D. L. Rankins, Jr.3, G. S. Smith4 and D. M. Hallford New Mexico State University5, Las Cruces 88003-0003 ABSTRACT

Livestock grazing lush Kochiu scopan'a (L.) Schrad. sometimes experience BW loss, hyperbilirubinemia, photosensitization, and polyuria. Animals fed kochia hay may exhibit milder or negligible signs of toxicosis but fail to utilize nutrients efficiently. To characterize early aspects of kochia toxicosis and to evaluate prospective treatments, 12 wether lambs (34 f 3 kg) were fed prebloom kochia hay (83% OM, 15% CP, and 6.3% total oxalate) and treated as follows: 1) no treatment; 2) drenched daily with aqueous %SO, to provide 30 mg of Zn/kg of BW, 3) injected i.p. twice weekly with N-acetyl-L cysteine (CYS) in saline (21 m a g of BW) plus trans-stilbene oxide (TSO) in corn oil (27 m a g of BW); and 4) treated as 2) plus 3). Treatments were imposed factorially (2 x 2) with three lambs per treatment. Kochia intake (ad libitum) averaged .57 kg/d (1.7%of BW) for 80 d, and digestibility of DM and CP were 44 and 59%,respectively, at wk 4, but BW loss was severe (6 to 11 kg/lamb). After 14 d, serum insulin and prolactin were decreased (P c .OS) below initial values (.48 to .ll and 102 to 28 ng/ml, respectively). Serum somatotropin increased (P c .05) from 4.5 to 6.8 ng/ml at 4 wk. Serum total bilirubin increased threefold at 3 wk (P c .05) and declined slightly thereafter through 10 wk. Early changes in serum enzymes reflected mild hepatotoxicosis without cholestasis, whereas histopathology (at 80 d) showed diffuse hepatocyte swelling and nephrosis. Treatment to stimulate hepatic glutathione production and conjugation provided no benefit, whereas drenching with %SO4 tended to exacerbate bilirubinemia and elevated serum lactate dehydrogenase, aspartate aminotransferase, and alanine aminotransferase activities. Key Words: Kochia scopariu, Toxicity, Sheep, Somatotropin, Prolactin, Insulin J. Anim. Sci. 1991. 69:29322940

Introduction

'Journal article 1530 of the New Mexico Agric. Exp. sk. CNW. ~FM in part ty the U.S. ~ e p t .of the Interior, Geological Survey, through the New Mexico Water Resources Res. Inst. Contents of this article do not necessarily reflect views and policies of the U.S. Dept. of the Interior. Mataials used in radioimmuwassays were provided by National Hormone and Pituitary Rogram (Univ. of Maryland School of hied.) and A. P. Parlow (Pituitary Hormones and Antisera Center, Harbor/ULCA Med. Center, Torrsacc, CA). Appreciation is expressed to L. Rankins. D. KieM, D. Penine, R. Reynolds, D. Holcombe, and R Spoon for technical and clerical aSSiStance.

h e n t address: Dept. of Anim. and Dairy Sci.. Auburn Univ., Auburn, AL 36849. '%o whom correspondence should be sent. b e p t . of ~nim.and m e sci. Received May 29, 1990. Accepted January 18, 1991.

Kochiu scopariu (L,.) Schrad (Kochia) is a hardy, drought-resistant plant widely used as emergency forage for livestock (Erickson and Moxon, 1947; Bell et al., 1952). Kochia is a prospective forage crop for arid areas (Stovall, 1970; Finley and Sherrod, 1971; Sherrod, 1971, 1973) despite occasional poisoning of livestock (Galitzer and Oehme, 1978; Dickey and Berryman, 1979; Sprowls, 1981; Dickey and James, 1983). Oxalate was implicated as a probable toxicant in these earlier reports, but recent research using lush kochia (Kiesling et al., 1984; Smith et al., 1986; Hoefler et al., 1988; Thilsted et al., 1989) has implicated alkaloids in kochia toxicity. Rankins (1987) and Rankins and Smith (1987) reported treat-

2932

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ALTERED METABOLIC HORMONES, IMPAIRED NITROGEN RETENTION, AND HEPATOTOXICOSIS IN LAMBS FED KOCHlA SCOPARIA HAY' s2

METABOLIC PERTURBATION IN LAMBS FED KOCHIA

ExperlmentalProcedure

Kochia was seeded and grown in irrigated plots at the New Mexico State University Agricultural Science Center at Clovis, NM. Foliage was harvested as hay at prebloom stage, chopped in a hammer mill to pass a 1.27cm screen, and fed in unrestricted amounts to 12 fie-wool wether lambs (34 f 3 kg) for 80 d during late summer and autumn. Lambs were penned individually in outdoor pens (1.5 m x 6 m) at Las Cruces, NM with access to trace mineralized salt6 and water. Hay intakes were monitored daily and BW were measured weekly. Lambs were assigned randomly to two treatments in a 2 x 2 factorial arrangement: three lambs (controls) received no treatment; three lambs received N-acetyl-Lcysteine plus trans-stilbene oxide (CYS + TSO: 21 mg of N-acetyl-L-cysteinebg of BW, dosed i.p. in saline twice weekly, plus 27 mg of TSO/kg of BW, dosed i.p. in corn oil twice weekly); three lambs received aqueous zinc sulfate (ZN:133 mg of zinc sulfate to provide 30 mg of Zn/kg of BW, orally drenched daily, beginning 3 d before onset of kochia feeding); and three lambs received CYS + TSO treatment plus ZN treatment. Blood samples were collected weekly via jugular venipuncture into sterile serum separator tubes, allowed to clot at room temperature for 35 min, and centrifuged at 2,300 x g for 15 min at 4'C. Serum was decanted and stored at -20'C until it was analyzed for clinical components (Chem-30 profile) by a c o m e r cid laboratory7.

%orton Salt Division of Morton Thiokol, Inc., Chicago, n; blocks had 95 to 98% NaCl with added Zn, Mn Pe, Cn, I, and Co. 'Southwest Medical Laboratory, Las Cruces, NM. All assays were conducted in duplicate or triplicate. Coefficients of variation (96) within and between assays were: iosulm 8.5 and 6.8; somatotropin 7.4 and 8.1; and prolactin 9.4 and 11.2, respectively. 9John Thilsted, Vet. Diag. Lab., New Mexico Dept. of Agric., Albuqque.

*

At d 0, 14, and 28, lambs were subjected to intensive blood sampling. Feed was removed at 1800 the day before blood was collected. Lambs were bled (jugular venipuncture) at O600 and 0700, and respective treatments were administered. Kochia hay was offered from 0700 until 0800, then removed for 4 h. Blood was collected hourly from 0800 until 1200. Serum was harvested as described above and stored at -20'C until it was analyzed. Serum insulin (Sanson and Hallford, 1984), somatotropin (Hmfler and Hallford, 1987), and prolactin (Spoon and Hallford, 1989) were quantified by double antibody RIA*. Ten days after kochia feeding began, all lambs were placed in metabolism stalls to determine nutrient digestibility and N balance. After a 7 d adjustment period, feces and urine were collected for 10 d. During collection of excreta, lambs were fed hay at 95% of previous ad libitum intake. All orts, feces, and urine were collected, measured, and sampled (10%) daily. Urine was collected daily into jugs containing .25 ml of toluene, and composite collections (10%) were preserved with .33 ml of toluene/100 ml of urine and stored at -20'C until they were analyzed for N (AOAC, 1984). Feed and fecal samples were oven-dried (50'C; 48 h), ground to pass a 2-mm screen in a Wiley mill, and analyzed for DM, N (AOAC, 1984). NDF, ADF, ADL, and ADIN ( b r i n g and Van Soest, 1970). Total and insoluble oxalates were determined by fractional extractions into lipophilic solvents from acidified vs nonacidified aqueous solutions and gas chromatography using a flame ionization detector (Rankins, 1989). Methodology was standardized by usage of purified oxalic acid as a reference standard and as an internal, recovery standard. At d 80 after the onset of kochia hay feeding, all lambs were slaughtered and examined grossly. Samples of livers and kidneys were collected into neutral buffered formalin and examined by a veterinary pathologist9. Data were subjected to ANOVA using GLM procedures of SAS (1982). Insulin, prolactin, and somatotropin data were subjected to split, split-plot analysis of variance for repeated measures over time (Gill and Hafs, 1971). The factorial arrangement of treatments was included in the main plot and tested using variation associated with animals within C Y S + TSO x ZN as the error. Week of sampling was included in the subplot, and hour

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ments that were beneficial to rats fed dried foliage from lush kochia. Experimentation reported here characterized early aspects of toxicosis in sheep fed hay from lush kochia and evaluated treatments that might alleviate early aspects of kochia toxicosis.

2933

2934

ET AL.

RA"S

m

CYS + TSOb

Item No. of lambs

Hay intake, 80 d, kg/d BW change, 80 d, kg Digestibility, d 17 to 27, % DM OM NDF

ADP CP Nitrogen balance, g/d Biological value of Nh, 46

No

Yes

5e

5=

58

56

-8 A

-82

45 58 48 31 57 -2.9 12

42 62 47 31 61 -1.7

20

SEd

No 6

.1 1.o

.76 -5.6f

3.9 3.2 3.5 3.8 3.5 .8 4.4

5Zf 6Zf 50 34 67f

-sf 26f

Yes

SEd

4= .44g -11.6

.1 1.o

355 5og

44 28 5 6 -4.18 5g

4.3 3.4 3.7 4.0 3.8 .9 4.8

aAnalysisof variance showed no CYS + TSO x ZN interactions (P > .25), therefon, main effect means me reported. + 27 mg of TSO/kg of BW dosed i.p. lwice weekly. '133 mg of ZnSO4 in aqueous solution/kg of BW in daily oral drench. dSE = standard error. TWO lambs treated with ZO were removed early in the trial because of circumstances umelated to the treatments. % b w values, within treatments, having different superscripts differ (P < .05). h ~ ~ s u m that e s metabolic fecal N = .5 g/100 g of DM intake a w ~endogenous urinary N = 33 mg/kg of BW; values calculated by Thomas-Mitchell equation (Maynard et al., 1979, p 436). b21 mg of C Y S

between five lambs that received CYS + TSO (.56 kg/d) and five lambs that did not (.58 kg/ d). Two lambs were removed from the experiment because of circumstances unrelated to treatments. However, four lambs drenched with ZnSO4 consumed less hay (.44kg/d) than six lambs given no &SO4 (.70 kg/& P < .05). All lambs lost BW during the 80-d study (8.3 f 1.0 kg), and treatment with CYS + TSO had no effect (P > .lo); lambs drenched with ZnSO4 lost 11.0 kg, whereas lambs given no %SO4 lost only 5.6 kg (P < .OS). With 83% OM, the kochia hay contained Results and Discussion approximately 3.3 McaVkg as GE. DigestibilA composite sample of the kochia hay fed ity of OM (Table 1) averaged 60% (* 3%), throughout the 1O-d metabolism phase of the yielding calculated DE values of 2.0 Mcavkg. study contained 91% DM and (% of DM) 83% Assuming ME to be .82 x DE (NRC,1985), OM, 17% ash, 69% NDF, 46% ADF, 15.4% ME would amount to 1.64 McaVkg. With CP (N x 6.25), 13% available CP (as [total N - intakes at .57 kg/d, ME would amount to about ADWJ x 6.23, 8.5% ADL, and .39% ADIN. .93 McaVd. Growing (34 kg) lambs fed The kochia hay contained 6.3% of DM as total nutritious feed should consume about 4% of oxalate and 5.4% of DM as soluble oxalate BW/d, amounting to 3.1 McaVd, and should gain 200 to 300 g/d QWC, 1985). Thus, for (determined as oxalic acid). During the 80-d trial, kochia hay intake lambs in this trial, kochia hay as sole diet averaged .57 kg/d (SE = f .07 kg), amounting should have provided energy sufficient to to 1.7% of BW, and did not differ (P > .lo) maintain BW or to sustain slight gains of sampling was the sub-subplot component. Serum clinical constituents were evaluated by split-plot analysis of variance for repeated measurements on animals (Gill and Hafs, 1971). When significant treatment x week interactions were detected, differences among weeks were separated using the lsd method (Steel and Tome, 1980). Effects of treatments on digestibility coefficients and N retention values were analyzed as a completely random design with 2 x 2 factorial arrangement (Steel and Tome, 1980).

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TABLE 1. PEED INTAKE AND BODY WEIGHT CHANGE FOR FTNEWOOL WETHER LAMBS (34 f 3 KG) FED HAY FROM LUSH KOCHIA FOLIAGE AS TOTAL DIET FOR 80 DAYS, WITH HAY D1GESTIBILTL"Y AND "ROGEN BALANCE MEASURED AT DAYS 17 THROUGH 27, AS AFFECTED BY TREATMENT WITH N-ACETYL-L-CYSTEINE (CYS) PLUS TRANS-STILBENP.OXIDE (730)AND(0R) ZINC SULFATE

METABOLJC PERTURBATTON IN LAMBS FJ2D KOCHLA

Roman, 1984), presumably through stimulation of hepatic glutathione production and glutathione-Stransferase activity. Table 2 shows serum concentrations of insulin, prolactin, and somatotropin at onset (wk 0) and after lambs had consumed kochia hay for 2 and 4 wk, Split, split-plot ANOVA showed neither treatment x sampling time (h) nor treatment x feeding time (wk) interactions for insulin or prolactiq therefore, means were p l e d across treatments and samphg times (h) to show effects of kochia ingestion (wk) and pooled across weeks and sampling times to examine effects of treatments. Senun insulin was decreased (P < .01) from .48 ng/ml at onset of kochia feeding to .l1 and .OS ngml at wk 2 and 4, respectively. Blood glucose levels (discussed below; measured at wk 0, 3, 6, 8, and 10) dropped from 82 mg/dl at onset to about 60 mg/d at wk 3 and 65 mg/d at wk 6. Thus, insulin levels reflect diminishing energy nutrition in these lambs that had received goodquality alfalfa hay before being fed kochia hay but were losing BW while being fed kochia hay. Serum prolactin concentrations (Table 2) dropped (P < .01) from 102 n g / d before lambs started to consume kochia hay (wk 0) to 28 n g / d at wk 2 and 36 ng/ml at wk 4. Many factors can affect s e r u m prolactin, including changes in photoperiod. Even the unusual activities and stresses of initial blood sampling (wk 0), which were obviously less stressful at subsequent bleedings, might have contributed to differences in prolactin levels at wk 0, 2, and 4. Nevertheless, it seems probable that some substance(s) in the kochia hay contributed to the drastic reduction in serum prolactin, and it seems probable that the lowering of serum prolactin level Contributed to negative N balance and BW loss. Clavine alkaloids in endophyte-infected tall fescue forage decrease prolactin levels in livestock, causing percurbed energy metabolism with excessive heat loss, depressed N retention, and poor feeding performance (Maag and Tobiska, 1956; Hurley et al., 1980; Elsasser and Bolt, 1987). Carboline alkaloids (harmane and harmine) were found in Kochia scopuriu studied by others @rest-Karbowska et al., 1978), but alkaloids in kochia from New Mexico have not yet been identified. Suppression of serum prolactin levels is a valuable index in diagnosis of tall fescue toxicosis in livestock (Kerr et al., 1990), and it may prove to be likewise

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(approximately 30 g/d). Instead, lambs lost 8.3 kg in 80 d, amounting to losses of 104 g/d For maintenance or slight gain of BW, lambs of this size would require about 53 g of digested CP daily (i.e., onethird of digested CP, [.85 x 191 g = 162 g]; based on values in NRC [1985]), whereas in this trial lambs obtained .57 kg hay x 15.4% CP x 59% apparent digestibility coefficient = 52 g of digested CP. Although not adequate to support BW gain, the intakes of both DE and digestible protein by lambs fed kochia hay in this trial were far too high to account for BW losses averaging 8.3 kg in 80 d Because ADIN was only .39% of DM, it might be presumed that most of the remaining N was proteinaceous. However, Karachi (1986) determined that alkaloids accounted for .4 to 1.7% of DM in lush kochia grown on irrigated plots in New Mexico and nitrate accounted for .2 to 3.4% of DM. An appreciable portion of the digested CP was, therefore, obviously provided to these lambs fed kochia hay in the form of nonprotein nitrogen (NPN). Sherrod (1973) attributed low N retention to relatively high nitrate levels in kochia. Nevertheless, it seems improbable that BW losses by the lambs in this study can be attributed primarily to excessive NPN in the kochia hay fed. Lambs fed kochia hay for 3 wk had negative N balance during the 10-d m e t a b lism trial that averaged 2.3 g N/d (Table 1). These N losses are commensurate with excessive BW losses (mean = 8.3 kg) during the 80-d trial. They reflect excessive urinary N from tissue protein degradation and suggest deranged metabolism of protein and(or) energy in view of values calculated above that indicate digested energy and protein sufficient for maintenance. Similar effects in animals fed kochia have been reported by Finley and Sherrod (1971), Sherrod (1973), Hoefler et al. (1988), and Cohen et al. (1989). Treatment with CYS + TSO provided neither benefit nor detriment to lambs fed kochia hay (Table 1) in terms of feed intake, BW change, or hay digestibility, although this treatment tended to improve N balance and biological value (a calculated value that has dubious interpretation under conditions of excessive BW loss). The dosages of CYS and TSO had been extrapolated on the basis of BW.75 from dosages that effectively stimulated heptachlor clearance by rats (Scheufler and

2935

2936

RANKINS ET AL.

tive test for plant alkaloids (Burns,1964). and severity of toxicosis in rats fed the dried herbage paralleled plant juice reactivity to Dragendorff's test (Smith et al., 1986, 1989). Serum somatotropin concentrations (Table 2) showed a treatment x week interaction (Pc .01) and are, therefore, presented by treatment within weeks. There were no treatment x weeks interactions or treatment x hour interactions; therefore means were pooled across hours. The interpretation of somatotropin data may be tenuous because sampling protocol was based on seven hourly bleedings at wk 0, 2, and 4. Somatotropin was elevated almost twofold (Pc .05) in all lambs at wk 4 over wk 0, but somatotropin in lambs treated with C Y S + TSO was elevated less (P< .08) than that in lambs without CYS + TSO. Effects of ZN treatment on serum somatotropin levels were complicated by treatment x hour interaction (P < .05), whereby Zn-treated lambs had higher values, but the pattern of hourly values changed in Zn-treated vs untreated lambs. The

TABLE 2. SERUM CONCENTRATTONS OF INSULIN, PROLACTIN, AND SOMATOTROPIN IN FINE-WOOL FHETHER LAMBS (34 f 3 kg) PED HAY FROM LUSH KOCHLA AS TOTAL DIET AND TREATED WITH N-ACETYGGCYSTEINB (CYS) PLUS TRANS-STILBENE OXIDE (TSO) OR ZINC SUJJATE @u) FOR 4 WEEKS Hormone

*UP

All lambs,W l P

2

0 Insulin, nghnl

Prolactin, nghnl

.48b 102 No

m u w m d Prolactiqng/mld

somtotropine, nlJml WkO Wk2 wk4

21

52 4.4 42 7.8€

.llC 28' CYS + TSO

SE (n = 72)

4 .08'

.oQ 17

3@

ZN

YeS

No

YeS

.26 62

24 59

55

4.6 4.0

4.6 4.1

5.59

h

.34

4.4 4.0 h

SE .oQ 6.7

.35 .42

-

%plit split-plot analysis of variance revealed no treatment x week or treatment x hour interactions (P > 50). Therefore. meam were pooled m s s treatments and hour. (Lamb were bled hourly for 7 h.) b * c values ~ ~ with merent superscript letters differ (P < .01). dsplit split-plot analysis of variance revealed no h'eatment x hour or treatment x week inmactions (P > 50). Therefore, means werc pooled across hour and week. Lambs were bled hourly for 7 h at wk 0,2, and 4. Analysis of variance showed no C Y S + TSO x ZN i n t ~ t i o n (P s > .80). Meaos within main effect treatments do not differ (P >

.lo).

eSplit split-plot analysis of variance revealed a treatmemt x week interaction (P < .01). Therefore, effects of treatment were examined within week. Analysis of variance showed no C Y S + TSO x ZN interaciton (P > .OS). %Low values differ (P < .OS). h N x hour interaction was detected (P < .OS). Findings . ed in text.

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valuable in assessing the nutritional and toxicological aspects of livestock responses to kochia forage. Foliage from lush kochia grown under irrigation in New Mexico was toxic when grazed by cattle (Kiesling et al., 1984; Thilsted et al., 1989), when fed as hay to sheep (Hoefler et al., 1988), and when fed to rats in dry fonn mixed with commercial rat feed (Smith et al., 1986, 1989). Jn all cases, early mild hepatotoxicity progressed to renal involvement (Smith et al., 1989; Thilsted et al., 1989). Early changes in serum constituents seem consistent with alkaloids toxicosis, although nitrate, oxalate, saponins, and other substances have been implicated (Galitzer and Oehme, 1978) as possible toxicants in kochia. Lush kochia foliage at Tucumcari, NM contained .4 to 1.2%total alkaloids by gravimetric measurement after solvent extraction and fractionation (Karachi, 1986). Lush kochia foliage at Clovis, NM varied widely in substances reactive to Dragendorff's reagent, a presump

2937

METABOLIC PERTURBATION IN LAMBS PED KOCHIA

unexplained. Serum Ca levels dropped slightly below the initial value (P< .05) but generally remained within the range of normal values for sheep fed hay. This shows that oxalate in the hay (6.3% of DM as total; 5.4% of DM as soluble) had not elicited hypocalcemia and probably was coincidental with, rather than a cause of, the deranged metabolism Mild elevation of unwnjugated bilirubin (2.9-fold; P < .05) at wk 3 and afterwards, without a sustained elevation of conjugated bilirubin, shows impaired conjugation of bilirubin and suggests impaired metabolism of hepatocytes. This response is typical of blood bilirubin levels in sheep fed hay from lush kochia in New Mexico (Hoefler et al., 1988). Mild hepatocyte damage is further indicated by slight elevation of lactate dehydrogenase, aspartate aminotransferase, and alanine aminotransferase (Table 3). No indication of biliary

TABLE 3. BLOOD SERUM CONSTITU&NTS IN FINE-WOOL WETHER LAMBS (34 f 3 kg BW) FED HAY FROM LUSH KOCHIA SCOPARIA AS TOTAL.DIET THROUGH 10 WEEKS" Week Constituent

0

3

Sodium, W t e r Potassium, mEqflitex Chloride, mEq/lter Bicarbonate (COZ), m€?@ter calcium, Ing/dl Phosphorus (0, Wdi Glucose, mgldl Triglycerides,mg/dl Cholesterol,mgldl Total protein, g/dl Albumin, gldl Globulin, g/d Blood urea N, mgldl Creatinine, m@di Blood urea NKreatinine Uric Acid,mddl Bilirubin (unconjugated), mg/dl Bilirubin (Conjugated), @dl Enzymes, Ukter Alkaline phosphatase Creatine kinase Gamma-glutamyl transpeptidase Lactate dehydrogenase Aspartate aminotransferase Alanine aminotransferase Aspartate aminotransferaSejAlanine aminotransferase

158b 5.4

152b 5.0 1lob 29' 9.3' 7.e 61OC 20.F 82d

lllb

27bc 10.8d 6.5' 82b 19.p 4ab

5.2' 3.7b l.Sb 20 .7b 28d .2@

6

5.9d

3.8b 2.1C 25 1.2c Isb .34d

.46d

.lab .01

152b 5.5 112b

w

668 524b 117b 16b

349 41' 5Ub 152bc 1l b

7

14 ~

102'

9.F 55bc 69 20.v 91' 6.3d 3.7b 2.6d 23 12' 23' .63' .36*

25b

46b

66c

4.1b 2.4' 1.8b 17 .7b 244

65d 3.7b 2.9 21 .9b 23'

41'

6

8 ~

1.6 .14 1.3 .8 .19 .32 3.5 1.2 4.8 .17 .08

9.4'

5.P 6oc 15.3'

.06 2.6 .06

1.2

.lob

.2@

.03

.26bc .o 1

.35'

.03

.01

.004

31b 1,025 29b 709h 2464 434

1,071' 25acd 31k

153b 5A 113b

24b 6.7b 4 9 49d llSb

.01

5 1' 1,178

SEf

10 132' 5.3

25b

.03

209 48d

8

ab"

5.7 349 1.3 134 32 6

861 41' 840k 341d

aod 7

~~

'Split-plot analysis of variance revded no time x treatment interactions (P> .w) except where noted by suptrsnipt 0. b*crd%hmsin the same rows that do not have a common letter in the superscript differ (P < f ~ ~ d a error, r d n = IO.

.as).

Downloaded from https://academic.oup.com/jas/article-abstract/69/7/2932/4705182 by Iowa State University user on 14 January 2019

overall pattern of somatotropin levels was consistent with the view that elevated somatotropin reflected severity of BW loss. It seems probable that serum somatotropin, like insulin (but unlike prolactin), responded to deranged energy metabolism rather than causing the derangement. Table 3 shows means of serum clinical constituents for all lambs fed kwhia hay at wk 0, 3, 6, 8, and 10 (means are p l e d across treatments, although interactions of treatments x weeks were noted in some cases). Nearly all values were decreased (P< .05) at wk 8, which suggests probable hemodilution at that time. Generally, glucose levels diminished (P < .05), cholesterol levels increased (P < .05), and triglycerides diminished (P < .05) by wk 8, which reflects the lowered plane of nutrition and increasingly poor condition of the lambs. Trends toward improvement at wk 10 are

2938

ET AL.

R 4 " S

TABLE 4. SERUM CONSTITUENTS IN FINE-WOOL WETHER L A M B S (34 f 3 kg BW AT ONSET) FED HAY FROM LUSH KOCHIA SCOPARlA AS TOTAL DIET THROUGH 10 WEEKSa WHILE TREATED WITH N-ACTYLL-CYSTEINE (CYqb FLUS TRANS-STILBENE OXIDE pSO)b AND OR ZINC SULFATE (ZN)'

CYS + TSO

zJ4

Constituent

No

Yes

No

sodium,mEqfliter Chloride, meq/llter Potassium, mEqfliter Bicarbonate (Cod, mesflrter

156 110 5.3 26 9.3 5.8 63' 62 350 2.1 18 .9 .30 .34 .o 1

155

155 110 5.40 25 9.1 6.4' 69 530 3.6' 2.10 17 .9 27 .270 .o 1

90 518 41 809

77 325 40 638

35

27

calci- @dl Phosphorus (i), mg/dl Glucose, m&dl Triglycerides, @dl fiburnin, g/dl Globulin, g/dl Blood urea N, mpjrdl Creatinine, @dl Uric acid, mg/dl Bilirubin (unconjugated),mddl Bilirubin (conjugated), mg/d Enymes, Ubter Alkaline phosphatase creatine kinase Gamma-glutamyl transpeptidase Lactate dehydrogenase Aspartate aminotransferase Alanine aminomamsferase

e

109

5.4 26 9.2 6.3 63' 66 3.40 2.3 19 1.0 .30 ,30 .a2

e

88 303

370 528

1220 250

Yes

SE

156 108 5.2' 28* 9.s 5.80 62' 82' 3.30 .'4.2 20 1.o .3P*

.&* .a2

78 553 430 1,18lo* 3160. 440.

.9 1.0 .07 .6 .19 .20 3.8 7 .10 .14 2.4 .04 .02 .06 .003 9 260 3.6 230 42 5

%pat-plot analysis of variance revealed no CYS + TSO x weeks or ZN x weeks interactions (except where noted by superscript 0); therefore, means were pooled across weeks, within treatments. %cates that within-treatment means differed (P< .OS)at one or more weeks (usually later rather than initially or early in trial). b.L1 mg of CYS + 27 mg of TSO/kg of BW, dosed i.p. twice weekly. '133 mg of ZnSO4 in aqueous solutioq/kg of BW, daily by oral drench. d~though split-plot analysis of variance revealed intaactions of treatment x week^ in several constituents, means were pooled across weeks and presented here, because differences between treatment means were small and biologically Unimportant. or because treatment effects were negligible at onset (wk 0 and 3) and significant (P < .OS) only at later time(S).

%nee-way interaction of CYS + TSO x ZN x weeks made CYS + TSO treatment effect uninterpretable, overall, except that the adverse effect of ZN was alleviated by CYS + TSO during early weeks but not later. *Main effect means differ (P < .05).

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and the early phase (wk 3) of treatment; differences occurred later (wk 6, 8, and[or] 10). Therefore, only main effect means for treatments have been reported. In essence, the detrimental effects of Zn, which became progressively worse with duration of kochia ingestion, were seen as increased bilirubinemia and greater leakage of lactate dehydrogenase, aspartate aminotransferase, and alanine aminotransferase (P c .05), which were increasing with duration of kochia feeding even in lambs not treated with Zn. Thus, Zn exacerbated signs of chronic kochia toxicosis in addition to causing adversities that seemed unrelated to

damage or cholestasis was noted because alkaline phosphatase and gamma-glutamyl transpeptidase levels diminished rather than increased &ott and Wolf, 1986). Treatment with CYS + TSO provided little benefit, if any, in alleviating adverse effects of kochia hay on serum constituents (Table 4), whereas ZN treatment produced adverse effects on some serum constituents (Table 4). even when prolonged ingestion of kochia had not done so (Table 3). Although statistical analysis revealed several interactions of treatment x week (P < .05), these are explainable as a lack of differences between onset (wk 0)

2939

METABOLIC PERTURBATION IN LAMBS FED KOCHIA

TABLE 5. EppEcrs OF PEEDING KOCHIA HAY ON WHOLE BLOOD TRAlTS IN LAMBS TREATED WlTH N-ACETYLLCYSTEINE + TRANS-STILBENEOXIDE OR ZINC SULFATE FOR 5 WEEKS'

Week Parameter

0

5

SE (n = 10)

WBCd RB6 Hematocrit, % MCVf McHg MCH+

6.2 5.6b 22Sb 39.8b 22.7b 55.7b

6.8 5.3' 21.e 39.1'

.57 .10 .42 .15 .26 .67

2O.e

51.4'

%plit-plot analysis of variance revealed no week x treatment interactions (P > .E)). CROW values with different snpcrscripts diffa (P < .05). dwhite blood cell count x Id. q e d blood cell count x 106. fMean corpuscular vohune (cM3). hiean corpuscular hemoglobin @g). hMean corpuscular heanoglobia concenfration (%).

further implicating alkaloids as the primary toxicant in the initial phase of kochia toxicosis. others have implicated saponins in kochia as a possible contributor to kochia toxicosis (Galitzer and Oehme, 1978; Dickie and James, 1983). Serum profiles for the lambs of this study show progressive decreases in activities of allcaline phosphatase and gamma-glutamyl transpeptidase, rather than the increases that should be expected (Lott and Wolf, 1986) from damaged gastrointestinal mucosal membranes and biliary tract tissues, which characterize saponin toxicosis (Oakenfull and Sidhu, 1989). Implications

Studies of nutrient composition and digestibility fail to predict nutritive value of Kuchia scoparia foliage as a forage crop for livestock. Moreover, serum clinical profiles in early phases of kochia toxicosis fail to reflect the severity of metabolic and toxic effects related to excessive urinary N and severe body weight loss. Although toxic alkaloids seem a probable cause, prophylactic administration of zinc and(or) treatments to stimulate hepatic production of cysteine offered no benefit. Acceptance of Kochia scoparia as a waterefficient forage crop will remain severely constrained until kochia toxicosis has been more M y characterized and more effectively prevented.

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ingestion of kochia. The dosage of Zn exceeded nutritional requirements and obviously exceeded the zone of tolerance as well. Whether a lesser dosage would alleviate adverse effects of dietary kochia deserves further investigation, because some aspects of kochia toxicosis in rats were alleviated by excessive dietary Zn (Rankins and Smith, 1987). Whole blood traits were evaluated in these lambs at the onset and at wk 5 (Table 5). Although means for most traits were lower (P c .05) at wk 5, presumably related to diet, the differences are small and probably Unimportant biologically. Neither CYS + TSO nor ZN treatments affected whole blood traits at wk 5. Histopathology of livers and kidneys collected d e r kochia ingestion for 80 d showed diffuse hepatocyte swelling and dilation of small bile ducts in all lambs. Nephrosis was evident in all Zn-treated lambs, and aggregations resembling oxalate crystals were found in kidneys O f two Zn-tr~ted lambs. Discussion. Kochia hay fed in this study had nutrient composition and digestibility suggesting good to moderately high quality hay for livestock. Although wethers consumed and digested energy and protein in amounts deemed sufficient to sustain moderate growth, they were in negative N balance by the 3rd wk and lost 8 kg (23% of initial BW) during 10 wk These severe effects were related to notable changes in metabolic hormones at wk 2 and 4, suggesting that nutritive quality of kochia hay is modified by nonnutritive substances that impair nutrient metabolism. Nutrient metabolism was already impaired seriously when signs of toxicosis became evident in the serum clinical profile. Serum profiles in these lambs fed only kochia hay showed little, if any, indication that oxalate was the primary toxicant, although oxalate composed 6.3% of kochia DM and aggregates in kidneys of two Zn-treated lambs resembled oxalate crystals. Similar observations in cattle that grazed toxic kochia (Kiesling et al. 1984) and wethers fed the same forage as hay (Hoefler et al., 1988) leave little doubt that oxalate content of kochia may contribute to the syndrome of toxicity. However, the present results support the idea (Smith et al. 1989; Thilsted et al., 1989) that initial hepatotoxicity, followed by renal damage, reflects changes more consistent with toxic alkaloids than with oxalate. The drastic, early depression of serum prolactin concentrations in lambs of the present study resemble early effects of toxic alkaloids in tall fescue,

2940

RANKINS ET A L

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