-3 6-. 'M,'
3 7- 3 Agricultural Research and Education Center
Jay, Florida 32565-9524
JAY, AREC RESEARCH REPORT WF87-3 Libranaarch, 1987
GRAZING EVALUATION OF WARM-SEASON PERENNIAL PASTURE (RASSES M PEI f94EERS
J. E. Bertrand and L. S. Dunav n University of Florida
Yearling steers of British breeding rotationally grazed four warm-season
perennial pasture grasses---(1) Pensacola bahiagrass, (2) Callie bermudagrass,
(3) Tifton hybrid bermudagrass 72-81 (unreleased cultivar) and (4) Tifton hy-
brid bermudagrass 72-84 (released jointly in the spring of 1985 by the
Louisiana Agricultural Experiment Station and USDA as Grazer bermudagrass) for
four consecutive seasons. Grazing began each year in May when sufficient forage
was available and was terminated when the forage was essentially grazed down in
late October or early November. The animal performance and forage dry matter
data resulting from these studies indicated that the three bermudagrasses should
be considered as potential warm-season perennial grasses for north Florida.
Tifton hybrid bermudagrass 72-84 appeared to be somewhat more cold hardy than
the other two bermudagrasses. However, the three bermudagrasses consistently
produced higher animal gains than Pensacola bahiagrass.
Pensacola bahiagrass has furnished the base for beef cattle production dur-
ing the warm season in north Florida. Promising new cultivars of bermudagrasses
that offer high quality and quantity of forage for beef cattle are now available
or are presently being evaluated for release. These bermudagrasses have potential
for improving the gain of beef cattle and thus reducing the cost of beef produc-
tion on warm-season perennial pastures.
The purpose of these studies was to evaluate warm-season perennial pasture
grasses (Pensacola bahiagrass and three bermudagrasses) with beef steers from
the standpoint of animal performance and forage characteristics. Relative dry
matter production is the only forage characteristic reported in this paper.
In 1982, 1983, 1984 and 1985, 32 yearling steers of British breeding (Angus
and Angus X Hereford crossbreds) were allotted at random from breed and weight
groups to four experimental groups of eight steers each. Each steer was implanted
in the ear with 36 mg of zeranol and tagged in the other ear with an insecticide
ear tag. An experimental group of steers was assigned to each of four warm-season
perennial pasture grasses--(1) Pensacola bahiagrass, (2) Callie bermudagrass,
(3) Tifton hybrid bermudagrass 72-81 (unreleased cultivar) and (4) Tifton hybrid
bermudagrass 72-84 (released jointly in the spring of 1985 by the Louisiana
Agricultural Experiment Station and USDA as Grazer bermudagrass). Four 1.25-acre
plots of each grass were grazed in a rotational system.
A complete fertilizer (8-24-24) was applied each year to all pastures at the
rate of 250 pounds per acre during the middle of March prior to grazing. Four
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applications of 100 pounds per acre each of ammonium nitrate were made during the
Grazing began in May each year when sufficient forage was available and was
terminated when the forage was essentially grazed down in late October or early
November. Each group of steers was rotated between the four plots of the pasture
grass assigned to it. Additional grazer animals of the same type and size were
added and removed as needed to keep the forage uniformly consumed.
Individual animal weights were taken after an overnight shrink (fast from
feed and water) at the beginning and end of the trial periods. A mineral mixture,
salt and clean drinking water were available to the animals at all times.
In order to obtain relative dry matter production for each of the four
grasses, wire cages were placed at random prior to grazing in a plot and removed
after grazing was terminated in the plot. The forage under the cages was clipped
to approximately the same height that the steers had grazed the surrounding for-
age. The clipped forage was weighed and representative samples were weighed,
dried and re-weighed.
RESULTS AND DISCUSSION
A summary of the performance data with beef steers grazing warm-season
perennial pasture grasses for four consecutive seasons is presented in Table 1.
Steers grazing Callie bermudagrass, Tifton hybrid bermudagrass 72-84 and Tifton
hybrid bermudagrass 72-81 gained faster (P<.01) than steers grazing Pensacola
bahiagrass (1.16, 1.14 and 1.02 vs .84 pounds/head/day, respectively). There
were highly significant differences between years in average daily gain. The
total gain per acre was 435 pounds with steers grazing Tifton hybrid bermuda-
grass 72-84, 431 pounds with steers grazing Tifton hybrid bermudagrass 72-81,
412 pounds with steers grazing Callie bermudagrass and 320 pounds with-steers
grazing Pensacola bahiagrass (Table 1). The high daily gain with steers graz-
ing Callie bermudagrass and Tifton hybrid bermudagrass 72-84 was mainly respon-
sible for the high total gain per acre; whereas, the high stocking rate with
steers grazing Tifton hybrid bermudagrass 72-81 was mainly responsible for the
high total gain per acre. The low daily gain with steers grazing Pensacola bahia-
grass was mainly responsible for the low total gain per acre. There were no
statistically' significant differences among means for any of the animal perfor-
mance parameters, except average daily gain. This was probably due to the large
variation in individual observations between years and the small number of
TABLE 1. SUMMARY OF PERFORMANCE DATA WITH BEEF STEERS GRAZING WARM-SEASON PERENNIAL
PASTURE GRASSES (AVERAGE FOR 1982, 1983, 1984 AND 1985)a
Pensacola Callie bermudagrasses
Item bahiagrass bermudagrass 72-81b 72-84
Initial no. of animals 32d 32 32 32
Length of grazing, days 166 158 162 162
Initial wt., pounds 585 604 602 596
Final wt., pounds 724 787 768 780
Total gain/animal, pounds 139 183 166 184
Daily gain, pounds .84g 1.16 1.02h 1.14
Animal days/acree 381 355 423 382
Stocking rate/acree 2.30 2.25 2.61 2.36
Total gain/acre, poundsf 320 412 431 435
Gain/acre/day, poundsf 1.93 2.61 2.66 2.69
aRotational grazing of four 1.25-acre plots of each pasture grass each year.
bUnreleased cultivar and not presently available commercially.
cReleased jointly in the spring of 1985 by the Louisiana Agricultural Experiment
Station and USDA as Grazer bermudagrass.
dFour replicates (years) eight experimental steers per year.
eAdditional grazer animals of the same type and size were added and removed as
needed to keep the forage uniformly grazed.
fThe gain with grazer steers was considered at the same rate as that with
g,hMeans in a row with different superscripts differ (P<.01).
A summary of the relative dry matter production of warm-season perennial
pasture grasses for four consecutive seasons is presented in Table 2. Tifton
hybrid bermudagrass 72-81 produced more (P<.01) dry matter than Callie bermuda-
grass and Pensacola bahiagrass (9,910 vs 8,030 and 7,730 pounds/acre, respec-
tively). The production of dry matter (9,200 pounds/acre) by Tifton hybrid
bermudagrass 72-84 was intermediate within the range.
TABLE 2. SUMMARY OF RELATIVE DRY MATTER PRODUCTION FOR WARM-SEASON PERENNIAL
PASTURE GRASSES (AVERAGE FOR 1982, 1983, 1984 AND 1985)
Pensacola Callie .bermudagrasses
Item bahiagrass bermudagrass 72-81a 72-84
Dry foragec 7,730d 8,030 9,910e 9,200de
aUnreleased cultivar and not presently available commercially.
bReleased jointly in the spring of 1985 by the Louisiana Agricultural
Experiment Station and USDA as Grazer bermudagrass.
CEstimated by use of wire cages placed on pastures being grazed.
d,eMeans in a row with different superscripts differ (P<.01).
Callie bermudagrass was damaged early in the 1982 season by rust; while
Tifton hybrid bermudagrass 72-84, probably because of a tighter sod and less
penetration of sunlight, suffered moderate damage in 1982 and 1983 from
infestations with spittlebugs.
The animal performance and forage dry matter data resulting from studies
conducted during four consecutive seasons indicated that the three bermuda-
grasses should be considered as potential warm-season perennial pasture
grasses for north Florida. Tifton hybrid bermudagrass 72-84 appeared to be
somewhat more cold hardy than Tifton hybrid bermudagrass 72-81 or Callie
bermudagrass. However, the three bermudagrasses consistently produced higher
animal gains than Pensacola bahiagrass.