'I
Spread of Tall Fescue
Endophyte by Cattle
Leaflet 104 R.A. Shelby, S.P. Schmidt, R.W. Russell,
M OST CATTLEMEN are now aware It appe
of the adverse effects on livestock gains and fection h
reproduction which can result from the experimel
presence of Acremonium coenophialum, the Substatio
fungus common in pastures of tall fescue in at the Pi
Alabama. Consequently, many have gone to table 2. E
great lengths to eliminate the fungus from have bee
their pastures. Unlike most fungi which are years, res
spread by spores carried by wind or water, rate of in
this fungus is an endophyte which lives about 2 p
within fescue plant tissue. It is spread only the appes
as live fungus within viable seeds of its host, which pre
tall fescue. Therefore, once an endophyte- Other re
free fescue pasture is established, the level
of endophyte cannot change unless infected GrClay,
Grasses: A
fescue seed are somehow introduced 
or sur- and Anim;
vival of infected plants 
is favored. 
3West, C
'Research Associate of Plant 
Pathology; R.T. Robt
Associate Professor and Assistant 
Professor of Fungus wi
Animal and Dairy Sciences; 
and Superintendent, Resistance
Beef Cattle Unit, E.V. Smith Research 
Center. Journal, V
and W.H. Gregory' July 1989
ars that the level of endophyte in-
as slowly increased in some of the
ntal pastures at the Black Belt
n at Marion Junction, table 1, and
edmont Substation at Camp Hill,
Endophyte levels in these pastures
n closely monitored for 3 and 4
pectively, and over that period the
crease for all pastures has averaged
ercent per year. Most alarming is
irance of the endophyte in fields
eviously had been endophyte-free.
searchers
2
' have shown that in-
K. 1988. Fungal Endophytes of
Defensive Mutualism Between Plants
als. Ecology 69(1);10-16.
.P., E. Izekor, D.M. Oosterhuis, and
bins. 1987. Association of Endophytic
th Drought Tolerance and Nematode
in Tall Fescue. Arkansas Farm Research
ol. 37.
Alabama Agricultural Experiment Station Auburn University
Lowell T. Frobish, Director Auburn University, Alabama
~i~%i~c
fected plants are better able to withstand
drought and insect feeding, which would
result in the infection level increasing in a
partially infected field. However, this would
not account for uninfected pastures be-
coming infected.
MATERIALS AND METHODS
Siegel et al.
4 
were able to recover
endophyte-infected seed from the feces of a
steer which had been fed seed via a rumen
cannula. This prompted the initiation of an
experiment at the Alabama Agricultural
Experiment Station to quantitatively deter-
mine the survival of the endophyte after it
has passed through the digestive system of
a steer under more normal conditions. In this
experiment, one 400-pound steer was placed
in a metabolism stall so that feed intake and
fecal output could be closely monitored. For
1 week prior to the experiment, the steer was
fed twice daily a meal consisting of 10
pounds of chopped Coastal bermudagrass
hay containing 13 ounces (375 grams) of 98
percent infected seed which had been heated
to kill both seed and endophyte. This was to
(1) condition the animal to eating seed so that
the treatment meal would not be refused, (2)
remove any live fescue seed from the animal,
and (3) establish a constant rate of feed
movement through the animal.
The steer was then fed a single meal con-
taining 7 ounces (188 grams) of live
endophyte-infected seed (approximately
83,000 seed) mixed with the hay diet. For the
remainder of the experiment, the previous
diet was resumed. After 10 hours, collection
of fecal samples was begun. Sampling in-
tervals were as follows: from 10 to 48
hours-every 2 hours; from 48 to 96 hours-
every 4 hours; from 96 to 168 hours-every
6 hours. After 168 hours, fecal collection was
ended. The fecal samples were weighed,
dried, and 10 grams was planted in four
replications in greenhouse pots in a manner
that would duplicate conditions which might
4
Siegel, M.R., M.C. Johnson, 
D.R. Varney,
W.C. Nesmith, R.C. Buckner, L.P. Bush, P.B.
Burns, T.A. Jones, and J.A. Boling. 1984. A
Fungal Endophyte in Tall Fescue: Incidence and
Dissemination. Phytopathology 74:932-937.
occur in the field. After 8 weeks, seedlings
were counted to determine percentage of
viable surviving seed and the percent of
endophyte infection was determined by the
staining test.'
RESULTS
A substantial percentage of fescue seed
were able to survive passage through the gut.
'Shelby, R.A. and L.W. Dalrymple. 1987. In-
cidence and Distribution of the Tall Fescue En-
dophyte in the United States. Plant Disease
71;783-786.
TABLE 1. CHANGES IN ENDOPHYTE LEVELS
AT BLACK BELT SUBSTATION, 1984-88
Field 1984 1988 Change
S2 .......... . 0 0 0
S5 .......... 0 0 0
Sll ......... 0 0 0
S7 .......... 0 7.5 7.5
F60A ....... 0 8 8
F1D ........ 5 16 11
S6 .......... 10 7 -3
F54A ....... 20 26 6
F3 .......... 35 37 2
F4 .......... 35 37 2
F1C ........ 38 33 3
F59 ......... . 45 85 40
S9 .......... 52 70 18
S4 .......... 55 78 31
S10 ......... 60 62 2
E4 .......... 75 95 20
E2 .......... 85 93 8
E13......... 89 94 5
E6 ........... 90 93 3
E8 .......... 90 100 10
S3........... . 90 93 3
E14 ......... 100 100 0
'Average increase = 7.8 percent in 4 years;
average annual increase = 1.95 percent.
TABLE 2. CHANGES IN ENDOPHYTE LEVELS AT
PIEDMONT SUBSTATION, 1983-88
Paddock 1983 1988 Change
4 ........... . 0 13 13
1 ........... 5 8 3
8 ........... 6 16 10
11 .......... 
16 
14 
-2
5 ........... 50 73 23
6 ........... 50 70 20
9 ........... 50 70 20
10 .......... 59 97 38
12 .......... 61 78 17
7 ........... . 63 67 4
2 ........... . 69 75 6
3 ........... 83 74 -3
'Average increase = 11.9 percent in 5 years;
average annual increase = 2.38 percent.
[21
Plants from
seed in 10 grams
Total live plants
Plants with endophyte
0 24 48 72 96 120 144 168
Hours after feeding
Numbers and endophyte status of fescue plants 
originating from feces.
Twelve percent of the live seeds fed to the
steer germinated and grew normally into
vigorous plants. Passage of live seeds in the
feces reached a peak at 22 hours, see figure,
and declined slowly until the last live seeds
were passed at 84 hours. Similarly, in a
substantial number of seed, the endophyte
was able to survive passage. As in the case
of total live seed, endophyte-infected seed
reached a peak at 22 hours, but declined
more rapidly. The last infected seed was
recovered at 38 hours. Apparently, condi-
tions in the rumen are sufficiently adverse
to kill the endophyte, given enough time. For
the entire period, the average infection of
recovered samples was 12 percent, down
from the original infection level of 98
percent.
CONCLUSIONS
The amount of endophyte able to survive
passage is potentially harmful. This experi-
ment attempted to duplicate conditions in
which cattle might be grazing an endophyte-
infected pasture with seedheads, or be fed
[31
10
8
6
infected hay containing viable seed. Several
factors will probably affect the efficiency and
chronology of endophyte dissemination.
First, 7 ounces of seed is a conservative
estimate of the daily intake of live seed for
cattle. Cattle are known to sometimes selec-
tively graze fescue seed heads; when they do,
they might consume many times that quan-
tity, resulting in more infected seed being
passed for a longer period. Second,
digestibility of the total forage intake will
also affect passage time. For example, a
more digestible forage, such as alfalfa hay,
would speed up the rate of passage; con-
versely, a less digestible diet might prolong
the passage of infected seed. Finally, it is
possible that nonruminants, such as horses,
might be even more effective in spreading in-
fected seed, since the conditions in the gut
are not as severe.
Because of the possibility of spreading
endophyte-infected seed when moving cat-
tle between infected and noninfected
pastures, cattlemen are cautioned against let-
ting infected pastures make seed or allow-
ing grazing or hay making while infected seed
are present. In case cattle eat viable infected
seed, it is suggested that they be quarantined
and fed an endophyte-free diet for a
minimum of 48 hours before being moved
to noninfected pastures. Although the rate
of spread of infection by this method is slow,
it can potentially allow the expense and ef-
fort of establishing endophyte-free pastures
to be compromised by increasing endophyte
levels over time.
Information contained herein is available to all
without regard to race, color, sex, or national origin.
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