Anti-quality factors associated with alkaloids in eastern temperate pasture

16 Pages·2004·0.12 MB·English

J. Range Manage.
54: 474–489 July 2001
Anti-quality factors associated with alkaloids in eastern
temperate pasture
F.N. THOMPSON, J.A. STUEDEMANN, AND N.S. HILL
Authors are professor emeritus of physiology, College of Veterinary Medicine University of Georgia, Athens, Ga 30602, animal scientist, J.Phil Campbell,
Sr., Natural Resource Conservation Center, USDA-ARS, Watkinsville, Ga 30677 and professor Department of Crop and Soil Sciences, University of Georgia,
Athens, Ga 30602.
Abstract Resumen
The greatest anti-quality associated with eastern temperature El principal factor anti-calidad asociado con los de zacates
pasture grasses is the result of ergot alkaloids found in endo- templados del este que se utilizan para praderas es el resultado
phyte-infected (Neotyphodium ceonophialum) tall fescue (Festuca de los alcaloides Ergot encontrados en el pasto Alta fescue infec-
arundinaceaSchreb.) The relationship between the grass and the tado de hongo endófito (Neotyphodium ceonophialum). La
endophyte is mutalistic with greater persistence and herbage relación entre el pasto y el endófito es mutualista, con mayor
mass as a result of the endophyte. Ergot alkaloids reduce growth persistencia y masa de forraje como resultado del endófito. Los
rate, lactation, and reproduction in livestock. Significant effects alcaloides Ergot reducen la tasa de crecimiento, la lactación y la
are the result of elevated body temperature and reduced periph- reproducción del ganado. Los efectos críticos son el resultado de
eral blood flow such that necrosis may result. Perturbations also la elevada temperatura corporal y el reducido flujo periférico de
occur in a variety of body systems. Planting new pastures with sangre que puede ocasionar en necrosis. También ocurren per-
seed containing a “non-toxic” endophyte appears to be a poten- turbaciones en una variedad de sistemas corporales. El plantar
tial solution. Ergotism results from the ingestion of the scelerotia praderas nuevas con semilla libre del hongo endófito parece ser
of Claviceps purpurea containing ergot alkaloids found on seed una solución potencial El Ergotismo resulta de la ingestión de la
heads. Ergotism resembles the effects of endophyte-infected tall esclerotia de Claviceps purpuerea que contiene alcaloides Ergot
fescue. Endophyte-infected perennial ryegrass (Lolium perenne la cual se encuentra en las estructuras de la planta que contienen
L.) contains ergot and lotirem alkaloids that result in reduced las semillas. El Ergotismo asemeja los efectos producidos por el
growth and tremors. Reed canarygrass (Phalaris Anundinacba zacate Alta fescue infectado por el hongo endófito. El ryegrass
L.) contains tryptamine, hordenine and gramine alkaloids that perenne infectado con el endófito contiene alcaloides ergot y
reduce growth. Annual ryegrass (Lolium multiplorum L. may lotirem que resultan en un crecimiento reducido y temblores. El
contain galls with cornetoxins which result in neurological signs. zacate “Reed canarygrass” contiene los alcaloides triptamina,
hordenina y gramina los cuales reducen el crecimiento. El rye
grass anual puede contener agallas con cornetoxinas las cuales
resultan en síntomas necrológicos.
Key Words: tall fescue, ergotism, perennial ryegrass, reed
canarygrass, annual ryegrass
Tall Fescue
The term “eastern temperature grass” is somewhat subjective
and could be defined to include any grass species grown in tem- The most notorious grass-related livestock anomaly in the United
perate zones or species that originate and predominate within the States is fescuetoxicosis, affecting over 8.5 million beef cows and
temperate regions of the world. Numerous grass species contain 700,000 horses (Ball et al. 1996). The economic impact of grazing
anti-quality compounds as defense mechanisms, so this discus- endophyte-infected (E+) tall fescue upon the beef industry has been
sion will be limited to grasses that are utilized in the eastern half estimated to exceed $700 million per annum (Hoveland 1990).
of the United States, have origins in temperature climatic Further economic impacts occur upon the horse and sheep industry.
regimes, and contain the C photosynthetic pathway common to The agronomic attributes of tall fescue (Festuca arundinacea
3
cool-season grasses. Using this definition of the term, this discus- Schreb.) make it an attractive forage species because of its ability
sion will focus on 2 grass species, i.e., tall fescue (Festuca arund- to withstand drought, poor soil conditions, and intensive defolia-
inacea Schreb.) and perennial ryegrass (Lolium perenne L.) that tion from grazing. It is utilized on approximately 14 million
form mutualistic associations with other organisms resulting in hectares of pasture and hayfields, most of which are located in the
anti-quality products, and 1 grass species, reed canarygrass eastern half of the United States. Fescue toxicosis occurs when the
(Phalaris anundinacea L.), in which anti-quality products are an plant is infected with the constitutive clavicipitaceous endophytic
endemic function of the plant genome. In addition, ergotism and fungus, Neotyphodium coenophialum(Glenn et al. 1996, formerly
annual ryegrass (Lolium multiflorumL.) toxicosis are the result of called Acremonium). The endophyte lives in intercellular spaces of
organisms parasitizing forages. sheath, stem, leaf, and seed tissues. There is no invasion of plant
cells nor does the endophyte become pathogenic. It is passed from
Manuscript accepted 24 Mar. 01. generation to generation via seed, so infected plants beget infected
474 JOURNAL OF RANGE MANAGEMENT54(4), July 2001
offspring and thus perpetuate the associa-
tion. In a survey of over 1500 pasture sam-
ples obtained throughout the United States,
more than 70% of the samples had 60% or
more endophyte infection rates (Shelby and
Dalrymple 1987). Seeds which were tested
generally had the same rate of presence as
pasture samples, but nearly 90% of the seed
samples had less than 20% viable (living)
endophyte. The obvious question then is,
“Why are fields highly infected if the endo-
phyte does not survive in the seed from
which they were planted?” Older tall fescue
stands are typically highly infected because
in mixed stands of endophyte-free (E-) and
E+ plants, E+ plants choke out and replace
the E- plants and hence, pastures convert
from low-infection rates to high-infection
rates as the process continues.
Fig. 2. Loline alkaloids found in endophyte–infected tall fescue (Porter 1994).
The grass benefits from the endophyte-
grass association in part by a group of
The endophyte receives a home and a (animal behavior), 3 (physiological) and 4
alkaloids produced by the endophyte or by
food supply in return for its contribution to (sera or plasma). In cases where extensive
the plant in response to the endophyte.
the plant. This means the endophyte is data exist, only a few selected articles
Ergot (Fig. 1) and clavine alkaloids,
never subjected to environmental forces were referenced to illustrate effects.
peramine, and saturated aminopy-
and is only dependent upon plant health The presence of ergot and perhaps other
rrolizidine (lolines) alkaloids (Fig. 2) are
for its survival (Hill 1994). Hence, it is in alkaloids in forage resulting in depressed
all biologically active compounds that
the plant’s interest to provide the needs for body weight gains in livestock grazing E+
serve as feeding deterrents and decrease
the endophyte; and the endophyte to pro- tall fescue particularly during the warm
reproduction and growth by both mam-
vide protection to the plant against climat- season is often referred to as summer fes-
mals (Porter 1994, Stuedemann et al.
ic and biological forces (e.g., insects) that cue toxicosis. Affected animals have an
1989) and insects (Clay et al. 1985, Clay
may be threatening. unthrifty appearance, long rough hair
1989, Siegel et al. 1991, Porter 1994).
coats, excessive salivation and elevated
Protection from defoliation suggests solar
respiratory rates and spend less time graz-
energy capture and retention is a para- Animal Toxicosis-Tall Fescue
ing during daylight hours (Stuedemann
mount priority in this association. The impact or effects of consumption of
and Hoveland 1988). Calving rates are
Reduced insect or livestock grazing results E+ tall fescue have been reviewed (Bush
also decreased (Porter and Thompson
in more photosynthetically active leaf et al. 1979, Stuedemann and Hoveland
1992) as well as milk yield in dairy cows
area, resulting in greater energy capture, 1988, Schmidt and Osborn 1993,
(Strahan et al. 1987). Fescue foot and fat
greater energy reserves, and greater re- Stuedemann and Thompson 1993).
necrosis are 2 other conditions in cattle
growth capacity when infected with the Readers are referred to those reviews for
associated with E+ tall fescue. Fescue foot
endophyte (Hill et al. 1990). Endophyte- specific information on the impact of E+
is a gangrenous condition of the hooves,
infected tall fescue has greater forage and tall fescue on animal response. A com-
tail and occasionally ears that occurs pri-
seed productivity than the E- form (Hill et pendium of the effects of the endophyte on
marily during the winter months (Yates
al. 1991) and is more drought tolerant animal response variables is presented in
1983). Fat necrosis occurs in mature cows
(West et al. 1993). Tables 1 (performance and production), 2
and is associated with masses of hard fat
in the abdomen, leading to poor digestion
and calving problems (Bush et al. 1979).
We postulate that both fat necrosis and
fescue foot are symptoms of fescue toxi-
cosis.
Milk Production and Calf Growth. Milk
production was reduced as much as 60%
in dairy cows consuming an E+ ryegrass-
tall fescue hybrid compared to the same E-
hybrid (Hemken et al. 1979). There was
also an associated decrease in forage
intake. In a subsequent study daily milk
production was significantly reduced in
mid-lactation Holsteins on E+ compared
to E- tall fescue (Strahan et al. 1987).
There was also an associated significant
decrease in daily dry matter intake on E+
Fig. 1. Ergot alkaloids found in endophyte–infected tall fescue (Porter 1994). (7.1 kg) compared to E- (9.1 kg) tall fes-
JOURNAL OF RANGE MANAGEMENT54(4), July 2001 475
Table 1. Effects of endophyte–infected fescue on animal performance criteria.
Response Endophyte Ergovaline Response
criteria level
Low E High E Low E High E Low E High E Feedstuff Animal Referencea
Average
daily gain (%) (mg d–1) (Kg day–1)
0 100 .96 .20 Seed Steers Schmidt el al. 1982
2 >90 .83 .45 Pasture Steers Hoveland et al. 1983
8 91 .97 .46 Pasture Steers Read and Camp 1986
<1 98 .21 –.05 Pasture Cows Gay et al. 1988
<10 >70 .66 .43 Pasture Steers Tolley et al. 1990
0 >85 .45 3.50 –.08 –3.5 Pasture Cows Peters etal. 1992
0 >85 .89 72 Pasture Suckling Peters etal. 1992
calves
25 58 .46 30 Pasture Steers Stuedemann et al.1993
Pregnancy
Rate (%)
1 98 95 55 Pasture Cows Gay et al.1988
21 77 89 74 Pasture Cows Tucker etal. 1989
0 >85 1.45 3.50 91 72 Pasture Cows Peters et al.1992
aSome values were adapted from specific research reports.
cue. Cows receiving E- tall fescue gained reduction in calf weights associated with grazing E+ tall fescue both lost weight and
12.0 kg during the experiment compared nursing cows grazing E+ tall fescue was had reduced pregnancy rates compared to
to a weight loss (–11.7 kg) in cows fed E+ reported by Gay et al. (1988). These cows grazing E- tall fescue. A decline in
tall fescue. The authors suggested that effects of E+ tall fescue are most detri- cow body condition postpartum negatively
there was no endophyte threshold level mental to calf-weaning weights consider- affects reproduction and results in a pro-
below which milk production in dairy ing that cow-milk production accounts for longed interval from parturition to first
cows would not be adversely affected. approximately 66% of the variance in calf- estrus (Wiltbank et al. 1964). In a 3-yr
Milk production was 75% greater in weaning weight. In this regard Danilson et cow study Gay et al. (1988) reported calv-
beef cows grazing E- compared to E+ tall al. (1986) calculated a 0.15 kg reduction in ing rates were 95 and 55% for the E- and
fescue (Schmidt et al. 1984). At 100 days milk production for each 10% increase in E+ tall fescue groups, respectively. In
postpartum, primiparous beef cows graz- pasture endophyte-infection level. Grazing another 3-yr study Washburn and Green
ing E+ tall fescue had 50% lower milk E+ tall fescue also reduced milk produc- (1991) reported that 65% and 39% of
production than those grazing E- tall fes- tion in ewes (Stidham et al. 1982). cows on low vs. high endophyte, respec-
cue (Schmidt et al. 1986). Beef cows graz- The effect of grazing E+ tall fescue on tively, raised a calf each year. Similarly,
ing E+ KY 31 tall fescue had a 25% calf-birth weight either had no effect Boling (1985) reported cows grazing low-
reduction in milk production compared to (Schmidt et al. 1986) or there was a reduc- endophyte infected Kenhy tall fescue had
cows grazing E- Mozark tall fescue or tion in birth weight (Bolt and Bond 1989). calving rates of 86% compared to 67% for
orchard grass, (6.0 and 8.0 kg/day, respec- Reproduction in Beef Cattle. This sub- E+ tall fescue.
tively) (Peters et al. 1992). Calf growth ject has been reviewed (Porter and A greater negative effect from grazing
associated with nursing cows grazing E+ Thompson 1992, Schmidt and Osborn E+ tall fescue upon reproduction occurred
tall fescue was also significantly reduced 1993). In studies summarized by Schmidt in beef heifers compared to cows. Heifers
compared to the other 2 groups. A similar and Osborn (1993), lactating beef cows raised on E+ tall fescue had delayed onset
Table 2. Effects of endophyte–infected tall fescue on behavioral response criteria.
Response Endophyte Ergovaline Response
criteria level
Low E High E Low E High E Low E High E Feedstuff Animal Referencea
Intake (%) Kg day–1
0.0 100 6.6 4.2 Pasture Steers Stuedemann et al.1989
0.0 96 6.0 3.2 Seed Steers Osborn et al. 1992
(mg/d) (% of BW)
0.0 >85 1.45 3.50 2.40 2.25 Pasture Cows Peters et al. 1992
(mg/kg BW.75)
0.0 0.053 2.55 1.76 Seed Sheep Aldrich et al. 1993b
& hay
Water (Lis in day–1)
intake
0.0 0.053 4.2 5.3 Seed Sheep Aldrich et al. 1993b
& hay
0.0 0.05 49.3 48.9 Seed Heifers Aldrich et al. 1993b
aSome values were adapted from specific research reports.
476 JOURNAL OF RANGE MANAGEMENT54(4), July 2001
Table 3. Effects of endophyte–infected fescue on physiological response criteria.
Response Endophyte Ergovaline Response
criteria level
Low E High E Low E High E Low E High E Feedstuff Animal Referencea
Skin (%) (ppb) Kcal m2hour–1
Vaporization
<50 381 113.7 91.3 Seed Heifers Aldrich et al.1993a
<50 285 41.9 34.4 Seed Steers Aldrich et al.1993b
(at 22°C)
<50 285 87.2 47.1 Seed Steers Aldrich et al. 1993b
(at 32°C)
Respiration (breath min–1)
rate
0.0 96 62 70 Seed Steers Osborn et al.1992
& hay
Heart rate (beats min–1)
0.0 96 68 51 Seed Steers Osborn et al.1992
& hay
Rectal
temperature (°C )
0.0 96 39.4 39.7 Seed Steers Osborn et al.1992
& hay
(mg/kg BW.75)
0.0 0.053 40.0 40.4 Seed Sheep Aldrich et al. 1993b
& hay
Core body
Temperature 0.0 0.053 38.3 39.3 Seed Sheep Aldrich et al. 1993b
& hay
aSome values were adapted from specific research reports.
of puberty and decreased first-service con- experienced dystocia. Supplementing ier (Monroe et al. 1988, Brendemuehl et
ception rates (Washburn et al. 1989). pregnant mares on E+ tall fescue with al. 1994b). Surviving foals were large-
Similarly, in another study there was a shelled corn had no effect on gestation framed and emaciated in appearance, with
96% conception rate in beef heifers raised length or incidence of dystocia (Earle et premature eruption of teeth and overgrown
on E- tall fescue compared to a conception al. 1990). Placentas from affected mares hooves (Monroe et al. 1988, Putnam et al.
rate of 55% on E+ tall fescue (Schmidt et were thickened, reddish colored and heav- 1991). Mares should be removed from E+
al. 1986). In the following year, only 33%
of the then primiparous cows grazing E+
Table 4. Effect of ingestion of endophyte–infected tall fescue on sera or plasma constituents of cattle.
tall fescue were successfully rebred com-
pared to 93% on E- tall fescue.
Response criteria Direction Reference
The adverse effect of the endophyte
Alkaline phosphatase reduced Bond et al. 1984
upon reproduction in cattle is mediated
Boling et al. 1989
partially at least, by increased early
Amylase increased Nutting et al. 1992
embryonic mortality. Cattle embryos Asparatate aminotransferase reduced Dougherty et al. 1991
transferred into heifers grazing E+ tall fes- Cholesterol reduced Bond et al. 1984
cue had decreased survival compared to Stuedemann et al. 1985a
embryos transferred into heifers grazing Lipham et al. 1989
Tolley et al. 1990
E- tall fescue (Rahe et al. 1991). Similarly,
Cortisol unchanged Aldrich et al. 1993a
cattle embryos taken from cows grazing
Creatine kinase reduced Dougherty et al. 1991
E+ tall fescue had decreased in vitro Growth hormone unchanged Elsasser and Bolt, 1987
cleavage, rate of development and quality Lipham et al. 1989
compared to those from cows grazing E- increased Thompson et al. 1987
tall fescue (Nasti et al. 1994). Insulin–like growth factor–1 reduced Filipov et al. 1999
Lactic dehydrogenase reduced Dougherty et al. 1991
Impact on Horses. The pregnant mare is
Luteinizing hormone unchanged Mizinga et al. 1992
very sensitive to the effects of grazing E+
Melatonin reduced Hurley et al. 1981
tall fescue (Cross 1997). Mean gestation Porter et al. 1990
length in mares consuming E+ tall fescue Prolactin decreased Hurley et al. 1981
was lengthened 27 days (Monroe et al. Elsasser and Bolt, 1987
1988). Others reported similar effects Thompson et al. 1987
Lipham et al. 1989
(Putnam et al. 1991, Redmond et al.
Thyroid stimulating hormone unchanged Elsasser and Bolt, 1987
1994). Severe dystocia frequently occurs
Thyroxine unchanged Aldrich et al. 1993a
with prolonged gestation in mares on E+ Triiodothyronine unchanged Aldrich et al. 1993a
tall fescue. Putnam et al. (1991) reported
that 10 of 11 mares grazing E+ tall fescue
JOURNAL OF RANGE MANAGEMENT54(4), July 2001 477
tall fescue at least 30 days prior to expect- al. 1989, Osborn et al. 1992) and sheep found in sheep on E+ diets (Zanzalari et
ed foaling (Taylor 1993). (Hemken et al. 1979, Aldrich et al. 1989). al. 1989).
Following foal delivery mares grazing An 8% depression in intake in steers fed Body Temperature, Respiratory and
E+ tall fescue had a high incidence of E+ tall fescue hay resulted in a 58% sup- Heart Rates. Inclusion of the endophyte
either agalactia or reduced milk yield pression in average daily gains (Schmidt in fed diets has resulted in increased rectal
(Monroe et al. 1988, Putnam et al. 1991). et al. 1982). Steers grazing E- tall fescue temperature and respiratory rate. In this
The milk from such mares was off-colored had a 43–69% greater dry matter intake regard, the effects of the endophyte were
(straw-colored with an oily appearance), compared to steers on E+ tall fescue investigated using temperature controlled
rather than the white milk of normal (Stuedemann et al. 1989). rooms (Hemken et al. 1981, Rhodes et al.
mares. This milk lacked normal While the negative effect of the endo- 1991, Osborn et al. 1992, Aldrich et al.
immunoglobulin concentrations and, con- phyte upon intake may due to palatability 1993b, Cornell et al. 1990). Calves con-
sequently, foals did not have normal pas- or secondarily to increased body tempera- suming a toxic ryegrass-tall fescue hybrid
sive immunity (Cross 1997). ture (Beede and Collier 1986), a separate at increased ambient temperatures had
Grazing E+ tall fescue alters the repro- neural mechanism is probable. increased rectal temperatures, respiratory
ductive endocrinology of the pregnant Metoclopramide, primarily a dopaminer- rates and depressed body weight gains
mare (reviewed by Cross 1997). Serum gic antagonist with some anti-serotinergic compared to those fed a non-toxic hybrid
concentrations of the pituitary hormone, activity (Freeman et al. 1992), increased (Hemken et al. 1981); however, at lower
prolactin, that is necessary for the onset of intake in lambs held at 32°C fed a high ambient temperatures there were no differ-
lactation (lactogenesis) were depressed. endophyte diet with no alteration in body ences in respiratory rate and rectal temper-
Serum progesterone concentrations were temperature (Aldrich et al. 1989). atures. In a later experiment using steers
also lowered, but serum concentrations of The effect of E+ tall fescue on intake is fed E-, E+ or E- diets plus ergotamine at
estradiol were increased. This indicates exacerbated by elevated environmental both a thermoneutral temperature (21°C)
that placental function is altered because temperatures (Hemken et al. 1981). When and a heat stressed environment (32°C),
progesterone and estradiol are secreted calf intake of E+ and E- tall fescue forage Osborn et al. (1992) reported both temper-
from that organ. was compared in environmental chambers, ature and endophyte increased rectal tem-
Grazing E+ tall fescue did not increase the E+ forage decreased intake only when perature and decreased heart rate, but no
body temperature in horses (Monroe et al. environmental temperatures exceeded significant interaction occurred between
1988), perhaps because of the ability of 31°C. In a similar experiment with calves endophyte and temperature. Respiratory
horses to dissipate heat by sweating. in environmental chambers at 21°C and rate was increased with the endophyte
Putnam et al. (1991) observed increased 32°C, and fed an endophyte-free tall fes- only at the elevated temperature.
sweating in pregnant mares grazing E+ tall cue diet with added ergotamine resulted in Ergotamine induced changes similar to
fescue. A relationship between grazing E+ reduced intake at both temperatures those found by feeding E+ diets. Both the
tall fescue and laminitis has been suggest- (Osborn et al. 1992). endophyte and added ergotamine
ed based upon epidemiologic and patho- In vitro dry matter digestibility was decreased peripheral body temperature;
logic reports (Rhorbach et al. 1995). superior for E+ hay compared to E- tall this was attributed to reduced peripheral
McCann et al. (1992a) reported no reduc- fescue hay (Schmidt et al. 1982). Chestnut blood flow. Similar changes in rectal tem-
tion in growth of yearling horses grazing et al. (1991) found no difference in organ- perature in cattle resulted from feeding E+
E+ tall fescue supplemented with concen- ic matter digestibility of E+ and E- tall or E- tall fescue diets when animals were
trate. In contrast, average daily gain was fescue in steers and Harmon et al. (1991) exposed to diurnal temperature changes
reduced by 57% in yearling horses grazing found no endophyte effect on dry matter (Aldrich et al. 1993a). Interestingly, this
E+ tall fescue without supplementation and nitrogen digestibility in steers. Others, experiment also revealed that there was a
(Aiken et al. 1993). Relative to mare fertil- however, found that diets containing E+ significant interaction between diet and
ity (Brendemuehl et al. 1994a) reported tall fescue had reduced dry matter and environmental temperature on skin vapor-
that mares grazing E+ tall fescue had organic matter digestibility in sheep ization; with skin vaporization increased
reduced fertility and increased early (Hannah et al. 1990, Fiorito et al. 1991, only in the E- group at an elevated temper-
embryonic mortality rates. Westendorf et al. 1993), cattle (Aldrich et ature. Therefore the effect of the endo-
Behavior, Intake and Digestibility. al. 1993a), and rats (Larson et al. 1991), phyte reduces the ability to remove excess
During daylight, cattle on E+ tall fescue which could be ambient temperature- body heat. A relationship was established
pastures spent less time grazing dependent (Hannah et al. 1990). between dietary ergovaline concentrations
(Stuedemann et al. 1985b, Lipham et al. A metabolic cost has been associated fed to cattle and rectal temperatures
1989). In sunlight, steers on E+ tall fescue with the endophyte. This was revealed by (Cornell et al. 1990). Ergovaline at 50
grazed 5–21% of the time between 1200 pair-fed experiments where the intake of ppb, lowest concentration, resulted in
and 1600 hours compared to 43–65% for animals receiving E- diet was maintained increased rectal temperature only at 30°C
steers grazing E- tall fescue (Stuedemann at the intake level of the E+ tall fescue ambient temperature and above.
et al. 1985b). This effect persisted for at seed-based diet group. Using this strategy Ergot alkaloids can increase body tem-
least 26 days after the steers were moved with rats and cows, a depression in body perature by a direct effect upon the tem-
from E+ to E- pastures. There is no known weight gains occurred in the animals perature regulating areas in the brain
explanation for this residual behavior. receiving E+ diets (Mizinga et al. 1992, (Nickerson 1970, Loew et al. 1978). This
Much of the reduction in animal perfor- 1993). Therefore, growth in rats and cattle central effect upon body temperature
mance has been attributed to reduced are affected by the endophyte in some occurs at a lower dosage compared to that
intake. The presence of the endophyte manner beyond intake. This could be due necessary to mediate vasoconstriction.
reduced intake in cattle (Hemken et al. to increased hepatic mixed function oxi- Spiers et al. (1995) investigated the effects
1981, Schmidt et al. 1982, Stuedemann et dase activity related to detoxification as of injecting rats with ergovaline in both a
478 JOURNAL OF RANGE MANAGEMENT54(4), July 2001
cold environment (7–9°C) and hot envi- vasoconstriction is found in the thickening effect upon GH secretion. The effects of
ronment (31–33°C). Treatment in the cold of the smooth muscle layer of the arteri- E+ tall fescue intake on serum GH have
environment resulted in a decrease in both oles in cattle following ingestion of the been variable (Oliver 1997). Both ergota-
rectal and tail temperature whereas treat- endophyte (Oliver and Schultze 1997). In mine and ergonovine elevated plasma GH
ment in the hot environment resulted in an this regard bovine vascular smooth muscle in steers (Browning et al. 1997). Serum
elevation of rectal temperature, but a proliferated in vitro in response to both IGF was reduced in steers grazing E+ tall
reduction in tail temperature. ergot alkaloids and N-acetyl loloine fescue (Filipov et al.1999, Hazlett et al.
The effects of ergot alkaloids are com- (Strickland et al. 1996). 1998 ), suggesting this may be an impor-
plicated as they are adrenergic and Prolactin, Neural Function and Hair tant mechanistic effect whereby the ergot
dopaminergic agonists as well as both Coat. Serum prolactin is reduced in live- alkaloids suppress growth.
serotinergic agonists and antagonists stock species consuming E+ diets (Hurley Ergot alkaloids may also alter energy
(Muller-Schweintzer and Weidmann et al. 1981, Bolt et al. 1983, Thompson et metabolism and electrolyte movement in
1978). Receptors for these activities are al. 1987, Lipham et al. 1989, McCann et the liver, as both ergonovine and ergota-
widely dispersed. In this regard treatment al. 1992b). Pituitary secretion of prolactin mine inhibited Ca2++-activated bovine
of previously dewormed heifers fed E+ is inhibited by dopamine and ergot alka- mitochondrial ATPase activity (Moubarak
diets treated with ivermectin, an loids are potent dopaminergic agents et al. 1998). As previously mentioned, E+
anthelmintic that binds to g-amino butyric (Lamberts and Macleod 1990). Ergot alka- intake increased mixed function oxidases
neural receptors (Barragry 1984), had loids were ranked relative to competitive in the liver of sheep (Zanzalari et al.
reduced core body temperature and binding to dopamine receptors on pituitary 1989).
increased intake upon heat exposure (Dr. cells (Larson 1997). Ergovaline shared Fat Metabolism. Serum cholesterol is
Spiers, University of Missouri, personal potency with other ergopeptines in this reduced by grazing E+ tall fescue in cattle
communication). Treatment of cattle graz- regard and the ergopeptine alkaloids had (Stuedemann et al. 1985a, Lipham et al.
ing E+ tall fescue with ivermectin topical- 10-fold greater activity compared to ergine 1989) and sheep (Bond et al. 1988). It is
ly before grazing and again at 56 days and ergonovine. unknown whether this was the result of
after beginning the experiment had Depressed serum prolactin with E+ diets increased cholesterol uptake by the tissues
increased weight gains (Bransby 1997). In indicates an impact of ergot alkaloids on or decreased hepatic secretion. The ergot
some experiments this treatment resulted both pituitary and neural function. While alkaloids may decrease lipolysis by an
in increased gains in cattle on E- tall fes- prolactin is required for the onset of lacta- adrenergic receptor activity in the liver
cue in spite of very low fecal egg counts. tion, it is not importantly related to growth (Oliver 1997). An association was made
Therefore, while ivermectin resulted in a (Eisemann et al. 1984). The central ner- between high-nitrogen fertilization of E+ tall
positive effect in cattle on E+ tall fescue, vous system and pituitary have an abun- fescue, reduced serum cholesterol and the
this effect may not have a specific effect dance of dopamine receptors. Meto- incidence of fat necrosis in cattle
against alkaloids in the forage. clopramide (dopamine antagonist) given (Stuedemann et al. 1985a). Serum triglyc-
Interestingly, a combination of an anabolic to steers grazing E+ tall fescue increased eride levels were also reported to be
ear implant containing estradiol and prog- serum prolactin, improved hair coat quali- decreased in cattle on E+ diets (Oliver
esterone plus ivermectin to cattle over- ty, body weight gains and more time was 1997). Together these studies indicate that
came the growth depressant effect of E+ spent grazing (Lipham et al. 1989). The ingestion of E+ diets alters lipid metabolism.
tall fescue. dull and shaggy hair coat changes associ- Serum Enzymes. Several serum
Vasoconstriction. In vitro ergot alka- ated with fescue toxicosis may also result enzymes, alkaline phosphatase, aspartate
loids mediated vasoconstriction of bovine from depressed serum prolactin. amino transferase, alanine amino trans-
dorsal pedal veins via α-2 adrenergic Administration of prolactin to hamsters ferase, and lactic dehydrogenase, are fre-
properties (Solomons et al. 1989). N- following pituitary removal resulted in quently reduced in cattle on E+ diets
acetyl loline had some effect in this regard hair changes appropriate for the photoperi- (reviewed by Stuedemann and Thompson
(Oliver et al. 1990). A subsequent study od under which they were maintained 1993, Oliver 1997). This general decrease
(Dr. Jack Oliver, University of Tennessee, (Niklowitz and Hoffmann 1988). In sheep, in enzymatic activity by E+ diets has been
personal communication) demonstrated increased daylight length that results in attributed to increased hepatic α-2 adren-
extreme potency of ergovaline in this increased serum prolactin, which is impor- ergic activity (Oliver 1997). Other possi-
regard. Most interestingly, Oliver et al. tantly related to a spring moult and pro- ble mechanisms include inhibitors of
(1998) demonstrated that venous prepara- duction of a summer coat (Lincoln 1990). enzymatic action, effects on cell prolifera-
tions from cattle on E+ diets had an As a specific cellular mechanism upon tion, increased clearance via the liver or
enhanced contractility to an alpha-2 adren- neural function, ergovaline inhibited kidney, loss of enzymatic cofactors and
ergic agonist. Dyer (1993) reported ergot Na+/K+ ATPase activity in a dose depen- alterations in conditions that might inhibit
alkaloids mediated vasoconstriction upon dent manner in rat brain homogenates enzymatic action, e.g. pH and tonicity
cattle uterine and umbilical veins via a (Moubarak et al. 1993). (Schultze et al. 1999). Dougherty et al.
serotinergic mechanism. Hepatic/Insulin-Like Growth Factor/- (1991) reported that circulating gamma
Vasoconstriction is important in the Energy Production. The major anabolic glutamyltransferase, as well as aspartate
pathogenesis of fescue foot. Yates et al. effect of growth hormone (GH) secreted aminotransferase and creatinine kinase
(1979) showed that administration of toxic from the pituitary is expressed via stimu- were reduced in cows fed E+ tall fescue
anion fractions from fescue resulted in lating secretion of insulin-like growth fac- seed. Gamma glutamyltransferase is pro-
decreased coronary band temperatures in tor-1 (IGF) prominently from the liver duced specifically in the liver in the
cattle. Decreased blood flow to the digit (Hossner et al. 1997). Secretion of IGF is bovine species (Duncan et al. 1994). It is
would result in decreased nutrient delivery modulated by diet and intake (Elsasser et pertinent to recognize that only an
and tissue death. A mechanism for the al. 1989). Circulating IGF has a negative increase in the circulating concentration of
JOURNAL OF RANGE MANAGEMENT54(4), July 2001 479
these enzymes is an indication of inflam- meters. Oliver (1997) indicated both total Willibrand factor, and angiotensin con-
mation of the organ(s) of origin. circulating leukocytes and individual types verting enzyme, were elevated in sera of
The reduction of alkaline phosphatase as of leukocytes (neutrophils, lymphocytes, cattle grazing E+ tall fescue (Oliver 1997).
the result of E+ diets is rather consistently eosinophils and monocytes) were lowered Endothelin is a potent vasoconstrictor
observed (Bond et al. 1984, Boling et al. in calves on E+ tall fescue, suggesting agent and is mitogenic (Anggard et al.
1989, Jackson et al. 1997, Gould and lowered immunocompetence. However, in 1990). Angiotensin converting enzyme
Hohenboken 1993, Schultze et al. 1999). a later report (Oliver et al. 2000) only results in the production of angiotensin II,
A steady decrease in the concentration of eosinophil numbers were reduced by E+ a potent vasoconstrictor enzyme (Hoorn
alkaline phosphatase was observed in tall fescue. and Roth 1993). Von Willibrand factor is
steers grazing E+ tall fescue (Schultze et Immunological effects. Saker et al. an adhesion molecule for platelets during
al. 1999). This enzyme catalyzes the (1998) indicated cattle on E+ tall fescue vascular injury (Blann 1993).
hydrolysis of monophosphate esters under had lowered indices of immunological Additionally, thromboxane B (stable
2a
alkaline conditions (Duncan et al. 1994). function. Additionally, a decreased anti- metabolite of thromboxane A ) a potent
2
Quantitative isoenzyme determinations of body titer in response to tetanus toxin vasoconstrictor from platelets, was report-
this enzyme obtained from cattle grazing occurred in steers grazing on E+ tall fes- edly elevated in the sera of cattle on E+
E+ indicated that the decrease in this cue (Dawe et al. 1997) and in rats on E+ tall fescue (Oliver 1997). This agent also
enzyme was due to lowered activities of diets challenged with sheep red blood cells has bronchoconstrictive effects in the lung
intestinal and bone isoenzymes (Schultze (Dew et al. 1990). In contrast, Rice et al. (Campbell 1990). Recently, it was found
et al. 1999). Therefore, an effect upon (1997) reported greater antibody response that steers grazing E+ compared to E- tall
serum enzymes extends beyond the liver. in challenged cattle grazing E+ tall fescue. fescue had a greater response to
Copper Status. Consumption of pre- Further evidence of immunosuppression is lipopolysaccharide as measured by
sumably high-endophyte tall fescue result- indicated by the decreased serum globulin increases in tumor necrosis factor, a cata-
ed in rapidly decreased circulating copper concentrations in steers grazing E+ bolic agent (Filipov et al. 1999); indicating
(Cu) and ceruloplasmin oxidase activity in (Schultze et al. 1999). Both the alpha and that E+ tall fescue sensitizes the animal to
cattle (Stoszek et al. 1979); however, body gamma globulin fraction decreased, but other excitatory agents.
weight gains were not improved by Cu the largest decrease occurred in the In summary, the pathogenesis of fescue
supplementation. Recent work indicates gamma globulin fraction. Since gamma toxicosis appears to originate from dam-
serum Cu concentrations were decreased globulins are of lymphoid origin (Duncan age to the vascular endothelium.
in E+ compared to E- tall fescue (Dennis et al. 1994), this could explain decreased Endothelial cells release mediators that
et al. 1998, Oliver et al. 2000). In a related immune responses. In support of these result in smooth muscle cell proliferation
report, steers grazing E+ compared to E- experimental observations, Purdy et al. in the arterioles. Further exposure of blood
tall fescue had reduced ceruloplasmin and (1989) reported that steers that had been vessels results in vaso-constriction with
serum Cu (Saker et al. 1998). The steers on E+ had increased morbidity and mor- ischemia so that nutrient flux is altered
grazing E+ tall fescue also had lowered tality following movements to feedlots. and dissipation of heat is reduced. The
indices of immunological competency Pathogenesis. Necropsy changes decrease in blood perfusion to the skin and
(lowered phagocytic activity and MHC observed in cattle that had grazed E+ tall lungs would contribute to heat stress while
class II expression). Copper supplementa- fescue were mostly limited to a thickening the same effect upon the GI tract would
tion increased the MHC class II expres- of the smooth muscle layer of the arteri- result in altered nutrient flux. The more
sion regardless of forage endophyte status. oles (Oliver and Schultze 1997). There distal portions of the body would be most
Additionally, Cu is required for hair pig- were GI tract lesions in several animals compromised by this scenario with the
mentation and red blood cell production indicating abscesses, enteritis and colitis. resultant loss of tail tips and limb digits.
(Barragry 1994). Perhaps the decreased Similarly, in earlier findings in cattle that The effects upon reproduction could be
circulating Cu levels contributes to the had grazed E+ tall fescue, Garner and either as a direct effect of ergot alkaloids
bronzed hair coat observed in Angus cattle Cornell (1985) reported swollen arterioles upon embryos, decreased nutient delivery
grazing E+ tall fescue. upon necropsy. Therefore, changes in cat- to the uterus, or altered uterine environ-
Blood Cells. The results of a 3 year tle on E+ tall fescue are largely referable ment. A direct effect of ergot alkaloids
grazing study indicate that the effect of E+ to the cardiovascular system. The patho- upon the brain may lead to increased body
tall fescue was an increase in numbers of genesis associated with ergotism is also temperature and decreased intake.
circulating red blood cells, however, there described as due to stimulation of smooth
was a reduction in both mean red blood muscles in blood vessels (primarily arteri-
cell volume and hemoglobin concentration oles) with congestion proximal to the Ergotism
in each cell (Oliver et al. 2000). These resulting vasoconstriction and ischemia
changes in red blood cell volume and distal to the vessel spasm (Osweiler 1981).
Ergot toxicity or ergotism occurs as the
hemoglobin are congruous with a decrease Ergot alkaloids mediated cytotoxicity
result of ingestion of the scelerotia of
in circulating Cu. Earlier work (Steen et upon the endothelial portion of blood ves-
Claviceps purpurea found on feed grains
al. 1979, Bond et al. 1984) indicated the sels in cattle grazing E+ tall fescue (Oliver
and pasture grasses. Ergot alkaloids identi-
hematocrit was likely suppressed in cattle 1997). The vascular endothelium is a
fied with the toxicosis have been identi-
grazing E+ tall fescue. In contrast, circu- known target for the ergot alkaloids
fied (Porter et al. 1987). The major ergot
lating numbers of red blood cells were not (Thompson et al. 1950). The endothelial
alkaloids found in sclerotia on fescue,
reduced in cattle on endophyte containing cells are metabolically active and serve as
wheat, and barley were ergotamine,
diets (Rhodes et al. 1991). Since Cu is an interface for toxic agents (Gimbrone
ergocristine and ergosine. Additionally,
related to red blood cell production, a Cu 1986). Biologically active agents of
ergocornine and ergocryptine were associ-
deficiency could alter red blood cell para- endothelial origin, endothelin, von
ated ergotized annual ryegrass (Schneider
480 JOURNAL OF RANGE MANAGEMENT54(4), July 2001
Animal Toxicosis–Perennial Ryegrass.
The effect of grazing endophyte-infected
(E+), lolitrem B-free E+ and E- varieties
of perennial ryegrass upon animal perfor-
mance and the incidence of ryegrass stag-
gers has been reported (Fletcher 1993,
Cunningham et al. 1993).
Animal Performance. Live weight
gains were reduced in sheep grazing E+
perennial ryegrass in the absence of rye-
grass staggers (Fletcher and Barrell 1984);
indicating a direct effect of the endophyte.
Fig. 3. Alkaloids found in endophyte–infected perennial ryegrass (ergot alkaloids not shown)(Porter Depressed body weight gains occurred
1994).
only in association with summer condi-
tions and the endophyte. Reduced serum
et al. 1996). The scelerotia of the fungus viable and non-viable tissue. In another prolactin also was associated with the
replaces some of the seedhead and appear report, gangreneous lesions on the rear of endophyte, presumably as the result of
as elongated dark-brown bodies of vari- the fetlock characterized ergotism in cattle ergovaline (Davies et al. 1993b). Grazing
able size. (Woods et al. 1966). Intestinal inflamma- the lolitrem B-free varieties of E+ perenni-
The signs of ergotism resemble fescue tion has been observed in both cattle and al ryegrass over an extended period did
toxicosis (Robbins et al. 1986, Schneider sheep with ergotism (Coppock et al. 1989, not result in improved live weight gains
et al. 1996). This similarity in signs is nat- Greatorex and Mantle 1973). The patho- over other perennial ryegrass endophyte
ural as both are the result of ergot alkaloid genesis of ergotism and fescue toxicosis is associations, however, animals grazing the
toxicity. Hyperthermia, decreased intake, identical with the disturbances resulting endophyte-free variety had the greatest
peripheral vasoconstriction leading to from endothelial damage to the vascular gain (Fletcher and Sutherland 1993a).
lameness and gangrene of distal portions system. Reference is made to the pathogen- Therefore, other anti-quality factor(s)
of the body especially in the hind limb esis of fescue toxicosis for this discussion. associated with the endophyte depressed
characterize both conditions in cattle gains in the absence of lolitrem B.
(Coppock et al. 1989, Mantle 1978a, Staggers. Ryegrass staggers is a neuro-
Robbins et al. 1986). Barley ergot fed to Perennial Ryegrass muscular disease that is of major animal
heifers resulted in tail sloughing, retained health significance in sheep, cattle and
winter coats, increased salivation, and res- horses in New Zealand and Australia. It is
Perennial ryegrass (Lolium perenne L.)
piratory rates during hot weather most prevalent in warm drought condi-
is of minor significance as an eastern tem-
(Skarland and Thomas 1972). Cold weath- tions and is associated with close grazing
perate forage grass (Balasko et al. 1995).
er predisposed cattle fed ergot to lameness (less than 2.5 cm) and when animals are
It’s primary region of adaptation is the wet
and gangrene (Mantle 1978b). Pregnant disturbed (Keogh 1973). Ryegrass stag-
and cool climate of the northeastern
heifers fed ergot failed to abort (Mantle gers occurs sporadically in most years on
United States and seed production regions
1978b), however, some ewes aborted fol- E+ perennial ryegrass in Australia
of the Willamette Valley in Oregon. As
lowing ergot feeding (Greatorex and (Cunningham et al. 1993). Severe out-
with tall fescue, perennial ryegrass is
Mantle 1974). Sheep fed either ergot or breaks have resulted in substantial live-
infected with a mutualistic endophyte,
ergotamine had anorexia, hyperventilation, stock losses with the greatest loss in young
Neotyphodium lolii, and E+ ryegrass has
excessive salivation, cold extremities, and lambs suggesting altered lactation (Foot et
increased growth and density compared to
some had necrosis of the tongue al. 1988).
the non-infected forms (Cunningham et al.
(Greatorex and Mantle 1973). Ergotism Animals with ryegrass staggers may
1993). Insect resistance mediated by the
has resulted in severe loss of milk produc- appear normal or have a fine tremor of the
endophyte can have a significant impact
tion associated with loss of body mass and head and neck at rest. When affected ani-
on the agronomic qualities of a pasture, as
infertility occurred in dairy cows mals are excited they move with a stiff,
Argentine stem weevil (Listronotus bona-
(Schneider et al. 1996). A reduction in uncoordinated, jerky gait that affects
nensis) kills the growing points of the E-
serum prolactin was associated with the either the front limbs or all limbs.
grass plant (Prestidge and Gallagher
toxicity. Severely affected animals may collapse
1988). The alkaloids found in N.
Gross and microscopic changes associat- with tetanic seizures, but rise and move
coenophialum infected tall fescue are also
ed with ergot resemble the vascular normally within a few minutes once the
found in N. lolii infected perennial rye-
changes in fescue toxicosis. In cattle, con- source of excitement is removed
grass, but in addition, N. lolii produces
striction of arterioles, endothelial damage, (Mortimer and di Menna 1985). Generally
tremorgenic indolediterpene alkaloids
vascular stasis, thrombosis, ischemia, and there are few deaths in affected livestock
(lolitrems) (Fig. 3). These tremorgenic
gangrene are described (Burfening 1973). unless associated with misadventure and
alkaloids produce involuntary convulsing
Another cattle report included areas of skin animals generally recover when moved to
when animals are stressed by excitation
necrosis at the base of the ear, flanks, tail- E- pastures (Cunningham et al. 1993).
(Fletcher 1982). Hence, livestock produc-
head, and around the distal portions of the Lesions associated with this condition are
ers utilizing perennial ryegrass are faced
limbs (Coppock et al. 1989). Micro- primarily biochemical, however, muscle
with the same dilemma as those utilizing
scopically arterioles were thickened. fiber degeneration and degeneration of
tall fescue in that they can use a toxic for-
Grossly there was distal swelling of the Purkinje’s cells in the cerebellum have
age base (endophyte-infected) or a non-
limbs with a demarcating line between been microscopically described (Munday
sustainable endophyte free variety.
JOURNAL OF RANGE MANAGEMENT54(4), July 2001 481
et al. 1985). These changes are considered
the result of altered neuronal metabolism,
neuronal exhaustion, and anoxic condi-
tions during seizures. The tremorgenic
action of several mycotoxins including
paxilline have been attributed to binding
to the gamma amino butyric acid (GABA)
receptors in neural tissue and inhibiting
-
GABA stimulation of Cl uptake (Gant et
al. 1987). The significance of this inhibito-
ry effect is found in the fact that GABA is
the major inhibitory neurotransmitter in
the nervous system. Consequently, recep-
tor blockade of the GABA system results
in increased sensitivity to stimulii.
Heat Stress. Increased respiratory rates
and rectal temperatures have been associ-
ated with grazing E+ perennial ryegrass
(Fletcher 1993). The rectal temperature
increase in a stressed environment was
greatest in the animals grazing E+ rye-
grass compared to E-, however, rectal
temperatures were intermediate in lambs Fig. 4. Alkaloids found in reed canary grass (Phalaris sp.) that are similar to serotonin (Cheeke
on E+ lolitrem B-free ryegrass. This 1998).
increase in rectal temperature was attrib-
boline, hordenine, and gramine alkaloids (Gallagher and Koch 1964). The problem
uted to ergovaline in the E+ lolitrem-free
(Marten 1973). Structures of these alka- occurred when P. aquatica L. dominated
forage. Animals with the greatest increase
loids are in Fig. 4 (Cheeke 1998). These the pasture with rapidly growing plants
in respiratory rates grazed forage with the
alkaloids are concentrated in the immature (Blood and Radostits 1989). Signs have
largest concentration of ergovaline. It is
leaf sheaths and blades (Woods et al. occurred within 4 hours of going on pas-
presumed that the presence of ergovaline
1979). They reduce palatability of the ture but usually between 12 and 72 hours
results in the effects as described for fes-
grass, and thus serve as animal deterrants after exposure. The cardiac disorder asso-
cue toxicosis.
to prevent overgrazing (Marten et al. ciated with “sudden death” has been
Fecal Contamination and Fly Strike.
1976). The tryptamine and carboline alka- attributed to an unknown toxin other than
Fecal contamination of wool and flystrike
loids create digestive disorders resulting in the tryptamine alkaloids (Bourke et al.
involving flies laying eggs in the skin
a greater incidence of diarrhea in sheep 1988). The cardiac syndrome or “sudden
beneath fecal contaminated areas is a
compared to either the hordenine or death” was regarded to be the result of
major economic problem in New Zealand
gramine alkaloids (Marten et al. 1981). forced exercise in sheep already exhibiting
associated with grazing E+ perennial rye-
Hordenine and gramine alkaloids simply nervous signs. Anderton et al. (1994) sug-
grass (Fletcher and Sutherland 1993b).
reduce average daily gains. Hence, there gested N-methyltyramine (structurally
Lambs grazing E- perennial ryegrass did
are metabolic differences in modes of related to hordenine) is causative. Both
not have these problems whereas this
action; however, forage refusal correlates tryptamine and tyramine alkaloids being
occurred in 29–31% of the animals on E+
better with total alkaloid concentration monoamine oxidase inhibitors provides a
perennial ryegrass.
than with the individual alkaloid classes mechanism for a cardiotoxic effect.
(Marten et al. 1976). The alkaloids in reed The typical nervous form occurs after
Phalaris Species (Reed canarygrass are under simple genetic con- more protracted exposure, usually 2–3
Canarygrass) trol and are highly heritable (Marum et al. weeks after sheep are put on new growth
1979, Woods et al. 1979). Fortunately, pasture (Blood and Radostits 1989). The
low alkaloid cultivars are commercially following signs were described: thoracic
Reed canarygrass (Phalaris arundi- available. Therefore, the obvious solution limb paresis, pelvic limb paresis, disturbed
nacea L.) is utilized primarily in the north- for prevention of Phalaris staggers is to equilibrium, hypermetria of the thoracic
ern half of the United States (Sheaffer and replant with low-alkaloid cultivars. limbs, fine mild tremors and a bounding
Martin 1995). It is adapted to poorly Field outbreaks of Phalaris toxicity pelvic gait (Bourke et al. 1990). Affected
drained or flooded areas and can be inva- have been reported for sheep and cattle sheep often are conscious and frightened
sive in these habitats (Merigliano and (Bourke et al. 1990, Nicholson et al. when approached. If they are recumbent,
Lesica 1998). Its primary utilization is in 1989). In sheep 2 toxicological entities they struggle in an attempt to rise. New
low lying areas where spring melting occur: a “sudden death” syndrome and a cases have occurred in association with
snows or streambanks provide moist habi- nervous syndrome (Bourke et al. 1988). forced exercise for as long as 12 weeks
tats. Reed canarygrass is also drought The “sudden death” is characterized by after removing sheep from the pasture
intolerant and, therefore, has limited use in sudden collapse especially when excited (Blood and Radostits 1989). The nervous
the southeastern U.S. (Sheaffer and Martin and is associated with cardiac abnormali- signs were replicated following adminis-
1995). Reed canarygrass may contain ties, cyanotic mucous membranes and dis- tration of the Phalaris alkaloids, 5-
methoxy-methyl tryptamine, 2 methyl turbed respiration. Affected sheep either methoxy dimethyltryptamine, gramine and
tryptamine, 2 methoxy-tetrahydro-b-car- die immediately or recover spontaneously hordenine, with the former being the most
482 JOURNAL OF RANGE MANAGEMENT54(4), July 2001
potent (Bourke et al. 1990). Phalarisalka- factor that reduced gains in Rival and bacteria to be infected with a bacterio-
loids act by binding to neural serotinergic Venture in the latter half of the grazing phage before the toxin can be produced
receptors that inhibit neurotransmission in season. (Ophel et al. 1993). The bacterium pro-
those pathways. Provision of cobalt to duces a yellow slime on the seed heads.
iodinized salt is preventive (Duynisveld Toxic nematode galls are orange in color
and Wittenberg 1993). Ryegrass Toxicosis whereas, the non-toxic gall is dark brown
Signs of toxicosis in cattle include stiff- or black. Nematodes in the gall may be
ness of the hocks, dragging the hind feet, visualized microscopically following addi-
Annual ryegrass (Lolium multiflorum
incoordination of the tongue and lips tion of water to the dry gall (McKay and
Lam., Lolium rigidum Gaud. in Australia)
which results in eating difficulty. Riley 1993).
is grown on approximately 1 million
Consequently, affected bulls died after a The mechanism of action of the coryne-
hectares in the United States, of which
wasting disease associated with P. car- toxins involves inhibition of an enzyme,
over 90% is found in the southeast
oliniana (Nicholson et al. 1989). uridine diphospho-N-acetylglucosa-
(Balasko et al. 1995). Annual ryegrass is
Microscopically degenerative lesions of mine:dolichol-phosphate N-acetyl-glu-
infected with an endophytic fungus whose
spinal cord tracts and in the cerebellum of cosamine phosphate transferase (UDT)
dissemination is fastidious compared to
sheep have been observed (Blood and necessary for glycosylation of proteins
endophytes belonging to the genus
Radostits 1989). Also, an abnormal green- (Jago et al. 1983). Therefore, toxicity
Neotyphodium. The endophyte resides in
ish pigment has been seen in the renal results from depletion or reduced activity
the basal 2 mm of the tiller, and is trouble-
medulla and in parts of the brain. of essential glycoproteins found in
some to locate in developing seedheads,
Animal Production. Total indole alka- enzymes, hormones, components of the
but it is passed from one generation to the
loid concentration (gramine, tryptamines cell membrane and membrane receptors
next in a limited number of seed within
and carbolines) was inversely correlated (Jago et al. 1983).
the raceme (Latch et al. 1987, Nelson and
with weight gains in lambs and steers Toxicosis may appear as soon as 2 days
Ward 1990). The endophyte has no
(Marten et al. 1976). Marten et al. (1981) or as late as 12 weeks after grazing the
adverse effects on livestock (Hickey and
indicated that a total alkaloid concentra- toxic forage. Signs in sheep associated
Hume 1994) nor does it provide resistance
tion greater than 2.0 mg/g dry weight of with this toxicosis include a high stepping
to insect predation (Prestidge 1991).
forage reduces animal gains. Similarly, gait, lack of coordination and convulsions
While the endophye is termed
palatability was correlated with total alka- (Cheeke 1998). An animal may have a
“Acremonium-like” there is no taxonomic
loid concentration (Simons and Marten convulsion and recover or remain recum-
evidence suggesting a common ancestry
1971). Recently released cultivars of reed bent and die with their feet in a paddling
with Neotyphodium.
canarygrass, ‘Rival’ and ‘Venture’, con- motion. Signs appear most obvious when
Animal Toxicosis. Annual ryegrass
tain only gramine and hordenine the animals are excited and resemble rye-
(Lolium rigidum) toxicosis in livestock is
(Duynisveld and Wittenberg 1993). Lamb grass staggers, however, a substantial mor-
a neurological disease caused by grazing
gains were superior on these cultivars tality is associated with annual ryegrass
annual ryegrass parasitized by the nema-
early in the grazing season compared to toxicosis. Convulsions and lack of coordi-
tode, Anguina agrostis (McIntosh et al.
‘Frontier’ reed canarygrass, a cultivar con- nation has been described for cattle and
1967). The causative agents are coryne-
taining the methoxy derivatives of the horses that had access to galls found on
toxins (Fig. 5) produced by the bacterium,
tryptamines and B-carbolines; however, chewing red fescue (Festuca rubra com-
Clavibacter toxicus, which is carried into
overall ADG was similar for the 3 culti- mutata Gaud.) (Galloway 1961). Annual
the seedhead by the nematode (Riley and
vars. Gramine concentration exceeded 2.0 ryegrass toxicosis per se has also been
Ophel 1992). The infected flower does not
mg/g during a portion of the trial in all 3 reported in horses (Creeper et al. 1996).
produce seed, but is replaced by a gall.
cultivars and this was assumed to be the The lethal dose of corynetoxins given
There appears to be a requirement for the
orally to sheep was 5 mg/kg. This total
lethal dose was the same whether adminis-
tered as a single dose or as repeated small-
er doses with a maximum interval of 9
weeks between doses being examined
(Jago and Culvenor 1987). Therefore, the
toxic effect is cumulative. Corynetoxins
result in extensive damage to the cerebel-
lum via damage to the endothelial cells in
capillaries (Finnie and Mukherjee 1987).
Gross and microscopic pathology includes
lipid deposition in the liver, diffuse hem-
orrhages, and perivascular edema particu-
larly in the cerebellar meninges (Blood
and Radostits 1989).
Hepatic damage determined by increas-
es in the serum concentration of 2 hepatic
enzymes, aspartate amino transferase
(AST) and glutamate dehydrogenase
(GLDH) occurred in ewes given sublethal
Fig. 5. Corynetoxin alkaloids found in toxic galls on annual ryegrass (Cheeke 1998).
doses of corynetoxins (Davies et al. 1996).
JOURNAL OF RANGE MANAGEMENT54(4), July 2001 483