Everglades Station Mimeo Report 60-16
RESULTS OF GRAZING EXPERIMENTS WITH YEARLING CALVES ON FOUR MAJOR
PASTURE GRASSES OF THE EVERGLADES FOR ONE YEAR
d. E. Haines and H. L. Chapman, Jr./
In the Everglades area perennial pasture forages are required to supply a
great majority of the necessary feed nutrients in beef cattle raising. The
value of a particular pasture grass is dependent upon its ability to maintain
and promote growth in beef animals during the entire year. Grasses not only
vary in the length of their growing season but also in the annual yield of total
Numerous pasture grass productivity studies have been conducted in many
parts of the world on a wide assortment of grass species using many different
methods and types of animals. In the Everglades area, Kidder et al (2) com-
pared the productivity of Roselawn St. Augustine, paragrass and caribgrass
over a five year period using a rotational and continuous grazing system. The
number of yearlings per two acre pasture was altered according to the quantity
of forage present in the ten respective test plots. These authors reported that
the annual live weight gains, per acre, were 1,004 lbs. for Roselawn St. Augus-
tine and 920 Ibs. for paragrass and caribgrass. A report by Allen (1), giving
more detail on the above study, indicated that pangolagrass test pastures,
established during the five year period, produced gains similar to those of
paragraes and caribgrass during a two and one-half year period.
The data reported herein was obtained from the previously established grass
test plots, plus additional test plots of Pensacola and Argentine bahiagrass.
These results are for a one year test period which ended in October, 1959.
Sixteen two-acre pasture lots, consisting of four Roselawn St. Augustine,
four paragrass, four pangolagrass, two Argentine bahiagrass and two Pensacola
bahiagrass, were utilized in the study. Yearling beef calves, of both sexes,
were used for a 12 months period beginning on October 8, 1958 and terminating
on October 7, 1959. The calves ranged from 350 to 500 Ibs. in weight at the
initiation of the trial and were of various breeding. Animals were assigned
to the various test plots on the basis of sex, weight and breed.
The number of animals maintained within a particular test plot was depen-
dent upon the available forage. As the quantity of forage decre eg -;.
increased a certain number of animals were removed or added to es fti ve
plot. Each plot was checked weekly for the purpose of making imal number \
adjustments and all changes were made by animal pairs so th even number
of animals were present in each lot at all times. Animal p e 4etine
t- the same lots from which they had been previously removed F ;
J:/ Haines, Assistant Animal Husbandman and Chapman, Associate li ,
nutritionist, Everglades Experiment Station, Belle Glade, Florida.
March 1, 1960
Animals were individually weighed at 14-day intervals. Occasionally some
lots were also weighed at seven day intervals when adjustments in animal
numbers were necessary. The total gains made by all animals in each test plot
for the year were converted to total pounds of live weight gains per acre of
grass. Data from test plots containing the same species of grass were combined
for the final comparisons.
Each test plot was equipped with an automatic water cup and mineral box.
The annual mineral consumption was obtained for each lot and converted to the
average consumption per animal.
The St. Augustinegrass and bahiagrass remained green throughout the year
while the paragrass and pangolagrass turned brown and contained a considerable
amount of dried and dead forage from the middle of January to the middle of
April. During this period of slow growth, Argentine bahiagrass plots appeared
to contain abundant green forage and some of the St. Augustinegrass lots
carried as many as three animals per acre. The maximum carrying capacity of
the pastures occurred in June and July when five animals per acre were used
to graze some of the lots containing each of the four grasses. The total
number of animal days (days x animals) for the year per acre were 707, 829,
960 and 1,117 days for pangolagrass, paragrass, St. Augustine and bahiagrass,
respectively. This means that pangolagrass, paragrass, St. Augustinegrass and
bahiagrass carried an average of 1.9, 2.3, 2.6 and 3.1 yearlings respectively,
per acre, on a yearly basis.
Probably the most important aspect of a grazing trial is the actual pounds
of live animal gain produced per acre for an annual period. Since both
Argentine and Pensacola bahiagrass performed very similar in regard to seasonal
carrying capacity and gains produced the data for these lots were combined.
The average total gains for each grass on an acre basis was 1077 lbs., 1070
Ibs., 1053 Ibs. and 861 Ibs. for bahiagrass, paragrass, St. Augustinegrass and
pangolagrass, respectively during the period of one year.
There were some two-week periods during which the animals lost weight.
Between November 5th and 19th as well as between July 1 and 15th negative geins
were recorded for thirteen of the lots. Although temperatures were normal dur-
ing this period the rainfall was very great. Other periods in which negative
gains were recorded to a lesser degree, were for the first two weeks in December,
the whole month of January and the first two weeks of February. In order to
show the seasonal variation that occurred in gains, the data was divided into
two-month periods and converted to the average pounds of gain produced per acre
daily, within these periods. The period consisting of the months of December and
January was the poorest productive period of the year for each of the grasses.
Paragrass appeared to reach its maximum productivity a little later in the year
than the other three grasses. The productivity of the bimonthly periods for
each of the grasses, on an acre basis, is shown in Table 1.
Table 1. Bi-monthly Average Daily Gain per Acre of Four Pasture Grasses
Average Pom nd of
St. Augustine Para
Gain per acre Da ._
Oct. & Nov.
Dec. & Jan.
Feb. & Mar.
Apr. & May
June & July
Aug. & Sept.
=UI- :- _LL J
The productivity data can be used to demonstrate the proportion of the
total annual gains occurring in each of the bi-monthly periods by converting
the data to percentages. Less than four percent of the annual gain for any of
the grasses occurred in the December-January period or 96 percent was produced
in the ten month period. Over 80 percent of the total gains were recorded in
the eight months from February through September. Previous records indicate
that low gains may occur in November, December, January, February or March so
the length of this period and its location may vary from year to year. The
percentage values for the bimonthly periods of this study and kind of grass
involved are shown in Table 2.
Table 2. Percentages of Total Yearly Gains by Bi-monthly Periods on Four
Bi-monthly No. of Percent of total yearly gain
period weeks St. Augustine Para Pangola Bahia
Oct. & Nov. 8 16.6 15.7 15.5 16.4
Dec. & Jan. 8 3.9 2.1 2.1 -1.9
Feb. & Mar. 8 18.0 10.9 19.8 22.9
Apr. & May 10 22.8 25.1 20.6 21.5
June & July 8 24.1 17.9 21.0 20.7
Aug. & Sept. 10 14.6 28.2 21.0 20.5
periods-" ~ I--
The overall daily mineral mixture consumption per animal averaged 0.108
lbs., however, the mineral consumption varied considerably within lots between
the four kinds of grasses. Animals on paragrass and pdnolagrass consumed much
less of the mineral mixture than those on St. Augustinegrdss aid bahiagrass.
The average mineral usage daily pei animal was 0.17, 0.14, 0.09 and 0.07 Ibs.
for those on St. Augustinegrass, bahiagrass, paiagrass and pangolagrass, respec-
Yearling calves were used to compare the annual productivity of St.
Augustinegrass, paragrass, pangolagrass and Pensacola and Argentine bahiagrass.
Test paddocks were two acres in size and were continuously grazed. The number
of calves in each test plot at a particular period was dependent upon the
quantity of forage available. Productivity was determined by the live weight
gains produced per acre.
Although bahiagrass carried a considerably greater number of animals
(animal days) that the other three grasses, the total annual gains produced on
bahiagrass were not significantly greater than those from calves on paragrass.
Paragrass carried a smaller number of animals (animal days) than St. Augustine-
grass but produced more pounds of live animal gains over the annual period.
Pangolagrass was the least productive of the four grasses both for carrying
capacity and gains produced. The annual live weight gains produced for bahia-
grass, paragrass, St. Augustinegrass and pangolagrass were 1077, 1070, 1053 and
861 Ibs. respectively, per acre.
Ninety-five percent of the annual gains made on each of the grasses occurred
in a ten months period from February through November. The period of maximum
gains and carrying capacity for all grasses occurred between June and September.
The average daily mineral mixture consumption per head for all calves was 0.108
Ibs. during the year.
1 Allen, R. J. Jr. 1957. Summarization of Grazing Trial Experiments.
Everglades Exp. Sta. Mimeo Rept. 57-11.
2 Kidder, R. W., R. J. Allen, Jr., H. L. Chapman, Jr. and D. W. Beardsley.
1957. Yield of Everglades Pastures as Measured by Growth of
Yearling Cattle. J. Animal Sci. 16: 1058.