EFFECTS OF SODIUM AND MAGNESIUM SULFATE IN DRINKING WATER ON MALLARD DUCKLINGS

EFFETS OF SODIUM AND MAGNESIUM SULFATE IN DRINKING WATER ON MALLARD DUKLINGS Authors: S. A. Mitchm, nd G. Wobeser Source: Journl of Wildlife Diseses, 24(1) : 3044 Published By: Wildlife Disese Assocition URL: https://doi.org/10.7589/0090355824.1.30 BioOne omplete (complete.bioone.org) is fulltext dtbse of 200 subscribed nd openess titles in the biologicl, ecologicl, nd environmentl sciences published by nonprofit societies, ssocitions, museums, institutions, nd presses. Your use of this PDF, the BioOne omplete website, nd ll posted nd ssocited content indictes your eptnce of BioOne s Terms of Use, vilble t www.bioone.org/termsofuse. Usge of BioOne omplete content is strictly limited to personl, eductionl, nd noncommercil use. ommercil inquiries or rights nd permissions requests should be directed to the individul publisher s copyright holder. BioOne sees sustinble scholrly publishing s n inherently collbortive enterprise connecting uthors, nonprofit publishers, cdemic institutions, reserch librries, nd reserch funders in the common gol of mximizing ess to criticl reserch.

Journl of Wildlife Diseses, 24(1), 1988, pp. 3044 Wildlife Disese Assocition 1988 EFFETS OF SODIUM AND MAGNESIUM SULFATE IN DRINKING WATER ON MALLARD DUKLINGS S. A. Mitchm2 nd G. Wobeser 3 Deprtment of Veterinry Pthology, Western ollege of Veterinry Medicine, University of Ssktchewn, Ssktoon, Ssktchewn, nd S7N OWO 2 Present ddress: Box 160, Redlyn, Iow 50668, USA Author to whom reprint requests should be ddressed ABSTRAT: Onedyold mllrd (Ans pltyrhynchos) ducklings were given drinking wter for up to 28 dys tht contined concentrtions of sodium nd/or mgnesium similr to those found in sline wetlnds. Growth, tissue development, nd biochemicl chrcteristics of these ducklings were compred to those rered on fresh wter. Much of the ingested slt ws excreted by pssge of voluminous fluid excret. This effect ourred in birds given wter with s little s 500 ppm Mg or 1,000 ppm N. The suprorbitl slt glnd ws ctive within 4 dys in ducklings drinking wter contining 1,500 ppm of N. Fether growth ws decresed in ducklings drinking wter with >1,500 ppm of either N or Mg. Ducklings drinking wter with 3,000 ppm of either ion, or 1,500 ppm of ech, grew more slowly thn control birds. Ducklings drinking wter with 3,000 ppm of either N or Mg hd reduced thymus size nd bone breking strength. Those drinking wter with 3,000 ppm of Mg, or 3,100 ppm N nd 1,300 ppm Mg lso hd less trbeculr bone nd enlrged drenls. Birds drinking the ltter wter hd n elevted concentrtion of N nd clcium, nd decresed concentrtion of phosphorus nd chloride in their serum, nd elevted plsm protein levels. Ducklings rered on fresh or slightly sline wter dpted very poorly to n brupt chnge to more sline wter (specific conductivity = 15,250 mhos/cm) t 14 dys of ge. These birds stopped eting, becme inctive nd some died within 3 dys; survivors hd mny tissue nd biochemicl bnormlities t 20 dys of ge. The level of slinity in these trils ws similr to tht in brckish or modertely sline wetlnds nd lower thn tht previously found to hve effects on growth nd fethering of ducklings. Mny of the sublethl effects were subtle nd nonspecific mnifesttions of stress, nd would be difficult to detect in wild ducklings on sline wetlnds. Key words: Ans p/t yrhynchos, duckling, wetlnd, slinity, toxicity, growth, fethering, biochemistry, pthology, experimentl. INTRODUTION The pririe pothole region is the mjor re of duck production in North Americ. The low precipittion nd high evportion rte in the region hve resulted in umultion of slts within wetlnd systems tht lck externl dringe. In Ssktchewn the mjor ctions in such wetlnds re N nd Mg, with sulfte being the common nion (Rwson nd Moore, 1944; Hmmer, 1978). Wterfowl use sline wetlnds for feeding (Serie nd Swnson, 1976; Krpu nd Swnson, 1978) nd molting. Islnds in some sline wetlnds re used intensively by nesting ducks (Duebbert et l., 1983), but the fte of broods produced on these wetlnds is unknown (Swnson et l., 1984). When exposed to hypertonic sline drinking wter, wterfowl osmoregulte minly by excreting excess N vi the suprorbitl slt glnd (Peker nd Linzell, 1975). Adult mllrds (Ans pltyrhynchos) cn tolerte wter contining bout 20 prts per thousnd of Nl but cnnot survive on sewter (Holmes et l., 1978). Ducklings re reported to be much less tolernt of slt (Ellis et l., 1963; Schmidt Nielsen nd Kim, 1964; Riggert, 1977) nd slt poisoning hs been suspected in Austrlin shelducks (Tdorn tdornoides) (Riggert, 1977). Swnson et l. (1984) found tht ducklings were consistently bsent from some sline wetlnds in North Dkot, while ducklings on other wetlnds were closely ssocited with locl freshwter inflows. Ducklings <13 dys of ge were unble to survive when provided only with sline wter from most of the ltter wetlnds. 30

MITHAM AND WOBESERSALINE WATER AND DUKLINGS 31 Informtion on the suitbility of sline wetlnds for wterfowl my become incresingly importnt. Becuse dringe is usully directed t fresh rther thn sline wetlnds, nd becuse current griculturl prctices result in incresed leching of slt from the soil with deposition of slt in lowlying res (Stnding ommittee on Agriculture, Fisheries, nd Forestry, 1984), sline wetlnds will likely comprise n incresing proportion of remining wetlnd re in the future. This study ws conducted to determine the effects of sodium sulfte (N2SO4) nd mgnesium sulfte (MgSO4) singly, nd in combintion, on the growth, tissue development, hemtology nd clinicl pthology of mllrd ducklings. Experimentl MATERIALS AND METHODS design Four trils were conducted. On dy 0 of ech tril mllrd ducklings obtined on the dy fter htching from Whistling Wings (Hnover, Illinois 61041, USA) were mrked with web tgs, weighed nd ssigned rndomly to groups of 10 ducklings which were plced in individul indoor pens equipped with het lmps. In Trils I nd II ech pen hd n re of 4.4 m2, wheres in Trils III nd lila ech pen hd n re of 3.3. m. There ws no significnt difference in verge weight of ducklings on dy 0 mong groups in ny of the trils. Ducklings hd ess to commercil duck nd goose strter (Tble 1) nd either Ssktoon tp wter (controls; Tble 2) or slt solution (Tble 3) d libitum. The slt solutions represented rnge of concentrtions of N nd Mg similr to tht found in sline wetlnds during June in southern Ssktchewn (Tble 2), nd were prepred by dding nhydrous N2SO, nd/or nhydrous MgSO4 on weight/volume bsis to Ssktoon tp wter. The conductivity of these solutions mesured with specific conductivity meter ws within the low to intermedite rnge s defined for wetlnds by vrious uthors (Fig. 1). Wter ws supplied in 10liter double wll vcuum poultry founts. Food ws supplied in trough type chicken feeders equipped with n ntiroost reel. Food consumption ws mesured by weighing food supplied nd food remining ech dy; no ttempt ws mde to collect spilled food, which ppered to be similr in mount mong groups. Trils I nd II lsted 28 dys. Ducklings received the sme slt solution for the durtion of TABLE 1. ontent of selected components in commercil duck nd goose strter used in ll trils. omponent Mnufcturer s gurnteed nlysis (%) Independent nlysis (%)t Protein (minimum) 20.0 21.1 Ft (minimum) 2.0 NT Fiber (mximum) 6.0 NT Slt 0.4 NT Sodium 0.14 lcium 0.9 0.82 Phosphorus 0.7 0.80 Mgnesium 0.14 From lbel of feed bg (source: Federted oopertives Ltd.. Ssktoon, Ssktchewn, nd S7N 17.3). Feed Testing Service, ollege of Agriculture, University of Ssktchewn, Ssktoon, Ssktchewn, nd S7N OWO. Not tested. the tril (Tble 3). Trils III nd lila were of 20 dys durtion; on dy 15 of these trils the originl slt solution ws discontinued nd ducklings in Groups 1A, 2A nd 3A of Tril III nd Groups 1A, 2 nd 3 of Tril lila were given wter contining 3,100 ppm N nd 1,300 ppm Mg (Tble 3). This ws n ttempt to mimic sitution in which young ducklings move onto permnent sline wetlnd when ephemerl freshwter wetlnds dry during summer. The concentrtion of N nd Mg given on dy 15 of these trils ws similr to tht found during June in wetlnd (Porter Lke) ner Ssktoon (Tble 2). linicl signs such s nsl glnd dischrge nd condition of droppings were monitored dily. Ducklings were weighed on lternte dys to dy 16 nd then every fourth dy until the completion of the tril. Smple collection nd nlysis On dy 14 of ech tril 1 ml of blood ws collected from the mettrsl vein of ech duckling. Osmollity of the serum ws mesured by freezing point depression (Advnced Wide Rnge Osmometer, Advnced Instruments, Inc., Needhm Heights, Msschusetts 02194, USA). oncentrtion of N, potssium nd chloride in serum ws mesured by ion selective electrodes with Beckmn E4A nlyzer (Beckmn Instruments, Mississug, Ontrio, nd L5T 1W5); Mg, clcium nd inorgnic phosphorus concentrtion in serum ws mesured with Bichromtic Anlyzer 100 (Abbot Lbortories, Mississug, Ontrio, nd L5N 3R7). Blood collected into heprinized cpillry tubes from ech duckling ws used for deter

32 JOURNAL OF WILDLIFE DISEASES, VOL. 24, NO, 1, JANUARY 1988 TABLE 2. Selected chemicl nd physicl chrcteristics of wter collected in June 1983 from wetlnds in Ssktchewn nd of Ssktoon tp wter.4 onductivity (zmhos/ Wetlnd Ltitude Longitude N Mg K SO4 l O cm) Axe Lke 51#{176}31 N 105#{176}13 W 460k 231 39 132 1,710 132 nil 4,500 Little Quill Lke 51#{176}55 N 104#{176}14 W 700 460 84 100 2,770 341 nil 7,000 Middle Quill Lke 51#{176}56 N 104#{176}12 W 920 530 100 200 3,780 466 nil 8,500 Rice Lke 52#{176}03 N107#{176}08 W 1,100 400 92 140 3,470 383 nil 8,500 Goose Lke Slough 51#{176}46 N107#{176}19 W 1,700 240 130 60 3,010 348 42 10,000 Porter Lke 52#{176}11 N106#{176}17 W 3,150 1,270 180 496 9,570 2,130 nil 23,500 Buffer Lke 52#{176}23 N 106#{176}00 W 9,500 2,300 290 520 21,300 6,960 nil 48,500 Ssktoon tp wter 22 14 3 32 75 7 nil 357 Anlyses performed by Anlytic Services, Ssktchewn Reserch ouncil, Ssktoon, Ssktchewn, nd S7N OWO. ppm. mintion of pcked cell volume (PV), totl plsm protein (TP) nd preprtion of blood smers. Totl white blood cell count ws estimted from the peripherl blood smer (Lynch et l., 1969). Only heterophils nd lymphocytes were counted in the differentil white blood cell count. Approximtely 10 smples of excret collected nd pooled from ech pen on dys 13 nd 27 in Trils I nd II nd on dy 13 of Trils III nd lila were dried, reconstituted s 5% solution in distilled wter, nd nlyzed for N nd Mg content. On the lst dy of ech tril, ducklings were weighed, 510 ml of blood were collected by crdic puncture, nd the birds were killed by crbon dioxide overdose. ulmen length, totl length nd quill length of the ninth primry fether, middle retrix length nd leg length from the hock to the longest clw tip were mesured. Slt glnds, right femur, liver, spleen, thymus, burs of Fbricius, left kidney, drenls nd gonds were fixed in neutrl buffered 10% formim. The left femur ws frozen. After fixtion, slt glnds, liver (without the gll bldder), spleen, thymic lobes, burs of Fbricius, left kidney nd one drenl glnd were weighed nd orgn weights were clculted s percent of body weight. One slt glnd, drenl, gond nd portion of liver, spleen, thymus, burs nd left kidney were embedded in prffin, sectioned t 5 jm nd stined with hemtoxylin nd eosin (H&E). After declcifiction in 20% formic cid for 48 hr, two sections were cut from the right femur, processed routinely nd stined with H&E. One section ws tken longitudinlly through the center of the femorl intercondyloid foss nd the other trnsversely through the midshft. Stined slides of tissues were exmined without knowledge of the group of origin. Selected vribles were rnked subjectively on scle of 0 to 6, with 0 being mrked decrese in the vrible being mesured, 3 being norml, nd 6 rnked s mrked increse. Tissue chrcteristics tht were rnked included the mount of burs, splenic nd thymic lymphoid tissue, vcuoltion of heptocytes, nd slt glnd nd drenl corticl hypertrophy. Histologic sections of liver tht hd been rnked from 3 to 6 for vcuoltion were stined with periodic cid Schiff (PAS) nd PAS fter tretment with distse. Vcuolted heptocytes stined positively for glycogen with PAS nd were negtive for glycogen when stined with PAS fter distse digestion, indicting tht vcuoles within heptocytes were glycogen. hrcteristics exmined on the longitudinl section of the distl femur included width of the zone of prolifertion nd of the zone of hypertrophy, extent of vsculr invsion of crtilge, number of osteoblsts nd osteoclsts in the epiphysis nd metphysis nd the mount of trbeculr bone. Midshft thickness nd number of osteoblsts were rnked on the cross section of the right femur. The frozen left femurs were thwed nd femorl bone breking strength ws determined by mesuring the force pplied perpendiculr to the long xis of the bone tht resulted in brekge (shin nd Lewis, 1984). Sttisticl nlysis Prmetric vribles were nlyzed by onewy nlysis of vrince (ANOVA); for vribles mesured over time, twowy ANOVA ws used. When ANOVA showed significnt difference mong tretment groups, Student NewmnKeuls procedure ws performed to detect which groups were significntly different (lph = <0.05). Nonprmetric ordinl scle

MITHAM AND WOBESERSALINE WATER AND DUKLINGS 33 TABLE 3. oncentrtion (prts per million) of N (N2SO4 OH2O) nd Mg (MgSO4 OH2O) dded to Ssktoon tp wter to prepre sline solutions used in Trils IlIlA. Approximte conductivity Tril Group(s) N Mg (zmhos/cm) specific Dys 028 I 1 tp wter 350 2 500 2,000 3 1,000 4,500 4 1,500 5,900 5 500 3,000 6 1,000 5,100 7 1,500 7,000 Dys 028 II 1 tp wter 350 2 3,000 11,000 3 3,000 12,000 4 1,500 1,500 11,500 5 6 1,500 500 500 1,500 8,000 8,300 7 500 500 4,600 8 3,100 1,300 15,250 Dys 014 III 1, 1A tp wter 350 2, 2A 500 250 3,650 3, 3A 1,000 500 6,250 Dys 1520 1,2,3 sbove IA, 2A, 3A 3,100 1,300 15,250 Dys 014 lila 1, 1A tp wter 350 2 500 250 3,650 3 1,000 500 6,250 Dys 1520 1 tp wter 350 IA,2,3 3,100 1,300 15,250 dt ws nlyzed by the KrusklWllis AN OVA nd multiple comprison procedure (Dniel, 1978) ws used to determine which groups were significntly different. Sttisticl significnce ws epted t the 0.05 probbility level. Vlues re reported s mens (stndrd devition). Detiled numericl dt re vilble in Mitchm (1985). Tril I RESULTS ontrol ducklings nd those receiving wter with 500 ppm N dded hd norml excret. All other ducklings in the tril hd fluid excret, beginning on dy 1 or 2 with the degree of chnge directly relted to the mount of either N2SO4 or MgSO4 dded to the drinking wter. Ducklings drinking solutions contining dded N2SO4 generlly hd more N nd less Mg in their excret, nd ducklings receiving MgSO4 hd more Mg nd less N in their excret thn did control birds (Tble 4). At the conclusion of the tril, there were few differences mong groups. Ducklings in the control group were lrger thn those

34 JOURNAL OF WILDLIFE DISEASES, VOL 24, NO 1, JANUARY 1988 60,000 45,001. 30,000 Sline Subsline Hypersline Sline Polysline Hypersline.,,O0( Mesosline E U 8000 Brckish 500 200 800 Modertely Brckish Slightly Brckish Modertely Sline (I, 0 E Oligosline Myxosline Fresh Fresh Fresh Stewrt nd Millr(197) Kntrud (1972) owrdin et l(1979) FIGt lu : 1. lssifiction systems for nturl wetlnds bsed on specific conductivity of the wter. in ny of the groups tht received sline wter, but the difference mong groups ws not significnt (Tble 4). ontrol birds consumed more feed during the tril thn did other groups. The only significnt difference found in body mesurements ws in the length of the ninth primry quill, with control birds hving significntly longer quills thn those ill the groups tht received the highest concentrtion of N nd Mg, respectively. I)ucklings in ll groups were pprently ble to compenste for the incresed N nd Mg intke, since there ws no evidence of hyperntremi or hvpermgnesemi, nd serum osmollitv did not differ significntly mong groups. On dy 14 the concentrtion of clcium in the serum ws decresed significntly in Group 6 ( = 2.62, SI) = 0.14 mmol/ liter) nd phosphorus ws decresed significntly in Groups 3 ( = 2.45, SD = 0.16 mmol/liter) nd 4 (1 = 2.60, SD = 0.19 mmol/liter) compred to the control group (1 = 2.84, SD = 0.13 nd I = 2.91, SD = 0.34 mmol/liter, respectively). The concentrtion of mgnesium ill the serum ws significntly elevted in Group 7 (1 = 2.35, SD = 0.66 mrnol/liter) on dy 14 nd in Group 6 ( = 2.64, SD = 0.34 mmol/liter) on dy 28 compred to tht of control ducklings t the sme time ( = 1.39, SD = 0.30 nd I = 1.96, SD = 0.31 mmol/liter, respectively). Tril II Ducklings in Groups 2, 4, 5 nd 8 were excreting fluid vi the nsl glnds by dy 4 of the tril, s evidenced by droplets round the nres nd osionl hed shking. Lter in the tril, ducklings in Group 7 osionlly hd fluid round the nres. Ducklings in Groups 2, 3, 4, 5, 6 nd 8 ll hd excret tht ppered more fluid thn tht of the control group. Ducklings drinking solutions contining the higher concentrtions of N2SO4 nd/or MgSO4 hd more N nd/or more Mg in their excret thn did control birds. Ducklings in Groups 2, 3, 4 nd 8 grew poorly, with Groups 3 nd 8 most severely ffected; food consumption followed similr pttern (Tble 5). Ducklings in Groups 3 nd 8 hd the shortest ninth primry quills, middle retrices nd legs nd Group 3 hd the shortest culmen (Mitchm, 1985). Groups 2 nd 4 were less, but

MITHAM AND WOBESERSALINE WATER AND DUKLINGS 35, cri ci 5. cr,1. v E i. E l l v N. z9 1 2. #{231} ) 4.9 9 z VI. > r 9 ci l 1. 5 ; l. 4 N [...5 ) i ) LI) 2 4 s l 1 l ) 5 N ) ).5. 5. t,., 4., 4 ;: 5 9,5 5 5 F z z,

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MITHAM AND WOBESERSALINE WATER AND DUKLINGS 37 still significntly ffected. By the end of the tril, ducklings in the control group hd molted most of their primry wing fethers, wheres molt hd not ourred in ny of the other groups. Ducklings in Groups 2 nd 8 hd significntly hevier slt glnds thn those in other groups. The liver of ducklings in Groups 3, 4 nd 8 ws significntly hevier thn tht of ll other groups. Thymic weight ws reduced significntly in Groups 2, 3 nd 8, s ws weight of the burs of Fbricius in Group 8. The verge kidney weight of Group 3 ws significntly hevier thn tht of ll other groups nd Groups 3 nd 8 hd lrger drenls thn the other groups (Tble 6). The force required to brek the left femur of ducklings from Groups 2, 3, 4, 6 nd 8 ws significntly less thn tht needed to brek the femur of control birds (Tble 7). Group 8 hd significntly less thymic nd splenic lymphoid tissue thn other groups. With splenic lymphoid depletion, corresponding hyperplsi in reticuloendothelil cells ws pprent. Vcuoltion of heptocytes ws incresed in Groups 4, 6 nd 8 nd slt glnds were hypertrophied in Group 8. Ducklings in Groups 3, 4 nd 8 hd significntly less trbeculr bone in the right femur thn did control birds (Mitchm, 1985). The concentrtion of N nd clcium in the serum ws significntly incresed nd tht of chloride nd phosphorus decresed in Group 8 s compred to Group 1 on dy 28 (Tble 5). The concentrtion of phosphorus in the serum ws reduced in Group 7 on dy 28 (Tble 5). The PV of Group 4 on dy 28 (1 = 0.465, SD = 0.146 liter/liter) nd the TP of Group 8 on dys 14 (1 = 51.1, SD = 5.4 g/liter) nd 28 (1 = 57.1, SD = 4.1 g/liter) were significntly elevted compred to controls (I = 0.363, SD = 0.104 liter/liter; I = 44.7, SD = 2.6 g/liter; I = 41.2, SD = 2.1 g/liter, respectively). Tril Ill During the first 2 wk of the tril, excret from ducklings in Groups 3 nd 3A ws modertely fluid. Those in Groups 2 nd 2A hd slightly fluid excret. On dy 14 the concentrtion of N in the serum of Groups 3, 3A, 2A nd 1A ws significntly elevted nd the serum chloride concentrtion of Group 3A (I = 112.6, SD = 3.6 mmol/liter), ws significntly incresed, when compred to Group 1 (1 = 107.4, SD = 2.3 mmol/liter). All groups, except Group 1, hd significntly elevted levels of serum Mg on dy 14. Groups 1A, 2A nd 3A were strted on wter contining 3,100 ppm N nd 1,300 ppm Mg on dy 15. Within 6 hr ducklings in Groups 2A nd 3A hd extremely fluid excret, while those in Group 1A hd slightly fluid excret. On dy 16 ducklings in Group 3A were inctive. By dy 18 ducklings in ll three groups huddled together nd those in Groups 1A nd 3A were severely depressed. On dy 19 three ducklings in Group 3A nd one in Group 1A died; the surviving ducklings in ll three groups were severely depressed, huddled together nd shivered. All remining ducklings were killed nd necropsied on dy 20. There ws no significnt difference in body weight mong groups to dy 12, but on dy 14 ducklings receiving the highest concentrtions of slts (Groups 3 nd 3A) were lighter thn those in other groups (Tble 6). On dy 20, Group 2 ducklings were significntly lrger thn ducklings from ll of the other groups (Tble 8). Groups 1A, 2A nd 3A, given the highly sline wter strting on dy 15, hd either grown very little or lost weight nd were significntly lighter thn ll other groups by dy 20 (Tble 8). Serum N, osmollity nd plsm TP, s well s slt glnd nd drenl weight nd extent of vsculr invsion of the zone of hypertrophy of the femorl epiphysel crtilge were ll incresed significntly in Groups 1A, 2A nd 3A when compred to control birds. As well, there ws hypertrophy of the slt glnd nd drenl. Leg length, serum potssium, nd weight of the burs of Fbricius nd thymus were reduced, s ws the mount of lymphoid tissue in the burs

38 JOURNAL OF WILDLIFE DISEASES, VOL. 24, NO. 1, JANUARY 1988 0. [ [ c. S.5 s )[ON.4 N.4 [.4.4 N 4 [[ [ [ [ [ s S t 4. 0 0 [ ) N If) l LI) > cb, ) 1)) S i. >. 0 0 0 0 0 r.4 F t VI [ ) ) [ l = s [00 l ) [ ) [ [ [ ) l [ S 3 LI)..4.. N ) N N ) l ) ) ) ) ) S )[[ l ) ) ) [ S.. s ) 6 #{243} ci S,, l l l l ) S 0 0 0 0, S...4, 5 5,. S

MITHAM AND WOBESERSALINE WATER AND DUKLINGS 39 nd thymus, nd trbeculr bone in the femur. Groups 1A nd 3A differed significntly from the control in hving elevted concentitions of Mg in the serum (Tble 9), together with lower totl white blood cell count s result of decrese in bsolute lymphocyte count. These birds lso hd less splenic lymphoid tissue nd heptocytic vcuoltion, reduced zone of hypertrophy of femorl epiphysel crtilge nd fewer osteoblsts (Mitchm, 1985). Groups 1A nd 2A hd decresed concentrtion of phosphorus in the serum (Tble 8). hnges found in only one of these three groups included reduced splenic weight nd number of osteoblsts (Group 1A) nd reduced force required to brek the femur (Group 3A). Group 3 differed from the control group in hving n incresed concentrtion of clcium in the serum nd reduced bursl lymphoid tissue. Group 2 hd incresed clcium concentrtion in the serum, nd lower thymic weight. Tril lila The results from this tril were similr to those obtined from the corresponding portion of Tril III nd most vribles mesured showed the sme generl trends (Mitchm, 1985). However, the ducklings in this tril were not s severely ffected, prticulrly cliniclly, by the chnge to the more sline wter on dy 15 of the tril. Group 3 ducklings dpted lest well. DISUSSION Mllrd ducklings cn survive when their only source of wter contins significnt mounts of N, Mg nd sulfte ions. The solutions used in these trils hd specific conductivity within the low to intermedite rnge of slinity for wetlnds (Fig. 1); nd were less sline thn nturl wters found to be lethl for ducklings (Swnson et l., 1984). Much of the slt pprently ws excreted through pssge of voluminous fluid excret. This effect ourred rpidly mong ducklings given wter contining s little s 500 ppm Mg or 1,000 TABLE 7. Force required to brek isolted femurs of mllrd ducklings given vrious types of sline wter s their only source of drinking wter for 28 dys (Tril II). Group n Force t breking point (kg) 1 (control) 9 15.1 2.1 2 (3,000 ppm N) 9 12.3 1.6 3 (3,000 ppm Mg) 8 7.6 2.0 4 (1,500 ppm N, 1,500 ppm Mg) 10 11.2 1.8 5 (1,500 ppm N, 500 ppm Mg) 10 14.1 1.6 6 (500 ppm N, 1,500 ppm Mg) 10 12.7 1.3 7 (500 ppm N, 500 ppm Mg) 9 13.9 1.9 8 (3,100 ppm N, 1,300 ppm Mg) 9 9.5 2.0 Vlues within columns followed by different superscripts re significntly different (P 0.05). ppm N, nd ws more prominent in birds drinking wter contining MgSO4 thn in those given N2SO4 solutions. The reltive contribution of urinry nd fecl excretion to this process ws not mesured, but both were probbly ctive in excretion. Both slts re cthrtic (Fingl, 1980) nd the Mg ion is lrgely responsible for this effect in the cse of MgSO4 (Reichelderfer et l., 1984). The group of ducklings receiving the highest concentrtion of Mg (Group 3, Tril II) hd enlrged kidneys, s did ll of the groups given highly sline wter t 14 dys of ge (Trils III nd lila) suggesting tht incresed renl excretion ourred. The slt glnds becme noticebly ctive within 4 dys in ducklings given wter contining 1,500 ppm N. Despite these mechnisms for slt excretion, wter contining concentrtions of these ions similr to tht found in mny pririe wetlnds hd sublethl effects on ducklings under lbortory conditions. The most obvious effects, other thn the pssge of fluid excret, were on growth nd food consumption. The mechnisms responsible for decresed food consumption nd the reltionship between food consumption nd I SD

40 JOURNAL OF WILDLIFE DISEASES, VOL. 24, NO. 1, JANUARY 1988 [I) QO[)0#{176} LI) c )oo ) c 0 5 5s. 0.5.0. [ ) 0. 0#{176} )Lt)OO 4 ) l )co 0..c [I) [I) N ll ) s. [ )NN.5 00 ] l l 0. 0..4.4.4 ].icth 0 [[ If) l l ), ) N )f)n 2 00. ) ]c0 ) ]l s l ) ). S [ Ot oo Ss oo zz SS ]0..0.0., 0. s. [f) )N & ) lcolf) VI 9> l ) l l) If) 00 )0l s 0.,.. 0 4 N QbL) c0l,) [l [.. [ )If S 1,.. Nc [ N ll ) S 5s l 00 l) 4.S )0#{176} 4 0#{176} ) l 0 0#{176}l00[ N l l ) s.,. _;; 5 0. s 0 2, s 5 ) S l 0 3,S) t c S 5 ss S

MITHAM AND WOBESERSALINE WATER AND DUKLINGS 41 TABI.E 9. oncentrtion of sodium, chloride nd mgnesium in the serum of mllrd ducklings given vrious types of sline wter for 14 dys (Tril III). oncentrt ion of elem ent i n serum (mmol/liter) N l Mg Group n I SD I SD I SD 1 1A (control) (control) 8 9 144,4b 149.9 3.2 2.8 107.4 110.6 2.3 3.6 0.88 2.05 0.15 0.33 2 2A 3 (500 ppm N, 250 ppm Mg) (500 ppm N, 250 ppm Mg) (1,000 ppm N, 500 ppm Mg) 8 10 10 148.0 150.1 150.0 1.7 2.1 4.4 109.8 109.4 107.6 1.1 2.2 5.2 2.15 1.93 2.38 0.43 0.40 0.35 3A (1,000ppmN,500ppmMg) 10 150.6 1.7 112.6 3.6 1.55 0.35 Vlues within columns followed by different superscripts re significntly different (P 0.05). growth re unknown. Pired feeding trils would be required to determine the proportion of the growth depression tht ws direct result of indequte food intke nd lterntively, decresed food consumption my hve resulted prtilly from smller body size in certin groups. Growth depression hs been observed in ducklings given solutions of Nl to drink (Holmes et l., 1961; Ellis et l., 1963; Riggert, 1977; Wink, 1980); in ducklings exposed to nturl sline lke wter (Swnson et l., 1984); nd in chickens given excess dietry Mg (Lee nd Britton, 1980; Lee et l., 1980). Fether growth ws decresed in ducklings given wter contining 1,500 ppm or more of either N or Mg, nd molt ws retrded in birds drinking wter contining 3,000 ppm of either ion. Swnson et l. (1984) noted retention of down in ducklings exposed to sline lke wter. onsumption of wter contining 3,000 ppm of Mg resulted in decresed growth of severl body prts, reduction in the mount of trbeculr bone in the femur, nd the bones broke more esily. These birds lso hd enlrged drenls nd the thymus ws decresed in size. The ltter chnges were probbly the result of stress (Freemn, 1971) with corticosteroidinduced lymphoid depletion (Glick, 1957; lmn, 1972; Glick, 1972). Ducklings receiving wter contining 3,000 ppm N hd reduced culmen length, thymus weight nd bone breking strength. The combintion of the two slts produced more complex effects. The group of ducklings receiving the lowest concentrtion of the two slts (Tril III, Group 2 with 500 ppm N + 250 ppm Mg) were hevier thn control birds. Those receiving 1,500 ppm of ech ion were significntly smller thn control birds nd hd reduced fether growth nd bone breking strength. Dyold ducklings were ble to survive on the most highly sline wter tested (3,100 ppm N, 1,300 ppm Mg, conductivity 15,250 mhos/cm), but t the end of the tril weighed less thn twothirds s much s controls. Also, they hd reduced fether growth, retrded molting, enlrged drenls, smll lymphoid orgns nd reduced trbeculr bone in their femurs. Additionlly, these birds lso hd severl chemicl bnormlities (elevted serum N nd clcium, nd plsm TP; decresed serum phosphorus nd chloride). The elevtion in N my hve been direct result of inbility to excrete sufficient N. Elevted plsm clcium levels hve been documented in cortisol treted birds (Siegel, 1968); thus the elevted clcium concentrtion could be stressinduced. Renl excretion of chloride is incresed when excess Mg is being excreted by the kidney (Mordes nd Wcker, 1978), which might explin the low chloride in these birds. Phosphorus depletion cn our lso when high levels of Mg re being consumed (Lotz et l., 1968). Hrvey et l. (1981) found tht sltstressed birds hd decresed heptic weight

42 JOURNAL OF WILDLIFE DISEASES, VOL. 24, NO. 1, JANUARY 1988 in proportion to body weight. Sltstressed birds tht were consuming less food should hve depleted heptic glycogen stores s result of ttempting to mintin glucose homeostsis (Dvison nd Lngslow, 1975). Ducklings in Groups 4, 6 nd 8 hd incresed heptic weight nd vcuoltion, which is n index of heptic glycogen s compred with the control group. Holmes et l. (1963) reported enlrgement of the liver with incresed heptic glycogen in domestic ducks given hypertonic N1, nd interpreted this to be the result of enhnced glucocorticoid ctivity. The gross nd histologic bone lesions reported by Lee et l. (1980) in chicks fed high levels of Mg (0.3, 0.5 nd 0.9% Mg dded to the rtion) were not observed in ducklings given the highest concentrtion of Mg. However, decrese in femorl trbeculr bone ws pprent in Groups 3, 4 nd 8 in Tril II. This my hve been the result of indequte food consumption, mlbsorption, or decresed retention of nutrients essentil for bone growth becuse of cthrsis (Lee et l., 1980), corticosteroidinduced bone loss (Peck et l., 1984), or combintion of these fctors. In these trils the force required to brek femurs of ducklings my be only nother mesure of duckling growth. It is not surprising tht the smller femurs from lighter ducklings broke with the ppliction of less force thn tht required to brek femurs from the hevier control ducks. For bone breking strength to be true mesure of the integrity of bone, it would hve to be considered in conjunction with other vribles such s bone sh, bone clcium, phosphorus nd Mg, nd bone length, weight nd volume. The ducklings in Trils III nd lila did not dpt well to chnge to more highly sline wter t 2 wk of ge. The birds stopped growing, becme depressed nd severl in Tril III died. This ws unexpected since dyold ducklings (Group 8, Tril II) survived on the sme wter, lthough they grew poorly. SchmidtNielsen nd Kim (1964) suggested tht ducklings cn better dpt to sline wter if the concentrtion of slt is incresed grdully, nd tht exposure to low levels of slt prime the slt glnds. This effect ws not evident in Trils III nd lila. However, the concentrtion of N (500, 1,000 ppm) given my hve been indequte to hve priming effect, becuse it did not cuse obvious slt glnd ctivity in erlier trils nd the slt glnds of Groups 2 nd 3 in Tril III were not significntly lrger thn those of control birds. Ducklings plced on the highly sline wter hd enlrged slt glnds, with microscopic evidence of hypertrophy s well s enlrged kidneys t dy 20, but it ppered tht they were unble to compenste completely for the incresed ion intke. All of the groups hd incresed serum osmollity, nd five of the six groups hd elevted serum concentrtions of either N nd/or Mg. Less consistent hemtologic chnges were decresed serum phosphorus, chloride, nd potssium, nd incresed TP nd PV, which ourred in three groups ech. Ducklings in Tril lila were not ffected s severely s those in Tril III. However, most mesured vribles showed the sme generl trend. The incresed concentrtion of clcium in serum nd the decresed size of lymphoid orgns seen in ll the groups, plus the incresed drenl weight nd drenl hypertrophy seen in birds in Tril III, re expected chnges in stressed birds. The decresed totl white blood cell nd lymphocyte count in Groups 1A nd 3A of Tril III were consistent with corticosteroidinduced leukopeni nd lymphopeni (Siegel, 1968). The bone lesions in ducklings in Groups 1A, 2A nd 3A in Tril III resembled chnges described in strved or proteindeficient nimls (Himes, 1978) nd/or in corticosteroidinduced bone loss (Peck et l., 1984), nd my hve resulted from combined cute stress nd mlnutrition. Swnson et l. (1984) found tht sline lke wter diluted to conductivity of 17,000 mhos/cm cused growth depres

MITHAM AND WOBESERSALINE WATER AND DUKLINGS 43 sion in mllrd ducklings. Our results indicte tht much lower concentrtions of the slts commonly found in pririe wetlnds hve sublethl effects on ducklings. These effects would be very difficult to detect in the field in birds of unknown ge. Mny of the chnges re nonspecific, could result from other stressors, nd my not be present in ducklings exposed to low concentrtions of slt. Severl fctors need to be considered in extrpolting our results to wterfowl in nturl hbitt. Wild ducklings my be ble to void toxic effects of sline wter through selection of less sline res or freshwter sources within sline mrsh (Swnson et l., 1984). In nturl sline environment the food consumed by ducklings might contin higher concentrtion of slt thn tht used in the lbortory, so the overll slt intke could be greter in the wild. Ducklings in the lbortory re exposed to different rnge of stressors thn re wild ducklings. Thus, it is impossible to predict how sline stressed ducklings would respond to vrious combintions of environmentl fctors such s severe wether, food shortge, predtor ctivity nd prsitism. The informtion from this study nd tht of Swnson et l. (1984) indicte tht sline wetlnds hve mrked limittions for duckling production nd my require specil mngement techniques such s provision of or enhncement of freshwter drinking res to chieve mximl wterfowl productivity. AKNOWLEDGMENTS We thnk D. Hncock, E. Hckett, E. Bueckert, I. Shirley, L. Stevenson, J. Diederichs nd D. Olexson for ssistnce with this project. The study ws funded by Medicl Reserch ouncil of nd Fellowship, nd by support from the Nturl Sciences nd Engineering Reserch ouncil of nd, Ducks Unlimited nd, the O Brien Foundtion nd ndin Wildlife Service. LITERATURE ITED.sII!N,. H.,.cxn J. E. LE\VIS. 1984. Evlution of hypervitminosis A in the rt by mesurement of tibil bone breking strin. Journl of Phrmcologicl Methods 1 1 : 9195. LANIAN, H. N. 1972. orticosteroids nd lymphoid cells. New Englnd Journl of Medicine 287: 388 397. DANIEL, W. W. 1978. Applied nonprmetric sttistics. Houghton Muffin, Boston, Msschusetts, 503 pp. DAvISON, T. F., AND D. R. L.A\usLow. 1975. hnges in plsm glucose nd liver glycogen following the dministrtion of gluconeogenic precursors to the strving fowl. omprtive Biochemistry nd Physiology 52A: 645649. DUEBBEIST, H. F., J. T. LUKE\IOE\, AND D. F. S11..Rp. 1983. oncentrted nesting of mllrds nd gdwlls on Miller Lke Islnd, North Dkot. The Journl of Wildlife Mngement 47: 729 740. ELLIS, R. A.,.. G0EwrENIILLEH, R. A. DELELLIS, AND Y. H. KABLOTSKY. 1963. The effect of slt wter regimen on the development of the slt glnds of domestic ducklings. Developmentl Biology 8: 286298. FINGL, E. 1980. Lxtives nd cthrtics. In Goodmn nd Gilmn s the phrmcologicl bsis of therpeutics, 6th ed., A. G. Gilmn, L. S. Goodmn, nd A. Gilmn (eds.). McMilln Publishing ompny, Inc., New York, New York, pp. 10021012. FREEMAN, B. NI. 1971. Stress nd the domestic fowl: A physiologicl pprisl. World s Poultry Science Journl 27: 263275. GI.lcK, B. 1957. Experimentl modifiction of the growth of the burs of Fbricius. Poultry Science 18: 1823. 1972. ortisone, ge nd ntibodymedited immunity. Interntionl Archives of Allergy 43: 766771. HANISIER, U. T. 1978. The sline lkes of Ssktchewn I. Bckground nd rtionle for sline lkes reserch. Interntionle Revue der Gesmten Hydrobiologie 63: 173177. HARVEY, S., H. KLANDORF, ANDJ. G. PHILLIPS. 1981. Effects of food or wter deprivtion on circulting levels of pituitry, thyroid nd drenl hormones nd glucose nd electrolyte concentrtions in domestic ducks (Ans pltyrhynchos). Journl of Zoology (London) 194: 341361. HINIEs, J. H. 1978. Bone growth nd development in proteinclorie mlnutrition. World Review of Nutrition nd Diet 28: 143187. HOLMES, W. N., D. G. BUTLER, AND J. G. PHILLIPS. 1961. Observtions on the effect of mintining glucouswinged gulls (Lrus glucescens) on fresh wter nd se wter for long periods. Journl of Endocrinology 23: 5361. J. RONSII.xW, AND J. GORSLINE. 1978. Some effects of ingested petroleum on sewterdpted ducks (Ans pltyrhynchos). Environmentl Reserch 17: 177190.

44 JOURNAL OF WILDLIFE DISEASES, VOL. 24, NO. 1, JANUARY 1988 J. G. PIIILI.IPS, AND I.. JONES. 1963. Adenocorticl fctors ssocited with dpttion of vertebrtes to mrine environments. In Recent progress in hormone reserch, Vol. 19, G. Pincus (ed). Acdemic Press, New York, New York, pp. 619672. KRAP,. L., AND. A. SWANSON. 1978. Foods of juvenile, brood hen nd postbreeding pintils in North Dkot. ondor 79: 504507. LEE, S., AND W. M. BRITTON. 1980. Mgnesium toxicity: Effect on phosphorus utiliztion by broiler chicks. Poultry Science 59: 19891994.,ANDG.N.R0WLAND. 1980. Mgnesium toxicity: Bone lesions. Poultry Science 59: 24032411. LOTZ, M., E. ZISMAN, AND F.. BARTTER. 1968. Evidence for phosphorusdepletion syndrome in mn. New Englnd Journl of Medicine 278: 409415. LYNH, M. J., S. S. RAPHAEL, L. D. MELLOR, P. D. SPARE, AND M. J. H. INwooD. 1969. Medicl lbortory technology nd clinicl pthology, 2nd ed. W. B. Sunders, Phildelphi, Pennsylvni, 1359 pp. MITHAM, S. A. 1985. Effects of rtificil nd nturl sline drinking wter on mllrd ducklings. MS. Thesis. University of Ssktchewn, Ssktoon, Ssktchewn, nd, 340 pp. MoRDES, J. P., AND W. E.. WALKER. 1978. Excess mgnesium. Phrmcologicl Reviews 29: 273 300. PEAKER, M., AND J. L. LINZELL. 1975. Slt glnds in birds nd reptiles. mbridge University Press, mbridge, Englnd, 307 pp. PEK, W.,. GENNARI, L. RAISZ, P. MEUNIER, E. RITZ, S. KRANE,. NUKI, AND L. V. AvI0LI. 1984. orticosteroids nd bone. lcified Tissue Interntionl 36: 47. RAWSON, D. S., AND J. E. MOORE. 1944. The sline lkes of Ssktchewn. ndin Journl of Reserch 22: 141201. REIHELDERFER, M., B. PERO, V. LORENZSONN, AND W. A. OLSEN. 1984. Mgnesium sulfteinduced wter secretion in hmster smll intestine. Proceedings of the Society for Experimentl Biology nd Medicine 176: 813. RIGGERT, T. L. 1977. The biology of the mountin duck on Rottnest Islnd, Western Austrli. Wildlife Monogrphs 52: 167. SHMIDTNIELSEN, K., AND Y. T. KIM. 1964. The effect of slt intke on the size nd function of the slt glnd of ducks. Auk 81: 160172. SEInE, J. R., AND. A. SWANSON. 1976. Feeding ecology of breeding gdwlls on sline wetlnds. The Journl of Wildlife Mngement 40: 6981. SIE;EL, H. S. 1968. Blood cells nd chemistry of young chickens during dily ATH nd cortisol dministrtion. Poultry Science 47: 18111817. STANDING OMMITTEE ON AGRIULTURE, FISHERIES, AND FORESTRY. 1984. Soil t risk, nd s Eroding Future. A report on soil conservtion to the Sente of nd. ommittees nd Privte Legisltion Brnch, The Sente of nd, Ottw, Ontrio, nd, 129 pp. SWANSON,. A., V. A. ADOMAITIS, F. B. LEE, J. R. SERIE, AND J. A. SHOESMITH. 1984. Limnologicl conditions influencing duckling use of sline lkes in southcentrl North Dkot. The Journl of Wildlife Mngement 16: 445450. WINK,. S. 1980. Effects of slt wter feeding nd reduced food intke on bone structure of domestic ducklings. Antomicl Record 196: 209A. Received for publiction 6 Jnury 1987.