This study compared a tall fescue/clover pasture system (TF) to a system with 25% of the area replaced with bermudagrass (TF+BERM) for stocking cattle. Over three years, total forage production, steer weight gain per hectare, and average daily gain was greater for TF+BERM than TF in the first year, but did not differ between the systems in the following two years. Although the bermudagrass provided summer forage and avoided tall fescue toxicosis in the first year, the lower digestibility of the bermudagrass pastures negated this benefit in subsequent years. Integrating bermudagrass provided limited benefits

1. Integrating bermudagrass into tall fescue-based pasture systems for stocker cattle
R. L. Kallenbach, R. J. Crawford, Jr., M. D. Massie, M. S. Kerley and N. J. Bailey
J ANIM SCI 2012, 90:387-394.
doi: 10.2527/jas.2011-4070 originally published online August 19, 2011
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3. Integrating bermudagrass into tall fescue-based pasture
systems for stocker cattle1
R. L. Kallenbach,*2 R. J. Crawford Jr.,† M. D. Massie,† M. S. Kerley,‡ and N. J. Bailey*
*Division of Plant Sciences, University of Missouri, Columbia 65211; †Southwest Missouri Agricultural
Research and Education Center, University of Missouri, Mt. Vernon 65712; and ‡Division of Animal Sciences,
University of Missouri, Columbia 65211
ABSTRACT: The daily BW gain of stocker steers
grazing tall fescue [Lolium arundinaceum (Schreb.)
S.J. Darbysh. = Schedonorus arundinaceus (Schreb.)
Dumort.]-based pastures typically declines during summer. To avoid these declines, in part to mitigate the
effects of tall fescue toxicosis, it is commonly advised
to move cattle to warm-season forage during this period. A 3-yr (2006, 2007, and 2008) grazing study was
conducted to evaluate the effect of replacing 25% of the
area of a tall fescue/clover (81% endophyte-infected)
pasture system with “Ozark” bermudagrass [Cynodon
dactylon (L.) Pers.] overseeded with clover (Trifolium
spp.) to provide summer grazing for stocker steers
(TF+BERM). The TF+BERM treatment was compared with a grazing system in which tall fescue/clover
(TF) pastures were the only type of forage available
for grazing. Our objective was to determine if replacement of 25% of the land area in a fescue system with
bermudagrass would increase annual beef production
compared with a system based solely on tall fescue. The
study was conducted at the Southwest Research and
Education Center of the University of Missouri near
Mt. Vernon. Each treatment was rotationally stocked
with 5 steers (248 ± 19.3 kg) on 1.7 ha. Fertilizer applications were applied at rates recommended for each
respective forage species. Total forage production, BW
gain per hectare, and season-long ADG of steers was
greater (P < 0.06) for TF+BERM than for TF in
2006, but none of these measures differed (P > 0.19)
in 2007 or 2008. In vitro true digestibility of pastures
was greater (P = 0.01) for TF (84.4%, SEM = 0.64%)
compared with TF+BERM (80.6%, SEM = 0.79%),
even in summer. The decreased in vitro true digestibility of the bermudagrass pastures likely negated any
benefit that animals in TF+BERM had in avoiding the
ergot-like alkaloids associated with endophyte-infected
tall fescue. Renovating 25% of the pasture system to
bermudagrass provided some benefit to the system
in years when summertime precipitation was limited
(2006) but provided no value in wetter years (2007 and
2008). Although renovating endophyte-infected tall fescue pastures to a warm-season forage is a widely used
practice to mitigate tall fescue toxicosis, the benefits of
this practice are limited if forage quality of the warm
season component is poor.
Key words: bermudagrass, grazing, pasture system, tall fescue
©2012 American Society of Animal Science. All rights reserved.
J. Anim. Sci. 2012. 90:387–394
doi:10.2527/jas.2011-4070
INTRODUCTION
Bacon and Hanlin]} tall fescue [Lolium arundinaceum
(Schreb.) S.J. Darbysh. = Schedonorus arundinaceus
(Schreb.) Dumort.] interseeded with medium red (Trifolium pratense L.) and white clover (Trifolium repens
L.; Cherney and Kallenbach, 2007). The tall fescue
component typically comprises approximately 75% of
the forage on a DM basis and heavily influences pasture production and quality. A mutualistic relationship
between the endophyte and host plant makes tall fescue
the most persistent and widely used forage in southern
areas of the Midwest (Buckner and Bush, 1979; Sleper
and West, 1996; Roberts and Andrae, 2004). However,
endophyte-infected tall fescue produces forage containing ergot alkaloids, and because of this, stocker cattle
BW gains are generally less than might otherwise be
Most forage systems for stocker cattle in the southern areas of the Midwest region of the United States
are based on endophyte-infected {Neotyphodium coenophialum [(Morgan-Jones and W. Gams) Glenn, C.W.
1
This material is based on work supported by the USDA under
Cooperative Agreement No. 58-6227-3-016. Any opinions, findings,
conclusions, or recommendations expressed in this publication are
those of the author(s) and do not necessarily reflect the view of the
USDA. This research was, in part, supported by the Missouri Agric.
Exp. Stn. (Columbia).
2
Corresponding author: kallenbachr@missouri.edu
Received March 16, 2011.
Accepted August 10, 2011.
387

4. 388
Kallenbach et al.
expected, especially during summer (Tucker et al.,
1989; Roberts and Andrae, 2004).
This study compared a tall fescueclover-based system (TF) with a tall fescue/bermudagrass system
(TF+BERM) for stocker calves. The TF+BERM
system was characterized by having 25% of the grazing area in “Ozark” bermudagrass [Cynodon dactylon
(L.) Pers.] and 75% of the area in the same tall fescue/
clover forage as TF. Bermudagrass was used as a component because of its ability to produce enough forage
to support relatively large stocking rates in summer
(Burns et al., 1984). The hypothesis was that replacing
25% of the pasture area of an endophyte-infected tall
fescue-based forage system with bermudagrass would
increase annual forage production and improve seasonlong steer BW gains. Our objective was to determine if
replacement of 25% of the land area in a TF+BERM
system with bermudagrass would increase annual beef
production compared with a system based solely on tall
fescue/clover.
MATERIALS AND METHODS
The animal management protocol was reviewed and
approved by the University of Missouri Animal Care
and Use Committee.
A 3-yr grazing study was conducted at the Southwest
Missouri Agricultural Research and Education Center
near Mount Vernon (37°04′55″ N, 93°53′21″ W). The
soil at this location was a mixture of Keeno cherty silt
loam, 2 to 9% slope (loamy-skeletal, siliceous, mesic
Mollic Fragiudalf); Hoberg silt loam, 2 to 5% slope
(fine-loamy, siliceous, mesic Mollic Fragiudalf); and
Gerald silt loam, 0 to 2% slope (fine, mixed, mesic Umbric Fragiaqualf).
Forage establishment was initiated 3 yr before the
grazing study. Soil samples were collected in the summer of 2002 from the entire area under experimentation. On the basis of the soil sample results, lime, P,
and K were applied at rates recommended by the University of Missouri Soil Testing Laboratory (Brown and
Rodriguez, 1983). Existing vegetation was sprayed with
glyphosate at 1.7 kg/ha of acid equivalent in the fall of
2002, and then moldboard plowed, disked, and planted
to a small grain in February of 2003. Small-grain forage
was grazed or hayed in the spring and summer of 2003,
and then the field was sprayed again with 1.7 kg/ha of
acid equivalent of glyphosate in late August of 2003. In
early September of 2003, “Kentucky 31” tall fescue was
no-till drilled into the entire area at 28 kg/ha of pure
live seed. The amount of endophyte infection of the
tall fescue seed was 84%; endophyte infection status
was documented to be 81% in June 2006 by collecting
25 tall fescue tillers from pastures and assaying tillers
with the immunoblot test described by Hiatt and Hill
(1997). In the spring of 2004, 25% (0.42 ha) of the
pastures designated to be TF+BERM were renovated
to “Ozark” bermudagrass. The area to be renovated to
bermudagrass was moldboard plowed, disked 2 times,
and cultipacked before being sprigged at 2.61 kL/ha
on June 4, 2004. Diuron [3-(3,4-dichlorophenyl)-1,1-dimethylurea] was applied just after sprigging at 1.9 kg/
ha of active ingredient to limit weed growth during
bermudagrass establishment. During the establishment
year, 67 kg/ha of N as NH4NO3 was applied on June
17 and August 17 to facilitate establishment. Pastures
designated to TF had no additional renovation.
Treatment and Experimental Design
Treatments consisted of 2 different forage systems,
each replicated 4 times. One treatment was a typical
endophyte-infected tall fescue pasture with an estimated 20% component of medium-red and white clover.
The other treatment was identical to the first except
that 25% of the pasture area was renovated to “Ozark”
bermudagrass. Incidentally, 25% was deemed appropriate because bermudagrass in southern portions of
the Midwest is more suitable as complementary forage
rather than as a solitary forage system because of its
seasonal growth pattern. Each of the 8 (2 treatments
× 4 replications) individual 1.7-ha systems was subdivided into 8 paddocks of equal area (Figure 1). Within
TF+BERM, the 2 bermudagrass paddocks were further
divided into 2 additional paddocks one-half the area of
the other paddocks (Figure 1).
Pasture and Forage Management
In all years (2006, 2007, and 2008) of the grazing
study, medium-red (5.5 kg/ha) and white clover (0.6
kg/ha) were overseeded in early March to all paddocks
(including those with bermudagrass) in each treatment.
Also each year, the bermudagrass was fertilized with
84 kg/ha of N (as urea) on May 1, June 14, and July
18 (±2 d) for an annual total of 252 kg/ha of N. Bermudagrass residue was burned during the last 2 wk
of February all years. Following current University of
Missouri guidelines, tall fescue in both treatments was
not fertilized with N in spring. Nitrogen fertilization
of tall fescue intended for grazing at this time of year
is generally not feasible because of the inability to efficiently utilize the excess forage produced. In addition,
N fertilization at this time of year makes it difficult to
maintain the legume component of the pasture. Furthermore, toxicity issues have been reported to be exacerbated over the summer months with N fertilization
at this time (Roberts and Andrae, 2004). To minimize
the potential for tall fescue toxicosis in this study, all of
the tall fescue/clover pastures received only 56 kg/ha of
N in mid-August to stimulate fall growth.
Forage Mass Determinations
During the grazing season, forage mass was determined weekly from each paddock by taking 50 rising
plate meter (RPM) readings. The RPM (Model F200,
Farmworks, Feilding, New Zealand) was calibrated just

5. Bermudagrass in tall fescue-based systems
389
each stocking period was determined by averaging the
growth rates of the unoccupied paddocks within each
treatment. Forage growth while animals were stocked
in an individual paddock was then added to the prestocked yield to determine the amount of forage available for grazing.
Steer and Grazing Management
Figure 1. Layout of 1 block of the grazing study. Each treatment
had 8 main paddocks. All 8 paddocks in the tall fescueclover-based
system (TF) consisted of tall fescue and clover, whereas 6 of the 8
paddocks in the tall fescue/bermudagrass system (TF+BERM) were
tall fescue and clover. The other 2 paddocks in TF+BERM were subdivided and consisted of bermudagrass and clover.
before the start of grazing and every 25 ± 3 d thereafter by clipping 0.82 × 4.6 m strips (n = 10 for a
paddock) from 2 selected paddocks within each of the
8 units. The strips were cut to a 2-cm height with a
flail-type harvester. The paddocks selected for calibration were the most recently stocked (poststocking) and
the next-to-be-stocked (prestocking) paddock within
each unit. In addition, a subsample [300 g (±50 g) of
fresh mass)] from the strips harvested in each unit was
weighed fresh and again after drying for more than 96
h in a forced-air oven at 50°C to determine DM.
The forage mass values of the poststocked and prestocked paddocks along with their corresponding RPM
measurements were then used, along with Julian date,
coded dummy variables for species (10 for tall fescue
paddocks, 20 for bermudagrass), and pre- or poststocked forage yield (10 for samples collected before
stocking, 20 for samples collected after stocking), in
stepwise regression to estimate forage yield for each
paddock. Stepwise regression equations were predicted
using the PROC REG statement (SAS Inst. Inc., Cary,
NC), with significance for variables to enter and stay
in the model set at 0.20. Model R2 ranged from 0.84
to 0.86, depending on year. After prestocked and poststocked forage yields were calculated, growth rate for
Angus cross steers and intact bulls (Bos taurus) were
acquired from a central Missouri sale barn 5 to 7 wk
before grazing each year. The calves were received at
the Beef Research and Teaching Facility near Columbia, MO, placed into a confined drylot, and offered a
typical receiving diet. Approximately 1 wk after arrival,
the calves were vaccinated with 7-way blackleg with
haemophilus (Ultrabac 7/Somubac, Pfizer, Exton, PA)
and bovine rhinotracheitis-virus diarrhea-parainfluenza-3-respiratory syncytial virus modified live virus vaccine with Mannheimia haemolytica toxoid (Pyramid 4+
Presponse SQ, Fort Dodge Animal Health, Fort Dodge,
IA) and were given an ear identification tag, and bulls
were castrated. The calves were transported to the
Southwest Missouri Agricultural Research and Education Center Research near Mt. Vernon approximately
3 wk after the purchase of the animals. Immediately
before or after transport, all steers were given a second round of vaccinations, dewormed with moxidectin
(Cydectin, Pfizer, New York, NY) or ivermectin (Ivomec, Merial, Duluth, GA), and implanted with zeranol
(Ralgro, Intervet/Schering-Plough Animal Health, Kenilworth, NJ). In late May, the steers were given fly tags
impregnated with pyrethroid and organo-phosphate insecticide. The steers were reimplanted with zeranol in
late June. Tilmicosin (Micotil, Elanco, Greenfield, IN)
or florfenicol (Nuflor, Intervet/Schering-Plough Animal
Health) was administered under the advisement of a
veterinarian following label recommendations to any
animals displaying symptoms of respiratory ailments.
Steers were weighed on 2 consecutive days at the beginning of the experiment and reweighed every 28 ± 7 d
thereafter until removal from pasture, when they were
again weighed on 2 consecutive days. Cattle were allowed ad libitum access to water and trace mineral salt
blocks for the duration of the experiment.
Five 248 ± 19.3-kg crossbred beef steers were assigned to each unit as tester animals, giving a stocking
rate of 3 steers/ha. Grazing began on April 5, 2006,
April 4, 2007, and April 2, 2008. The steers were rotationally stocked within each unit. Animals were moved
to a new paddock within each unit when the residual
forage where the animals were grazing was 5 to 7 cm
in height. In spring, hay was harvested from individual
paddocks within each treatment when forage growth
rates exceeded expected animal intake. Hay was fed
back to steers when pasture growth was limiting during
summer. In TF+BERM, bermudagrass paddocks were
preferentially stocked if forage was available for grazing. For example, within TF+BERM, if a bermudag-

6. 390
Kallenbach et al.
Table 1. Calibration statistics for near-infrared spectroscopic determination of CP, in
vitro true digestibility (IVTD), and ergovaline concentrations of rotationally stocked
tall fescueclover and bermudagrass pastures
Constituent
CP, %
IVTD, %
Ergovaline, µ/kg
n
R2
Mean
SEC1
SECV2
1-VR3
87
87
150
0.98
0.97
0.87
16.3
81.7
233
0.49
1.42
53
0.7
1.94
69
0.96
0.94
0.77
1
SEC = SE of calibration, calculated in modified partial least squares regression.
SECV = SE of cross-validation, calculated in modified partial least squares regression.
3
1-VR = 1 minus the variance ratio, calculated in cross-validation in modified partial least squares regression.
2
rass and a tall fescue/clover paddock were both ready
to be grazed, the bermudagrass paddock was stocked
and the tall fescue/clover paddock was grazed at a later
time or allowed to accumulate growth until hay was
made. Steers did not graze bermudagrass paddocks after approximately September 20 each year to ensure
plant carbohydrate accumulation for winter survival.
All steers for both treatments were removed from the
study by individual pasture throughout the month of
November (except for a single pasture in yr 1 and 3,
from which steers were removed in mid-October). The
criterion for steer removal from pasture was based on
available forage so as to not restrict forage intake.
Forage Nutritive Value Determinations
Forage nutritive value samples were collected each
time steers entered a paddock in the rotation. These
samples were taken by clipping hand-sized samples of
forage to a 2-cm height from 25 to 30 locations in the
paddock. Samples were frozen at the time of collection, and then freeze-dried upon return of the researcher to the laboratory. After freeze-drying, samples were
ground in a cyclone mill to pass a 1-mm screen. The
ground samples were evaluated for CP, in vitro true
digestibility (IVTD), and ergovaline using a near-infrared reflectance spectrophotometer (Foss Model 5000
scanning monochromator, Foss NIRSystems, Silver
Spring, MD) driven by Infrasoft International software
(Infrasoft International, Port Matilda, PA). The spectrophotometer was calibrated for each component by
regression of chemically derived data against spectral
data in a modified partial least squares regression model
(Westerhaus et al., 2004; Table 1). The calibration for
CP (n = 87) was determined by thermal conductivity
detection with a Leco FP-428 N analyzer (Leco Corp.,
St. Joseph, MI), and calibration of IVTD (n = 87) was
determined by a 48-h in vitro digestion, followed by an
NDF solution wash (Spanghero et al., 2003). Rumen
fluid collected from a cannulated cow on a forage-based
diet was used for the in vitro digestion calibration samples. Calibration standards for ergovaline (n = 150)
were attained by following the procedures outlined by
Hill et al. (1993).
Statistical Analyses
Forage production, nutritive value, and ergovaline
concentrations were analyzed as a randomized complete
block with 2 treatments and 4 replicates, as described
by Steel and Torrie (1980). The model used included
year and block as the main plots, forage treatment as
subplots, and all possible interactions. Year and interactions with year were considered random effects, and
all others were considered fixed effects. Repeated-measures ANOVA procedures were used to test the effects of
treatments. The PROC MIXED procedure (SAS Inst.
Inc.) was used, assuming first-order autoregressive correlation among the repeated measures. Animal performance data (ADG, BW gain/ha) were also analyzed as
a randomized complete block using the model described
above. The experimental unit for all measurements of
animal performance was a group of 5 steers on each of
the 8 pastures (2 forage treatments × 4 replications).
RESULTS AND DISCUSSION
Forage Production
There was a year × treatment interaction (P < 0.01)
for total forage produced, so data were analyzed by
year. The TF+BERM produced more total forage (P
= 0.04) than TF in 2006, but total forage produced in
2007 and 2008 did not differ (P = 0.38 and P = 0.89,
respectively) between treatments (Table 2). Although
only 25% of the total pasture area was dedicated to
bermudagrass in TF+BERM, the contribution of bermudagrass paddocks accounted for 31 to 42% of the
total forage produced, and accounted for 47 to 56% of
the grazing days annually (Table 2). The reason for the
larger than anticipated contribution of the bermudagrass paddocks to grazing days can be attributed to 2
factors. First, during the 3 yr of study, the bermudagrass paddocks annually produced an average of 12,180
kg/ha (SEM = 351 kg/ha) of forage, compared with
7,030 kg/ha (SEM = 373 kg/ha) for tall fescue/clover
paddocks. Second, if forage in the bermudagrass paddocks was ready for grazing in TF+BERM, then those
paddocks were stocked and any excess forage was harvested for hay from the tall fescue/clover paddocks.

7. 391
Bermudagrass in tall fescue-based systems
1
Table 2. Forage production characteristics of rotationally stocked stocker-steer systems
Treatment
Item
2006
Total forage produced,2 kg/ha
Contribution of bermudagrass paddocks to total forage, %
Days grazing tall fescue/clover paddocks, d
Days grazing bermudagrass/clover paddocks, d
2007
Total forage produced, kg/ha
Contribution of bermudagrass paddocks to total forage, %
Days grazing tall fescue/clover paddocks, d
Days grazing bermudagrass/clover paddocks, d
2008
Total forage produced, kg/ha
Contribution of bermudagrass paddocks to total forage, %
Days grazing tall fescue/clover paddocks, d
Days grazing bermudagrass/clover paddocks, d
TF
SEM
6,080
0
181
—
7,470
0
223
—
8,980
0
231
—
TF+BERM
182
—
3.5
—
358
—
1.0
—
355
—
1.0
—
SEM
7,690
42
91
117
8,060
38
106
118
8,920
31
119
104
P-value
485
2.6
3.4
3.8
433
1.7
7.9
7.9
103
0.4
2.8
3.7
0.04
0.38
0.89
1
TF was a typical tall fescue/clover system, whereas TF+BERM had 75% of the area in tall fescue/clover and 25% in “Ozark” bermudagrass/
clover.
2
Includes forage harvested as hay.
There was a year effect (P < 0.01) for hay (excess
forage) harvested but no year × treatment interaction
(P = 0.96). Pooled over 3 yr, hay harvested was greater
for TF+BERM (P = 0.02), with 1,910 kg/ha (SEM =
218 kg/ha) compared with 1,570 kg/ha (SEM = 184
kg/ha) for TF. Hay fed back to the steers was different between treatments only in 2006, when steers in
TF required 220 kg/animal (SEM = 29 kg/animal),
compared with 22 kg/animal (SEM = 22 kg/animal)
for steers in TF+BERM. The reason for the relatively
large SEM values for hay fed is that hay was fed only
during 2006 and that only 1 small round bale (113 kg)
was fed in 1 replication of TF+BERM during 2008.
Figure 2. Crude protein of forage as steers entered a different
paddock over the course of the grazing season. TF was a typical tall
fescue/clover system, whereas TF+BERM had 75% of the area in tall
fescue/clover and 25% in “Ozark” bermudagrass/clover. Steers were
rotationally stocked from early April to approximately mid-November.
Data are combined over 3 yr. Bars equal 2 × SEM to give 95% confidence intervals. Nonoverlapping bars indicate a significant difference
at the 0.05 level.
Net hay production (hay harvested minus hay fed) was
1,890 kg/ha (SEM = 230 kg/ha) for TF+BERM and
was 1,350 kg/ha (SEM = 258 kg/ha) for TF. Assuming the 5 steers in each treatment weighed 320 kg each
and were offered hay at 3% of BW daily, the net hay
produced for the 1.7-ha system would supply feed for
an additional 67 d for steers in TF+BERM and for 48
d for steers in TF each year.
Forage Nutritive Value of Pastures
There was a year effect (P = 0.01) but no year ×
treatment interaction (P = 0.08) for CP. With all years
pooled, the seasonal trends of forage CP are given in
Figure 2. Crude protein concentrations were typically
equal or greater for TF+BERM compared with those
for TF. Pooled over years and the entire grazing season,
TF+BERM averaged 16.8% CP (SEM = 0.37), whereas TF averaged 15.8% (SEM = 0.53). During the growing season, the greatest difference in CP was in May to
early June, when steers in TF+BERM were first turned
into the bermudagrass paddocks. Crude protein in both
treatments was least in late July and early August;
however, CP never averaged less than 12.5% for either
treatment during the growing season.
In vitro true digestibility had no year effect (P =
0.55) or year × treatment interaction (P = 0.39); therefore, data were pooled over years. The forage offered to
the cattle in TF had a greater (P = 0.01) IVTD concentration than the forage offered in TF+BERM (Figure
3). Averaged over the 3 yr, IVTD was 84.4% (SEM =
0.64) for TF and 80.6% (SEM = 0.79) for TF+BERM;
most of this difference between treatments coincided
with the use of bermudagrass in midsummer (Figure
3). Although the addition of warm-season grasses to
cool-season-based systems is often thought to improve
season-long forage quality, the digestibility of bermu-

8. 392
Kallenbach et al.
Figure 3. In vitro true digestibility (IVTD) of forage as steers
entered a different paddock over the course of the grazing season. TF
was a typical tall fescue/clover system, whereas TF+BERM had 75%
of the area in tall fescue/clover and 25% in “Ozark” bermudagrass/
clover. Steers were rotationally stocked from early April to approximately mid-November. Data are combined over 3 yr. Bars equal 2 ×
SEM to give 95% confidence intervals. Nonoverlapping bars indicate a
significant difference at the 0.05 level.
dagrass, even well-managed bermudagrass, as was the
case in this study, is often less than expected. Kloppenburg et al. (1995) reported that bermudagrass pastures
in New Mexico had an in vitro OM digestibility of approximately 8 percentage units less than did pastures of
native rangeland grasses. Further, Fisher et al. (1991),
who examined the masticates of beef steers grazing several forage species, including tall fescue and bermudagrass, found that masticates from animals grazing tall
fescue averaged 78% IVDMD, compared with 64% for
bermudagrass pastures.
Ergovaline concentrations in TF increased as the leaf
sheath and stem component of the sample increased in
the spring (Figure 4). The concentration of ergovaline
in tall fescue samples decreased though mid-August,
followed by a seasonal increase to more than 450 µg/
kg in autumn. When steers were stocked onto tall fescue paddocks within TF+BERM, ergovaline concentrations were not different from the coinciding samples
from TF (P = 0.88). The increase in ergovaline during
the autumn was most likely not due to the presence of
leaf sheaths, but was likely the result of N fertilization
(Rottinghaus et al., 1991) and seasonal changes in ergovaline production (Rogers et al., 2011).
vs. 380 kg/ha for TF and TF+BERM, respectively, P
= 0.61). However, because the P-value for the year ×
treatment interaction for season-long ADG was 0.10,
Figure 5 includes season-long ADG values by year. Season-long steer ADG between treatments was not different in 2007 (P = 0.61) and 2008 (P = 0.24). However,
there was a difference between the treatments (P =
0.02) in 2006. Precipitation (Figure 6) was typical in
2006, and tall fescue growth slowed enough in midsummer to warrant hay feeding (ad libitum). This partially
explains the difference (P = 0.02) for steer ADG for TF
compared with TF+BERM in 2006. In the other 2 yr,
precipitation from June through September was more
than the 30-yr mean, which allowed for adequate tall
fescue production throughout the summer, thus partially negating the advantage of having bermudagrass
in the system. With precipitation patterns similar for
2007 and 2008, it may actually have been detrimental
to have bermudagrass in the system because steers were
reintroduced to ergovaline from tall fescue in autumn
(Stuedemann et al., 1985).
Average daily gain by period of year is also given in
Figure 5. Whereas year did not affect ADG (P > 0.11),
the year × treatment interaction (P < 0.06) within periods was sometimes significant, so data are presented
by year. Steer ADG in the spring was 0.45 and 0.31
kg greater during 2006 and 2007, respectively (P =
0.03, both years), for steers in TF+BERM than for
steers in TF. In the spring of 2008, steer ADG was
not different (P = 0.93). During summer, steer ADG
was typically about two-thirds of that in spring, but
treatments were not different for any of the 3 yr (P >
0.46). In autumn, there were no differences between
treatments in any year (P > 0.13). However, this might
be misleading because in each of the first 2 yr, 5 to 7
of the steers (out of 20/treatment, blocks combined) in
TF+BERM had negative ADG responses (as much as
−1.3 kg/d), whereas none of the steers in TF exhib-
Steer BW Gain
There was no year effect (P > 0.10), and no year ×
treatment interaction (P ≥ 0.10) for season-long ADG
or BW gain/ha. When pooled over years, season-long
ADG of steers in TF was 0.61 kg/d, whereas that of
steers in TF+BERM was 0.59 kg/d (P = 0.78). Patterns of BW gain per hectare were similar to ADG
responses because stocking rate was equal and the number of days grazing for each treatment was similar (405
Figure 4. Ergovaline concentration of forage samples collected as
steers were turned into a different tall fescueclover-based paddock.
Steers were rotationally stocked from early April to approximately
mid-November. Data are combined over 3 yr. Bars equal 2 × SEM.

9. Bermudagrass in tall fescue-based systems
Figure 5. Average daily gain of steers by period of year. Spring
was considered April to June, summer was June through August, and
autumn was September to when steers were removed from test in late
October or November. All 8 paddocks in the tall fescueclover-based
system (TF) consisted of tall fescue and clover, whereas 6 of the 8 paddocks in the tall fescue/bermudagrass system (TF+BERM) were tall
fescue and clover. The other 2 paddocks in TF+BERM were subdivided and consisted of bermudagrass and clover. Steer BW at turnout was
248 ± 19 kg. Bars equal 2 × SEM to give 95% confidence intervals.
Nonoverlapping bars indicate significant difference at the 0.05 level.
ited this response. Individual steers with negative ADG
in autumn exhibited typical visual symptoms (longer
hair coats, unthrifty appearance, less time grazing) of
livestock being introduced to toxic tall fescue for the
first time, although no physiological data were collected
from them.
Because forage IVTD was often greater in TF (Figure 3), these steers should have gained BW at a greater
rate than steers in TF+BERM. However, this was not
the case. Endophyte infection of the tall fescue likely
influenced forage intake of the steers in TF (Peters et
al., 1992; Stewart et al., 2008) and this likely negated
any improvement of forage IVTD. However, the uneven
performance of steers in TF+BERM when moved to
tall fescue paddocks in the autumn might be attributed to the reintroduction of ergovaline in the diet.
Stuedemann et al. (1985) stocked steers on tall fescue
393
pasture with 1% endophyte infection from April 4 to
May 16, and then moved one-half of the animals onto
tall fescue with 95% infection by a toxic, wild-type endophyte (“Kentucky 31”). Steers moved to 95% infected
tall fescue pastures lost an average of 0.11 kg of BW/d
in the following 2 wk, whereas the group of steers that
remained on the 1% infected pastures continued to gain
1.4 kg of BW/d during the same 2-wk period (Stuedemann et al., 1985). A similar effect may have taken
place with steers in this study when moved from bermudagrass to endophyte-infected tall fescue in autumn.
Perhaps one way that producers could maximize the
benefits of adding bermudagrass would be to remove
the steers from the system in mid to late summer. The
fall growth of infected tall fescue could then be stockpiled for another class (or new group) of animals in late
winter because ergovaline declines during the winter
months (Kallenbach et al. 2003).
Other studies have shown that moving stocker steers
from endophyte-infected tall fescue to other forage species in summer improved ADG. For instance, Aldrich
et al. (1990) discovered that moving animals grazing
endophyte-infected tall fescue to sorghum × sudangrass
(Sorghum spp.) pastures in summer improved ADG by
approximately 0.15 kg compared with animals that
remained on endophyte-infected tall fescue. Similarly,
Forcherio et al. (1992) compared grazing systems when
steers grazed infected tall fescue pasture in spring and
then were moved to Caucasian bluestem [Bothriochloa
bladhii (Retz.) S.T. Blake] pastures in early summer.
The ADG of steers in this system was not different
from that of steers stocked on endophyte-free tall fescue
pasture for the entire grazing season (Forcherio et al.,
1992). On the other hand, Scaglia et al. (2008) converted 20% of a tall fescue/clover-based forage system
to switchgrass (Panicum virgatum L.) for summer grazing by cow-calf pairs. Neither cow nor calf BW gain was
Figure 6. Total precipitation for the study area by month for 2006,
2007, and 2008, and the 30-yr mean. Precipitation data were collected
at the University of Missouri Southwest Research and Education Center, near Mt. Vernon (weather station index number 23-5862-04).

10. 394
Kallenbach et al.
improved for this system compared with a 100% tall
fescue/clover-based system.
In conclusion, the hypothesis that replacing 25% of
the pasture area of an endophyte-infected tall fescuebased forage system with bermudagrass would increase
annual forage production and improve season-long steer
BW gains was rejected. In only 1 of 3 yr did annual forage production and ADG increase, although in a year
when weather conditions were closer to the 30-yr mean
than in the other 2 yr. The decreased IVTD of the
bermudagrass pastures limited animal BW gains such
that steers grazing toxic, endophyte-infected tall fescue/clover pastures performed equally. Perhaps using a
cultivar of bermudagrass with greater IVTD concentrations, providing greater amounts of pregrazing herbage
for steers when grazing bermudagrass (thus allowing
animals greater selectivity), or reducing the temporal
stocking rate of the bermudagrass pastures would have
given different results. Even though moving animals to
nontoxic pastures is a widely used practice to mitigate
tall fescue toxicosis, the benefits of this practice are
limited unless the forage quality of the warm-season
component is almost equal to or better than that of the
endophyte-infected tall fescue it replaces.
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