicl performnce, productivity nd welfre however, ws offered s usul. In phse 3: (rehydrtion), of ruminnts [8, 9]. Wter loss nd ssocited decese in t the end of the third dy of wter deprivtion, wter ws feed intke reduced milk yield in gots [10-12]. Wter offered freely to the nimls; this period lsted for 2 dys. deprivtion lso cused n increse in the viscosity of The mesurements of feed nd wter intke (when mde milk s well s concentrtions of protein, ft, lctose nd ville), urine volume, ody weight (BW), rectl minerls [13]. During dehydrtion, the physiologicl temperture (Tr) nd collections of lood nd urine chnges which tke plce my lter the disposition of smples were performed, initilly, every dy during common drugs dministered in gots minly due to dehydrtion nd fter 4 hrs nd for 2 dys following reduced distriution of drugs in tissues nd slower rehydrtion. elimintion s result of diminished liver nd kidney functions [14], thus reducing the efficiency of tretments Climtic Conditions: The experiment ws conducted nd helth sttus. during dry summer conditions. The dily mximum, The Nuin gots originted in Sudn nd they minimum nd men mient temperture (T) nd constitute out 46% of the got popultion in the reltive humidity (RH) were otined from Shmt country. They re considered s the min diry reed nd Meteorologicl Sttion locted out 500 meters from re rered minly in the semi-rid zone in the northern prt the experimentl site. The dily men (T) ws 34.8 C of the country, north of ltitude 12 N [15]. During hot dry (rnge C) nd the men (RH) ws 25.5%. summer conditions, the gots my suffer vrious degrees of dehydrtion, consequently their physiologicl Feed nd Wter Consumption: Ech niml ws responses my e ffected. This study ws initited with supplied dily t 8.00.m. with 1.0 kg of lucerne hy the ojective of evlution of the effects of wter (CP: 17.5 %; ME: 7.8 MJ/kg) nd 6.0 litres of tp wter. deprivtion nd rehydrtion on ody weight, feed intke, The feed ws weighed on digitl lnce while the lood constituents nd urine excretion in Nuin gots drinking wter ws mesured (when ville) in under tropicl summer conditions. grduted ucket. The dily feed intke nd wter consumption of ech niml were otined y weighing MATERIALS AND METHODS the feed residue to the nerest 10 gm nd mesuring the wter left y grduted mesuring cylinder to the Animls: Eight helthy dult non-gestting nd nerest 10 ml. Smples of lucerne hy were collected nd non-lctting Nuin gots were used in the study. dried t 105 C in n oven to constnt weight for the The gots were 2-3 yers old nd weighed kg t the determintion of dry mtter content. Loss of wter due to eginning of the study. The nimls were kept under evportion ws ssessed y mesuring the mount lost shde in the niml house for n dpttion period from n identicl ucket kept eyond the rech of the of 2 weeks. During this period the nimls ecme nimls. ccustomed to hndling nd vrious experimentl conditions. All nimls were sujected to clinicl Rectl Temperture (Tr): The rectl temperture of exmintion efore the eginning nd during the course gots ws mesured y digitl clinicl thermometer of the study nd were given prophylctic nticteril (Hrtmn -United Kingdom) with n ccurcy of ±0.1 C. tretment. The nimls were er tgged for identifiction nd ccommodted individully in metolic cges to Body weight (BW): During the experimentl period, the fcilitte mesurements of feed nd wter intke nd nimls were weighed in the morning to the nerest collection of totl urine volume kg using spring lnce (SALTER - Englnd). 179

3 Blood Collection nd Processing: Blood smples (6 ml) were drwn from the jugulr vein of nimls using disposle syringes. Immeditely 1 ml of lood ws trnsferred to cpped test tue contining n World J. Agric. Sci., 6 (2): , 2010 U cr C cr = P cr Where nticogulnt (K 3 EDTA) for lood nlysis. 1 ml of C cr = Clernce of cretinine (ml/min), lood ws kept in test tue contining sodium fluoride U cr = Concentrtion of cretinine in urine (mg /ml); nd fter centrifugtion, the plsm smple ws used for V = Rte of urine formtion (ml / min) glucose determintion. The rest of the lood smple ws P cr = Concentrtion of cretinine in plsm (mg/ml). llowed to sty for 4-5 hrs t room temperture nd then centrifuged (Gllenkmp Junior) t 3000 r.p.m. for 15 min. The stndrd vlues for cretinine clernce (GFR) Hemolysis-free serum ws trnsferred to clen plstic were expressed s (ml/min/kg ody weight). vils nd immeditely frozen t -20 C for susequent nlysis. Urine Collection nd Anlysis: Urine ws collected dily t 8.20 in plstic ottles fitted eneth the metolic Pcked Cell Volume (PCV): The (PCV) of erythrocytes cges. To ech ottle, liquid prffin ws dded with the ws determined (in duplicte) using microhemtocrit oject of stopping evportion, while 10 ml of centrifuge (Hettich, Tuttlingen, Germny). concentrted hydrochloric cid were dded s preservtive. The volume of urine voided y ech niml Plsm Glucose: The plsm glucose level ws ws mesured in mesuring cylinder to the nerest determined y the enzymtic colorimetric method using 10 ml. Smples of urine (10 ml) were kept frozen t (-20 C) kit (Rndox Lortories Ltd, London). for susequent nlysis of ure ccording to the technique used for serum smples. Serum Metolites: Serum totl protein concentrtion ws determined using Biuret regent [16]. Serum lumin Sttisticl Anlysis: The experimentl dt were concentrtion ws determined y colorimetric method sujected to stndrd methods of sttisticl nlysis [17]. Serum ure concentrtion ws determined y the [20]. Anlysis of vrince test (ANOVA) ws used to enzymtic colormetric test (Berthot) using kit evlute the effects of stte of hydrtion on the (Spinrect, S.A., Spin). Serum cretinine level in plsm prmeters mesured. The control nd treted group were nd urine ws mesured ccording to the method compred during the course of the experiment. The descried [18]. student (t) test ws used to compre the control nd treted group initilly nd during dehydrtion nd Serum Minerls: The concentrtions of serum sodium rehydrtion. (N) nd potssium (K) were determined y flme photometer (Jenwy PFP7, United Kingdom ) [16]. RESULTS Serum Osmollity: The osmollity of serum ws The effects of experimentl tretments on wter determined y freezing point depression utilizing n consumption, feed Intke, ody weight (BW) nd rectl osmometer (Osmometer 030, Gonotec GmH, Berlin, temperture (Tr) re shown in Tle 1. Germny). Wter Consumption: During norml hydrtion Glomerulr Filtrtion Rte (GFR): The endogenous (euhydrtion) there ws no significnt difference in wter cretinine clernce ws used for estimtion of (GFR) in consumption etween treted nd control group. gots ccording to the stndrd method [19]. In this At the end of dehydrtion period, treted gots drnk n method, the serum nd urine concentrtions of verge of 4.6 litres of wter during the first 15 min. of endogenous cretinine were determined, lso the totl rehydrtion. The men ingested wter ccounted for 31% urine volume excreted in 24 hrs ws collected nd of their dehydrted (BW). In the first dy of rehydrtion mesured. The renl clernce ws determined y the the treted group mintined significntly (P<0.01) higher following eqution: wter intke compred to the control. V 180

4 Tle 1: Effects of dehydrtion nd rehydrtion on wter consumption, feed intke, ody weight (BW) nd rectl temperture (Tr) of gots Dehydrtion Rehydrtion Prmeter Euhydrtion Dy 1 Dy 2 Dy 3 4 hr Dy 1 Dy 2 Wter consumpt-ion (L/dy) Control 2.65± ± ± ± ± ±0.21 Treted 2.77± ± ± ±0.67 LS NS ** NS Feed intke (kg/dy) Control 0.84± ± ± ± ± ±0.06 Treted 0.91± ± ± ± ± ±0.19 LS NS ** *** *** - * * Body weight (kg) Control 20.0± ± ± ± ± ± ±0.75 Treted 19.15± ± ± ± ± ± ±0.47 LS NS ** ** *** NS NS - Tr ( C) 8:0.m. Control 38.58± ± ± ± ± ± ±0.08 Treted 38.60± ± ± ± ± ± ±0.17 LS NS NS * * NS NS NS Mens ering different superscripts re significntly different LS: Level of significnce *P< 0.05, **P< 0.01, ***p< NS: Not significnt Tle 2: Effects of dehydrtion nd rehydrtion on serum concentrtions of (N), (K) nd serum osmollity in gots Dehydrtion Rehydrtion Prmeter Euhydr-tion Dy 1 Dy 2 Dy 3 4 hr Dy 1 Dy 2 N (meq/l) Control ± ± ± ± ± ± ±2.35 Treted ± ± ± ± ± ± ±3.78 LS NS NS NS NS NS NS NS K (meq/l) Control 4.12± ± ± ± ± ± ±0.21 Treted 4.25± ± ± ± ± ± ±0.29 LS NS NS NS NS NS NS NS Osmollity (mosmol/ kg) Control 287.5± ± ± ± ± ± ±7.76 Treted 297.0± ± ± ± ± ± ±8.14 LS NS * ** ** * NS NS Mens ering different superscripts re significntly different LS: Level of significnce *P< 0.05, **P< 0.01 NS: Not significnt Tle 3: Effects of dehydrtion nd rehydrtion on (PCV), serum concentrtions of totl protein, lumin, ure, cretinine nd plsm glucose in gots Dehydrtion Rehydrtion Prmeter Euhydr-tion Dy 1 Dy 2 Dy 3 4 hr Dy 1 Dy 2 PCV (%) Control 24.25± ± ± ± ± ± ±1.70 Treted 24.50± ± ± ± ± ± ±0.50 LS NS * ** *** ** * NS Totl protein (g/dl) Control 7.60± ± ± ± ± ± ±0.74 Treted 7.00± ± ± ± ± ± ±0.52 LS NS NS * * * NS NS Alumin (g/dl) Control 3.27± ± ± ± ± ± ±0.31 Treted 3.10± ± ± ± ± ± ±0.21 LS NS NS * * * * NS Ure (mg/dl) Control 28.00± ± ± ± ± ± ±3.74 Treted 29.30± ± ± ± ± ± ±2.11 LS NS NS * * * NS NS Cretinine (mg/dl) Control 0.630± ± ± ± ± ± ±0.11 Treted 0.60± ± ± ± ± ± ±0.21 LS NS NS * * * NS NS Glucose (mg/dl) Control 70.50± ± ± ± ± ± ±5.73 Treted 71.75± ± ± ± ± ± ±3.65 LS NS NS NS NS NS NS NS Mens ering different superscripts re significntly different LS: Level of significnce *P< 0.05, **P< 0.01, ***P< NS: Not significnt 181

5 Tle 4: Effect of dehydrtion nd rehydrtion on urine volume, (GFR) nd urine concentrtions of ure in gots Dehydrtion Rehydrtion Prmeter Euhydr-tion Dy 1 Dy 2 Dy 3 4 hr Dy 1 Dy 2 Urine volume (L/dy) Control 0.73± ± ± ± ± ±0.29 Treted 0.89± ± ± ± ± ± ±0.54 LS NS * ** ** * * NS (GFR) (ml/min/kg) Control 2.30± ± ± ± ± ± ±0.31 Treted 2.43± ± ± ± ± ± ±0.34 LS NS * ** ** NS NS NS Ure(g/dL) Control 1.48± ± ± ± ± ±0.31 Treted 1.33± ± ± ± ± ± ±0.39 LS NS NS * * NS NS NS Mens ering different superscripts re significntly different LS: Level of significnce *P< 0.05, **P< 0.01 NS: Not significnt Feed Intke: The dily food intke ws significntly (P<0.01) decresed during wter deprivtion. After rehydrtion, the norml level of food intke ws not restored within 2 dys. Body Weight (BW): The men (BW) of treted gots decresed significntly in the first nd second (P<0.01) nd the third dy (P<0.001) of dehydrtion. At the end of dehydrtion period, treted gots lost 22.2% of the initil BW. They regined the (BW) loss t 4 hrs fter rehydrtion. Rectl Temperture (Tr): Dehydrtion resulted in significnt (P<0.05) increse in rectl temperture (Tr) in dys 2 nd 3. (Tr) of treted group tended to decrese following rehydrtion. The results of the effects of tretments on lood constituents re shown in Tles 2 nd 3. Pcked Cell Volume (PCV): The (PCV) ws significntly higher in the first (P<0.01) s well s the second nd third dy (P<0.001) of wter deprivtion. Within 4 hrs following drinking, there ws significnt (P<0.01) decrese in (PCV) of rehydrted gots; the decrese in dy 2 ws just significnt (P<0.05). The norml (PCV) level ws recovered 2 dys fter rehydrtion. Serum Totl Protein: Wter deprivtion resulted in significnt (P<0.05) increse in serum totl protein concentrtion for treted group in dys 2 nd 3. Within 4 hrs of rehdyrtion, the totl protein level decresed significntly (P<0.05) nd recovered the control level in the second dy of rehydrtion. Serum Alumin: The lumin level for treted group incresed significntly (P<0.05) in dys 2 nd 3 in response to wter deprivtion. After rehydrtion, it decresed significntly (P<0.05); the norml control level ws recovered in the second dy of rehydrtion. Serum Ure: The ure level incresed significntly (P<0.05) during wter deprivtion. The ure level decresed 4 hrs fter rehydrtion nd mintined control level in the second dy of rehydrtion. Serum Cretinine: The cretinine level showed significnt (P<0.05) increse in response to wter deprivtion. The cretinine level restored norml vlue in the second dy of rehdyrtion. Plsm Glucose: The plsm glucose level ws not ffected significntly y wter deprivtion nd rehydrtion. Serum (N) nd (K): The levels of (N) nd (K) were not influenced significntly y dehydrtion nd rehydrtion. Serum Osmollity: The osmollity of serum exhiited significnt increse in dy 1 (P<0.05) nd in dys 2 nd 3 (P<0.01). After rehydrtion, serum osmollity decresed significntly (P<0.01) nd it recovered the norml level in the second dy. The effects of tretments on urine prmeters re shown in Tle 4. Urine Volume: The volume of urine decresed significntly in the first dy (P<0.05) nd in the second nd third dy (P<0.01) of dehydrtion. Following 182

6 rehydrtion, urine volume incresed significntly (P< 0.01) wter deprivtion [21]. For comprison, Dorper sheep in the first dy nd restored the control vlue in the were le to restore the entire (BW) loss immeditely second dy. following wtering tht terminted 4 dys of dehydrtion [26], while Awssi sheep replenished only 52% of their Glomerulr Filtrtion Rte (GFR): The (GFR) showed (BW) loss, ut needed 24 hrs to restore the reminder [28]. significnt decrese in the first dy (P<0.0.5) nd in the Therefore the cpcity for rehydrtion following wter second nd third dy (P<0.01) of wter deprivtion. deprivtion could e influenced y reed nd species, Rehydrtion resulted in grdul increse in (GFR) of physiologicl chrcteristics s well s therml treted group; the control vlue ws recovered in the third environment. dy of rehydrtion. The feed intke of Nuin gots ws ffected y hydrtion stte. During the first dy of wter deprivtion, Urine Ure: The ure concentrtion incresed Nuin gots reduced feed intke y out 60% nd feed significntly (P<0.05) during the second nd third dy of intke continued to decline s wter deprivtion ws wter deprivtion. Following rehydrtion, the ure level extended (Tle 1) during the third dy of wter tended to decrese nd it ttined the control group vlue deprivtion, the gots consumed only 5% of the control in the second dy. level of food intke. Drinking ws shown to e ssocited with feed intke in ruminnts [29-31]. The osmollity of DISCUSSION rumen fluid which increses during wter deprivtion represents n importnt feedck signl for control of The results showed tht Nuin gots lost 22.2% of feeding [32, 33] nd infusion of wter into the rumen ws their initil ody weight (BW) during 3 dys of wter shown to stimulte feeding in sheep [34]. Furthermore, deprivtion (Tle 1). The mjor loss occurred in the first studies on pygmy gots indicted tht (AVP) which is dy. This result is in greement with previous findings elevted during dehydrtion inhiits food intke y [21] which reported tht locl Sudi Arin gots lost n ctivtion of lph 1-drenergic receptors [35]. The verge of 20.6% of their initil (BW) during 3 dys of decline in food intke during wter deprivtion could lso wter deprivtion. It hs een noted tht Ardi gots e viewed s n dptive mesure employed y nimls lost 20% of their initil (BW) when wter-deprived for inhiting rid res for conserving ody wter. Egyptin 4 dys [22]. The lck Bedouin gots were reported to Bldi gots mintined reltively higher level of lose 20% of their (BW) within 3 dys under moderte feeding; their feed intke ws 35% of the control level summer conditions [23]. Therefore the Nuin got is fter 3 dys of wter deprivtion [36]. However, Ardi comprle to other got reeds in the Middle Est with gots lmost cesed feeding following 2 dys of wter respect to (BW) loss during dehydrtion. The reported deprivtion during summer [22] nd in locl gots of Sudi loss in (BW) is ssocited with loss of ody wter s well Ari, 3 dys of wter deprivtion resulted in 85% s reduction in feed nd wter intke. However, ody reduction in feed intke [21]. mss loss during wter deprivtion is lrgely relted to Wter deprivtion influenced the het lnce of reduction in totl ody wter [24-26] prticulrly in hot Nuin gots; despite the mrked decrese in feed intke environments. A close reltionship etween the tht could influence the energy udget, the rectl mgnitude of (BW) loss nd ody wter loss ws temperture (Tr) incresed significntly in the third dy of previously reported in Desert gots nd sheep [25]. wter deprivtion (Tle 2). Thermoregultion in mmmls The Nuin gots, when rehydrted, ingested is linked inextricly with ody fluid lnce [37], immeditely (within 15 min.) volume of wter ccounting prticulrly in conditions when het lod my originte for 31 % of dehydrted (BW). This corresponded to their from hot environment or metolic genertion of het (BW) loss or slightly more. This result is in generl [38]. Evportive cooling vi sweting which constitutes conformity with findings which indicted tht lck mjor cooling venue during het stress for gots Bedouin gots were le to drink volume of wter tht dpted to hot rid zone [39], is usully reduced in mounted to 28-36% of their (BW) t the end of dehydrted nimls [40, 41]. Dehydrtion- induced dehydrtion session [23, 27], occsionlly the wter intke hyperthermi my e dptive in conserving wter s it exceeded their loss in (BW). However, it hs een increses the temperture t which the nimls switch reported tht Sudi got reeds consumed wter from thermoregultion vi convection nd rdition to equivlent to 23.5 % of dehydrted (BW) fter 3 dys of evportive cooling [42]. The decrese in rectl 183

7 temperture of Nuin gots during wter deprivtion is prtilly to increse in secretion of the hormone (AVP). in greement with the findings of other reserchers who It hs een reported tht wter deprivtion incresed reported significntly higher ody temperture in (AVP) level in gots [56] nd this would hve opposed dehydrtion thn in euhydrton in gots exposed to hot loss of ure s (AVP) promotes ure resorption in the environment [21, 22, 43]. kidney [57]. The rise in ure level could lso e ssocited The results showed stedy nd significnt increse with ctolism of ody proteins during dehydrtion [58]. in (PCV) s wter deprivtion dvnced, reching the The results indicted tht in Nuin gots, urine ure highest level in the third dy of dehydrtion (Tle 3). concentrtion incresed significntly with prolongtion of Four hours following drinking, there ws decrese in wter deprivtion; following rehydrtion the ure level (PCV) of rehydrted gots. The euhydrtion (PCV) level tended to decrese nd it ssumed the control level in the ws recovered fter 2 dys of rehydrtion. An increse in second dy (Tle 4). These chnges in ure (PCV) following wter deprivtion ws oserved in gots concentrtion seem to e relted inversely to the volume under hot dry conditions [21, 36]. The reported increse of urine excreted. in (PCV) during wter deprivtion is clerly ssocited In the current study, during wter deprivtion, serum with reduced plsm volume. Previous studies indicted cretinine level incresed significntly compred to tht lood s well s plsm volume were reduced during control vlue (Tle 2). An lmost similr rte of wter deprivtion in gots nd sheep [23, 25, 26]. Chnge increse ws reported in locl gots of Sudi Ari [21]. in plsm volume during dehydrtion cn e ssessed However, moderte increse in plsm cretinine level indirectly y utilizing the increse in (PCV) [44]. ws oserved following 3 dys of wter restriction in Elevtions in (PCV) nd plsm osmollity re usully Brki sheep [59]. The ccumultion of cretinine in plsm ssocited with reduced plsm volume in response might e consequence of generl reduction in urinry to wter restriction [25]. However, use of gut wter excretion rte during wter deprivtion [60], or it could e helps to ttenute the rise in plsm osmollity during relted to chnges in clernce, since the endogenous dehydrtion [45]. cretinine clernce rte ws found to e closely The plsm protein concentrtions re ffected y correlted to (GFR) [61]. The plsm cretinine cn e fluid lnce; dehydrtion cuses loss of fluid nd used s n indictor of (GFR) in domestic nimls [62]. susequent hyperproteinemi [46]. Accordingly, the As n djustment to wter lnce during wter reported increse in serum totl protein nd lumin deprivtion, gots reduced (GFR) which eventully concentrtions during wter deprivtion in Nuin gots resulted in reduction in urine volume. The rise in serum (Tle 2) is relted lrgely to decrese in plsm volume. cretinine could e relted to the mintennce of renl It hs een indicted tht the increse in totl plsm function t lower level, which consequently reduced the protein concentrtion during therml dehydrtion my rte of clernce of cretinine. enhnce preservtion of plsm volume [47]. Furthermore, Wter deprivtion did not induce significnt chnge plsm lumin is considered vitl for osmotic equilirium in plsm glucose level (Tle 2). Similrly, previous etween the lood nd ody tissues [48]. An increse in studies hve not reported significnt chnges in glucose protein concentrtion during wter deprivtion hs een level in response to wter restriction in gots [21, 63]. reported in other got reeds [11, 49-51]. However, other studies reported decline of 13% in The significnt rise in serum ure concentrtion plsm glucose level of Sudnese desert sheep wtered during wter deprivtion (Tle 2) is ttriuted to every 72 hrs [52]. The decrese in feed intke tht hemoconcentrtion. Similr responses were reported in ccompnied wter restriction should hve resulted in gots nd sheep [21, 28, 52]. However, decline in urinry decrese in plsm glucose level. However, it seems tht totl nitrogen nd ure output ws reported in connection decrese in plsm glucose level does not necessrily with wter deprivtion in gots nd sheep [53, 54], which prllel tht of food intke [63]. In the present study the resulted in nitrogen retention. Short periods of wter gret extent of reduction in food intke ws not deprivtion in gots nd sheep cn improve nitrogen ccompnied y similr trend in plsm glucose level. lnce [2] y incresing ure recycling, prticulrly with In the cmel, high plsm glucose level during wter low qulity feeds [53]. A decline in the rte of ure deprivtion ws relted to decrese in insulin secretion excretion ssocited with wter restriction my occur s [64]. In contrst, glycogenolysis nd gluconeogenesis the (GFR) is usully reduced during wter deprivtion might hve een provoked since plsm glucgon level [55]. The increse in serum ure level my lso e relted incresed in response to wter deprivtion in rts [65]. 184

8 Furthermore, previous studies indicted tht (AVP) which is elevted during wter deprivtion, incresed lood glucose level in pygmy gots y n lph - drenergic mechnism [66]. These possile chnges in endocrine responses might hve een involved in the mintennce of norml glucose level despite the gret reduction in food intke of Nuin gots in the present study. The results did not revel significnt chnges in serum (N) levels in response to wter deprivtion (Tle 3). This pttern of response could e relted to ntriuresis tht ws reported previously during dehydrtion in nimls including sheep [67]. Similrly the plsm (N) level remined unchnged during wter deprivtion in Brmer gots [49] nd Ynks sheep [68]. The stility of serum (K) level during wter deprivtion in the current study could e ssocited with the reported mrked decline in food intke (Tle 1). Previous studies reported tht plsm (K) level in Brmer gots ws unchnged fter 4 dys of wter deprivtion [49]. However, other studies reported tendency of increse in plsm (K) level in wter-deprived sheep under hot summer conditions [63]. Wter deprivtion in Nuin gots resulted in significnt progressive rise in serum osmollity (Tle 3). This response is in greement with previous reports in gots [21, 51] nd sheep [28, 52]. The increse in serum osmollity is presumly relted to increse in colloid osmotic pressure ssocited with increse in concentrtions of plsm proteins (Tle 2). The rise in osmollity during wter restriction my contriute to the mintennce of plsm volume y encourging wter movement from the interstitil fluid into the vsculr system. The results indicte tht the hydrtion stte of Nuin gots resulted in mrked chnges in renl function. During wter deprivtion, the significnt decrese in urine volume to 35 % of euhydrtion vlue (Tle 4) indictes ctivtion of wter sving mechnisms. The kidneys ssume mjor role in controlling wter loss in response to the ction of the ntidiuretic hormone (AVP) which usully increses in dehydrted gots [11,51]. The norml urine volume in Nuin gots ws restored fter 2 dys following rehydrtion, indicting tht there ws moderte diuresis in response to drinking. This suggests dely in sorption of wter from the rumen which hs een previously reported in the lck Bedouin got [69] nd the cmel [70]. However, lctting Swedish gots developed mrked diuresis fter wter loding [71] nd cttle re known to e susceptile to wter intoxiction following rehydrtion [72]. In the present study, the decline in urine volume during wter deprivtion ws ssocited with significnt decrese in (GFR) to 58% of the vlue otined in euhydrtion stte (Tle 4). In lck Bedouin gots tht were dehydrted to loss of out 30% of their initil (BW), the (GFR) decresed to 50 % of the level mesured in hydrted stte nd urine flow dropped to 24 % of the vlue mesured in hydrted nimls [73]. Following rehydrtion, the norml (GFR) level in Nuin gots ws restored in the second dy. CONCLUSION The results indicte tht the Nuin got is dpted to cute chnges in stte of hydrtion. The rte of (BW) loss during wter deprivtion is comprle to vlues reported for other reeds dpted to hot dry conditions. The moderte diuresis following rehydrtion suggests tht oth the stomch nd kidney were involved in mechnisms of homeostsis Future studies should investigte the effect of stte of hydrtion on endocrine responses nd productivity trits including milk yield nd composition. ACKNOWLEDGEMENTS We thnk the lortory stff of the Deprtment of Physiology, Fculty of Veterinry Medicine for technicl ssistnce nd tking cre of experimentl nimls. REFERENCES 1. FMAR (Federl Ministry of Animl Resources), Annul Report. Deprtment of Sttistics. Khrtoum, Sudn. 2. Silnikove, N., The physiologicl sis of dpttion in gots to hrsh environment. Smll Ruminnt Res., 35(): Mloiy, G.M.O., T.I. Knui, P.K. Towett, S.N. Wmugu, J.O. Miron nd M.M. Wnyoike, Effects of dehydrtion nd het stress on feed intke nd dry mtter digestiility in Est Africn ruminnts. Comprtive Biochemistry nd Physiology, 151A: Boone, M. nd M.T. Deen, Physiology nd pthophysiology of the vsopressin-regulted renl wter resorption. Pflugers Arch., Eur. J. Physiology, 456(6): Andersson, B., I.G. Leksell nd M. Rundgren, Regultion of wter intke. Annul Review of Nutrition, 2:

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