Everglades Station Mimeo Report EES64-7 Octger, 1963
Grazing Trial Results for One Year (1961-1962 (
C. E. Haines and R. J. Allen, Jr.1 '
The value of any forage to be used for grazing purposes can best be determined
by the performance of animals grazing the materials being tested. By laboratory
procedures, chemists are able to ascertain the quantity of the various nutrient
constituents in a forage while an agronomist can estimate expected total yields
of forage by the use of various clipping or collection methods. However, these
data are not necessarily related to animal performance when grazing or to the
productivity of the forage in terms of animal production. This can only be obtained
by the use of animals over the entire period of forage production.
Grazing trials with cattle have been conducted at the Everglades Experiment
Station for many years using numerous species of forages. In more recent years,
the most prominent pasture forages on the organic soils of south Florida have been
Roselawn St. Augustinegrass, paragrass, pangolagrass, Argentine bahiagrass and
Pensacola bahiagrass. Thus, current grazing studies have included some of these
species. For the past two years, Haines and Allen (1, 2) have compared the pro-
ductivity of these grasses via grazing cattle and reported that Roselawn St.
Augustinegrass produced the most pounds of animal gains per acre. This study was
continued and the data reported herein was obtained during the following year.
Twelve lots, each two acres in size, were randomly located within a forty acre
field. Four of the lots were established in Roselawn St. Augustinegrass, four in
paragrass, two in Argentine bahiagrass and two in Pensacola bahiagrass. "Base"
animals (yearling steer calves) were used to continuously graze the blocks for 49
weeks. Animals were assigned to the test blocks on the basis of initial weight and
breeding. The calf groups were mixtures of purebreds and crossbreds. The trial
began on November 2, 1961 and terminated on October 11, 1962.
A minimum stocking rate of two yearlings per acre was maintained throughout
the entire period on each test block. When forage production exceeded that consumed
by the "base" animals, other yearlings called "grazers" were added to the particular
block or blocks. These "grazers" were added or removed in pairs at weigh dates
which occurred every two weeks. The "grazers" were kept in a "pool group" when not
grazing the extra forage in the test blocks and were maintained in good condition
so that when they reentered the prospective test blocks they continued grazing
During the winter period, the base animals in one half of the blocks of each
grass were supplied chopped sugarcane as a pasture supplement. An average of 20
pounds of sugarcane per head daily was provided for a 12 week period when forage
production was at a low level. The yearlings in the other half of the test blocks
(6 blocks) were given no additional supplemental feed during the year.
Assistant Animal Husbandman and Assistant Agronomist, respectively, Everglades
Experiment Station, Belle Glade, Florida.
During the winter period, chopped sugarcane was very helpful to the yearlings
grazing the paragrass blocks, but of no benefit to the steers on Roselawn St.
Augustinegrass or the bahiagrass blocks. Steers on paragrass that were provided
sugarcane, gained an average of 45 pounds during the 12 weeks period while those
steers not supplemented lost an average of 25 pounds each. This difference in
weight change of 70 pounds was statistically significant. These results agree
rather well with information obtained during the previous two years under similar
treatments. A summary of the animal responses to sugarcane provided during the
winter is shown in Table 1.
Table 1. Average Steer Weight Changes During a 12 week Winter Period Showing
Differences Due to Sugarcane Supplementation (Ibs.).
Kind of grass No Sugarcane Sugarcane Benefit from Cane
St. Augustine .-103 +101 -2
Para -25 .:-45 +70
Argentine Bahia +114 +65 -49
Pensacola Bahia +78 -'130 +52
The productivity of the grasses varied a great deal throughout the year.
Poorest animal gains and lowest carrying capacity occurred inthe 12 weeks period
between November 2 and January 25. During this quarter of the year, less than 6%
of the total annual gains were recorded for any of the grasses. In fact; only
St. Augustinegrass approached this value while the other grasses fell far short of
this mark. In this particular quarter, 5.0% of the annual gains were produced by
St. Augustinegrass compared to 3.1% and 1.8% for paragrass and Argentine bahiagrass
and negative gains for Pensacola bahiagrass. These figures are far below the
average level of 25% for a quarter of a year. No doubt, gains were depressed by
the poor growth of these grasses in this season plus the severe cold snap in early
The deficit in productivity as measured by total pounds of weight gains during
the quarter discussed above, was somewhat "balanced out" by weight gains produced
in the quarter commencing on April 19 and ending on July 12. Almost one half of
the total annual gains from paragrass were recorded during this period. Percent-
ages of the total pounds of animal gain during this quarter were 42.6%, 49.1%,
40.7% and 32.4% for St. Augustinegrass, paragrass, Argentine bahiagrass and
Pensacola bahiagrass, respectively. The months of April, May and June have also
been months of high productivity in previous years.
Quarterly gains were also above the average level of 25% between July 12 and
October 11 for all four of the grasses. These values were 27.4%, 38.5%, 32.2%
and 32.2% for St. Augustinegrass, paragrass, Argentine bahiagrass and Pensacola
bahiagrass, respectively. It was interesting to note that the productivity was
the same for both of the bahiagrasses.
During the quarter of January 25 through April 19 the productivity of two of
the grasses came very close to matching the model of 25%; this was 24.9% for St.
Augustinegrass and 25.3% for Argentine bahiagrass. However, total gains were very
poor by steers on paragrass (9.3%) and above standard for the Pensacola bahiagrass
(36.9%) in this quarter.
The seasonal fluctuations in productivity of the various grasses is illustrated
in figures 1 and 2. It must be emphasized that these values illustrate the pounds
of animal gain and of course are related to some extent by the numbers of steers
present in the various blocks during different times of the year. The greater the
carrying capacity the largerr the total weight gains expected. For these figures,
the total pounds of animal weight gains, per acre, for each two week period were
adjusted by using data from adjacent periods and calculating "running averages".
The "running average" used for a particular weigh date was obtained by combining
the gains for this period with those of the previous and following periods. The
average of these three values was used as the adjusted value or "running average"
for the middle weigh period. Although this procedure tends to lower the peaks of
the productivity curves the values indicated are considered more realistic for actual
The graph in Figure 1 shows that negative productivity occurred for paragrass
in January and February. However, the productivity of St. Augustinegrass was always
on the positive side even though it was low in January, October and December. n
comparing the productivity of these two forages it appears that St. Augustinegrass
reached a higher peak of production than paragrass. This was not expected because
previous data indicated that paragrass reached a higher peak of productivity than
St. Augustinegrass, but that it was only for a short period of time, and not long
enough to counter balance the high overall rate of productivity of St. Augustinegrass
that occurred over a longer period of the year. The curves also show that the high
productivity period for St. Augustinegrass occurred about one month sooner than for
paragrass. In figure 2, the productivity of Pensacola bahiagrass appears to be much
more uniform throughout the year than Argentine bahiagrass. However, in the overall
amount of beef produced per acre, Argentine bahiagrass was superior to Pensacola
bahiagrass. In earlier studies (1, 2) the productivity curves and overall perfor-
mance of these two bahiagrasses have been rather similar.
The actual pounds of beef produced and number of animal units supported by
these four grasses were compiled for the 49 week period. A summary of the annual
productivity, per acre, of each grass is shown in table 2. These figures indicate
that St. Augustinegrass showed the highest rate of productivity, both in terms of
carrying capacity and pounds of beef produced per acre of forage. For the past
few years paragrass has ranked second in productivity but in this present study
Argentine bahiagrass surpasses paragrass. This was the poorest year for paragrass
and the best for Argentine bahiagrass of the three most recent years of this study.
It is suspected that the below average rainfall during this year may have caused
this reversal in productivity since paragrass responds favorably to high moisture
conditions. The values for the productivity of Pensacola bahiagrass were similar
to those recorded in previous years.
Table 2. Total Annual Weight Gains and Carrying Capacity Per Acre.-
Kind of Grass Grazing Days Weight Gains (Ibs.) Daily gains (Ibs.)
St. Augustine 1,054 1,120 1.06
Para 889 874 0.98
Argentine Bahia 1,005 909 0.90
Pensacola Bahia 784 680 0.87
A sample of the forage in each test block was collected in the middle of each
month for laboratory analysis. The analyses are considered as the average nutrient
content of the particular forage for the month of collection. These average proxi-
mate analysis figures are shown in Table 3 and indicate that highest crude protein
contents occurred in the month of April. The moisture content of the forage also
tended to run high during this same month. The fact that grasses grown on organic
soil tend to run high in crude protein and moisture is well illustrated by these
values. Although there may be a relationship between forage composition and the
rate of gain put on by beef steers correlations of these factors were not studied.
The annual productivity of four of the major pasture forages for organic soils
of south Florida were compared by using yearling steers as grazing animals. During
the winter, one'half of the steers on each pasture grass were provided with chopped
sugarcane as a pasture supplement. A minimum stocking rate of two yearlings per
acre was employed throughout the study and additional yearlings were used during
periods of excess forage production.
Only yearlings grazing paragrass benefited by the supplementation of sugarcane.
Steers on Roselawn St. Augustinegrass, Argentine bahiagrass and Pensacola bahiagrass
gained as well without sugarcane as those that received the sugarcane. Annual
productivity data showed that the average pounds of beef produced per acre were
1120; 874, 909 and 680 for Roselawn St. Augustinegrass, paragrass, Argentine bahia-
grass and Pensacola bahiagrass, respectively. The number of animal units supported
by each grass per acre was 1054, 889, 1005 and 784 grazing days for Roselawn St.
Augustinegrass, paragrass, Argentine bahiagrass and Pensacola bahiagrass, respectively:
Thus, Roselawn St. Augustinegrass continues to be superior as a pasture forage for
continuous year around grazing on the organic soils of south Florida.
1. Haines, C. E. and R. J. Allen, Jr. 1961. Grazing Trial Results for One Year
(1959-1960). E. E. S. Mimeo Rpt. 61-11.
2. Haines, C. E. and R. J. Allen, Jr. 1962. Grazing Trial Results for One Year
(1960-1961). E. E. S. Mimeo Rpt. 62-26.
Table 3. Total Rainfall, Average Moisture, Protein, Fiber and Fat Content of Four Grasses by Monthly Periods. I
Forage samples secured in the middle of each month for
Protein value expressed as percent of crude protein in
Percent Protein 2/
St. Augustine Para Argentine
12.3 16.o 16.3
13.8 14.0 13.9
12.1 12.3 11.7
15.0 14.2 20.1
15.4 15.4 14.4
18.7 29.6 21.9
15.6 22.4 18.3
15.5 21.6 16.0
13.3 14.5 15.5
13.5 18.2 18.3
12.0 14.4 13.6
13.3 16.5 15.4
Table 3 Continued
Month of Crude Fiber -
Para Argentine B
3/ Crude fiber values expressed as percent of drymatter content.
4/ Ether extract, expressed as percent of drymatter content.
Augustine Para Argentine
4.7 5.7 6.2
2.9 3-3 1.4
2.0 2.4 1.7
31 2.6 2.7
2.8 3.1 2.0
4.5 6.0 5.0
4.7 3.5 3.0
3.5 3.3 3.2
3.3 2.8 3.2
2.7 3.1 2.4
0.8 1.2 1.2
3.4 3.8 4.4
B Pensacola B
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