Early Aspects of Locoweed Toxicosis and Evaluation of a Mineral Supplement or Clinoptilolite as Dietary Treatments1f2 S. E. Bachman3, M. L. Gal ean4, G. S. Smith, D. M. Hallford, and D. Graham
J.
Department of Animal and Range Science, New Mexico State University, Las Cruces 88003-0003
ABSTRACT: Sixteen crossbred beef heifers were used to determine the efficacy of serum clinical profiles as diagnostic tools for detection of early stages of locoweed toxicity and to test the ability of two mineral supplements for prevention or therapy of toxicosis. Dietary treatments were (DM basis) 1) 100% sorghum sudangrass hay, 2) 8OYo sorghum sudangrass hay:20% locoweed, 3) 80% sorghum sudangrass hay:200/0locoweed plus 100 g of Silent Herder Mineral Mix (a mineral supplement reported to alleviate locoweed toxicity), and 4) 80% sorghum sudangrass hay:20% locoweed plus 100 g of clinoptilolite (a natural zeolite clay). Diets were fed at 1.5% of BW for 28 d, after which heifers had ad libitum access to sorghum sudangrass hay for 14 d. Jugular blood was sampled before feeding every 7 d, and at 2, 4, 6 , and 8 h after feeding on d 28. Compared with controls, heifers fed locoweed had elevated (P c .011 serum alkaline phosphatase activities from d 7 through
35. On d 42, alkaline phosphatase activities in heifers previously fed locoweed were lower ( P < .051than in control heifers. Serum glutamic oxaloacetic transaminase activities were elevated (P < .011 in heifers fed locoweed from d 7 through 42 compared with control heifers. In heifers fed locoweed, serum Fe concentrations were less (P e .01) on d 7 through 28, but no treatment effects were noted (P > .lo) on d 35 or 42. On d 28, serum somatotropin, prolactin, and melatonin concentrations did not differ (P > .lo) among treatments, but insulin was lower (P < .051 in heifers fed Silent Herder and clinoptilolite than in heifers fed only locoweed. Diets containing 20% locoweed altered the serum concentrations of alkaline phosphatase, glutamic oxaloacetic transaminase, and Fe; these serum constituents may serve as indices of early stages of locoweed toxicosis. Neither Silent Herder nor clinoptilolite ameliorated the toxic effects of locoweed.
Key Words: Poisonous Plants, Toxicity, Zeolites, Blood Chemistry
J. Anim. Sci. 1992. 70:3125-3132
Introduction 'Journal Article 1636 of the New Mexico Agric. Exp. Sta., Las Cruces. This research is a contribution from contract number 58-5428-1-110, USDA-ARS. 2The authors gratefully acknowledge Farr Better Feeds, Guymon, OK for the gift of Silent Herder Mineral Mix and Leonard Resources, Albuquerque, NM for the gift of clinoptilolite clay. Additional appreciation is expressed to the New Mexico State Univ. Endocrinol. Lab. for RIA, and the following for support of RIA: National Hormone and Pituitary Program (Univ. of Maryland School of Medicine) and A. F. Parlow (Pituitary Hormones and Antisera Center, Harbor/UCLA Medical Center, Torrance, CAI for anti-oPRL, iodination and biological grades of oPRL, anti-oGH, and iodination and biological grades of oGH, and Lilly Res. Lab. (Indianapolis, IN) for oInsulin. Thanks to Kelly Allred, New Mexico State Univ.,who identified the species of locoweed that was fed.
Locoweeds are poisonous plants found throughout the western United States. Locoweed poison ing was fiist officially reported in 1873 (Vasey, 18731 and remains a serious problem today (James and Panter, 19801. Locoweed toxicosis causes reduced weight gains, abortions, birth defects, the %esent address: 111 Anim. Sci. Res. Center, Univ. of Missouri, Columbia 652 11. 'Clayton Livestock Res. Center, Rt. 1, Box 109, Clayton, NM 88415.
3 125 Downloaded from https://academic.oup.com/jas/article-abstract/70/10/3125/4705758 by UNIVERSITY OF CALIFORNIA, Berkeley user on 26 July 2018
Received December 5, 1991. Accepted June 4, 1992.
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neurotic behavior known as locoism, and death (Molyneux et al., 1985). Visual symptoms appear only after chronic ingestion of locoweeds, and late stage of toxicity seem to be irreversible (Huxtable and Dorling, 1982). One objective of our experiment was to monitor the early stages of locoweed toxicosis by evaluating changes in blood metabolites and hormones. Certain minerals may ameliorate pernicious effects of locoweeds. Hence, a second objective was to test the efficacy of a mineral mix reported to alleviate locoweed toxicity (Silent Herder Mineral Mix) and a naturally occurring zeolite clay, clinoptilolite, in the prevention of locoweed toxicosis.
Experimental Procedure Silent Herder Mineral Mix is reputed to cure bloat, grass tetany, brisket disease, scours, waterbelly, and larkspur and locoweed toxicities (Anderson, 19821. Silent Herder is marketed throughout much of the western United States, with some reports of successful treatment for locoweed poisoning; however, little scientific evidence is available to substantiate these observations. Zeolites are aluminosilicate minerals with unique three-dimensional structures arising from a framework of [Si04l4- and [A104I5- coordination polyhedra. The frameworks usually contain open channels and cavities that bind molecules of a general size or configuration. They are used widely as molecular sieves, in waste-water treatment, as cracking catalysts in petroleum refining, and as animal feed supplements (Dyer, 1988). Clinoptilolite, a naturally occurring zeolite often added to animal feeds (Mumpton and Fishman, 19771, may bind swainsonine and prevent its absorption from the gut. Sixteen crossbred (British breeds) heifers (average BW 295 f 8 kg) were assigned randomly to four treatments (four per treatment) in a cornpletely random design. Heifers were individually penned outside (5-m x 2-m pens) and fed sorghum sudangrass hay (Table 1) in decreasing amounts from 2% BW to 1.5% BW over 7 d. After the 7-d adaptation period, heifers received the following diets at 1.5% of BW (DM basis, adjusted weekly) for 28 d: sorghum sudangrass hay (positive control); 80 O/O sorghum sudangrass hay:20% locoweed (negative control); 80% sorghum sudangrass: 20% locoweed plus 100 g of Silent Herder Mineral Mix; 80% sorghum sudangrass hay:20% locoweed plus 100 g of finely ground (-50 mesh) clinoptilolite. Silent Herder is a product of Anderson Research Laboratory, Bozeman, MT that contains 40% NaC1, 20% NaH2P04, 20% “Dycedol” (calcined Downloaded from https://academic.oup.com/jas/article-abstract/70/10/3125/4705758 by UNIVERSITY OF CALIFORNIA, Berkeley user on 26 July 2018
Table 1. Chemical composition of sorghum sudangrass hay and the mixture of 80% hay:20% locoweed (Oxytropis sericea) 80% Hay:
Item Dry matter, OO/
100% Hav 92.7
91.8 %
Ash
CP NDF ADF ADL
20% locoweed
12.9 12.6
65.4 40.9 6.2
ofDM 12.0 12.4 62.1 40.8
8.7
dolomitic limestone that supplies Ca as 5% of total mixture and Mg as 3% of total mixture), 10% wheat bran, 10% dried molasses, and traces of anise (Anderson, 1982). Heifers were fed at 1.5% of BW to simulate typical intake levels on winter/ spring range in New Mexico. Inclusion of locoweed a t 20% of the diet typifies locoweed consumption of grazing cows that had previously consumed locoweed (M. H. Ralphs, personal communication). All heifers received, daily, 300 g of a 95% hominy feed plus 5 YO molasses (as-fed basis) supplement into which Silent Herder or clinoptilolite was mixed manually. Heifers were allowed 15 to 30 min to consume the supplement (mineral1 mixture before being fed roughage. Heifers were allowed free access to water and plain salt. Feed refusals were collected daily and consisted primarily of locoweed root portions, although small quantities ( < 25 g) of supplement (mineral) mix were sometimes refused. On d 29, heifers were moved to a group pen (10.5 m x 35 m) and allowed ad libitum access to sorghum sudangrass hay and water for 2 wk. Feed intake was not measured during this 2-wk period. White point locoweed (Oxytropis sericea) was collected in Union County, NM in May and June 1990, and included all aerial portions (prebloom/ bloom) and some root portions. Locoweed and sorghum sudangrass hay were ground in a tub grinder to pass a 5-cm screen before mixing andtor) feeding; chemical composition is shown in Table 1. Mineral compositions of Silent Herder and clinoptilolite are shown in Table 2. Heifers were weighed and blood samples were collected by jugular venipuncture before feeding (0700) on d 0, 7, 14, 21, 28, 35, and 42. Blood was allowed to clot for 30 min at ambient temperature and centrifuged at 1,000 x g for 15 min. Serum was separated and frozen. Serum samples collected on d 0 through 42 were analyzed for 30 serum constituents by a commercial medical diagnostic laboratory (Southwest Medical Laboratory, Las
LOCOWEED TOXICOSIS IN HEIFERS
Cruces, NM). On d 28, additional blood samples were collected at 2, 4, 6, and 8 h after feeding. Hourly serum samples (including 0 h) were analyzed for concentrations of insulin, somatotropin, prolactin, and melatonin by RIA as described by Sanson and Hallford (19841, Hoefler and Hallford (19871, Spoon and Hallford (19891, and English et al. (19861, respectively. Throughout the experiment, care was taken to alleviate or minimize any source of stress or pain to the heifers. Data from daily serum samples were pooled into three groups (d 0; d 7, 14, 21, and 28; and d 35 and 42) and analyzed within group by split-plot ANOVA (Gill and Hafs, 1971). Treatment was included in the main plot, and sampling day and its interaction with treatment were included in the subplot. Main-plot effects were tested by heifer within treatment. Intake (grams/kilogram BW) and BW measurements from d 1 through 28 were analyzed by split-plot ANOVA, as described for daily serum samples. Data from hourly samples on d 28 were analyzed by split-plot ANOVA. Treatment was included in the main plot, and sampling time and its interaction with treatment were included in the subplot. If the ANOVA F-test was significant (P e .lo), means were separated by orthogonal contrasts. Contrasts were 1) positive control vs locoweed, 2) negative control vs minerals, and 3) Silent Herder vs clinoptilolite. All analyses were computed using the GLM procedure of SAS (1984).
Table 2. Elemental analysis* of Silent Herder Mineral Mixb and clinoptiloliteCfed to beef heifers
Item Macroelement, 010 of DM Na Ca P Mg K Microelement, mg/kg of DM
Al B co cu Fe Mn Se Zn
Silent Herder 16.00 6.91
5.38 3.60 .42 477
13 2.5 5 471 49 .14
36
Clinoptilolite .42 1.15 .02 .16
.66 17,625 19 4.5 1
3,880 474
.03 27
*Analysis performed by Soil, Plant, and Water Testing Laboratory, Dept. of Agron. and Hort.,New Mexico State Univ., L a s Cruces 88003. bA product of Anderson Research Laboratory, Bozeman, MT, provided by Farr Better Feeds, Guymon, OK. CNaturally occurring zeolite clay, provided by Leonard Resources, Albuquerque, NM. Downloaded from https://academic.oup.com/jas/article-abstract/70/10/3125/4705758 by UNIVERSITY OF CALIFORNIA, Berkeley user on 26 July 2018
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Results and Discussion Loco is a Spanish word meaning crazy and describes the behavior of animals in latter stages of locoweed poisoning. Locoweeds (13 members of the Astragalus and Oxytropis families; James et al., 1970) contain the toxic alkaloid swainsonine (indolizidine-l,2,84riol; Molyneux and James, 1982). Swainsonine inhibits the lysosomal enzyme a,Dmannosidase, a member of a group of enzymes that catabolize oligosaccharides into simple sugars (Dorling et al., 1985). Inhibiting a,D-mannosidase causes osmotically active oligosaccharides to accumulate in lysosomes, creating serious inclusions that on microscopic examination appear as cytoplasmic vacuoles (Huxtable and Dorling, 19821. Accumulated lysosomal oligosaccharides disrupt cell function and have been found in most tissues of locoweed-intoxicated animals, except skeletal muscle and gastrointestinal tract cells (Van Kampen and James, 1970). In the final stages of locoism, central nervous system tissue shows swelling of axonal hillocks (meganeurites) and growth of new dendrites and synapses (Walkley and Siegel, 1989). Because swainsonine is excreted (Huxtable and Dorling, 19821, cessation of locoweed ingestion results in disappearance of cytoplasmic vacuoles in all affected tissues; yet, the altered geometry and synaptic formations in nervous tissue of severely affected animals is permanent and may be the cause of irreversible symptoms of toxicity [Walkley and Siegel, 1989). Therefore, as stated earlier, one objective of the present study was to characterize the early stages of locoweed toxicosis by complete serum clinical profiles, before symptoms of locoism became visually apparent and were irreversible. The validity of serum activities of mannosidase as a determinant of locoweed toxicosis has been questioned (Huxtable and Dorling, 19821, and altered concentrations of selected serum constitutents have been reported and used as indices of toxicity (see discussion below). Presently available are inexpensive autoanalytical techniques to measure complete serum clinical profiles (30 serum constituents), allowing further characterization of locoweed toxicosis. A sampling day x treatment interaction (P e .lo) was noted for heifer BW; however, no treatment effects (P > .lo) were detected within days (data not shown). Heifers began the experiment with a n average BW of 295 kg, and after 28 d BW averaged 299 kg. Heifers fed locoweed occasionally refused small amounts (usually e 100 g1 of root portions, apparently because of low palatability. One heifer receiving the negative control treatment refused increasing amounts of feed as the experiment progressed. Decreased intake with increased
BACHMAN ET AL.
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degree of toxicosis has been reported (Van Kampen and James, 1969). Neither sampling day x treatment interactions nor treatment effects were noted (P > .lo) for the following (overall means and SE in parentheses): Na (140, .2 mEq/L), K (4.3, .04 mEq/L), C1 (98, .3 mEq/L), HCO, (27, .4 mEq/L), Ca (9.3, .1 mg/dL), P (6.4,.1 mg/dL), anion gap (14.5, .5 mEq/L), osmolality (275, .5 mOsm/L), glucose (79, 1 mg/dL), cholesterol (79, 2 mg/dL), urea N (11, .2 mg/dL), creatinine (1.3, -02mg/dL), uric acid (3, .01 mg/dL), albumin (3.9, .02 g/dL), globulins (3.9, .05 g/dL), total proteins (7.8, .05 g/dL), direct bilirubin (.O2, .003 mg/dL), indirect bilirubin (.14, .01 mg/dL), total bilirubin (. 16, .01 mg/dL), alanine transferase (26, .6 U/L), creatine kinase (205, 8 U/L), and gamma glutamyl transpeptidase (17, .5 U/LI. Our findings on serum glucose and P concentrations agree with those of James et al. (19701, who reported no changes in these serum constituents in sheep fed locoweed. Lack of altered Ca concentration in the present experiment contradicts the data of James et al. (19701, who reported decreased Ca concentration in wethers during wk 5, 6, and 7 after feeding a diet containing approximately 15% locoweed. We fed locoweed for only 28 d, and it is possible that changes in serum Ca concentration
might OCCUT only at some later stage(s1of toxicosis. Lack of differences in albumin, globulin, and total protein concentrations in our experiment agree with previous findings (Sharma et al., 1984) in which ewes consuming 340 g/d of locoweed had no differences in these constituents. Sampling day x treatment interactions were not detected (P > .lo) for d 7 through 28, but a sampling day x treatment interaction was detected (P e .lo) for d 35 and 42 for serum alkaline phosphatase (ALKP) activities (Table 3). Serum ALKP was greater ( P e .01) by 7 d after feeding locoweed, remained elevated (P e .01)through d 35 (7 d after cessation of feeding locoweed), and then dropped below (P < .lo) control levels on d 42. In addition, heifers fed Silent Herder had lower (P e .lo1 ALKP activities than did heifers fed clinoptilolite on d 35. James et al. (1970) noted elevated ALKP on d 7 through 49 in wethers fed a diet containing approximately 12% locoweed; however, decreased ALKP by 14 d after cessation of feeding locoweed has not been noted previously. Alkaline phosphatase activity is a n index of diseased bone or liver tissue, or obstruction of the biliary tract Wallach, 1974). Lack of differences (P > .lo) in measure of direct, indirect, total bilirubin, or Ca and P concentrations in our experiment suggest no obstruction of the biliary tract or bone pathology
Table 3. Serum alkaline phosphatase (ALKP) and glutamic oxaloacetic transaminase (SGOT)in beef heifers fed roughage diets with or without 20% (DM basis) locoweed, and for 14 days after cessation of locoweed feeding (days 35 and 42), as affected by supplemental mineral compounds Treatmenta ~
Positive control
Item
Negative control
Silent Herder
ClinoDtilolite
SE Contrastb
Day 0 ALKP, U/L SGOT, U/L
201 104
207 106
NS NS
216 100
31 8
1,128 224
125 9
272
271
13
1**
372
472
37
1**,3'
108
177
20
1**
246 110
Days 7, 14, 21, and 26' ALKP, U/L SGOT, U/L
273 107
997 233
SGOT, U/L
103
268
1,243 254
1** 1**,3*
Days 35 and 42' Day 35 ALKP, U/L
228
374
ALKP, U/L
246
177
Day 42 &Allheifers received 300 g (as-fed basis) of a hominy feed/molasses mixture daily. Heifers were fed Silent Herder and clinoptilolite (100 gl mixed with hominy feed/molasses for a 28-d period. During d 29 through 42, heifers were allowed ad libitum access to sorghum sudangrass hay. bContrasts evaluated were 1 = positive control vs locoweed, 2 = negative control vs minerals, 3 = Silent Herder vs clinoptilolite. NS = nonsignificant Lp ,101. CNo treatment x day interactions were detected Lp > ,101.
+P < *P
.lo). CNo treatment x day interactions were detected (P .IO). **P < .01.
because of locoweed ingestion; this finding implicates hepatocytes as the source of increased ALKP. Supporting our inference that increased ALKP is a result of hepatocyte pathology, Van Kampen and James (1970) reported cellular vacuolization of hepatocytes in ewes fed 380 g/d of locoweed. In addition, decreased ALKP 14 d after cessation of feeding locoweed in our experiment agrees with data of Huxtable and Dorling (19821, who noted disappearance of cellular vacuolization of most tissues within 10 to 12 d after cessation of feeding a forage containing swainsonine. Sampling day x treatment interactions were not detected (P > .lo) for serum glutamic oxaloacetic transaminase activities (SGOT; synonymous with aspartate amino transferase; Table 3). In heifers fed locoweed, SGOT was greater (P < .01) by d 7 and remained elevated (P < .011 through d 42 compared with controls. Activities of SGOT in heifers fed Silent Herder were greater (P < .05) than in heifers fed clinoptilolite during d 7 through 28. These data agree with previously published reports of elevated SGOT in sheep fed locoweed (James et al., 1968, 1970; Le Grande et al., 1985). Elevated SGOT is a n index of diseased muscle, liver, or brain tissue (Wallach, 1974). Swainsonine does not seem to affect muscle tissue Wan Kampen and James, 19701, but cellular vacuolization bas been noted in brain tissue and hepatocytes Wan Kampen and James, 1970). In contrast to ALKP, SGOT activity did not decrease to nearnormal levels within 14 d of cessation of feeding locoweed. Vacuolization of neural tissue may persist longer than in other tissues (Huxtable and Downloaded from https://academic.oup.com/jas/article-abstract/70/10/3125/4705758 by UNIVERSITY OF CALIFORNIA, Berkeley user on 26 July 2018
Dorling, 19821, suggesting that neural tissue was one source of elevated SGOT. No sampling day x treatment interaction was detected (P > .lo) during d 7 through 28 for serum concentration of Fe, but a n interaction was noted (P < .lo) on d 35 and 42 (Table 41. Serum Fe concentration was lower IP < .011 in heifers fed locoweed than in control heifers by d 7 after feeding locoweed and remained lower (P < .01) than in controls through d 28. However, no treatment differences (P > .lo) were noted on d 35 and 42. The Fe concentration of positive control heifers was numerically lower on d 42 than had been noted previously for this treatment group, possibly negating detectible effects of lowered Fe resulting from locoweed ingestion. The cause of the lower serum Fe concentrations in positive control heifers on d 42 is unknown. Effects of locoweed on Fe have not been reported previously. Serum Fe concentration is decreased during conditions of nephrosis and several anemias (Wallach, 19741. Locoweed toxicosis caused vacuolization of the proximal convoluted tubules, distal convoluted tubules, loops of Henle, and collecting ducts of sheep kidney Wan Kampen and James, 1969) and decreased erythrocyte count, hemoglobin concentration, and packed cell volume in a calf (James et al., 1970). Either locoweed-induced nephrosis or effects on erythrocytes could be responsible for the decreased serum Fe concentration in our experiment. Week x treatment interactions (P < .lo) for serum lactate dehydrogenase (LDHI activities required presentation of data by sampling day
3130
BACHMAN ET AL.
A sampling day x treatment interaction was detected (P < .lo) for d 7 through 28 for serum triglyceride concentration (TRIG) but not (P > .lo) for d 35 and 42 (Table 5). Numerical trends over the 42-d feeding period suggest that TRIG in control heifers increased and TRIG in heifers fed locoweed decreased or remained constant. On d 14 and 28, these trends led to greater (P < .01, P < .05, respectively) TRIG in control heifers than in heifers fed locoweed. In addition, on d 14 the negative control heifers had greater (P < .lo1 TRIG than the heifers fed minerals. Increased TRIG in control heifers during the experimental period suggests that excess dietary energy was converted to triglycerides in the liver. Because these were actively growing heifers fed a medium-quality roughage a t 1.5% of BW, excess energy intake seems unlikely. Despite the unknown cause of
(Table 5). On d 14, LDH was greater (P .01)in heifers fed Silent Herder than in heifers fed clinoptilolite. Although this numerical trend was apparent on both d 21 and 28, no differences (P > . l o ) were noted. On d 28, heifers fed locoweed had greater (P < .05) LDH concentrations than did control heifers. No differences (P > .lo) were noted on d 35 and 42. On d 42, all treatment groups had numerically greater means than on d 0. Increased serum LDH is indicative of disease of cardiac and skeletal muscle, liver damage, and some anemias Wallach, 19741. Locoweed intoxication does not cause vacuolization of cardiac or skeletal muscle (Van Kampen and James, 1970). Damaged hepatocytes and erythrocytes, as indicated by increased LDH, is consistent with lower serum Fe concentration and elevated ALKP concentration in heifers fed locoweed in our experiment.
Table 5. Serum lactate dehydrogenase (LDH) activity and triglyceride (TRIG) concentration in beef heifers fed roughage diets with or without 20% (DM basis) locoweed, and for 14 days after cessation of locoweed feeding (days 35 and 42), as affected by supplemental mineral compounds Treatmenta Item
Positive control
Negative control
1,040 14
1,007 16
Silent Herder
Clinoptilolite
SE
Contrastb
1,009 14
1,051 17
68 2
NS NS
1,130 14
1,151 16
49 2
NS NS
1,267 12
1,069 11
39 2
3" 1**,2+
1,313 14
1,178 14
48 2
NS NS
1,369 12
1,230 13
58 1
1* 1**
1,310
1,290
69
NS
1,182
1,114
60
NS
14
2
NS
Day 0 LDH, U/L TRIG, mg/dL
Day 7 LDH, U/L TRIG, mg/dL
1,192 19
1,149 16
LDH, U/L TRIG, mg/dL
1,079 24
1,094 16
LDH, U/L TRIG, mg/dL
1,162 17
1,236 17
LDH, U/L TRIG, mg/dL
1,127 20
1,236 14
LDH, U/L
1,239
1,269
LDH, U/L
1,178
1,112
Day 14
Day 21
Day 28
Day 35 Day 42 Day 35 and 42' TRIG, mg/dL
19
18
17
aAll heifers received 300 g (as-fedbasis) of a hominy feed/molasses mixture daily. Heifers were fed Silent Herder and clinoptilolite (100 g) mixed with hominy feedlmolasses. During d 29 through 42, heifers were allowed ad libitum access to sorghum sudangrass hay. bContrasts evaluated were 1 = positive control vs locoweed, 2 = negative control vs minerals, 3 = Silent Herder vs clinoptilolite. NS nonsignificant (P > .lo). CNo treatment x day interactions were detected (P > ,101.
-
+P < .lo. * P c .OS. **P < .01. Downloaded from https://academic.oup.com/jas/article-abstract/70/10/3125/4705758 by UNIVERSITY OF CALIFORNIA, Berkeley user on 26 July 2018
LOCOWEED TOXICOSIS IN HEIFERS
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Table 6. Serum metabolic hormones in beef heifers fed roughage diets with or without 20% (DM basis) locoweed, as affected by supplemental mineral compounds Treatment& Positive control
Item
Negative control
Silent Herder
Clinoptilolite
SE
Contrastb
10.0 56 .4 45
2.0 15 .1 11
NS NS
Day 28' Somatotropin, ng/mL Prolactin, ng/mL Insulin, ng/mL Melatonin, pg/mL
7.3 37 .5
44
7.5 71 .8 52
11.4 67 .5 52
2*
NS
&Allheifers received 300 g (as-fedbasis) of a hominy feed/molasses mixture daily. Heifers were fed Silent Herder and clinoptilolite (100 g) mixed with hominy feedlmolasses. bContrasts evaluated were 1 = positive control vs locoweed, 2 = negative control vs minerals, 3 = Silent Herder vs clinoptilolite. NS = nonsignificant (P > .IO). CMeansare averaged over sampling times of 0 (before feeding), and 2,4,6,and 8 h after feeding on d 28 of the experiment. No treatment x sampling time interactions were detected (P > .lo).
*P
c .OS.
increased TRIG, heifers fed locoweed did not respond similarly to control heifers. This finding may relate to altered hepatic pathology suggested by increased ALKP and LDH in heifers fed locoweed. Sampling time x treatment interactions were not detected (P > .lo) for any serum hormone measured on d 28. Locoweed ingestion did not affect (P > .lo) concentrations of somatotropin, prolactin, or melatonin (Table 6). Serum insulin concentration was greater (P e .05) in negative control heifers than in heifers receiving Silent Herder or clinoptilolite. Mineral supplements seemed to ameliorate the insulin-increasing effects of locoweed. Greater insulin concentration in animals fed locoweed has not been reported previously. Swainsonine may have caused pancreatic islet cell vacuolization/dysfunction, which caused increased insulin release. Van Kampen and James (1989)reported that feeding 227 g of locoweed to wethers for 60 d elongated pancreatic islet cells, but distinct vacuolization could not be demonstrated. In summary, we interpret these serum metabolite and hormone profiles to suggest that feeding locoweed a t 20% of a limit-fed (1.5% of B W roughage diet for 28 d caused damage to erythrocytes, liver, kidney, and nervous tissue and possibly to pancreatic islet cells. Changes in serum constituents appeared within 7 d of feeding locoweed, and most constituents returned to normal within 14 d after cessation of feeding locoweed. These data agree with previous histological examination of tissues of swainsonine-intoxicated animals. Silent Herder and clinoptilolite alleviated locoweed-induced increases in insulin concentrations but did not affect other serum constituents, suggesting that neither Silent Herder nor clinoptilolite alleviates the effects of locoweed toxicity. Downloaded from https://academic.oup.com/jas/article-abstract/70/10/3125/4705758 by UNIVERSITY OF CALIFORNIA, Berkeley user on 26 July 2018
Implications Feeding locoweed at 20% of a limit-fed roughage diet to heifers for 28 d altered some serum metabolite and hormone profiles. We interpret these profiles as locoweed-induced damage to erythrocytes, liver, kidney, and nervous system cells. Neither Silent Herder Mineral Mix nor the natural zeolite clinoptilolite proved effective as a treatment for locoweed toxicosis.
Literature Cited Anderson, E. C. 1982. Forty Million Cows Can't Be Wrong! Anderson Research Laboratories, Bozeman, MT. Dorling, P. R., C. R. Huxtable, S . M. Colegate, and B. G. Winchester. 1985. The pathogenesis of chronic Swainsona sp. toxicity. In: A. A. Seawright, H. P. Hegarty, L. F. James, and R. F. Keller (Ed.) Plant Toxicology. Proc. of the AustraliaUSA Poisonous Plant Symp. p 249. Queensland Poisonous Plants Committee, Queensland Dept. of Primary Ind., Anim. Res. Inst., Yeerongpilly, Queensland, Australia. Dyer, A.1988.An Introduction to Zeolite Molecular Sieves. John Wiley and Sons, Chichester, U.K. English, J., A. L. Poulton, J. Arendt, and A. M. Symons. 1986.A comparison of the efficiency of melatonin treatments in advancing oestrus in ewes. J. Reprod. Fertil. 77:321. Gill, J. L., and H. D. Hafs. 1971.Analysis of repeated measurements of animals. J. Anim. Sci. 33331. Hoefler, W. C., and D. M. Hallford. 1987. Influence of suckling status and type of birth on serum hormone profiles and return to estrus in earlypostpartum, spring-lambing ewes. Theriogenology 27:887. Huxtable, C. R., and P. R. Dorling. 1982. Poisoning of livestock by Swainsona spp.: Current status. Aust. J. Vet. Med. 5950. James, L. F., K. L. Bennett, K. G . Parker, R. F. Keeler, W. Binns, and B. Lindsay. 1968. Loco plant poisoning in sheep. J. Range Manage. 21:360. James, L. F., and K. E. Panter. 1989. Locoweed poisoning in livestock. I n L. F. James, A. D. Elbein, R. J. Molyneux, and C. D. Warren (Ed.) Swainsonine and Related Glycosidase Inhibitors. p 23. Iowa State University Press, Ames. James, L. F., K. R. Van Kampen, and A. E. Johnson. 1970.
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Physiopathologic changes in locoweed poisoning of livestock. Am. J. Vet. Res. 313863. Le Grande, C. E., L. F. James, R.W. McMullen, and K. E. Panter. 1985. Reduced progesterone and altered cotyledonary prostaglandin values induced by locoweed (Astragulus Zentiginosus) in sheep. Am. J. Vet. Res. 46:1903. Molyneux, R. J., and L. F. James. 1982. Loco intoxication: Indolizidine alkaloids of spotted locoweed (Astragalus Zentiginosus). Science Washington D c1 216:190. Molyneux, R.J., L. F. James, and K. E. Panter. 1965. Chemistry of toxic constituents of locoweed (Astragalus & Oxytropis) species. In: A. A. Seawright, H. P. Hegarty, L. F. James, and R. F. Keller (Ed.) Plant Toxicology. Proc. of the AustraliaUSA Poisonous Plant Symp. p 266. Queensland Poisonous Plants Committee, Queensland Dept. of Primary Ind., Anim. Res. Inst., Yeerongpilly, Queensland, Australia. Mumpton, F. A., and P. H. Fishman. 1977. The application of natural zeolites in animal science and aquaculture. J. Anim. sci. 45:1188. Sanson, D. W., and D. M. Hallford. 1984. Growth response, carcass characteristics and serum glucose and insulin in lambs fed tolazamide. Nutr. Rep. Int. 29:481.
Downloaded from https://academic.oup.com/jas/article-abstract/70/10/3125/4705758 by UNIVERSITY OF CALIFORNIA, Berkeley user on 26 July 2018
SAS. 1984. SAS User's Guide: Statistics. SAS Inst. Inc., Cary, NC. Sharma, R. P., L. F. James, and R. J. Molyneux. 1984. Effect of repeated locoweed feeding on peripheral lymphocytic function and plasma proteins in sheep. Am. J. Vet. Res. 45:2090. Spoon, R.A., and D. M. Hallford. 1989. Growth response, endocrine profiles and reproductive performance of fine-wool lambs treated with ovine prolactin before breeding. Theriogenology 32:45. Van Kampen, K. R.,and L. F. James. 1909. Pathology of locoweed poisoning in sheep. Vet. Pathol. 6:413. Van Kampen, K. R.,and L. F. James. 1970. Pathology of locoweed (Astragalus lentiginosusl poisoning in sheep. Vet. Pathol. 7:503. Vasey, G. 1873. Commissioner of Agriculture, Monthly Report, October, 503. Wallach, J. 1974. Interpretation of Diagnostic Tests (2nd Ed.). Little, Brown and Company, Boston, MA. Walkley, S.U., and D. A. Siegel. 1989. Comparative studies of the CNS in a swainsonine-induced and inherited feline CLmannosidosis. In: L. F. James, A. D. Elbein, R.J. Molyneux, and C. D. Warren (Ed.) Swainsonine and Related Glycosidase Inhibitors. p 57. Iowa State University Press, Ames.
J.
Department of Animal and Range Science, New Mexico State University, Las Cruces 88003-0003
ABSTRACT: Sixteen crossbred beef heifers were used to determine the efficacy of serum clinical profiles as diagnostic tools for detection of early stages of locoweed toxicity and to test the ability of two mineral supplements for prevention or therapy of toxicosis. Dietary treatments were (DM basis) 1) 100% sorghum sudangrass hay, 2) 8OYo sorghum sudangrass hay:20% locoweed, 3) 80% sorghum sudangrass hay:200/0locoweed plus 100 g of Silent Herder Mineral Mix (a mineral supplement reported to alleviate locoweed toxicity), and 4) 80% sorghum sudangrass hay:20% locoweed plus 100 g of clinoptilolite (a natural zeolite clay). Diets were fed at 1.5% of BW for 28 d, after which heifers had ad libitum access to sorghum sudangrass hay for 14 d. Jugular blood was sampled before feeding every 7 d, and at 2, 4, 6 , and 8 h after feeding on d 28. Compared with controls, heifers fed locoweed had elevated (P c .011 serum alkaline phosphatase activities from d 7 through
35. On d 42, alkaline phosphatase activities in heifers previously fed locoweed were lower ( P < .051than in control heifers. Serum glutamic oxaloacetic transaminase activities were elevated (P < .011 in heifers fed locoweed from d 7 through 42 compared with control heifers. In heifers fed locoweed, serum Fe concentrations were less (P e .01) on d 7 through 28, but no treatment effects were noted (P > .lo) on d 35 or 42. On d 28, serum somatotropin, prolactin, and melatonin concentrations did not differ (P > .lo) among treatments, but insulin was lower (P < .051 in heifers fed Silent Herder and clinoptilolite than in heifers fed only locoweed. Diets containing 20% locoweed altered the serum concentrations of alkaline phosphatase, glutamic oxaloacetic transaminase, and Fe; these serum constituents may serve as indices of early stages of locoweed toxicosis. Neither Silent Herder nor clinoptilolite ameliorated the toxic effects of locoweed.
Key Words: Poisonous Plants, Toxicity, Zeolites, Blood Chemistry
J. Anim. Sci. 1992. 70:3125-3132
Introduction 'Journal Article 1636 of the New Mexico Agric. Exp. Sta., Las Cruces. This research is a contribution from contract number 58-5428-1-110, USDA-ARS. 2The authors gratefully acknowledge Farr Better Feeds, Guymon, OK for the gift of Silent Herder Mineral Mix and Leonard Resources, Albuquerque, NM for the gift of clinoptilolite clay. Additional appreciation is expressed to the New Mexico State Univ. Endocrinol. Lab. for RIA, and the following for support of RIA: National Hormone and Pituitary Program (Univ. of Maryland School of Medicine) and A. F. Parlow (Pituitary Hormones and Antisera Center, Harbor/UCLA Medical Center, Torrance, CAI for anti-oPRL, iodination and biological grades of oPRL, anti-oGH, and iodination and biological grades of oGH, and Lilly Res. Lab. (Indianapolis, IN) for oInsulin. Thanks to Kelly Allred, New Mexico State Univ.,who identified the species of locoweed that was fed.
Locoweeds are poisonous plants found throughout the western United States. Locoweed poison ing was fiist officially reported in 1873 (Vasey, 18731 and remains a serious problem today (James and Panter, 19801. Locoweed toxicosis causes reduced weight gains, abortions, birth defects, the %esent address: 111 Anim. Sci. Res. Center, Univ. of Missouri, Columbia 652 11. 'Clayton Livestock Res. Center, Rt. 1, Box 109, Clayton, NM 88415.
3 125 Downloaded from https://academic.oup.com/jas/article-abstract/70/10/3125/4705758 by UNIVERSITY OF CALIFORNIA, Berkeley user on 26 July 2018
Received December 5, 1991. Accepted June 4, 1992.
BACHMAN ET AL.
3126
neurotic behavior known as locoism, and death (Molyneux et al., 1985). Visual symptoms appear only after chronic ingestion of locoweeds, and late stage of toxicity seem to be irreversible (Huxtable and Dorling, 1982). One objective of our experiment was to monitor the early stages of locoweed toxicosis by evaluating changes in blood metabolites and hormones. Certain minerals may ameliorate pernicious effects of locoweeds. Hence, a second objective was to test the efficacy of a mineral mix reported to alleviate locoweed toxicity (Silent Herder Mineral Mix) and a naturally occurring zeolite clay, clinoptilolite, in the prevention of locoweed toxicosis.
Experimental Procedure Silent Herder Mineral Mix is reputed to cure bloat, grass tetany, brisket disease, scours, waterbelly, and larkspur and locoweed toxicities (Anderson, 19821. Silent Herder is marketed throughout much of the western United States, with some reports of successful treatment for locoweed poisoning; however, little scientific evidence is available to substantiate these observations. Zeolites are aluminosilicate minerals with unique three-dimensional structures arising from a framework of [Si04l4- and [A104I5- coordination polyhedra. The frameworks usually contain open channels and cavities that bind molecules of a general size or configuration. They are used widely as molecular sieves, in waste-water treatment, as cracking catalysts in petroleum refining, and as animal feed supplements (Dyer, 1988). Clinoptilolite, a naturally occurring zeolite often added to animal feeds (Mumpton and Fishman, 19771, may bind swainsonine and prevent its absorption from the gut. Sixteen crossbred (British breeds) heifers (average BW 295 f 8 kg) were assigned randomly to four treatments (four per treatment) in a cornpletely random design. Heifers were individually penned outside (5-m x 2-m pens) and fed sorghum sudangrass hay (Table 1) in decreasing amounts from 2% BW to 1.5% BW over 7 d. After the 7-d adaptation period, heifers received the following diets at 1.5% of BW (DM basis, adjusted weekly) for 28 d: sorghum sudangrass hay (positive control); 80 O/O sorghum sudangrass hay:20% locoweed (negative control); 80% sorghum sudangrass: 20% locoweed plus 100 g of Silent Herder Mineral Mix; 80% sorghum sudangrass hay:20% locoweed plus 100 g of finely ground (-50 mesh) clinoptilolite. Silent Herder is a product of Anderson Research Laboratory, Bozeman, MT that contains 40% NaC1, 20% NaH2P04, 20% “Dycedol” (calcined Downloaded from https://academic.oup.com/jas/article-abstract/70/10/3125/4705758 by UNIVERSITY OF CALIFORNIA, Berkeley user on 26 July 2018
Table 1. Chemical composition of sorghum sudangrass hay and the mixture of 80% hay:20% locoweed (Oxytropis sericea) 80% Hay:
Item Dry matter, OO/
100% Hav 92.7
91.8 %
Ash
CP NDF ADF ADL
20% locoweed
12.9 12.6
65.4 40.9 6.2
ofDM 12.0 12.4 62.1 40.8
8.7
dolomitic limestone that supplies Ca as 5% of total mixture and Mg as 3% of total mixture), 10% wheat bran, 10% dried molasses, and traces of anise (Anderson, 1982). Heifers were fed at 1.5% of BW to simulate typical intake levels on winter/ spring range in New Mexico. Inclusion of locoweed a t 20% of the diet typifies locoweed consumption of grazing cows that had previously consumed locoweed (M. H. Ralphs, personal communication). All heifers received, daily, 300 g of a 95% hominy feed plus 5 YO molasses (as-fed basis) supplement into which Silent Herder or clinoptilolite was mixed manually. Heifers were allowed 15 to 30 min to consume the supplement (mineral1 mixture before being fed roughage. Heifers were allowed free access to water and plain salt. Feed refusals were collected daily and consisted primarily of locoweed root portions, although small quantities ( < 25 g) of supplement (mineral) mix were sometimes refused. On d 29, heifers were moved to a group pen (10.5 m x 35 m) and allowed ad libitum access to sorghum sudangrass hay and water for 2 wk. Feed intake was not measured during this 2-wk period. White point locoweed (Oxytropis sericea) was collected in Union County, NM in May and June 1990, and included all aerial portions (prebloom/ bloom) and some root portions. Locoweed and sorghum sudangrass hay were ground in a tub grinder to pass a 5-cm screen before mixing andtor) feeding; chemical composition is shown in Table 1. Mineral compositions of Silent Herder and clinoptilolite are shown in Table 2. Heifers were weighed and blood samples were collected by jugular venipuncture before feeding (0700) on d 0, 7, 14, 21, 28, 35, and 42. Blood was allowed to clot for 30 min at ambient temperature and centrifuged at 1,000 x g for 15 min. Serum was separated and frozen. Serum samples collected on d 0 through 42 were analyzed for 30 serum constituents by a commercial medical diagnostic laboratory (Southwest Medical Laboratory, Las
LOCOWEED TOXICOSIS IN HEIFERS
Cruces, NM). On d 28, additional blood samples were collected at 2, 4, 6, and 8 h after feeding. Hourly serum samples (including 0 h) were analyzed for concentrations of insulin, somatotropin, prolactin, and melatonin by RIA as described by Sanson and Hallford (19841, Hoefler and Hallford (19871, Spoon and Hallford (19891, and English et al. (19861, respectively. Throughout the experiment, care was taken to alleviate or minimize any source of stress or pain to the heifers. Data from daily serum samples were pooled into three groups (d 0; d 7, 14, 21, and 28; and d 35 and 42) and analyzed within group by split-plot ANOVA (Gill and Hafs, 1971). Treatment was included in the main plot, and sampling day and its interaction with treatment were included in the subplot. Main-plot effects were tested by heifer within treatment. Intake (grams/kilogram BW) and BW measurements from d 1 through 28 were analyzed by split-plot ANOVA, as described for daily serum samples. Data from hourly samples on d 28 were analyzed by split-plot ANOVA. Treatment was included in the main plot, and sampling time and its interaction with treatment were included in the subplot. If the ANOVA F-test was significant (P e .lo), means were separated by orthogonal contrasts. Contrasts were 1) positive control vs locoweed, 2) negative control vs minerals, and 3) Silent Herder vs clinoptilolite. All analyses were computed using the GLM procedure of SAS (1984).
Table 2. Elemental analysis* of Silent Herder Mineral Mixb and clinoptiloliteCfed to beef heifers
Item Macroelement, 010 of DM Na Ca P Mg K Microelement, mg/kg of DM
Al B co cu Fe Mn Se Zn
Silent Herder 16.00 6.91
5.38 3.60 .42 477
13 2.5 5 471 49 .14
36
Clinoptilolite .42 1.15 .02 .16
.66 17,625 19 4.5 1
3,880 474
.03 27
*Analysis performed by Soil, Plant, and Water Testing Laboratory, Dept. of Agron. and Hort.,New Mexico State Univ., L a s Cruces 88003. bA product of Anderson Research Laboratory, Bozeman, MT, provided by Farr Better Feeds, Guymon, OK. CNaturally occurring zeolite clay, provided by Leonard Resources, Albuquerque, NM. Downloaded from https://academic.oup.com/jas/article-abstract/70/10/3125/4705758 by UNIVERSITY OF CALIFORNIA, Berkeley user on 26 July 2018
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Results and Discussion Loco is a Spanish word meaning crazy and describes the behavior of animals in latter stages of locoweed poisoning. Locoweeds (13 members of the Astragalus and Oxytropis families; James et al., 1970) contain the toxic alkaloid swainsonine (indolizidine-l,2,84riol; Molyneux and James, 1982). Swainsonine inhibits the lysosomal enzyme a,Dmannosidase, a member of a group of enzymes that catabolize oligosaccharides into simple sugars (Dorling et al., 1985). Inhibiting a,D-mannosidase causes osmotically active oligosaccharides to accumulate in lysosomes, creating serious inclusions that on microscopic examination appear as cytoplasmic vacuoles (Huxtable and Dorling, 19821. Accumulated lysosomal oligosaccharides disrupt cell function and have been found in most tissues of locoweed-intoxicated animals, except skeletal muscle and gastrointestinal tract cells (Van Kampen and James, 1970). In the final stages of locoism, central nervous system tissue shows swelling of axonal hillocks (meganeurites) and growth of new dendrites and synapses (Walkley and Siegel, 1989). Because swainsonine is excreted (Huxtable and Dorling, 19821, cessation of locoweed ingestion results in disappearance of cytoplasmic vacuoles in all affected tissues; yet, the altered geometry and synaptic formations in nervous tissue of severely affected animals is permanent and may be the cause of irreversible symptoms of toxicity [Walkley and Siegel, 1989). Therefore, as stated earlier, one objective of the present study was to characterize the early stages of locoweed toxicosis by complete serum clinical profiles, before symptoms of locoism became visually apparent and were irreversible. The validity of serum activities of mannosidase as a determinant of locoweed toxicosis has been questioned (Huxtable and Dorling, 19821, and altered concentrations of selected serum constitutents have been reported and used as indices of toxicity (see discussion below). Presently available are inexpensive autoanalytical techniques to measure complete serum clinical profiles (30 serum constituents), allowing further characterization of locoweed toxicosis. A sampling day x treatment interaction (P e .lo) was noted for heifer BW; however, no treatment effects (P > .lo) were detected within days (data not shown). Heifers began the experiment with a n average BW of 295 kg, and after 28 d BW averaged 299 kg. Heifers fed locoweed occasionally refused small amounts (usually e 100 g1 of root portions, apparently because of low palatability. One heifer receiving the negative control treatment refused increasing amounts of feed as the experiment progressed. Decreased intake with increased
BACHMAN ET AL.
3128
degree of toxicosis has been reported (Van Kampen and James, 1969). Neither sampling day x treatment interactions nor treatment effects were noted (P > .lo) for the following (overall means and SE in parentheses): Na (140, .2 mEq/L), K (4.3, .04 mEq/L), C1 (98, .3 mEq/L), HCO, (27, .4 mEq/L), Ca (9.3, .1 mg/dL), P (6.4,.1 mg/dL), anion gap (14.5, .5 mEq/L), osmolality (275, .5 mOsm/L), glucose (79, 1 mg/dL), cholesterol (79, 2 mg/dL), urea N (11, .2 mg/dL), creatinine (1.3, -02mg/dL), uric acid (3, .01 mg/dL), albumin (3.9, .02 g/dL), globulins (3.9, .05 g/dL), total proteins (7.8, .05 g/dL), direct bilirubin (.O2, .003 mg/dL), indirect bilirubin (.14, .01 mg/dL), total bilirubin (. 16, .01 mg/dL), alanine transferase (26, .6 U/L), creatine kinase (205, 8 U/L), and gamma glutamyl transpeptidase (17, .5 U/LI. Our findings on serum glucose and P concentrations agree with those of James et al. (19701, who reported no changes in these serum constituents in sheep fed locoweed. Lack of altered Ca concentration in the present experiment contradicts the data of James et al. (19701, who reported decreased Ca concentration in wethers during wk 5, 6, and 7 after feeding a diet containing approximately 15% locoweed. We fed locoweed for only 28 d, and it is possible that changes in serum Ca concentration
might OCCUT only at some later stage(s1of toxicosis. Lack of differences in albumin, globulin, and total protein concentrations in our experiment agree with previous findings (Sharma et al., 1984) in which ewes consuming 340 g/d of locoweed had no differences in these constituents. Sampling day x treatment interactions were not detected (P > .lo) for d 7 through 28, but a sampling day x treatment interaction was detected (P e .lo) for d 35 and 42 for serum alkaline phosphatase (ALKP) activities (Table 3). Serum ALKP was greater ( P e .01) by 7 d after feeding locoweed, remained elevated (P e .01)through d 35 (7 d after cessation of feeding locoweed), and then dropped below (P < .lo) control levels on d 42. In addition, heifers fed Silent Herder had lower (P e .lo1 ALKP activities than did heifers fed clinoptilolite on d 35. James et al. (1970) noted elevated ALKP on d 7 through 49 in wethers fed a diet containing approximately 12% locoweed; however, decreased ALKP by 14 d after cessation of feeding locoweed has not been noted previously. Alkaline phosphatase activity is a n index of diseased bone or liver tissue, or obstruction of the biliary tract Wallach, 1974). Lack of differences (P > .lo) in measure of direct, indirect, total bilirubin, or Ca and P concentrations in our experiment suggest no obstruction of the biliary tract or bone pathology
Table 3. Serum alkaline phosphatase (ALKP) and glutamic oxaloacetic transaminase (SGOT)in beef heifers fed roughage diets with or without 20% (DM basis) locoweed, and for 14 days after cessation of locoweed feeding (days 35 and 42), as affected by supplemental mineral compounds Treatmenta ~
Positive control
Item
Negative control
Silent Herder
ClinoDtilolite
SE Contrastb
Day 0 ALKP, U/L SGOT, U/L
201 104
207 106
NS NS
216 100
31 8
1,128 224
125 9
272
271
13
1**
372
472
37
1**,3'
108
177
20
1**
246 110
Days 7, 14, 21, and 26' ALKP, U/L SGOT, U/L
273 107
997 233
SGOT, U/L
103
268
1,243 254
1** 1**,3*
Days 35 and 42' Day 35 ALKP, U/L
228
374
ALKP, U/L
246
177
Day 42 &Allheifers received 300 g (as-fed basis) of a hominy feed/molasses mixture daily. Heifers were fed Silent Herder and clinoptilolite (100 gl mixed with hominy feed/molasses for a 28-d period. During d 29 through 42, heifers were allowed ad libitum access to sorghum sudangrass hay. bContrasts evaluated were 1 = positive control vs locoweed, 2 = negative control vs minerals, 3 = Silent Herder vs clinoptilolite. NS = nonsignificant Lp ,101. CNo treatment x day interactions were detected Lp > ,101.
+P < *P
.lo). CNo treatment x day interactions were detected (P .IO). **P < .01.
because of locoweed ingestion; this finding implicates hepatocytes as the source of increased ALKP. Supporting our inference that increased ALKP is a result of hepatocyte pathology, Van Kampen and James (1970) reported cellular vacuolization of hepatocytes in ewes fed 380 g/d of locoweed. In addition, decreased ALKP 14 d after cessation of feeding locoweed in our experiment agrees with data of Huxtable and Dorling (19821, who noted disappearance of cellular vacuolization of most tissues within 10 to 12 d after cessation of feeding a forage containing swainsonine. Sampling day x treatment interactions were not detected (P > .lo) for serum glutamic oxaloacetic transaminase activities (SGOT; synonymous with aspartate amino transferase; Table 3). In heifers fed locoweed, SGOT was greater (P < .01) by d 7 and remained elevated (P < .011 through d 42 compared with controls. Activities of SGOT in heifers fed Silent Herder were greater (P < .05) than in heifers fed clinoptilolite during d 7 through 28. These data agree with previously published reports of elevated SGOT in sheep fed locoweed (James et al., 1968, 1970; Le Grande et al., 1985). Elevated SGOT is a n index of diseased muscle, liver, or brain tissue (Wallach, 1974). Swainsonine does not seem to affect muscle tissue Wan Kampen and James, 19701, but cellular vacuolization bas been noted in brain tissue and hepatocytes Wan Kampen and James, 1970). In contrast to ALKP, SGOT activity did not decrease to nearnormal levels within 14 d of cessation of feeding locoweed. Vacuolization of neural tissue may persist longer than in other tissues (Huxtable and Downloaded from https://academic.oup.com/jas/article-abstract/70/10/3125/4705758 by UNIVERSITY OF CALIFORNIA, Berkeley user on 26 July 2018
Dorling, 19821, suggesting that neural tissue was one source of elevated SGOT. No sampling day x treatment interaction was detected (P > .lo) during d 7 through 28 for serum concentration of Fe, but a n interaction was noted (P < .lo) on d 35 and 42 (Table 41. Serum Fe concentration was lower IP < .011 in heifers fed locoweed than in control heifers by d 7 after feeding locoweed and remained lower (P < .01) than in controls through d 28. However, no treatment differences (P > .lo) were noted on d 35 and 42. The Fe concentration of positive control heifers was numerically lower on d 42 than had been noted previously for this treatment group, possibly negating detectible effects of lowered Fe resulting from locoweed ingestion. The cause of the lower serum Fe concentrations in positive control heifers on d 42 is unknown. Effects of locoweed on Fe have not been reported previously. Serum Fe concentration is decreased during conditions of nephrosis and several anemias (Wallach, 19741. Locoweed toxicosis caused vacuolization of the proximal convoluted tubules, distal convoluted tubules, loops of Henle, and collecting ducts of sheep kidney Wan Kampen and James, 1969) and decreased erythrocyte count, hemoglobin concentration, and packed cell volume in a calf (James et al., 1970). Either locoweed-induced nephrosis or effects on erythrocytes could be responsible for the decreased serum Fe concentration in our experiment. Week x treatment interactions (P < .lo) for serum lactate dehydrogenase (LDHI activities required presentation of data by sampling day
3130
BACHMAN ET AL.
A sampling day x treatment interaction was detected (P < .lo) for d 7 through 28 for serum triglyceride concentration (TRIG) but not (P > .lo) for d 35 and 42 (Table 5). Numerical trends over the 42-d feeding period suggest that TRIG in control heifers increased and TRIG in heifers fed locoweed decreased or remained constant. On d 14 and 28, these trends led to greater (P < .01, P < .05, respectively) TRIG in control heifers than in heifers fed locoweed. In addition, on d 14 the negative control heifers had greater (P < .lo1 TRIG than the heifers fed minerals. Increased TRIG in control heifers during the experimental period suggests that excess dietary energy was converted to triglycerides in the liver. Because these were actively growing heifers fed a medium-quality roughage a t 1.5% of BW, excess energy intake seems unlikely. Despite the unknown cause of
(Table 5). On d 14, LDH was greater (P .01)in heifers fed Silent Herder than in heifers fed clinoptilolite. Although this numerical trend was apparent on both d 21 and 28, no differences (P > . l o ) were noted. On d 28, heifers fed locoweed had greater (P < .05) LDH concentrations than did control heifers. No differences (P > .lo) were noted on d 35 and 42. On d 42, all treatment groups had numerically greater means than on d 0. Increased serum LDH is indicative of disease of cardiac and skeletal muscle, liver damage, and some anemias Wallach, 19741. Locoweed intoxication does not cause vacuolization of cardiac or skeletal muscle (Van Kampen and James, 1970). Damaged hepatocytes and erythrocytes, as indicated by increased LDH, is consistent with lower serum Fe concentration and elevated ALKP concentration in heifers fed locoweed in our experiment.
Table 5. Serum lactate dehydrogenase (LDH) activity and triglyceride (TRIG) concentration in beef heifers fed roughage diets with or without 20% (DM basis) locoweed, and for 14 days after cessation of locoweed feeding (days 35 and 42), as affected by supplemental mineral compounds Treatmenta Item
Positive control
Negative control
1,040 14
1,007 16
Silent Herder
Clinoptilolite
SE
Contrastb
1,009 14
1,051 17
68 2
NS NS
1,130 14
1,151 16
49 2
NS NS
1,267 12
1,069 11
39 2
3" 1**,2+
1,313 14
1,178 14
48 2
NS NS
1,369 12
1,230 13
58 1
1* 1**
1,310
1,290
69
NS
1,182
1,114
60
NS
14
2
NS
Day 0 LDH, U/L TRIG, mg/dL
Day 7 LDH, U/L TRIG, mg/dL
1,192 19
1,149 16
LDH, U/L TRIG, mg/dL
1,079 24
1,094 16
LDH, U/L TRIG, mg/dL
1,162 17
1,236 17
LDH, U/L TRIG, mg/dL
1,127 20
1,236 14
LDH, U/L
1,239
1,269
LDH, U/L
1,178
1,112
Day 14
Day 21
Day 28
Day 35 Day 42 Day 35 and 42' TRIG, mg/dL
19
18
17
aAll heifers received 300 g (as-fedbasis) of a hominy feed/molasses mixture daily. Heifers were fed Silent Herder and clinoptilolite (100 g) mixed with hominy feedlmolasses. During d 29 through 42, heifers were allowed ad libitum access to sorghum sudangrass hay. bContrasts evaluated were 1 = positive control vs locoweed, 2 = negative control vs minerals, 3 = Silent Herder vs clinoptilolite. NS nonsignificant (P > .lo). CNo treatment x day interactions were detected (P > ,101.
-
+P < .lo. * P c .OS. **P < .01. Downloaded from https://academic.oup.com/jas/article-abstract/70/10/3125/4705758 by UNIVERSITY OF CALIFORNIA, Berkeley user on 26 July 2018
LOCOWEED TOXICOSIS IN HEIFERS
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Table 6. Serum metabolic hormones in beef heifers fed roughage diets with or without 20% (DM basis) locoweed, as affected by supplemental mineral compounds Treatment& Positive control
Item
Negative control
Silent Herder
Clinoptilolite
SE
Contrastb
10.0 56 .4 45
2.0 15 .1 11
NS NS
Day 28' Somatotropin, ng/mL Prolactin, ng/mL Insulin, ng/mL Melatonin, pg/mL
7.3 37 .5
44
7.5 71 .8 52
11.4 67 .5 52
2*
NS
&Allheifers received 300 g (as-fedbasis) of a hominy feed/molasses mixture daily. Heifers were fed Silent Herder and clinoptilolite (100 g) mixed with hominy feedlmolasses. bContrasts evaluated were 1 = positive control vs locoweed, 2 = negative control vs minerals, 3 = Silent Herder vs clinoptilolite. NS = nonsignificant (P > .IO). CMeansare averaged over sampling times of 0 (before feeding), and 2,4,6,and 8 h after feeding on d 28 of the experiment. No treatment x sampling time interactions were detected (P > .lo).
*P
c .OS.
increased TRIG, heifers fed locoweed did not respond similarly to control heifers. This finding may relate to altered hepatic pathology suggested by increased ALKP and LDH in heifers fed locoweed. Sampling time x treatment interactions were not detected (P > .lo) for any serum hormone measured on d 28. Locoweed ingestion did not affect (P > .lo) concentrations of somatotropin, prolactin, or melatonin (Table 6). Serum insulin concentration was greater (P e .05) in negative control heifers than in heifers receiving Silent Herder or clinoptilolite. Mineral supplements seemed to ameliorate the insulin-increasing effects of locoweed. Greater insulin concentration in animals fed locoweed has not been reported previously. Swainsonine may have caused pancreatic islet cell vacuolization/dysfunction, which caused increased insulin release. Van Kampen and James (1989)reported that feeding 227 g of locoweed to wethers for 60 d elongated pancreatic islet cells, but distinct vacuolization could not be demonstrated. In summary, we interpret these serum metabolite and hormone profiles to suggest that feeding locoweed a t 20% of a limit-fed (1.5% of B W roughage diet for 28 d caused damage to erythrocytes, liver, kidney, and nervous tissue and possibly to pancreatic islet cells. Changes in serum constituents appeared within 7 d of feeding locoweed, and most constituents returned to normal within 14 d after cessation of feeding locoweed. These data agree with previous histological examination of tissues of swainsonine-intoxicated animals. Silent Herder and clinoptilolite alleviated locoweed-induced increases in insulin concentrations but did not affect other serum constituents, suggesting that neither Silent Herder nor clinoptilolite alleviates the effects of locoweed toxicity. Downloaded from https://academic.oup.com/jas/article-abstract/70/10/3125/4705758 by UNIVERSITY OF CALIFORNIA, Berkeley user on 26 July 2018
Implications Feeding locoweed at 20% of a limit-fed roughage diet to heifers for 28 d altered some serum metabolite and hormone profiles. We interpret these profiles as locoweed-induced damage to erythrocytes, liver, kidney, and nervous system cells. Neither Silent Herder Mineral Mix nor the natural zeolite clinoptilolite proved effective as a treatment for locoweed toxicosis.
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