Front Cover
 Title Page
 Table of Contents
 Agronomic studies
 Soil studies
 Animal response
 Seepage irrigation
 Economic analysis
 General discussion of results over...
 Back Cover

Group Title: Bulletin - University of Florida. Agricultural Experiment Station ; no. 789
Title: Pasture programs and beef cattle breeding systems for beef production in north central Florida
Full Citation
Permanent Link: http://ufdc.ufl.edu/UF00027252/00001
 Material Information
Title: Pasture programs and beef cattle breeding systems for beef production in north central Florida
Series Title: Bulletin University of Florida. Agricultural Experiment Station
Physical Description: 47 p. : ; 23 cm.
Language: English
Creator: Koger, Marvin, 1915-
Publisher: Agricultural Experiment Stations, Institute of Food and Agricultural Sciences, University of Florida
Place of Publication: Gainesville Fla
Publication Date: 1977
Subject: Beef cattle -- Feeding and feeds -- Florida   ( lcsh )
Beef cattle -- Breeding -- Florida   ( lcsh )
Genre: government publication (state, provincial, terriorial, dependent)   ( marcgt )
bibliography   ( marcgt )
non-fiction   ( marcgt )
Bibliography: Includes bibliographies.
Statement of Responsibility: Marvin Koger, editor.
General Note: Cover title.
General Note: "Beef Research Unit Experimental Phase No. 3"--T. P.
Funding: Bulletin (University of Florida. Agricultural Experiment Station)
 Record Information
Bibliographic ID: UF00027252
Volume ID: VID00001
Source Institution: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: aleph - 000929875
oclc - 18432902
notis - AEP0680

Table of Contents
    Front Cover
        Front Cover
    Title Page
        Title Page
    Table of Contents
        Table of Contents
        Page 1
        Page 2
    Agronomic studies
        Page 3
        Page 4
        Page 5
        Page 6
        Page 7
        Page 8
    Soil studies
        Page 9
        Page 10
        Page 11
        Page 12
        Page 13
        Page 14
        Page 15
        Page 16
        Page 17
        Page 18
        Page 19
        Page 20
        Page 21
        Page 22
    Animal response
        Page 23
        Page 24
        Page 25
        Page 26
        Page 27
        Page 28
        Page 29
        Page 30
    Seepage irrigation
        Page 31
        Page 32
    Economic analysis
        Page 33
        Page 34
        Page 35
        Page 36
        Page 37
        Page 38
        Page 39
        Page 40
        Page 41
        Page 42
    General discussion of results over a 20-year period
        Page 43
        Page 44
        Page 45
        Page 46
        Page 47
    Back Cover
        Page 48
Full Text

Bulletin 789 (technical)

Pasture Programs and Beef Cattle Breeding
Systems for Beef Production
In North Central Florida
Beef Research Unit
Experimental Phase No. 3

Marvin Koger, Editor

Agricultural Experiment Stations
Institute of Food and Agricultural Sciences
University of Florida, Gainesville


May 1977

Pasture Programs and Beef Cattle Breeding
Systems for Beef Production
In North Central Florida
Beef Research Unit
Experimental Phase No. 3

Marvin Kogera, R. E. L. Greene', G. B. Killinger'
W. G. Blue", and J. M. Myers'
In collaboration with
N. Gammon"
A. C. Warnick" and
J. E. Moore"

aAnimal Science Department
bFood and Resource Economics Department
cAgronomy Department
'Soil Science Department
eAgricultural Engineering Department


In tro d u action ............. ......................................................................................................................... 1

Agronomic Studies..... .................................. 3

Methods ... .......................... .......... 3

R e su lt s ................. ................................ .......................................... ........... ........................... .... 4

u m m a r y ............................................ ................................ ..................... ............................. 7

S oil S tu dies ........................................................... .............................. 9

Methods. .... ......................... ........... ......................... 9
R e s u lt s ................. ................................................................................. ................................................ ..1 0

Summary ............................. ................................. ................... 19

L literature C ited ... ............................ ........... ............... .................. ...........20

Animal Response .......... ..................... ................................... .... 23
M eth ods ............ ................................... .... ............................. ............................... ........ ..... 23

R esu lts .......... ............. ............ ..... .. .......................... ................ ...................... 24

Su m m ary ............................ ............................................ ...................... ................................... 28
L iteratu re C ited ............................... ................... .................................................... 29

Seepage Irrigation ...................................... ..................................... 31

R results ........ .... .. ................................................................... 31

Economic Analysis .................................................................. .. ....... ......... 33

Investment Per Acre in Pasture ...................... .... .... 33

Item s of In p u t ...................................... ........ ............ .................... .... .......................... 33

A m ount of B eef P produced ........................... ............................................. .................... ......... 34

Method Used to Show Value of Beef Produced and to Charge Items
of Costs for Each Program ............................................................. 35
Annual Income and Expense .................................................................................. 40
Summary .............................................................................. 42

General Discussion of Results Over a 20-Year Period ....................................... 43

S u m m a ry ......................... ................................................... ............................................................................. 4 7

The Beef Research Unit of the Florida Agricultural Experi-
ment Station was established near Gainesville during 1951 and
1952. The first undertaking at this unit was a long-term project
to investigate "Pasture Programs and Cattle Breeding Systems
for Beef Production in North Central Florida." The project was
an interdisciplinary undertaking involving the joint efforts of
five departments: Agricultural Engineering, Agronomy, Animal
Science, Food and Resource Economics, and Soils. The project
was governed by a coordinating committee including one or more
research specialists and an administrator from each of the five
Pasture programs were evaluated by grazing with cows and
calves in a systems approach including all components of the
beef production system so that the data could be applied to com-
mercial cattle production. The animals used to evaluate the pas-
ture programs were utilized also to compare five alternative
mating systems for commercial beef production and to observe
the differential response of these groups to the different pasture
programs. Representative animals from each of the mating
groups were used in a balanced design annually to graze each of
the pasture programs.
The project was conducted in three phases and spanned 21
years from 1952 to 1972. Different sets of pasture programs were
compared during the three phases. Data from the pasture pro-
grams evaluated during the first two phases were presented pre-
viously in Florida Agricultural Experiment Stations Bulletins
(technical) 631 and 740. However, data on comparative perfor-
mance of cattle in the different mating systems have not been
presented previously.
The objectives for this bulletin were (1) to report the data
from the three pasture programs compared during the last
(third) phase of the project, (2) to present the comparative per-
formance of cattle from the five mating systems tested, and (3)
to present an overall evaluation of results obtained over the en-
tire 21 years of the project. Detailed information on methods and
experimental procedures utilized are presented in the sections
by the departments. These departmental sections, along with the
two bulletins published previously, were reviewed to prepare the
21-year summary included as the last section of this bulletin.


By G. B. Killinger

The third phase of agronomic research involved three pasture
programs over the 7-year period October 1965 through Septem-
ber 1972. The program and pasture layout is shown diagramati-
cally in Figure 1, and details on the treatments used in each
program are shown in Table 1. Program 1 was a standard pas-
ture based on results of Phases 1 and 2. Program 2 was designed
to evaluate the benefits of renovating old clover-grass pastures
which had become infested with smutgrass (Sporobolus poiretii)
and which had declined in productivity. Starting in the fall of
1964, one-fourth of the Program 2 acreage in each replication
was renovated each year, so all renovation was completed by the
fall of 1967. Renovation consisted of plowing and seeding to
small grains, ryegrass, and clover. The Pensacola bahiagrass,
not completely killed by the plowing, reestablished itself during
the following spring and summer. In Program 3 one-half of the
clover-grass pastures were under seepage irrigation coupled with
an increase in fertilizer for the irrigated portions.
Annual forage production was estimated for each pasture by
harvesting samples from caged plots. Twenty, thirty-two, and
sixteen cages were sampled in Programs 1, 2, and 3, respectively,
at approximately 30-day intervals during the growing season.
Harvested forage was usually in an active growth stage. A sam-
ple consisted of a 10-foot strip 3.3 feet wide from each caged
area. At each harvest the cages were moved to a new freshly

Table 1.-Description of Pasture Programs.
Annual Fertilization*
Program Forage Total 0-10-20
Number Plants Acres (Ibs./A)
1 Clover-grass 65.47 300
2 Clover-grass 70.30 300**
3 Clover-grass 18.57 300
Irrigated Clover-grass 16.08 500
SIn the fall of 1967 all of the 0-10-20 applied contained 200 pounds of
Fritted Trace Elements 503 per ton of fertilizer. Dolomite limestone was
applied at a rate of 1 ton per acre to pasture 21 E, F, and G, 22 A, D, E,
and F, and to 32 A.
In the year of renovation of Program 2 pastures the winter crop received
500 Ibs./A of 8-8-8 fertilizer at seeding and was top dressed with 200
Ib/A of ammonium nitrate.








I -i


- I-








12 A
21 A
22 A

31 A
32 A

5 20 2 60
2 66
6 16
6 64
5 44
8.63 3 10
I 63
5 18
1 73
5 82
3. 8 0 23
8 04

mowed site, which was within 30 feet of a permanent marker.
These markers made it possible to correlate soil and plant data
from the same areas. Green weights of the samples were re-
corded, and 2- to 3-pound green subsamples were weighed and
dried at 1350F. Oven-dry weights were recorded, and estimates
of dry matter production per acre were calculated. Dry samples
from early-, mid-, and late-season harvests were ground in a
Wiley mill and saved for chemical analysis during 1966, 1968,
1970, and 1972. Rainfall and minimum temperatures are shown
in Table 2. The 1966-67 and 1970-71 seasons were unusually dry,
which resulted in reduced production of both clover and grass.
Minimum temperatures ranged from 15 to 260F and numbers of
days below 320F from 9 to 33 for the 7-year period.

Table 2.-Average Annual Rainfall and Minimum Temperatures During
Annual Days 32*F
Period* Rainfall Minimum Temperature or below
Inches Month F
1965-66 58.32 Jan. 15 24
1966-67 42.23 Feb. 18 26
1967-68 53.75 Jan. 21 33
1968-69 52.25 Dec. 20 25
1969-70 57.74 Jan. 20 22
1970-71 42.70 Jan. 15 31
1971-72 60.00 Jan. 26 9
"October 1 through September 30.


Estimated annual yields per acre of oven-dry forage are re-
corded for each program in Table 3. Program 1 pastures consis-
tently yielded more forage than those in either Program 2 or 3,
and Program 2 pastures were more productive than those in
Program 3 in five of the seven years. Renovation of the Program
2 pastures early in the period gave partial control of smutgrass,
but bahiagrass sod did not completely cover all pastures for sev-
eral seasons, resulting in some yield reduction. Good stands of
clover were re-established quickly in all renovated pastures. Rye-
grass and oats furnished 2,000 to 4,000 pounds per acre dry
weight of forage during February and March of the first year
of renovation for each pasture. However, overall yields for the
7-year period were not improved by this procedure or by irriga-
tion of part of the Program 3 pastures.

Table 3.-Estimated Oven-Dry Forage Yields for Each Program, 1966-1972.
Program 1966 1967 1968 1969 1970 1971 1972 Average

Ibs per acre
1 5962 6472 7493 8290 6890 7556 6816 7068
2* 6131 6240 5751 7430 6260 6168 6277 6322
3 5886 5781 6828 7692 5430 5705 5372 6099
Average 5993 6164 6691 7804 6193 6476 6155 6496
*These data include the dry weight of annual forages during renovation.

Table 4.-Crude Protein in Oven-Dry Forage.

Program Year: 1966 1968 1970 1972
No. Date: 5-23 7-18 9-26 5-14 7-15 9-23 4-23 7-30 9-30 4-26 7-5 10-3

1 15.9 9.5 8.5 15.1 8.6 6.7 23.0 15.3 15.2 13.4 9.9 9.0
2 15.6 9.9 8.8 14.3 8.2 6.7 23.3 13.6 15.0 15.9 9.3 9.6
3 14.5 9.5 8.4 15.7 8.7 6.3 21.2 13.8 14.8 15.7 10.0 91

Table 5.-Mineral Content of Forage on Oven-Dry, Sand-free Basis for Three Programs.

Mineral Early Season Mid Season Late Season
and Year Prog. Prog. 2 Prog. 3 Prog. Prog. 2 Prog. 3 Prog. 1 Prog. 2 Prog. 3
and Year Prog. 1 Prog. 2 Prog. 3 Prog. 1 Prog. 2 Prog. 3 Prog. 1 Prog. 2 Prog. 3


























0.33 0.35
0.32 0.28
0.37 0.39
0.30 0.30
0.33 0.33

1.94 2.26
1.77 1.76
2.47 2.17
1.88 1.81
2.02 2.00
0.86 0.84
0.62 0.69
0.36 0.36
1.10 1.03
0.74 0.73

0.29 0.29
0.25 0.14
0.41 0.41
0.22 0.21
0.29 0.26




No clear-cut explanation for the low estimated forage yields
in all programs is available at this time. Yields have remained at
6,000 to 7,000 pounds per acre dry weight per acre for 12 or
more seasons, compared with about 9,000 pounds per acre for
clover-grass pastures during Phase 1 (1953-1957).
Crude protein content of oven-dry forage harvested at early-,
mid-, and late-season periods in alternate years is shown in Table
4. There was no significant difference among programs. As would
be expected, the early-season forage was markedly higher in pro-
tein than at later periods. Because of more favorable moisture
and temperature during the early months of 1970, clover growth
was excellent. This resulted in higher crude protein values at all
harvest periods that year.
Mineral contents of forage harvested at three periods in al-
ternate years are shown in Table 5. The phosperous content ap-
pears adequate for normal animal and plant performance. The
potassium content was high for early-season forage because of
heavier concentrations of clover in the sward. Both calcium and
magnesium were in the optimum range each season. There was
no significant difference among programs for mineral content.

Three forage programs involving southern white clover-Pen-
sacola bahiagrass pastures were evaluated over a 7-year period.
Only phosphate and potash fertilizers were applied annually, and
minor elements were applied when needed as determined by soil
tests. The standard clover-grass pastures (Program 1) produced
more forage than similar pastures that were renovated (Pro-
gram 2) or irrigated (Program 3). Annual forage production
ranged from 6,100 to 7,100 pounds of oven-dry material per acre
for the three programs. Good quality forage was obtained in all
programs, as indicated by the cattle production data reported in
the Animal Science section of this report.

By W. G. Blue

Sampling procedures.-Soil samples (0- to 6- inch depth)
were collected annually within a 30-foot radius of permanent
posts placed at random within pasture subdivisions. Ten cores
were composite for each sample. This procedure tended to re-
duce the effect of natural soil variation and permitted measure-
ment of changes that occurred as a result of experimental treat-
ments. Thus, 20 samples were collected annually from Program
1, 34 from Program 2, and 16 from Program 3. The samples
were dried, screened, and analyzed by the Cooperative Extension
Service Soil Testing Laboratory. Soil p1H was measured in a 1:2
volume soil: water suspension. Soil K, P, Ca, and Mg were ex-
tracted by ammonium acetate (pH 4.8) using 5 g of soil and 25
ml of solution. Phosporus was determined colorimetrically, K by
flame emission spectrophotometry, and Ca and Mg by atomic
absorption spectrophotometry.
Plant analyses.-Plant samples from the first, fourth, and
sixth cage harvests in 1971 as collected and prepared by Agron-
omy Department personnel were analyzed to determine adequacy
of soil nutrients and fertilizer treatments for plant mineral nu-
trition. One-gram samples were dry-ashed at 450 C for a mini-
mum of 4 hours. The ash was dissolved in 5 N HC1, taken to dry-
ness to dehydrate Si, and redissolved in sufficient 5 N HC1 to give
50 ml of 0.2 N solution. Phosphorus was determined colorimetri-
cally; K by flame emission spectrophotometry; Ca, Mg, Mn, Cu,
Zn, and Fe by atomic absorption spectrophotometry; and S gravi-
Availability of accumulated nutrients.-Since some nutrients,
including P and the micronutrients, are known to accumulate in
flatwoods soils (Spodosols) from fertilization, particularly after
liming, a small-plot experiment was superimposed on these
grazed programs in early 1971, to measure availability of ac-
cumulated nutrients. Five treatments were located in each of
four pastures replicationss) on the experimental area. These
were fenced to prevent contamination from cattle and were cov-
ered with a plastic sheet briefly in the fall to eliminate the effects
of general pasture fertilization. Treatments from 1952 through
1970 included periodic liming and micronutrient applications,
and annual application of P, K, and S. Initially 2 tons of calcitic

lime per acre were incorporated into the surface 6 inches of soil.
Subsequently, 3 tons of calcitic lime and 2 tons of dolomitic lime
were surface applied to the established sods. Phosphorus and K
were surface applied primarily as ordinary superphosphate and
potassium chloride to provide total quantities of 450 and 1,300
pounds per acre of P and K, respectively, through 1970. The
superphosphate was also the primary S source. In 1952, at ini-
tiation of the grazing experiment, and in 1957, Mn, Cu, and Zn
were applied as sulfates to supply 7.9, 7.9. and 7.6 pounds per
acre of each, respectively, and B as borox to supply 0.68 pounds
per acre. In 1967, a micronutrient frit (FTE 503 which con-
tained 18.8% Fe, 7.5% Mn, 7.0% Zn, 3.0% Cu, 3% B, and 0.2%
Mo) was applied at 30 pounds per acre.
Results from the experiment were reported in detail else-
where (4)1, but the importance of the results warrants discus-
sion of the three basic treatments. The treatments were: 1
none; 2, N only at 400 pounds per acre in 1971 and 200 pounds
per acre in 1972 and 1973; and 3, N, P, K, Mg, S, and FTE 503
at 400, 43, 165, 76, 100, and 30 pounds per acre, respectively, in
1971 and 200, 21, 84, 76, 100, and 30 pounds per acre, respec-
tively, in 1971 and 200, 21, 84, 76, 100, and 30 pounds per acre
respectively, in 1972 and 1973. Individual plots were 8 by 15 feet.
Plots were harvested four times per year-approximately May
15, July 1, August 10 and October 1. Composite soil samples were
taken from each replication in March 1971, and from individual
plots in October of each year. Forage samples were dried at
70 C, and ground by a stainless steel Wiley mill with 20-mesh
screen. Soil and plant samples were analyzed by procedures
previously described.
Soil analyses.-The original objective with respect to liming
was to increase pH of the surface soil (0 to 6 inches) to 6.0 to
encourage white clover growth. Because of the pH dependency
of the cation exchange capacity (CEC), increasing soil organic
matter, and poor distribution and slow reaction of surface-ap-
plied lime, this pH was not measured regularly until 1968, at
which time the total lime application was 7 tons per acre (Table
6). Soil pH remained above 6.0 from 1968 through 1972 without
additional lime.
Ammonium actetate (pH 4.8) extractable nutrients were

1Numbers in parentheses refer to, Literature Cited at the, end of the

relatively constant from 1965 through 1972 (Table 6). Addi-
tional lime, surface applied in 1967, increased soil pH although
there was relatively little effect on extractable Ca and Mg.
During Phase 2 of this study, it was demonstrated that lime was
concentrated at the soil surface as a result of surface applica-
tion, and much of this was undoubtedly not extracted by the
ammonium acetate.
Extractable P did not change appreciably except that it was
substantially lower in the fall of 1972. Total soil P analyses from
this experiment and supplementary laboratory studies (3) in-
dicated that applied P accumulated in the surface soil. This is
known to occur as soil pH is increased (11). Laboratory data
indicated that about 60% of the P applied at rates used in the
field study would be retained in the surface soil if the pH were
maintained at 6.0. Total P analyses of field samples confirmed
that approximately this percentage was retained. This accumu-
lated P was shown to be available to white clover and Pensacola
bahiagrass (13). Response to applied P in greenhouse pot ex-
periments was nil when soil contained 600 pounds per acre of
total P; response to currently applied P was small for soils with
300 pounds per acre. Unfortunately, neither P extracted by am-
monium acetate (pH 4.8) nor by the Bray-Kurtz No. 1 reagent
(0.03 N NH4F + 0.025 N HC1) was related to total P. Stronger
extractants such as Bray-Kurtz No. 2 (0.03 N NH4F + 0.1 N
HC1) have not been tested.
Potassium extracted from surface soil varied slightly among
years, but it did not differ drastically from concentrations in vir-
gin soils (45 pounds per acre) even though at least 1,300 pounds
of K per acre were applied between 1952 and 1972. Supplemen-
tary studies indicated that there was some K retained in the soil
throughout the rooting zone though there was no horizon where
K was concentrated. This accumulated K was absorbed by deep-
rooted grasses (4), but it would be of limited value to white
clover, since this plant apparently requires a higher K concen-
tration in the surface soil for its annual re-establishment from
seed. The CEC which is largely responsible for retention of the
basic nutrients is derived primarily from organic matter in
these surface soils. Cation exchange from organic matter is pH
dependent; i.e., it increases as pH is increased. Theoretically,
elevation of soils pH to 6.0 would increase the capacity of the
soil to retain K; however, liming to increase soil pH also adds
Ca and Mg which act as competing ions. These ions are held
more strongly than K and in effect exclude K from the exchange

Table 6.-pH and Ammonium Acetate

(pH 4.8) Extractable Nutrients in Soils from Three Pasture Programs on Flatwoods


1966 1967



P, Ib./acre
13.0 17.2
13.8 17.6
13.6 17.4
13.5 17.4
K, Ib./acre
76 76
70 68
54 78
67 74
Ca, lb./acre
1888 2282
1416 1900
1670 2082
1658 2088
Mg, Ib./acre
154 118
116 84
142 120
137 107






























sites. Practically, liming of soils dominated by organic matter
to increase CEC and K retention is ineffective. This fact is em-
phasized by these field studies where 1,300 pounds of K per acre
were applied over 20 years. All forage was grazed and nutrient
recycling provided ample opportunity for K accumulation, but
essentially none accumulated in the surface soil.
Plant Analyses.-Several essential nutrients are deficient in
virgin flatwoods soils for intensive forage production. Nitrogen
can be considered as the key to grass production. This element
has relatively little residual effect beyond the year of application.
It is needed in largest quantity of any of the essential nutrients,
and its cost has always been high relative to value of beef pro-
duced. Therefore, N fertilizers were not applied during Phase
3 of this experiment. Symbiotic N fixation by white clover and its
subsequent mineralization provided N for the grass. The effec-
tiveness of white clover on these soils for forage production in
the spring and as source of N for grasses is without question.
All other essential nutrients were applied either annually or
periodically through the experimental period. Some of these nu-
trients accumulated near the soil surface, and others leached
from the soil. The effectiveness of the treatments was evaluated,
in part, by analyses of forage samples collected from cages in
1971 (Table 7). Forage from harvest 1, April 22, was primarily
white clover. All nutrients analyzed were more than adequate.
Forage from harvest 4, July 29, and harvest 6, September 28,
was primarily from Pensacola bahiagrass; as with white clover,
all nutrients were in adequate concentration in forage. In spite
of the low K concentrations in soils at the end of the growing
season in October, K from the soil plus that supplied in the
annual fertilization was sufficient to provide concentrations
above minimum levels in both the white clover and bahiagrass
throughout the year. White clover requires approximately 2%
K in its oven-dry vegetation for optimum growth and Pensacola
bahiagrass 0.6% (7). The P requirement of white clover is ap-
proximately 0.17% for Pensacola bahiagrass (13). The S re-
quirement of white clover is approximately 0.15% (10), and it
is likely less for bahiagrass. Calcium concentrations in white clo-
ver were substantially higher than 1.0% shown to be adequate by
Andrew and Norris (1), and values above 0.30% for Pensacola
bahiagrass were adequate according to a study by Rodriquez
and Blue (12). Micronutrient concentrations in white clover
forage were ample according to the study by Rodriquez and Blue

Table 7.-Analyses of Oven-Dry White Clover-Pensacola Bahiagrass Forage from Three Harvests in 1971 from the
Three Programs.*
Oven-Dry Forage Nutrient Concentrations
Programs P K Ca Mg S Mn Cu Zn Fe
% ppm
Harvest 1, April 22, 1971
1 0.36 2.43 1.59 0.33 0.34 47 9 65 109
2 0.36 2.32 1.60 0.32 0.31 51 9 65 151
3 0.35 2.19 1.54 0.33 0.31 43 9 55 119
Harvest 4, 7/29/71
1 0.26 1.71 0.33 0.20 23 14 62 50
2 0.27 1.82 0.33 0.19 26 13 56 50
3 0.27 1.67 0.37 0.21 19 12 174 57
Harvest 6, 9/28/71
1 0.27 1.45 0.40 0.19 0.23 36 8 62 80
2 0.27 1.53 0.42 0.21 0.24 32 8 47 69
3 0.27 1.46 0.44 0.25 0.24 22 8 86 67
*Forage from harvest 1 was primarily white clover, while that from harvests 4 and 6 was primarily Pensacola bahiagrass.

Availability of Accumulated Nutrients.-Soil pH, organic
matter, and ammonium acetate (pH 4.8) extractable nutrients as
averages of four selected locations replicationss) on the Phase
3 experimental area for March 22, 1971, at initiation of this
supplementary study and in October 1971, 1972, and 1973 are
shown in Table 8. These data are in general agreement with
those in Table 7 with respect to nutrient concentrations. Higher
levels of P and K in the initial spring samples were caused by
fertilization during the preceding November. These nutrients
had not been removed by plant absorption, leaching, or reactions
with the soil which reduce solubility in ammonium acetate (pH
4.8). Subsequently, the plot areas were covered with a plastic
sheet at time of fall fertilization to prevent contamination.
White clover was an essential part of the grazed experiments
in Phase 3 because it provided forage during early spring and
symbiotically fixed N for grass growth during the summer. Since
fertilizer was not fall-applied in the study of residual nutrient
availability, growth of clover was poor.
All plant samples from the 3-year study of residual nutrient

Table 8.-pH Organic Matter and Ammonium Acetate (pH 4.8) Ex-
tractable Nutrients from Limed and Continuously Fertilized
Flatwoods Surface Soil Planted to White Clover and Pensa-
cola Bahiagrass.
NH4OAc(pH 4.8) extractable
Treatments pH O.M. P K Ca Mg
% Ib/acre
Pre-experimental, March 22, 1971
Avg. 5.9 4.95 26.2 132 3080 156
October 8, 1971
1 5.6 11.2 50 2960 130
2 5.5 15.8 26 2360 92
3 5.4 23.6 60 2780 178
October 6, 1972
1 5.9 9.2 22 2300 70
2 5.9 8.0 16 1820 42
3 5.6 9.0 28 2220 90
September 16, 1973
1 5.9 9.4 16 1800 38
2 5.9 7.0 14 1820 12
3 6.0 6.2 16 1660 68
*Treatments 1, 2, and 3 were superimposed at selected locations in 1971 on
Programs 1, 2, and 3. The treatments were (1) none, (2) N only, and (3) all
nutrients except Ca.

Table 9.-Forage Yields and Nutrient Concentrations in August Harvests of Pensacola Bahiagrass from Established Pas-
ture Programs on Flatwoods Soils Resulting from Superimposed Treatments.

Oven-Dry Nutrient Concentrations in Oven-Dry Forage
Treatments* Forage N P K Ca Mg S Mn Cu Zn Fe

lb/acre % ppm
1 3280a 1.23a 0.25a 1.49a 0.37a 0.28a 0.32b 27a 6a 37a 47a
2 5520b 1.54b 0.23a 1.23a 0.49b 0.34a 0.24a 29a 7a 41a 59b
3 5330b 1.70b 0.24a 1.84b 0.46b 0.39a 0.34b 45b 8a 60a 64b

1 1780a 0.95a 0.20b 1.16b 0.40a 0.24a 0.26a 44a 8a 32a 45a
2 3010b 1.21ab 0.18a 0.68a 0.53a 0.24a 0.25a 54a 8a 35a 54a
3 4780c 1.46b 0.20b 1.36b 0.48a 0.32a 0.24a 100b 9a 52b 51a
1 1610a 1.23a 0.23a 0.79b 0.53b 0.29a 0.33b 78a 6a 45a 98a
2 2530a 1.83c 0.25a 0.44a 0.73b 0.25a 0.23a 118a 7a 57b 95a
3 4990b 1.40b 0.24a 0.96c 0.45a 0.38b 0.36b 140a 7a 64c 97a
*Treatments 1, 2, and 3 were superimposed at selected locations in 1971 on Programs 1, 2, and 3. The treatments were: (1) none,
(2) N only, and (3) all nutrients except Ca.

availability were analyzed in order to calculate total nutrient
uptake. Analytical data for forage from the third harvest (Au-
gust) of each year are presented in Table 9. Data from this
harvest were selected because Pensacola bahiagrass was domi-
nant, and its highest rate of growth occurs during the July-
August period. In 1971, forage yields at the third harvest were
affected primarily by N fertilization. Yield and forage N were
relatively low from Treatment 1 where N was omitted. Another
marked difference was higher K concentration in forage from
treatment 3 which received K fertilizer. However, minimum
forage K concentrations during 1971 probably did not limit
yields; Gamon (7) showed that the critical concentration in oven-
dry Pensacola bahiagrass was near 0.6%. Differences in concen-
trations of other elements were not large and none approached
In 1972, the N fertilizer rate was reduced to 200 pounds per
acre due to some sod deterioration from the 400 pounds per acre
rate used in 1971. Forage yield and N concentration were lowest
from Treatment 1. Forage yield and K concentration were low
for Treatment 2 without K fertilization in comparison with
Treatment 3. Other nutrients were adequate, though there were
significant differences among them.
In 1973, yield, and N and K concentrations were again ex-
tremely low from Treatment 1. Forage K concentration was
only 0.44% from Treatment 2 and yield was severely depressed.
At the fourth harvest it was only 0.33 %. Forage N concentra-
tion from Treatment 2 was significantly higher than from other
treatments which emphasized the deficiency of K. Phosphorus
and S were in adequate concentrations in forage throughout the
experiment. Significant differences in concentrations among
other elements occurred, but none was in the deficient range. Of
interest was the increase in forage Mn concentration with years.
Nitrogen and other fertilizer salts added during this experiment
probably caused a reduction in pH at the soil surface. The avail-
ability of Mn increased as indicated by higher concentration in
forage from comparable harvests. Forage micronutrient con-
centrations from Treatment 3 were also influenced by annual
application of the frit.
Forage yields were high for the 3-year experimental period
which placed considerable stress on soil nutrient supplies. These
soils without N fertilizer mineralize 30 pounds N per acre per
year. Uptake of N in forage from Treatment 1 exceeded this
amount each year (Table 10). Some of this N was fixed symbio-

Table 10.-Forage Yields and Nutrient Uptake by White Clover-Pensacola Bahiagrass from Established Pasture Programs
on Flatwoods Soils Resulting from Superimposed Treatments.
Oven-Dry Forage Nutrients
Oven-Dry ----------------------------
Treatments* Forage N P K Ca Mg S Mn Cu Zn Fe

1 10490a 158.4a 28.0a 163.2a 72.4a 28.6a 31.7a 0.32a 0.09a 0.40a 0.60a
2 15070b 253.7b 38.1b 212.4b 92.8a 49.0b 39.1a 0.50a 0.13b 0.66b 0.96b
3 16110b 285.3b 42.9c 300.3c 107.4a 58.3b 54.0b 0.78b 0.13b 0.90c 1.12b
1 6520a 77.4a 14.0a 83.5a 35.6a 16.6a 16.2a 0.32a 0.05a 0.25a 0.36a
2 10390b 151.0b 21.4b 93.1a 62.0b 26.4a 25.5b 0.69a O.08b 0.45b 0.62b
3 15500c 229.7c 36.4c 239.1b 88.5c 50.4b 43.0c 1.60b 0.14c 0.89c 1.03c
1 4800a 68.9a 11.3a 38.5a 31.2a 13.8a 16.3a 0.36a 0.03a 0.20a 0.40a
2 7950b 133.0b 18.6b 43.3a 54.7b 20.9a 19.2a 0.88b 0.06b 0.41b 0.64a
3 14390c 212.2c 34.1c 134.1b 70.7b 53.0b 50.9b 2.04c 0.11c 0.85c 1.17b
1 21820a 304.7a 53.3a 285.2a 139.2a 58.9a 64.1a 1.11a 0.17a 0.85a 1.36a
2 33420b 537.8b 78.0b 348.7a 209.4b 96.4b 83.9b 2.06b 0.27b 1.50b 2.22b
3 46000c 727.0c 113.4c 673.7b 264.Oc 161.7c 147.8c 4.43c 0.38c 2.64c 3.32c
*Treatments 1, 2, and 3 were superimposed at selected locations in 1971 on Programs 1, 2, and 3. The treatments were: (1) none,
(2) N only, and (3) all nutrients except Ca.

tically by white clover, but a substantial amount was evidently
mineralized in these soils where organic matter and N had accu-
mulated during the previous 19 years of white clover-grass pro-
duction. Uptake of K was also large compared to surface soil sup-
ply (Table 10). Potassium extracted from the soil initially was
only about 130 pounds per acre; yet more than 300 pounds per
acre were removed in forage from treatment 2 which emphasized
the importance of small K accumulations throughout the soil pro-
file as a source of K for the deep-rooted grasses. Uptake of other
nutrients was proportioned to yield levels which were dependent
on additions of N and K during the experiment. Uptake of nu-
trients from Treatment 2, other than N, was substantially less
than quantities previously applied. However, except for Ca, they
exceeded quantities extracted from the surface soil by ammonium
acetate (pH 4.8). Extractable K and Mg declined to extremely
low levels in soil from Treatment 2 by the end of the 3-year
study. Potassium was obviously deficient, but Mg continued to
be adequate for plant growth based on forage Mg concentrations.
The continued adequacy of P and S over the 3-year experimental
period without applying either nutrient was of interest.

The objective of the liming program used through all phases
of this study was to maximize white clover growth by main-
taining surface soil pH at 6.0 and providing an optimum balance
of Ca and Mg. Because of the continuing increase in organic mat-
ter which gave higher CEC, and surface liming which delayed
reaction of lime with the soil, pH 6.0 was not consistently
achieved until 1968 after addition of 7.0 tons of lime per acre.
Approximately 60% of the applied P accumulated in the surface
of these limed soils. Initial total P in the surface soil was in the
range of 80 to 100 pounds per acre; the average in 1967 was 250
pounds per acre. Ammonium acetate (pH 4.8) extractable P in
the virgin soil averaged about 6 pounds per acre and in 1972 it
was approximately 10 pounds per acre. Only a small fraction
of total P is extracted by acid ammonium acetate and the per-
centage extractable is not uniform. Therefore, total soil P cannot
be estimated accurately from extractable P values. However,
accumulated P has substantial availability and annual P fertili-
zation can be reduced on pastures where lime programs have
been adequate and where consistent fertilization has been prac-

Potassium did not accumulate in these soils in spite of re-
cycling by the grazing animal and annual K application. In some
years, extractable K in the surface soil was higher than in virgin
soil, but in 1972 extractable K in soils treated for 21 years and
in virgin soils was essentially identical. Small additional amounts
were present in the soil profile, and some was utilized by grasses
fertilized with N. However, for legume-grass pastures annual
K fertilization is essential.
Calcium and Mg were adequate for optimum plant growth as
evidenced by soil levels and plant composition. Calcium/Mg
ratios throughout Phase 3 of this study were in the range of
12 to 20. These were somewhat higher than considered ideal for
many soils, but the strong affinity of exchange sites on organic
matter for Ca relative to Mg permits adequate Mg for plant nu-
trition over a wide range of ratios. Probably a more important
consideration is maintenance of reasonably high levels of Mg in
the soil. Quantities in the range of 110 to 150 pounds per acre
were adequate.
Supplementary studies confirmed the continuing need for N
and K in pasture production and the adequacy of other accumu-
lated nutrients over a 3-year period of intensive forage pro-
Excellent legume-grass pastures can be grown following
treatments used at the Beef Research Unit, if the correct legume-
soil combinations, based primarily on moisture relationships, are
selected. The first priority is a lime program which will maintain
soil pH at approximately 6.0 and Ca/Mg ratios in the range of
10 to 15. Soil analyses will be useful in maintaining adequate pH
and nutrient levels. Annual fertilization with P, K, and S is es-
sential. Eventually P fertilization can be reduced, as this element
accumulates in the soil. Potassium must be applied annually.
Micronutrients should be applied initially and periodically ac-
cording to recommendations.

Literature Cited
(Soil Studies)
1. Andrew, C. S., and D. O. Norris. 1961. Comparative responses to cal-
cium of five tropical and four temperate pasture legume species. Aust.
J. Agr. Rev. 12:40-55.
2. Blue, W. G. 1970. The recovery of autumn and winter applied potassium
by a warm-season grass from Leon fine sand. Soil and Crop. Sci. Soc.
Fla. Proc. 30:9-15.
3. Blue, W. G. 1970. The effect of lime on retention of fertilizer phos-
phorous in Leon fine sand. Soil and Crop Sci. Soc. Fla. Proc. 30:141-150.

4. Blue, W. G. 1974. Utilization of residual nutrients accumulated in
Florida's acid flatwoods soil under fertilized white clover-Pensacola
bahiagrass pasture. Proc. XII Internat. Grassland Congr. (Moscow,
Russia) PartI. 33-41.
5. Blue, W. G., and N. Gammon, Jr. 1966. The re-establishment of pro-
ductivity by fertilization of deteriorated white clover-Pensacola bahia-
grass pasture on Leon fine sand. Soil and Crop Sci. Soc. Fla. Proc.
6. Blue, W. G., and N. Gammon, Jr. 1970. Soil studies. p. 5-12. In. Koger,
M., W. G. Blue, G. B. Killinger, R. E. L. Greene, J. M. Myers, N. Gam-
mon, Jr., A. C. Warnick, and J. R. Crockett. Production response and
economic returns from five pasture programs in North Central Florida.
Fla. Agr. Exp. Sta. Bul. 740 (tech). p. 45.
7. Gammon, Jr., N., and W. G. Blue. 1952. Potassium requirement for
pastures. Soil Sci. Soc. Fla. Proc. 12:154-156.
8. Gammon, Jr., N. 1953. Sodium and potassium requirements of pangola
and other pasture grasses. Soil Sci. 76:81-90.
9. Neller, J. R. 1963. Comparisons of phosphorous fertilization for pas-
tures on flatwoods soils in Florida. Fla. Agr. Exp. Sta. Bul. 651.
p. 12.
10. Neller, J. R., G. B. Killinger, D. W. Jones, R. W. Bledsoe, and H. W.
Lundy. 1951. Sulfur requirements of soils for clover-grass pastures
in relation to fertilizer phosphates. Fla. Agr. Exp. Sta. Bul. 475. p. 32.
11. Neller, J. R., D. W. Jones, N. Gammon, Jr., and R. B. Forbes. 1951.
Leaching of fertilizer phosphorus in acid sandy soils as affected by lime.
Fla. Agr. Exp. Sta. Cir. S-32. p. 7.
12. Rodriquez-Gomez, M., and W. G. Blue. 1973. Effects of lime. and micro-
nutrients on growth and composition of three warm-season grasses on
Leon fine sand. Soil and Crop Sci. Soc. Fla. Proc. 33:205-208.
13. Rodulfo, S., and W. G. Blue. 1970. The availability to forage plants of
accumulated phosphorus in Leon fine sand. Soil and Crop Sci. Soc. Fla.
Proc. 30:167-174.

By Marvin Koger

The pasture programs studied during the three successive
phases of the project were evaluated by grazing with a cow-calf
production system supplemented with data from other partici-
pating departments. Multiple use was made of the cattle in the
project by involving them in a comparison of five mating sys-
tems, beginning with a foundation of Brahman-native females
typical of Florida cattle in the early 1950's. The mating systems
compared were: 1, upgrading to Angus sires; 2, upgrading to
Hereford sires; and three 2-breed-of-sire rotations, including
3, Angus and Hereford, 4, Angus and Brahman, and 5, Hereford
and Santa Gertrudis. Since two sire breeds were represented in
Systems 3, 4, and 5, there were a total of eight mating groups.
Cows from each of six of these groups were used to graze each
of the pasture programs which were evaluated during Phases
2 and 3 of the project. Two groups were carried on reserve pas-
tures and utilized as filler cows to replace animals removed from
the experimental pasture programs during the year. Inclusion of
animals from different breeding systems on each of the pasture
programs proved to be a fortunate design since it turned out that
breed groups responded differently to pasture programs.
Each year in October all non-pregnant cows were eliminated
and replaced with pregnant heifers which had been bred in non-
experimental pastures. The number of cows with which a pasture
was stocked was a subjective decision based on previous ex-
perience. The objective was to maintain enough cattle on the pro-
gram to graze off all of the accumulated forage by November 15
to December 1. At this time, the cattle were removed to fields on
which silage for winter feed had been grown and continued there
until clover was ready for grazing, usually March 1,- 10 days.
The silage fed was charged against the program.
In evaluating pastures with cows and calves on a system
basis, the pastures must be stocked with a nearly constant num-
ber of cows, with fluctuations in amount of forage being adjusted
by age at which calves are removed and by the amount of supple-
mental feed added to the program. The dry matter content of
estimated forage and silage utilized was equal approximately to
the NRC recommendation for cows and growing calves. It ap-
peared that the amount of forage wasted through trampling was

not excessive. It was assumed that the procedures used yielded
a satisfactory comparison of the pasture programs.
Bulls were placed with the cows for a period of 70 days (-
5 days) beginning March 10. Calves were weighed and graded
all at one time during the last 10 days of August. During the last
five years of the trial, calves were left with the cows for another
four to six weeks. Since the practice was not followed throughout
the project, all the programs were evaluated on the basis of the
late August weights. On good pastures, however, the practice of
later weaning of calves is an economical one for many operations.
Steer calves were placed on feed at weaning and fed to aver-
age slaughter weights of approximately 950 pounds. Heifer
calves were wintered on roughage (pasture, hay, or silage) with
4 to 6 pounds of a protein-energy supplement until clover was
available for grazing. Heifers were bred to calve during the
normal calving season at two years of age. Upon calving they
were put on a full feed of corn silage plus 5 to 8 pounds of a
grain-protein supplement until the beginning of the breeding
season, March 10. After this, they were managed in the same
manner as mature brood cows. Young cows were not added to
experimental pastures until the mating season at 3 years of age.

Results by pasture program.-The least squares means and
standard errors for the production traits are shown in Table 11.
Analyses of variance are shown in Table 12. These data show
that the only individual trait significantly influenced by pasture
Table 11.-Least Squares Means for Cattle Performance Traits by
Pasture Program, 1965-1972.
Trait 1 2 3
Carrying capacity, cows per acre .74 .70 .80
Pregnancy rate, % 92.31.4 91.2--1.4 94.1+1.8
Calf survival, % 94.9+1.1 93.6E1.2 95.61.5
Weaning rate, % 87.61.6 85.4+1.8 90.0+2.0
Birth weight, lb. 66.1 +0.5 66.10.5 65.4_-0.6
205-day weight, lb. 458.1-2.2 460.7-2.3 462.6-2.9
Weaning weight, lb. 508.5+2.4 511.42.5 514.4-3.2
Condition, score 10.9+0.1 11.10.1 11.1+0.1
Production per cow, Ib. 445.4 436.7 463.0
Calf production per acre, Ib. 329.8 306.3 370.4
August weight of cows, lb. 1090 1093 1096

program was condition score (P < .05). Average score for Pro-
gram 1 was 10.9, compared with 11.1 for each of the other two
programs. This difference was too small to be of any economic
significance. For production per cow (a composite of weaning
rate and weaning weight) Program 3 ranked highest with 463
pounds, followed by Program 1 with 445 pounds and Program
2 with 437 pounds. These differences reflect mainly small differ-
ences in weaning rate. The programs ranked in the same order,
but with larger differences, for calf production per acre. There
is no satisfactory test of significance for these differences, al-
though the low value for Program 2 would appear to be real
because of the reduced carrying capacity in the program due to
renovation during the first four years of Phase 3.
These results are consistent with those from the previous
phase in indicating that Program 1, fertilized at the rate of 300
pounds of 0-10-20 per acre, continued to produce at a high, and
easily the most economical, rate of any program tested. The
clipping plot yields reported in the Agronomy section for Phase
3 are in agreement with the animal response data. In retrospect
it was an error in judgement not to have included also a lower
level of fertilization on clover pastures in an attempt to establish
the point at which further reduction lowered production under
continuous grazing where most of the fertilizer nutrients are re-
turned to the soil.
The effects of mating systems.-The major items of interest
with respect to the mating systems investigated include: 1. the
comparative performance of foundation animals and their pres-
ent-day descendents, 2. the effectiveness of different mating sys-
tems, and 3. the differential response of different breed groups
on the different pasture programs.
A progressive improvement in production performance of the
cattle over time is shown in Table 13. These data show that im-
provement occurred for all production traits, with annual pro-
duction per cow increasing from 225 to 448 pounds. A portion of
this increase can be explained by the use of silage for winter feed
and inclusion of clover in more of the pastures. There was
enough overlap of successive generations, however, that the evi-
dence is clear that most of the improvement observed was ge-
netic. The partitioning of effects into genetic and environmental
components will be the subject of .a more detailed publication
Differences in the production characteristics of the cattle re-
sulting from the five mating systems are shown in Table 14.

Table 12.-Mean Squares from Analyses of Variance for Production Traits, 1965-1972.
Pregnancy Calf Birth 205-day Weaning Condition
df Rate Survival Weight Weight Weight Score
Year (Y) 7 .1201 .2483** 483** 6,965** 8,930** 35.69*"
Breed (B) 5 .0485 .0313 3,131** 105,372"* 131,103"* 1.53
Program (P) 2 .0598 .0321 42 1,557 2,499 4.49"
Sex 1 1,964** 327,390** 400,732** 6.69*"
YxB 35 .1000 .0520 88 3,073 3,836 1.60*
YxP 14 .0807 .0462 167** 2,021 2,353 2.98**
BxP 10 .0285 .0382 93 4,897** 5,906** 2.40*
Calf Age-L 1 206 546 321,812** 34.71**
Calf Age-Q 1 202 7,723* 10,597* 3.33
Remainder 924" .0725 .0522 80 1,863 2,280 1.00
"Degrees of freedom shown are for birth and weaning traits. Those for pregnancy rate and calf survival were 919 and 985, re-
*P <.05
"P <.01

Table 13.-Production Performance of Cow Herd at Progressive Stages
of Breeding Project.


Preg. Wean Wean Prod.
Rate Rate Weight per Cow Ratio

% % lb. lb. %
Brahman-Native Foundation 60 58 388 225 100
Selected Brahman-Native Cows 73 68 418 284 126
First Generation Crossbred Cows 85 82 436 358 159
Experimental Groups, 1965-72 92 88 511 448 199

Table 14.-Average Production Performance for Five Experimental
Breeding Programs at Beef Research Unit, 1961-1972.
Breeding Systema
Gr. Gr. A-H A-B H-SG
Trait A H Rot. Rot. Rot.
Pregnancy rate, % 90.2 91.0 93.6 89.9 90.3
Calf survival, % 95.6 93.2 94.7 92.6 92.1
Weaning rate, % 86.2 84.5 88.6 83.3 83.2
Weaning weight, Ib 463 534 501 515 541
Production per cow, Ib 400 458 444 428 450
Condition score of calf 11.1 11.3 11.2 11.0 11.0
Avg. Wt. of cows, lb 1008 1173 1091 1082 1140
Prod. per cow/cow wt., % 40 39 41 40 39
20-month heifer wt., Ib 743 828 792 817 856
Fourteen-month steers
Carcass wt., Ib 510 578 558 576 576
Carcass grade ch- g+ ch- g+ g
Feed/gain, Ib 10.8 10.3 10.2 10.2 10.1
aBreed designation:
Gr. A=graded to Angus
Gr. H=graded to Hereford
A-R Rot= Angus-Hereford sire rotation
A-B Rot=Angus-Brahman sire rotation
H-SG Rot= Hereford-Santa Gertrudis sire rotation

These data, used in a separate study (4), came from both Phases
2 and 3, and thus are not directly comparable with those of
Tables 11, 12 and 13. Here it is seen that the principal differences
were in size and growth rate. This would be anticipated in view
of the sire-breeds represented. Difference in weaning rate were
statistically non-significant due to large standard errors for
bimodal data. Considering that all non-pregnant females were
eliminated from all groups, large differences in fertility would
not be anticipated. Some of the differences observed, however,

may in fact be real. One of the items of greatest interest in these
data was annual production per cow expressed as a percent of
cow weight. It was used in this study as an indicator of total
efficiency during the preweaning phase of the production cycle.
As shown in Table 14, this value varied from 39% to 41%, indi-
cating little difference in total production efficiency. Likewise,
there were no large differences in feed conversion by steers, with
feed required per pound of liveweight gain varying from 10.8
for grade Angus to 10.1 for the Hereford-Santa Gertrudis rota-
tion group.
Because of differences between early generation grade animals
and straightbred cattle, these results are not directly comparable
with other cross-breeding studies in Florida, all of which have
shown significant advantages for crossbred cattle in weaning
rate, growth rate, and annual production per cow (2, 3, 5, and
6). Previous investigations have utilized purebred or high grade
cattle as reference groups. The lower grade animals in this study
descended from a Brahman-native-British crossbred foundation
with most of the grades being less than four generations re-
moved from this base. It is not surprising, thus, that the grades
in this study compared more favorably with crossbreds. A study
of time trends in these cattle indicated that at the close of the
trial the grade animals were losing stature as compared with
the rotation crossbreds (4).
Possibly the most significant response observed in this long-
term study was the comparative performance of the different
breed groups on the different pasture programs. The analyses of
variance for Phase 3 (Table 12) show that, overall, pasture pro-
gram did not significantly influence production performance.
Pasture programs, however, did show a highly significant inter-
action with breeding system, agreeing with previous results from
the Ona Agricultural Research Center (5, 6) and with results
from the genotype-environment interaction study in which the
Brooksville station has been involved (1). If such interactions
are real, as the evidence indicates, it means that both the animal
and forage components of the production system must be con-
sidered jointly to achieve maximum results.
Individual animal response data from Phase 3 showed no
significant influence due to pasture program. Program 3, which
was irrigated, had a slightly higher carrying capacity than the
check program (number 1, fertilized at the rate 300 pounds of

0-10-20 annually) while the carrying capacity of Program 2 was
reduced during the first four years during which 1/4 of the pro-
gram was renovated each year. Following renovation, production
and carrying capacity returned to approximately the same level
of the check program.
An important feature during Phase 3 was that there was a
highly significant breed group x pasture program interaction for
calf growth traits. This response was in agreement with other
recent reports and emphasized the necessity for considering both
the forage and cattle breeding programs jointly in order to max-
imize production efficiency.
The response of the cattle to selection and different mating
systems over a 20-year period was evaluated at the termination
of Phase 3. Annual production per cow, averaged over all breed
groups, increased from 225 pounds for the foundation cattle to
448 pounds during Phase 3, an improvement of 99%. Indica-
tions were that most of this improvement was genetic, being due
to a combination of intensive selection and hybrid vigor.
Summarization of data by the five mating systems showed
highly significant differences in size and growth rate as would
be anticipated from the sire breeds employed. Differences in
weaning rate and estimated total production efficiency were non-
significant. There were indications by the end of the trial, how-
ever, that the grades were beginning to lose stature as compared
with the rotation crosses.

Literature Cited
(Animal Response)
1. Butts, W. T., M. Koger, O. F. Pahnish, W. C. Burns, and E. J. Warwick.
1971. Performance of two lines of Hereford cattle in two environments.
J. Anim. Sci. 33:923.
2. Crockett, J. R., R. W. Kidder, M. Koger, and D. W. Beardsley. 1973.
Beef production in a crisscross breeding system involving the Angus,
Brahman and Hereford. Fla. Agri. Exper. Sta. Bul. No. 759 (technical).
3. Kidder, R. W., M. Koger, J. H. Meade, and J. R. Crockett. 1964. Sys-
tems of crossbreeding for beef production in Florida. Fla. Agri. Exper.
Sta. Bul. No. 673.
4. Koger, Marvin, and A. C. Warnick. 1973. Breeding systems for improve-
ment of native cattle. J. Anim. Sci. 37:235.
5. Koger, Marvin, F. M. Peacock, W. G. Kirk, and J. R. Crockett. 1975.
Heterosis effects on weaning performance of Brahman-Shorthorn calves.
J. Anim. Sci. 40:826.
6. Peacock, F. M., M. Koger, W. G. Kirk, E. M. Hodges, and A. C. Warnick.
1971. Reproduction in Brahman, Shorthorn and crossbred cows on dif-
ferent pasture programs. J. Anim. Sci. 33:458.

By J. M. Myers

Pasture Program 3 involved the use of seepage irrigation as
a cultural practice. Approximately 33 acres of pasture was in-
cluded in the program with one-half of it being subject to irriga-
tion. The other half of the pasture in the program was treated
the same as Pasture Program 1.
The physical components of the seepage irrigation system
consisted of a deep well water source, a turbine pumping unit,
main ditch with water level control structure, and "V" shaped
lateral ditches spaced 135 feet apart. The lateral ditches had flat
side slopes and were about 18 inches deep. Pasture plants grew
within the bounds of the ditches as well as they did on the land
between the ditches. Nine shallow wells, about three feet deep,
were randomly located in the pasture to facilitate measuring
depths to the water table.
Management of seepage irrigation was based on depth to the
water table during various parts of the growing season. When
clover was the primary plant species on the pasture, the irriga-
tion pump was started when the water table receded to an aver-
age depth of 24 inches below the soil surface. Pumping would
continue until the water table was raised to an average level of
18 inches below the soil surface. When grass was the primary
pasture plant, the water table was allowed to recede to 30 inches
before pumping was started and was continued until the water
table was raised to 18 inches below the surface. During average
dry periods, about three days of pumping were required to raise
the water table from 30 inches to 18 inches below the surface,
and in three to five days it would recede back to 30 inches.
For the seven-year duration of the experiment, an average
of approximately 23 inches of irrigation water was required per
year to maintain the desired water table levels.

Details of production responses and the economic evaluation
of the program are presented in other sections of this bulletin.
Pasture Program 3 produced annually about 40 pounds of beef
per acre more than Program 1, which was treated similarly ex-
cept for irrigation and the addition of 200 pounds per acre of
0-10-20 fertilizer on the irrigated area. These results do not re-
flect typical responses to seepage irrigation. The properties of

the experimental area were marginal in meeting the physical
requirements for seepage irrigation. The slope of the land sur-
face and the vertical water movement restraining layer beneath
the surface exceeded standard requirements. This contributed
to excessive horizontal water movement which made irrigation
water requirements larger than normal and shortened the time
interval between irrigation applications. Usually favorable mois-
ture conditions for growing non-irrigated clover grass programs
prevail at the Beef Research Unit. Thus, a limited response to
irrigation at this unit would be anticipated. That economic
analyses showed a positive net return for the irrigated pasture
during Phase 3 would suggest that on sites where moisture con-
ditions are not for growing clover without irrigation, installation
of facilities for seepage irrigation could be a profitable venture
on favorable sites.

By R. E. L. Greene

Income and expenses were calculated for each program. The
experimental data were supplemented with data from other
studies to show the approximate income and expenses for various
programs on a commercial operation if the experimental prac-
tices were used and similar weaning percentages, culling rates,
and calf and culled cow weights were obtained.

Investment Per Acre in Pasture
In the experiment, the level of practices followed annually
appeared sufficient to maintain or improve the pastures. There-
fore, in calculating annual average expenses, the costs of estab-
lishing the pastures were not depreciated over a stated number
of years. An annual interest charge was made based on the
needed capital investment per acre to establish the pastures in
the three programs. The cost of establishing clover-grass pasture
was estimated to be $128 per acre. A value of $120 per acre was
added to the established costs to cover the value of land, fencing,
watering equipment, corrals and scales. Thus, the total invest-
ment for clover-grass was $248 per acre. A value of $120 per
acre was used as the needed investment in a well and facilities
to irrigate the pastures in Program 3, which were irrigated by
means of seepage irrigation.

Items of Input
Acres of pasture per cow.-The number of cows assigned to
each program varied slightly from year to year. The average
number of cows over the experimental period was used in cal-
culating acres of pasture per cow. As indicated in Table 11, the
average acres of pasture per cow was 1.35 in Program 1, 1.43
in Program 2, and 1.25 in Program 3.
Fertilizer and lime.-All non-irrigated pastures received an
annual application of 300 pounds per acre of a 0-10-20 fertilizer
and irrigated pastures 500 pounds. Lime was applied to pastures
in each program every three years at the rate of a ton per acre
with the kind of lime alternated between high calcic and dolomite
Supplemental feeds and minerals.-A record was kept of the
kinds and amounts of supplemental feeds and minerals fed to

cows on each program each year. The kinds and amounts of feed
fed varied from year to year, but basically the cows received
corn silage, a protein supplement or a ration mixture, and a
mineral mixture. However, in calculation cost of supplemental
feeds and minerals for each program, the kinds of feed and
amounts used was those comsumed by the cows in the 1971-72
season (Table 15).

Table 15.-Supplemental Feeds and Minerals Fed per Cow.
Program Number
Item 1 2 3
Cottonseed meal 146 146 146
Blackstrap molasses 365 365 365
Corn silage 4352 4339 5549
Minerals 40 44 46
aBased on supplemental feeds and minerals fed cows assigned to each program
in the 1971-72 season.

Amount of Beef Produced
The annual production of beef from calves, on each program
(per acre and per cow) was calculated from the average calf
crop weaned and the average weight of calves when they were
removed from the pastures (Table 16). No credit was given for
change in cow weights, but a figure was included in beef pro-
duction for normal culling of cows. The percentage of cows nor-
mally sold as culled cows in a commercial herd each year was
estimated to be 12%. This figure was used to estimate the
amount of beef sold from a culled cow on each program.
The production of beef from a calf varied from 306 pounds
per acre on Program 2 to 370 pounds on Program 3. Production
of beef per acre from a culled cow was 93 pounds on Program
2 and 105 pounds in Program 3.
The gross weight of a calf and a culled cow was reduced by
4% to adjust for normal shrinkage in marketing. The adjusted
sales weight of beef produced from a calf was 294 pounds on
Program 2 and 355 pounds on Program 3. Gross and adjusted
production of beef from a calf and culled cow were not adjusted
for supplemental feeds fed during the winter period, since costs
of such feeds were included in the total costs calculated for each

Table 16.-Measures of Efficiency in Beef Production by Programs.
Program Number
Item 1 2 3
Percent calf crop weaned 87.6 85.4 90.0
Percent of brood cows sold
as culled cowsb 12.0 12.0 12.0
Average weight per animal (lbs.)
Calf when removed from pasture 508 511 514
Cow when culled 1,112 1,112 1,091
Production of beef per acre (Ibs.)
From calf 330 306 370
From culled cow 98 93 105
Production of beef per cow (Ibs.)
From calf 445 437 463
From culled cow 133 133 131
Adjusted sales weights for beef
produced (Ibs.)c
From calf:
Per acre 317 294 355
Per cow 427 420 444
From culled cow sold:
Per acre 94 89 101
Per cow 128 128 126
aBased on percent calf crop weaned from all cows exposed on each program.
bIt was estimated that 15 percent of the cows in a commercial herd would be
culled each year; 12 percent would be sold as culled cows; and 3 percent
would die.
cGross weight was reduced by 4 percent to adjust for normal shrinkage in

Method Used to Show Value of Beef Produced
and to Charge Items of Costs for Each Program
Calculations were made of the estimated annual income and
expenses for each program based on the level of experimental
practices used. The value of beef produced was based on the
state average price of feeder calves grading Good at Florida
auction markets in September 1972. The value of beef for culled
cows was based on the price of slaughter cows grading Commer-
cial in August 1972. Price of beef for calves was adjusted for
variations in market grade score of calves on each program.
Expenses included costs of maintaining pastures, supplemen-
tal feeds and minerals, breeding fees and other costs of main-
taining the cows. Charges for items purchased were those paid
by the Experimental Station for items used at the Beef Research
Unit during the 1971-72 season. Prices and costs rates used in
calculating income and expenses are shown in Table 17.

Table 17.-Prices and Cost Rates

Used in Calculating Income and


State average price for
feeder calves grading Good
in September, 1972
Price per program adjusted
for market score of
Program 1
Program 2
Program 3
Culled cows grading Commercial
in August, 1972

0-10-20 fertilizer

Spreading fertilizer

41 percent cottonseed meal
Blackstrap molasses
Corn silage
Special mineral mix


Price of beef





Maintenance operations

Feed and Minerals

Average Rate

$ 41.96






Cost of operating equipment
Annual cost of maintaining

Breeding fees
Labor on cattle
Veterinary, medicines
and insurance
Prorated annual replace-
ment cost of brood cow
Interest on investment in
Depreciation and repairs
on buildings and fences

Irrigation cost

per dollar invested

Other costs for cattle
animal unit
animal unit

animal unit
animal unit

animal unit

animal unit


10 percent





animal unit 3.50
animal unit 4.00

aBased on prices and costs rates used in summarizing data for the 1971-72
season, except adjusted for higher rates for certain other costs for cattle.
'Cost per ton spread on pastures.

Table 18.-Estimated Cost per Acre of Renovating Land and Seeding
Temporary Grazing.
Price per Rate per Cost per
Item Unit Unit Acre Acre
Florida 500 oats Bu. $ 2.15 2 $ 4.30
Kendland red clover Lb. .65 10 6.50
Noland white dutch clover Lb. 1.35 2 2.70
Rust resistant rye grass Lb. .22 15 3.30
8-8-8 fertilizer Cwt. 2.25 5 11.25
Ammonium nitrate Cwt. 4.40 1 4.40
Spreading fertilizer Cwt. .30 5 1.50
Applying top dressing Cwt. .45 1 .45
Breeding, disking and
breaking Acre 10.00 1 10.00
Total $44.40

Value of beef sold.-The value of beef sold was based on the
adjusted sale weight of beef produced from calves and culled
cows. The value of beef was calculated by multiplying the ad-
justed sales weight by the price per hundredweight for these
Fertilizer and lime.-The charge for fertilizer and lime was
calculated by multiplying the amounts applied by the prices paid
for these items. The cost of lime was prorated over a three-year
period. The per ton charge for lime included the cost of spread-
ing the material on the land.
Pasture maintenance.-Cost of spreading fertilizer was
charged on a per ton basis. Mowing was charged on a per hour
basis. In each case, the rate used was assumed to cover the cost
of labor, power, and use of equipment. Only those areas that
needed mowing were mowed each year. The per acre and per
cow charges for mowing was based on the total charge for
mowing divided by number of acres or cows assigned to a pro-
The expenses of pasture renovations and growing temporary
grazing crops are not included as a cost in the summary for Pro-
gram 2, since these practices were discontinued before the end
of Phase 3 of the experiment.1

1In the original plan of the experiment, one fourth of the pastures in Pro-
gram 2 were to be renovated each year. Temporary grazing crops were to
be seeded on the acres renovated. These practices were carried out in
1965-66 and 1966-67.

Table 19.-Average Income and Expenses per Acre and per Cow for Various Programs.
Per Acre Per Cow

Item Program Number Program Number
1 2a 3 1 2a 3

Sale of calf
Sale of culled cow
Cost of maintaining pastures:
0-10-20 fertilizer
Applying fertilizer
Operating costs
Fixed costs of equipment
Total direct costs
Investment charge
Total cost of main-
taining pastures
Feed and minerals:
Cottonseed meal
Blackstrap molasses
Corn silage


$ 6.26
$ 11.63


$ 6.26
$ 11.21


$ 8.27
$ 13.35

- $ 12.05
- 5.77

S 11.63

$ 11.21

$ 31.17

$ 15.70


$ 8.45
$ 15.70


$ 8.95
$ 16.03

- $ 15.06
- 7.21

$ 16.03

$ 28.99 $ 28.57 $ 48.53 $ 39.14 $ 40.85 $ 60.66

$ 4.99
$ 22.83

$ 4.71
$ 21.66

$ 5.39
$ 28.50

$ 6.74
$ 30.82

$ 6.74
$ 30.97


$ 10.34
$ 16.69

$ 38.96

$ 6.74
$ 35.62


Table 19.-Average Income and Expenses per Acre and per Cow for Various Programs. (Continued)

Per Acre Per Cow
Item Program Number Program Number
1 2a 3 1 2a 3

Other cost for cattle:
Breeding fees $ 6.67 $ 6.29 $ 7.20 $ 9.00 $ 9.00 $ 9.00
Labor on cattle 4.45 4.20 4.80 6.00 6.00 6.00
Vet., med., & ins. 2.78 2.62 3.00 3.75 3.75 3.75
Taxes 3.70 3.50 4.00 5.00 5.00 5.00
Prorated annual replacement
cost of brood cow $ 33.33 $ 31.47 $ 36.00 $ 45.00 $ 45.00 $ 45.00
Interest on investment
in cows 15.56 14.68 16.80 21.00 21.00 21.00
Depreciation & repairs on
buildings & fences 2.59 2.45 2.80 3.50 3.50 3.50
Other 2.96 2.80 3.20 4.00 4.00 4.00
Total $ 72.04 $ 68.01 $ 77.80 $ 97.25 $ 97.25 $ 97.25
Total expenses $123.86 $118.24 $154.83 $167.21 $169.07 $193.53
Less value of culled cow sold $ 26.53 $ 25.12 $ 28.50 $ 36.12 $ 36.12 $ 35.56
Net cost of beef produced
from calf $ 97.33 $ 93.12 $126.33 $131.09 $132.95 $157.97

Net returns $ 35.71 $ 30.27 $ 29.62 $ 48.12 $ 43.32 $ 37.08

aExpenses for Program 2 do not include cost of renovation and temporary grazing; i.e., expenses were based on post renovation per-
formance of program only.
eCost of lime is prorated on a yearly basis.

Land in temporary grazing was fertilized with an 8-8-8 fer-
tilizer at the rate of 500 pounds per acre. Temporary pastures
were top dressed with ammonium nitrate. The rate of applica-
tion was 200 pounds per acre in 1965-66 and 100 pounds per acre
in 1966-67. The estimated 1971-72 cost per acre of renovating
land and planting temporary grazing following practices used in
1966-67 is given in Table 18.
Cost of irrigation.-Cost of irrigation was charged on the
basis of the estimated cost of operating equipment to irrigate
200 acres. The 1971-72 cost of installing such equipment would
be about $24,000 or $120 per acre. It is estimated that the fixed
costs per acre of maintaining such equipment is 10 percent of
the investment cost. Operating cost per acre depends on hours
operated. Operating cost was calculated at 60 cents per hour.
Annual charge to cover cost of investment in establishing
pastures.-The investment charge was based on 7 % of the esti-
mated cost of establishing pastures including land, fencing,
watering equipment, corrals, and scales. The charge was made
to cover cost of capital invested in establishing the pastures. The
interest charge for irrigation equipment is included in the fixed
costs of operating the equipment.
Supplemental feeds and minerals.-The costs of these items
was calculated by multiplying the amount fed in 1971-72 as
shown in Table 15 by the prices in Table 17.
Other costs for cattle.-In the experiment, heifers for herd
replacement were not raised on the experimental pastures. To
obtain cost estimates that would approximate a commercial oper-
ation, charges were made on a per cow basis to cover estimated
costs of breeding fees, labor on cattle, veterinary services, medi-
cines and insurance, taxes, prorated annual replacement cost of
a brood cow, interest on investment in cows, depreciation 'on
buildings and fences, and other costs. Brood cows were valued
at $300 per head. A 71% rate of interest was used.

Annual Income and Expense

Total income from beef produced varied from $148.51 per
acre on Program 2 to $184.45 on Program 3 (Table 19). Income
per cow varied from $212.39 on Program 2 to $230.61 on Pro-
gram 3.
Total expenses per acre ranged from $118.24 on Program 2
to $154.83 on Program 3. Total expenses per cow varied from
$167.21 on Program 1 to 193.53 on Program 3. The net cost of

beef produced from calves after crediting the value of culled
cows sold was $97.33 per acre on Program 1, $93.12 on Program
2, and $126.33 on Program 3. Net returns per acre varied from
$35.71 on Program 1 to a low of $29.62 on Program 3.
The data are summarized in Table 20 and are expressed on
the basis of cost per acre, cost per cow, and gross cost per hun-
dredweight of beef sold from calves and culled cows. Total pas-
ture cost per acre varied from $28.57 on Program 2 to $48.53

Table 20.-Cost per Acre, Cost per Cow and Gross Cost per Hundred-
weight of Beef Sold from Calves and Culled Cows.


Fertilizer and lime"
Pasture maintenance
Cost of irrigation
Investment charge
Total pasture costs
Supplemental feeds and
Other costs for cows
Total costs

Fertilizer and lime"
Pasture maintenance
Cost of irrigation
Investment charge
Total pasture costs
Supplemental feeds and
Other costs for cows
Total costs

Fertilizer and lime"
Pasture maintenance
Cost of irrigation
Investment charge
Total pasture costs
Supplemental feeds and
Other costs for cows
Total costs

$ 9.66

$ 28.99

$ 22.83

$ 13.04

$ 39.14

$ 30.82

Program Number
Cost per acre
$ 9.66

$ 28.57

$ 21.66

Cost per cow
$ 13.82

$ 40.85

$ 30.97

Gross cost per hundredweight
$ 2.26 $ 2.42
.46 .39

4.05 4.35
$ 6.77 $ 7.16

$ 5.34
$ 28.94

$ 5.43
$ 29.63


$ 11.90
$ 48.53

$ 28.50

$ 14.88
$ 60.66

$ 35.62
of beef sold'
$ 2.51
$ 10.22

$ 6.00
$ 32.60

"Covers cost of spreading on pastures.
bBased on pounds of beef sold from calves and culled cows.

on Program 3. The cost per acre for irrigating pastures in Pro-
gram 3 was $17.82. The cost per cow for supplemental feeds and
minerals was $30.82 on Program 1 and $35.62 on Program 3.
Other costs of cows were calculated at $97.25 per cow for each
program. The gross cost per hundredweight for calf and culled
beef sold varied from $28.94 on Program 1 to $32.60 on Pro-
gram 3.

This experiment was designed to compare production perfor-
mances of beef cows on various forage programs, supplemental
feeds and management systems and to determine the relative
economics of each. The experimental data were supplemented
with data from other studies to show the approximate income
and expenses for the various programs if followed on a commer-
cial operation. The cost of establishing grass-clover pastures was
estimated to be $248 per acre. Brood cows were valued at $300
per head. The rate of interest charged was seven percent.
Net returns per acre varied from $35.71 on Program 1 to a
low of $29.62 on Program 3. The gross cost per hundredweight
of beef sold from calves and culled cows was $28.94 on Program
1, $29.63 on Program 2, and $32.60 on Program 3.

By Marvin Koger
A significant feature of this project was that it was a long-
term systems approach which yielded significant information
that had been, and possibly would have continued to be, over-
looked in short-term projects. Examples of unanticipated results
were (a) that clover thrived better under grazing than in plots,
(b) that fertilizer requirements for maintenance of clover pas-
tures under grazing were less than generally recommended, (c)
that clover pastures significantly improved reproductive perfor-
mance of cattle above what was obtained on grass pastures, (d)
that the tendency toward alternate year calving was more pro-
nounced in some breed groups than in others, and (e) that breed
groups ranked significantly different on different pasture pro-
Soil changes.-Organic matter content of the virgin soils
prior to establishment of pastures was 2.25% in 1951. In 1957
organic matter had increased to 3.04%7 and in 1964 to 3.82%
with further small increases in some locations through 1972.
This increase in organic matter resulted in higher cation ex-
change capacity and increased water-holding capacity of surface
Plant composition.-Since pastures were established on
virgin soils, nearly pure stands of grass and clover were achieved
initially. One-third of the area was planted to bahiagrass and
two-thirds to Pangola digitgrass. The bahiagrass persisted vir-
tually as a pure stand (except in a few low areas subject to
frequent flooding) for a period of approximately 12 years, after
which smutgrass encroached into the bahiagrass sod but at a
slower rate than into other grasses. Pangola established well and
produced heavily for two years, after which time the grass
began to die out in the more heavily fertilized pastures. In 1955
one-half of the Pangoladigitgrass was plowed up and replaced
by Coastal bermudagrass. The remaining Pangola was replaced
by Coastal bermuda in 1957-58 due to inability to maintain or
reestablish Pangola stands. Establishment of Coastal bermuda-
grass varied from good in a few areas to poor in others. Most
stands began to deteriorate within a year, being gradually re-
placed by bahiagrass, native grasses, and weeds. By the end of
phase 3 in 1972, smutgrass appeared to be increasing in density
at an accelerated rate.

Forage yields and carrying capacity.-Forage production
was estimated from caged clipping plots. While the procedure
does not duplicate harvesting of forage by cattle, and individual
plots are associated with a large sampling error, results from
adequate numbers of plots are a valuable tool in assessing levels
of forage production. Estimated oven-dry yields from clover-
grass pastures fertilized at the rate of 300 to 600 pounds of
0-10-20 annually were 7,963, 6,873, and 6,496 pounds, respec-
tively, for the three successive phases. These results indicate a
decline in production of 18%o associated with the loss of Pangola-
digitgrass, followed by a small decline thereafter.
Carrying capacity of the pastures for cattle was estimated
annually on the basis of previous experience in grazing the pro-
gram. The pastures were stocked accordingly at the beginning
of each breeding season. The assigned number of cattle remained
on the program until all of the grazable forage was utilized in
the fall. This method while subjective was successful in achieving
approximately uniform grazing pressure on all programs and
utilizing accumulated forage by approximately December 1.
Good clover production and cattle performance with minimal
wastage of feed were achieved by the procedure. On the above
basis, the number of acres required per cow (including calves
and sires) was 1.25 for phase 1, 1.39 for phase 2, and 1.35 for
phase 3. Thus, the two methods used for evaluating forage yields
were in general agreement that production declined with the loss
of Pangoladigitgrass from the pastures but remained relatively
constant during Phases 2 and 3. This would indicate that, while
seriously detracting from the appearance of pastures, the en-
croachment of smutgrass during Phase 3 had not seriously
affected forage yields by the end of the trial. This appears a
reasonable result, since smutgrass was grazed readily by the
cattle during spring months and apparently to some extent dur-
ing the fall. Some of the invaded areas should be continued under
grazing for a number of years. It may prove to be more practical
to graze a natural balance of stands including smutgrass than to
go to the expense of attempting periodic eradication.
Performance of cattle.-One of the most significant re-
sponses observed in the study was that an increase in annual
production per cow from 225 pounds in Phase 1 to 448 pounds
in Phase 3. The performance of typical foundation females re-
vealed a tendency to calve during alternate years. Demonstration
that this tendency could be alleviated through culling of non-
pregnant cows, cross-breeding, and use of good bulls, in com-

bination with showing the value of clover pastures, contributed
to a dramatic improvement in forage production, quality of man-
agement, and beef cattle production in Florida and throughout
the southeastern United States. The achievement of a 90% calf
crop and 500 pound calves at the research unit, along with other
projects at Ona and Belle Glade, had a demonstration value of
great impact on the beef cattle industry. Production levels of this
magnitude had been undreamed of in Florida during the early
1950's. In the planning stages of the project, even leading scien-
tists among reviewers held that the maximum calf crop attain-
able in Florida could not exceed 70% because of a semitropical
The genetic basis for the progressive improvement in animal
performance may be stated as follows. The foundation females
generally had low fertility (being alternate-year producers) and
poor growth rate but moderately good maternal ability. Their
first-generation crossbred progeny had good growth potential
(average genotypic value plus hybrid vigor), and thus, showed
a highly significant advantage over typical Brahman-native
calves. The first generation crossbred females had excellent ma-
ternal ability, good fertility, and intermediate breeding value
for growth. Their second-generation progeny had genes for good
growth rate from two top crosses of selected bulls and a high
level of hybrid vigor. This combined with excellent maternal
ability in the first-generation crossbred dams resulted in a sec-
ond striking improvement in weaning weights. Further improve-
ment in either maternal ability or growth potential would be ex-
pected to be slow with improvement derived only from additive
breeding value of sires for maternal ability, growth rate, and
adaptability to the area. The full potential for improvement
through hybrid vigor had been achieved in the second generation
crossbred calf nursing the first-generation crossbred dam. The
results realized during the remainder of the trial were in agree-
ment with these expectations.
Highly significant differences in size and growth rate were
obtained in cattle from the different breeding programs com-
pared. In total efficiency of production performance differences
were non-significant. The results from this trial differ from those
of other crossbreeding trials in that crossbreds were compared
with grades which descended from a crossbred foundation. For
the first two generations, animals in the upgrading systems were
similar both genotypically and phenotypically to the crossbreds.
Intense selection for fertility, maternal ability, and growth re-

sulted in surprisingly similar total performance in all groups
over a period of over 15 years. There were indications, however,
that the grade groups were gradually losing stature during the
last few years of the trial.

Over a period of 20 years, a total of 13 different pasture pro-
grams were compared. Variables considered were three grass
varieties, clover, native range, irrigation, fertilization rates,
renovation, and combinations of these factors. The different
pasture programs were evaluated by grazing with producing
cows and calves included in a comparison of five mating systems.
Caged clipping plots were used to estimate forage production.
Supplemental studies were made to assess both the accumulation
of organic matter and fertilizer nutrients and also the need for
annual application of N and K.
With proper liming of the soil and annual fertilization ex-
cellent clover-grass pastures were maintained in nearly a steady
state of production over the 20-year period. The most economical
level of fertilization for maintenance of these pastures was 300
pounds of 0-10-20 annually. This was the lowest rate tested.
The carrying capacity for cattle for all of the clover-grass
programs was approximately 1.3 acres per cow for grazing from
approximately March 1 to December 1. An additional 0.2 acre
was needed to produce corn silage for winter feed. Estimated
forage yields from caged plots and published dry matter require-
ments for producing cows and calves suggested that there was
little wastage of the pasture forage produced. The production
performance of cattle in the five mating systems compared
showed an annual production per cow during Phase 3 that was
99% above that of the native cattle from which they descended.
This increase apparently resulted mostly from hybrid vigor due
to crossbreeding and intense selection for fertility, growth rate,
and maternal ability. Differences between the five mating sys-
tems were highly significant for size and growth rate. Annual
production per unit of cow weight, however, varied only from
39% to 41%, suggesting no significant differences in total pro-
duction efficiency.
Economic analyses showed none of the all-grass programs to
be economical under the conditions of these trials. Clover-grass
programs fertilized at rates varying from 300 to 600 pounds of
0-10-20 annually showed positive net returns. Production costs
vary sharply with time, however. The physical inputs and pro-
duction responses reported herein should be considered in light
of prevailing costs in extrapolation of the results.

Institute of Food ad Agricultural Sciences


This public document was promulgated at an annual cost
of $3,011.50 or a cost of 40.1 cents per copy to report and
evaluate results from long-term study of pasture programs
and beef cattle breeding systems for beef production in
North Central Florida.

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