f~. UNIVERSITY OF
.F LOR IDA
Agricultural Experiment Station
Institute of Food and Agricultural Sciences
Range Cattle REC, Research Report RC-2004-3
Cattle and Forage
October 14, 2004
Range Cattle REC Field Day 2004
The University of Florida, Institute of Food and Agricultural Sciences (UF/IFAS)
extends a cordial welcome to all ranchers, forage producers and industry representatives
attending the 2004 Range Cattle Research and Education Center Field Day.
The importance of research and the extension of information is never more
evident than what has occurred during the five week period in August and September
2004 in which three major hurricanes made landfall on Florida shores. UF/IFAS has
evaluated and released grasses that perform well in wet areas. The importance of animal
identification and record keeping becomes most helpful in sorting out animal ownership
and herd make-up. The importance of developing and evaluating breeding seasons such
that calves are born, raised, weaned and marketed during periods least impacted by
summer and early fall hurricanes, and torrential rains common to south Florida.
It is the purpose of UF/IFAS to help Florida expand domestic and international
business, enhance natural resources, provide consumers with a wide variety of safe and
affordable food, support community development, maintain a sustainable food and fiber
system, conserve and improve environmental quality, and improve the quality of life.
It is the purpose of UF/IFAS to develop and distribute research information that
will keep Florida agriculture profitable and sustainable. The information presented at this
field day emphasizes this commitment.
Range Cattle REC Field Day -
Table of Contents
Sch ed ule of E vents .................. .... .. .......................... .... ........ .. ...............3
Cow and Calf Gains on Creeping Signalgrass and Bahiagrass
Rob Kalm bacher .................. .. .... .............................................. .
Effects of Liming and Nitrogen Fertilization on Bahiagrass Decline
M martin Adjei ............ .... ....... .... ................................ 13
Forage / Cow-Calf Production in Slash Pine Bahiagrass Silvopasture
Ike Ezenwa ..................................................................... ........... 19
Limpograss Options for South Florida Cattlemen: Stockpiled Forage, Hay,
and Round-Bale Silage
John A thing ton ................................................. .. .. ............. ................... 25
Influence of Management on Yield and Persistence of Rhizoma Peanut
on Flatwood Soils
Paul M islevy ................................................... ........ ....... ......... 30
- Range Cattle REC Field Day -
Schedule of Events
Registration and Coffee
Welcome Findlay Pate
Extension / Research Interface: Where the Rubber Meets the
UF / IFAS, Range Cattle REC Importance to Florida's Cattle
Cow and Calf Gains on Creeping Signalgrass and Bahiagrass
Effects of Liming and Nitrogen Fertilization on Bahiagrass
Forage / Cow-Calf Production in Slash Pine Bahiagrass
Limpograss Options for South Florida Cattlemen: Stockpiled
Forage, Hay, and Round-Bale Silage
Influence of Management on Yield and Persistence of Rhizoma
Peanut on Flatwood Soils
COW AND CALF GAINS ON CREEPING SIGNALGRASS AND BAHIAGRASS
R.S. Kalmbacher, J.D. Arthington, and F.M. Pate
The Florida cow-calf industry has historically been based on relatively large
pastures with minimal input. While several perennial grasses are commonly grown in
pasture, bahiagrass fits well in a system of extensive management and is the major
perennial pasture grass with 2.5 million acres state-wide. However, the loss of almost
100,000 acres of bahiagrass in the mid-1990s to tawny mole cricket highlighted the need
to identify other grasses with qualities similar to bahiagrass.
Brachiaria grasses have greatly increased the productivity of grazing lands on the
infertile, acid soils that cover up to 170 million acres in Brazil. They are high-yielding
grasses with reasonable nutritive value. Creeping signalgrass (Urochloa humidicola, syn.
Brachiaria humidicola ), a highly stoloniferous species, is sown on about 3% of that area
where low soil fertility, imperfect drainage, and extensive management predominate. It
shares many of the desirable characteristics of bahiagrass: produces moderate yield with
low soil fertility, establishes from seed, and persists with frequent, close grazing.
Although creeping signalgrass does not tolerate the wide range of soil conditions and
temperatures that bahiagrass does, it is adapted to the wet, infertile soils of the warmer
central and south Florida, where the majority of the state's cattle are produced.
Creeping signalgrass was tested in clipping and mob-grazing trials at the Range
Cattle Research and Education Center (REC) and further south at the Immokalee REC.
However, there has been no measurement of livestock production on creeping
METHODS AND MATERIALS
In June 1998, three of six, 5-acre pastures were randomly selected and sown to
either creeping signalgrass (Naterra Seed Co., Brazil) or Pensacola bahiagrass at 10 and
20 lb seed/acre, respectively. During the trial, grasses were fertilized once annually with
50 lb N/acre in the spring. Beginning in May 2000 to May 2003, each pasture was
stocked with five, pregnant Brangus cows and their calves (1 cow-calf pair/acre). Cattle
were rotated weekly among four, 1.25 acre paddocks in each of the six, 5-acre pastures
from May to October.
Cows and calves were weighed the first week of August when calves were
weaned and removed. Each group of five cows returned to their previously assigned
pastures where they remained until the end of October when they were weighed again.
Calf weights were adjusted for sex and mean age at the respective weigh dates.
At May, August, and October weigh dates, cows received a body condition score (BCS).
Scores were visual evaluations based on a range of 1 to 9 with 1 = very thin cows and 9 =
very fat cows.
Forage production was determined every 28 d from May to October and available
forage was measured weekly from May to October on the day cattle were rotated into
successive 1.25 acre paddocks. Hand-plucked samples of grass, which simulated what
cattle were eating, were taken for crude protein and in vitro dry matter digestion
Rainfall during the grazing season and temperature in the winter preceding each
grazing season varied widely over the 4 yr (Table 1). The driest year on record (62 yr) at
the Range Cattle REC was 2000, which was preceded by a relatively warm winter. In
contrast, May to October 2001 was the wettest of the 4 yr, and it was preceded by a very
cold winter. There were 17 instances of frost from 22 Nov. 2000 to 19 Apr. 2001 with a
minimum 230 F, and signalgrass was severely injured. The remaining 2002 and 2003
had more rainfall than that of the 62-yr mean with winter temperatures similar to the
Table 1. Rainfall in the May to October grazing periods, and number of incidences
of frost and minimum temperatures in the November-April period before each
Year May June July Aug. Sept. Oct. Total Frostt Minimum*
------------------------- inches ---------------------- -- no.-- --F--
2000 0.05 3.78 4.50 5.25 8.03 2.23 23.84 3 30
2001 1.30 10.58 14.26 10.11 17.76 2.38 56.39 17 23
2002 1.28 13.85 11.05 12.25 5.46 3.14 47.03 7 28
2003 5.36 15.80 4.51 10.09 11.04 1.14 47.94 6 28
62-yr 3.71 8.58 8.51 8.10 7.34 3.10 39.34 8.9 27
SNumber of instances.
$ Minimum temperature recorded in each of 4 yr compared with the mean annual
minimum temperature over 62 yr.
At weaning in August, cow weight and BCS tended to be greater on creeping
signalgrass compared with bahiagrass pastures (Table 2). At the end of grazing in
October, cow weight depended on both grass and year (Table 2). For creeping
signalgrass, cow weight in October was affected by year while there were no year effects
for final cow weights on bahiagrass. With the exception of 2001 when the grazing season
was shortened to allow creeping signalgrass recovery after the freeze, cows from
signalgrass pastures weighed more than cows from bahiagrass. Cows grazing creeping
signalgrass had higher BCS in October compared with cows grazing bahiagrass (Table
At weaning in August, calf weights and average daily gain (ADG) tended to be
greater on signalgrass than bahiagrass (Table 2). Mean age of calves at weaning was
261, 262, 267, and 273 days for 2000 to 2003, respectively. Average daily gain from
May to August was affected by year with the ranking: 2000 = 2002 > 2001 = 2003. Note
that 2000 was the driest year (Table 1).
Table 2. Effect of grass pasture on various cow and calf responses. 4-year means.
Cow weight, May (lb)
Body condition*, May
Cow weight, August (weaning) (lb)
Body condition*, August
Cow weightO, October (lb)
Body condition*, October
Calf weight May (lb)
Calf weight#, August (weaning) (lb)
Calf average daily gain (lb/day)
t Probability of a difference between grasses.
* Body condition score 1= very thin cows, 9= very fat cows.
Grass x year interaction (P=0.01). Within grasses, means over years followed by the
same letter are not different (P>0.05, LSD).
# Adjusted for sex and mean age.
Forage Production and Available Forage
Bahiagrass forage production exceeded that of signalgrass from May to June, but
the reverse was true for July to October (Fig. la). The greatest incremental increase in
production for creeping signalgrass was 2700 lb DM/acre which occurred between June
(1220 lb DM/acre) and July (3920 lb DM/acre). Much of this was from stems and seed
heads. The comparable increase in accumulation for bahiagrass was 1100 lb DM/acre.
Between August and October, month to month production was similar between grasses.
Annual production was greater for creeping signalgrass (8740 lb DM/acre) than bahiagrass
(7520 lb DM/acre).
Available forage was similar for grasses in May and June, but for July through
October, there was more available forage in creeping signalgrass than bahiagrass pastures
(Fig. lb). After July, much of the forage from creeping signalgrass was stem which
formed a residual stubble layer. During the 1-wk grazing periods, cattle ate mostly leaves
that had regrown on the stubble layer during the 21-d rest periods.
Crude protein in bahiagrass was 11% in May, and it increased above 12% in June
followed by a decline to < 10% in September (Fig. 2a). There was a trend for crude
protein in bahiagrass to increase in October. Crude protein in creeping signalgrass was
always significantly lower than that in bahiagrass. Crude protein in creeping signalgrass
was highest in June (11%) and lowest in September (< 8%).
Creeping signalgrass IVOMD was always greater than that of bahiagrass (Fig.
2b). Greatest IVOMD for creeping signalgrass was 57% in June and lowest IVOMD
was to 53% in October. Bahiagrass IVOMD reached a maximum of 50% in July, then
declined to 45% in October.
Ground Cover and Insects
Following the 2001winter freeze, signalgrass live-plant cover in April averaged
52%. By late-June 2001, creeping signalgrass ground cover had increased to 85%.
Except for the freeze, signalgrass maintained relatively good ground cover throughout the
trial. Bahiagrass was the major weed in creeping signalgrass pastures followed by
common bermudagrass. Weed presence was more obvious in dry spring months, but
following rain in June and the resumption of creeping signalgrass growth, weeds
contributed essentially nothing to available forage.
Spittlebug larvae and their spittle masses were found from June to October on
creeping signalgrass. Their occurrence was patchy, and populations varied with year. No
insects pests were noted above ground on bahiagrass, but mole crickets were found in
traps in pastures of both grasses.
The comparatively good weight gains of cows grazing signalgrass in the 3-month
period after weaning is important because of the need for cows to regain body condition
prior to calving, which can be difficult to achieve on bahiagrass in late summer. Body
condition at calving is the determining factor influencing return to estrus and pregnancy
in beef cows. Abundant rain coupled with mature bahiagrass tend to lower cow-weight
gain in late summer and early fall. Creeping signalgrass, a low-input grass on a par with
bahiagrass, may have an advantage over the less nutritious bahiagrass and the more
nutritious grasses requiring costly management.
Mean calf weaning weights from creeping signalgrass were not substantially
greater than bahiagrass. The difference between grasses was minimized because of the
relatively short time calves were on trial. Also, a nursing calf is buffered by milk from
the cow, so nutritional aspects of pasture prior to weaning may affect cows more than
The difference in calf ADG between grasses for the period these calves were on
trial favors creeping signalgrass. Provided cows are in good body condition (BCS > 5),
which signalgrass cows were in August, fall-calving cows could nurse calves for an
additional 2 months beyond the standard weaning age of 7 to 8 months. In years when
calf prices are high, keeping cows and calves on creeping signalgrass for an additional 60
days could be profitable. This assumes calf ADG would continue at the same rate after
early August, however the decline in protein in creeping signalgrass could limit calf
growth in August to September. Also, calf ADG may be lower in years with high
Annual production on both grasses was abundant, but there were problems with
rate and time of growth and the composition of grass growth. In one of the early
publications from the Range Cattle Station, Dr. Elver Hodges declared that the major
problem with bahiagrass as 'inefficient use of the rapidly-maturing forage'. In this
regard, creeping signalgrass intensifies the rate and timing problem because 30% of
annual growth came in a 30-day period beginning with the start of summer rain. Much of
this is low-quality reproductive growth that is difficult to utilize under grazing. A stiff,
residual, straw-like stubble-layer formed by August, and remained for the duration of the
To utilize the flush of growth, stocking density on creeping signalgrass should be
temporarily increased at the start of the rainy season. Bahiagrass also has a variable
growth rate that creates a problem with proper grazing management, but cattlemen can
overlook it. However, it is not likely that creeping signalgrass will meet rancher
expectations with set-stocked pastures. Where signalgrass is in commercial use, such as
at Deseret Cattle & Citrus, underutilization of early summer growth is a major problem.
While neither grass is really productive in April and May, bahiagrass has an
advantage with about 12-18% of annual production in these months. Bahiagrass will
respond to a little rain, but signalgrass is essentially nonproductive in April and early
Persistence and Adaptability
The greatest impediment to signalgrass persistence will be cold. Based on 62-yr
means at the Range Cattle REC, the 23 F freeze we experienced in 2001 has occurred in
lof 6 yr. While a winter freeze may not eliminate creeping signalgrass due to the strong
stoloniferous habit of growth, cold will render a pasture unproductive and open to weed
growth until mid-summer. The first pasture sown to signalgrass was 300 acres at Deseret
in 1996, and that pasture has persisted for 8 yr. We suggest that planting of creeping
signalgrass pasture be restricted to the Florida peninsula south of Orlando.
While signalgrass is noted to be tolerant of intermittent flooding, we found it had
little more tolerance of flooding than bahiagrass. Signalgrass did not grow in ditches and
depressions where water (2 inches) remained for several weeks. Signalgrass is not
adapted to dry sites.
Spittlebugs could almost always be found somewhere in signalgrass pastures
throughout the rainy season. While signalgrass is tolerant, it is not resistant to
spittlebugs. The possibility remains that spittlebug could weaken signalgrass pasture just
as it does for limpograss pasture in central Florida.
Although creeping signalgrass has nutritional advantages over bahiagrass, lack of
cold tolerance, limited growth prior to June, and excessive growth in July are the main
problems that render signalgrass inferior to bahiagrass. Creeping signalgrass could be a
valuable part of a bahiagrass-based pasture program on ranches south of Orlando because
signalgrass can provide for greater cow weight gain between weaning and calving. It
offers the possibility of providing good grazing for fall-calving cows nursing calves for
up to 2 months beyond the standard weaning age of 7 to 8 months of age.
Fig. 1. (a) Cumulative forage production of creeping signalgrass and bahiagrass and
(b) Available forage. Means of 2000-2003.
May June July August September October
- -" Bahiagrass
May June July August September October
May June July August September October
Fig. 2. Nutritive value of creeping signalgrass and bahiagrass (a)
Crude protein and (b) In vitro organic matter digestibility (IVOMD).
Means of 2000-2003.
July August September October
May June July August September October
: A %%%% /
July August September October
- -v Bahiagrass
EFFECTS OF LIMING AND NITROGEN FERTILIZATION
ON BAHIAGRASS DECLINE
Martin B. Adjei
Bahiagrass decline, a major problem with our premier pasture grass, usually
begins with yellowing of pasture in small or big patches. Later, affected areas turn brown
and die and are normally associated with the borrowing and tunneling activity of mole
crickets. On damaged areas with high mole cricket population, the surface 6 to 10 inches
of soil layer is honeycombed with numerous mole cricket galleries and the ground feels
spongy when stepped on. Severely damaged pasture has virtually no root system and is
easily pulled from the soil by cattle or foot traffic in a pasture. Research and surveys
conducted throughout south central Florida implicate pasture and grazing management
factors in mole cricket induced bahiagrass decline.
Soil acidity (pH): Soil acidity refers to the concentration of active hydrogen
ions (H ) in the soil. It is measured by an index called pH. The lower the pH, the more
active hydrogen ions are present and the more acid the system. A pH of 7 (as is the case
for distilled water) is neutral (H+ = OH-), and for soil, a pH of 7 is too high for most
forages grown in Florida. A pH of 5 to 6 is slightly acidic and satisfactory for most
Florida forages to grow. A pH of 4 is too low or very acid and will result in poor root
growth or function of most Florida forages.
Nitrogen (N) Fertilization: Soil acidity tends to increase with repeated use of N
fertilization, and liming with calcium or calcium/magnesium compounds capable of
reducing soil acidity becomes necessary. For example, it requires 60 pounds (lb) of lime
to neutralize the acidity from 100 lb of ammonium nitrate and 110 lb of lime to neutralize
the acidity from 100 lb of ammonium sulfate. Increasing soil acidity to pH less than 5
can reduce the availability of boron, molybdenum and sulfur in the soil, reduce pasture
production by more than a third, regardless of N fertilization, and predispose grass to
yellowing and damage by soil-born insects.
In one of our multi-county trials, the Range Cattle Research and Education Center
decided to evaluate the long-term combined effect of liming and N-fertilization on
bahiagrass pasture performance. We applied three types of fertilizer and a control (no
fertilizer) annually to portions of bahiagrass pasture that were either limed to maintain a
pH of 5.0 or not limed at a pH of about 4.3. The four fertilizer treatments applied every
spring from 1998 to present were: 1) 60 lb/A of N from ammonium sulfate (N), 2) 60-25-
60 lb/A of N-P205-K20 from ammonium sulfate, triple super phosphate and muriate of
potash (NPK), 3) 60-25-60 lb/A of N-P205-K20 plus 20 lb/A of a Frit Industries Inc.
micro-nutrients mix which contained B, Cu, Mo, Fe, Mn, Mo and Zn (NPKM), 4) no
fertilizer control (Cont.). About a ton of lime was applied every two to three years to
maintain a pH of 5 on limed areas. Bahiagrass performance was measured by dry matter
yield, crude protein content, forage digestibility, and condition of bahiagrass ground
cover in spring.
Dry Matter Yield
Effect of Lime
On one of the pastures at Ona (pasture 71A) and in Pasco and Manatee sites,
forage yield was not affected by liming to a pH of 5 throughout the 3-5 years (Fig. 1).
The no-lime plots at these sites retained a pH of about 4.5 for the entire period. However,
lime treatment increased bahiagrass forage yield by 24% across all fertilizer treatments
on pasture 87 at Ona where the no-lime, fertilized plots showed a pH decline to about 4.3
Effect of fertilizer
Yield increase from fertilizer application compared with non-fertilized control
ranged from 18% on the Manatee site to 31% on the Pasco site with the Ona (Hardee)
sites in the middle. However, we hardly noticed any clear differences in forage yield
among the N, NPK and NPKM fertilizer treatments on the two Hardee pastures and on
the Manatee pasture (Fig. 1). On the other hand, forage DM yield increased by 10%
when the NPK and NPKM treatments were applied compared with the N only treatment
on the deep sandy soil at the Pasco site.
Lime application had little to no effect on seasonal average crude protein content
or digestibility (IVOMD) of bahiagrass forage but seasonal crude protein content
increased by about 2% units (12% vs. 10%) with the application of any fertilizer
containing N. This protein enhancement attribute of N was greater immediately after N
application in spring and diminished with time through the season. Forage IVOMD for
the no-fertilizer control was always among the lowest (47%) although improvement with
N application varied from site to site.
Spring Vegetative Ground Cover
Effect of lime and Fertilizer
At the beginning of grazing in spring of 1998, all the newly established bahiagrass
plots at Ona had an excellent stand of nearly 100% green ground cover (Fig. 2). Two
years later (2000), color of bahiagrass ground cover on plots started to sort out into lime
vs. no-lime sections, where all limed plots were completely green in the spring but the
color of no-lime plots depended on fertilizer treatment. This interaction between lime
and fertilizer treatment became even more pronounced with passage of time. In 2002,
five years into the experiment, minimum spring color change or damage to bahiagrass
sward (1-4% ground cover) was noticed for plots limed to pH 5 whether or not they
received fertilizer or for no-lime plots that were not fertilized on both Hardee sites (Fig
2). Damage was most severe (20-69% of ground cover) when bahiagrass was not limed
but received yearly application of any N-containing fertilizer. The combination of acid
soil conditions (pH less than 4.5) and repeated N fertilization seemed to weaken
bahiagrass root-stolon system, cause severe yellowing in the early spring growth and
made it easier for mole cricket damage to occur.
Effect of Sludge:
Some livestock producers apply lime-stabilized sludge to pastures to reduce the
cost of fertilizer and lime. Lime is added in the processing of sludge primarily to control
pathogens, insect vectors and odor which makes limed-sludge an excellent source of
slow-release plant nutrients (especially N and P), organic matter and lime. During
application, the pH of limed-sludge could range between 7 and 11, N content between 3%
and 5% of dry sludge and P content between 2% and 4% of dry sludge. Four years
repeated application of limed-sludge at the Range Cattle REC, Ona has shown that, when
used at recommended agronomic rate (200 lb N/A), bahiagrass forage production
responds well to sludge organic fertilizer and there is no damage to the sward. In those
studies, we applied sludge up to 160 lb N yearly and improved annual dry matter yield
from 2 T/A where no sludge was applied to 5 T/A. There was no excessive build up of
plant nutrients or trace metals in the soil from sludge application and soil pH only
increased from 5.0 to 5.3 in 4 years. However, bahiagrass roots cannot function
properly to absorb sufficient iron, manganese and other micronutrients when the soil pH
approaches 7. Several bahiagrass pastures in Polk, Pasco and Hardee counties where
excessive amounts of sludge were applied repeatedly attained a soil pH of about 7 and
lost substantial portions of the grass stand to weeds similar to symptoms of bahiagrass
decline. It was easy to identify the strips on those pastures where sludge was dumped.
Under grazing conditions in south-central Florida, bahiagrass forage DM yield
and crude protein content on typical flatwoods soils improve substantially with N but not
with P or K fertilizer application. The situation may be different on the deep sandy soils
where the addition of some P and K to N fertilizer could make a difference. Repeated N
fertilization without adequate lime application to bahiagrass pastures induces widespread
early spring yellowing and eventual stand loss to weeds. In acid soil situations, you are
better off first liming to raise the soil pH to 5 or greater before applying N fertilizer. As
precautions to using limed-sludge, apply material uniformly over pasture at
recommended agronomic rate, monitor the soil pH every 2-3 years, and alternate limed-
sludge use with inorganic N-fertilizer such as ammonium sulfate or nitrate in order to
stay within the optimum pH range of 5.0 to 6.0.
Figure 1. The effect of fertilizer and lime application on bahiagrass forage
production in south central Florida. Bars represent 3-yr means for Manatee
and Pasco sites and 5-yr means for Hardee sites.
Hardee (71A) Manatee Pasco
a aaZ N
-z ^ NPK
a 1 NPKM
-.. / ..v \
ab b b2525 N
_c r Cont
b b a
(A) Hardee 71A N
120 Z77 NPK
> 110- Cont
o0 ns ns ns
C 100- n a a n
0 90 b b
) cc | b_
All No lime Lime No lime Lime
1998 2000 2002
130 (B) Hardee 87
120 ZZZ NPK
o ns ns Cont
S100 -a a
0- c |C
All No lime Lime No lime Lime
1998 2000 2002
Figure 2. The interaction between fertilizer, lime and year on percentage spring live,
green bahiagrass ground cover (damage consisted of yellow, brown and weedy cover).
FORAGE/COW-CALF PRODUCTION IN SLASH PINE-BAHIAGRASS
Grazing of cattle under pines is an age-long tradition in Florida. Under the old
practice of forest grazing, cattle ate native grasses, forbs, shrubs and other vegetation.
With high cost of land, taxes, and increased production costs, cattlemen are forced to
consider new ways of increasing returns from their ranches. In this regard, silvopasture is
promising. Silvopasture is a form of agroforestry in which cattle graze sown pastures
under planted trees. Greater return from silvopasture could result from diversification as
well as intensification of operations on the land. In addition to beef and forage,
silvopasture will also yield timber, pine straw, and hunting leases. Thus, overall
profitability of silvopasture may be superior to open pasture. There are also
environmental benefits of improvement of water quality, soil conservation, and wildlife
habitat that are more difficult to quantify in economic terms.
Silvopasture is more complex than open pasture. Successful management
demands a good understanding of the interacting components. Forage yields are not
significantly depressed by trees the first 10 years after tree planting or in areas that are
more than 7 ft from the nearest tree row. Ten to 15 years after planting the tree crowns
close and forage yields decline. During this period, tree thinning is desirable, depending
on site productivity, target product, and landowner objectives. The double-row
configuration in which trees are planted in double rows spaced 8 ft apart with 4 ft within
the rows, and 40 ft between double-rows addresses deficiencies of square and rectangular
planting patterns in traditional forestry. The double-row configuration maintains the same
tree density and timber volume as traditional configurations, but the wider alley between
the tree rows maintains open areas for grazing and easier access for application of
Many silvopasture studies in the Southeast were conducted on soils with better
production potentials than the sandy acid soils of south and central Florida. Whereas
some locations in the southeast produce better quality timber, and are closer to the mills
and timber markets, south and central Florida are in a unique circumstance as cattle are a
more important component of silvopasture than timber. There is a lack of information on
cattle productivity in silvopasture, and the dynamics of forage production in the system
under grazing. The objectives of our study were to determine cattle and forage production
in a pine-bahiagrass silvopasture at a critical stage of tree growth (10 to 15 years after
tree establishment) and the beneficial effects of thinning tree stands when herbage yields
are expected to begin to decline due to tree canopy closure.
The study was conducted on a 40-acre pine-bahiagrass silvopasture (pasture 48) at
Ona. The trees were established in December 1991 on an 11-year-old 'Pensacola'
bahiagrass pasture at the density of 454 trees/acre in the 4 ft x 8 ft x 40 ft, double-row
configuration. The silvopasture was sown to 'Florida' carpon desmodium (Desmodium
heterocarpon) in 1994 and 'Shaw' vigna (Vignaparkeri) in 2001. By 2002, tree survival
was 44% or 200 trees/acre after 9 years of grazing. To quantify cow-calf production and
the effect of thinning of tree stands, we cross-fenced the 40-acre pine-bahiagrass
silvopasture into two 20-acre blocks. In the winter of 2002-2003, about 75 inferior
trees/acre were cut and removed from one 20-acre block (thinned) leaving about 125
merchantable trees/acre. The remaining 20-acre block (unthinned) contained an average
of 200 trees/acre. A 20-acre open pasture (pasture 53 W), also of Pensacola bahiagrass (>
20-year-old) with Florida carpon desmodium and Shaw vigna served as a control. All
pastures were fertilized in March with 300 lb/acre of a 16-4-16 fertilizer. All pastures
were grazed similarly from March to May 2003.
On 1 June 2003, Braford cows (4-12 years of age) and calves (avg. 112 days of
age) were assigned at 1 cow-calf pair/acre to each of the three pastures. Before the cows
and calves were placed on the pastures, they were weighed and given a body condition
score (BCS). Weights and cow BCS were again obtained in September when cows were
removed from pasture and calves were weaned. Calf weights were adjusted for sex and
mean age at weaning. Cows had free-choice access to a loose mineral mixture year-
Forage production was measured every 42 days during the grazing period.
Available forage was determined every 28 days by harvesting forage from a strip of grass
from center of alleys to between double-tree rows in each silvopasture and at random in
Forage Production and Available Forage
Forage production was greater in open pasture (9090 lb dry matter (DM)/acre)
than in the two silvopastures which were not different (avg. = 6685 lb DM/acre) (Table
1). The trends in forage production during the grazing period differed among the
pastures. In the two silvopastures, production declined linearly, while in open pasture
forage production increased from 27 May to 21 July, then declined through 29
September. On average, more forage was available in the open pasture (2000 lb DM/acre)
than in silvopastures (avg. 1220 lb DM/acre) (Table 1).
Table 1. Total forage dry matter production and average available forage (28-days)
on bahiagrass-slash pine silvopasture and open bahiagrass pasture (no
pines). Pastures were stocked with 1 cow-calf pair/acre from 1 June to 15
Pasture Production Available
---------- lb (DM)/acre -----------
Thinned (125 trees/acre) 6270 bt 1230 b
Unthinned (200 trees/acre) 7100 b 1210 b
Open (no trees) 9090 a 2000 a
t Means in columns followed by the same letter are not different (P > 0.05).
SFor the period 27 May to 29 Sept. 2003.
Means of four, 28-day periods from 27 May to 15 Sept. 2003.
Cow weights and BCS
There were no differences among pastures for cow weights and BCS at the start of
the grazing period on 1 June, but at the end, on 15 September all pastures were different
from each other for both responses (Table 2). On average, cow weight in the thinned
silvopasture decreased from 1096 to 884 lb, from 1150 to 975 lb in unthinned
silvopasture, and from 1120 to 1074 lb in open pasture. Body condition scores of the
cows decreased 0.3, 1.2, and 1.5 units for cows in open, unthinned, and thinned pastures,
respectively. More rainfall was received over the 1 June to 15 September period (36 in)
than the 62-year mean (28 in) for this period. In June, pastures were saturated with
frequent periods (1-2 week) of standing water (- 1 in).
Table 2. Cow and calf weights and cow body condition scores (BCS) on bahiagrass-
slash pine silvopasture and open bahiagrass pasture (no pines) from 1 June
(start) to 15 Sept. (end) 2003.
Thinnedt Unthinned; Open pasture
Cow weight at start (lb) 1096 a 1150 a 1120 a
Cow weight at end (lb) 884 c 975 b 1074 a
Cow BCS at start 5.0 a 5.2 a 5.2 a
Cow BCS at end 3.5 c 4.0 b 4.9 a
Calf weight at start (lb) 315 a 317 a 326 a
Calf weight at end, weaning (lb) 392 b 396 b 466 a
Avg. daily gain (lb/day) 1.6 b 1.6 b 2.9 a
t 125 trees/acre.
Means in a row followed by the same letter are not different (P > 0.05).
Calf weights and daily gains
Pastures were not different for calf weight at the start (1 June, 2003), but at
weaning (15 Sept. 2003), calf weight was greater on open pasture (466 lb) than that of
calves on thinned (392 lb) and not-thinned (396 lb) silvopastures, which were not
different. Calf average daily gain was also greater on open pasture with 2.9 lb/day than
on the silvopastures with an average of 1.6 lb/day.
Calf weaning weight on the 12-year old silvopasture was 15% lower and cow
weight loss was 4 times more than that on open pasture. These represented drastic
reductions in livestock production compared with production when the trees were
younger. Between March and October 1994 to 1997, when pines were 3 to 7- years old,
Drs. Findlay Pate and Rob Kalmbacher measured calf weaning weights on this
silvopasture. Stocked at 1 cow-calf pair/acre, the 4-year average weaning weight of
calves was 451 lb, which is similar to that of open pasture in the present study. The
marked reduction in cattle performance in the silvopasture over the years can be
attributed to reduced forage production due to increasing tree growth so that animal
demand exceeded the ability of the silvopasture to supply forage. In general, lower forage
yields of bahiagrass are obtained under pines than when bahiagrass is grown in open
Thinning pines did not increase forage production or animal output. It is possible
that more thinning is required at this stage to further reduce the impact of the trees on
forage production. Perhaps, in our region, it may be best to target production of fence
posts or pulpwood, which would mean shorter rotations of 10-15 years, coinciding with
the period when trees reduce forage production the most. In this way, trees are harvested
for target products and reduction in livestock production is curtailed. The rotation may
then be repeated.
If silvopasture is to be an economically viable management option for land
owners in central Florida, then increasing value of timber beyond 12 year of age and
income from other sources, such as sale of hunting leases, must offset declining returns
LIMPOGRASS OPTIONS FOR SOUTH FLORIDA CATTLEMEN:
STOCKPILED FORAGE, HAY, AND ROUND-BALE SILAGE
John Arthington and Findlay Pate
Limpograss (Hemarthria altissima) is the second most utilized pasture forage in
south Florida. Over the past 30 years, south Florida Cattlemen have benefited from the
high dry matter yields, appreciable digestibility, and persistence of limpograss. One
important production characteristic of limpograss relates to its superior winter yield,
compared to other warm-season perennial grasses. In south Florida, limpograss can be
expected to produce as much as 30 to 40 % of its annual growth in the winter months.
This unique quality differs from most all other sub-tropical, perennial forages.
At the Range Cattle Research and Education Center (RCREC), we have
completed three complete production years investigating the performance of cow-calf
pairs grazing winter stockpiled limpograss. Two treatments were compared; 1) 0.75
acres of limpograss and 1.50 acres of bahiagrass per cow-calf pair, or 2) 1.80 acres of
bahiagrass per cow-calf pair with supplemental winter hay. All pastures were spring
fertilized with 60 pounds N per acre. Limpograss pastures received an additional fall
application of fertilizer (60 pounds N per acre). During September, October, and
November, cows assigned to the bahiagrass/limpograss combination treatment were
grazed primarily on bahiagrass alone allowing the limpograss to stockpile for winter
utilization. Cows assigned to the bahiagrass only treatment were provided adequate
winter hay to support an average body condition score of 5.0 (moderate condition). Cows
assigned to the winter stockpiled limpograss received no supplemental winter hay. All
cows were provided five pounds of supplemental molasses (16% crude protein) daily
from November 1 to mid-April. A 90-day breeding season was initiated on January 1.
In this study, cows grazing winter limpograss pastures were provided with no
winter hay; however, cows grazing the bahiagrass pastures consumed an average of 1400
pounds of hay per cow during each winter season (January to late March). Cows
assigned to the stockpiled limpograss pastures experienced a slightly greater loss of body
weight during the winter months, but a greater gain in body weight during the summer
months, compared to cows grazing bahiagrass pastures and winter hay (Table 1).
Grazing treatment had no effect on calf weaning weight (average weaning weight
= 547 pounds; SEM = 8.2). Pregnancy rates were also not affected by grazing treatment
(average over all three years = 92.2 and 91.6 % for cows grazing bahiagrass and
bahiagrass/limpograss pastures, respectively).
Table 1. Effect of pasture forage treatment on cow body weight change
during the winter and summer seasons.
Season Bahiagrass + Hay Stockpiled Limpograss SEM
------------------------ pounds ------------------------
Winter -88 -115 14.7
Summer 47 65 12.7
aSeasons extend from October to April and April to August for winter and summer,
This initial 3-year study suggests that 0.75 acres of stockpiled limpograss can be
substituted for approximately 1400 pounds of stored hay for wintering lactating beef
cows. Considering an average hay cost of $70 per ton along with a standard wastage of
15%, the value of this stockpiled limpograss would be approximately $110 per acre.
Considering these values, stockpiled limpograss may or may not be economically
advantageous for south Florida cattlemen. An economic analysis of both pasture systems
is appropriate for each individual ranch. Calving seasons that differ from those used in
this study may have a significant impact on the value achieved from the limpograss. As
well, persistence of stand will greatly impact economic return, as the high-cost of
establishment is spread over greater or fewer production seasons.
The current study only investigated the use of limpograss as a winter stockpiled
forage source. Although 30 to 40% of the annual growth of limpograss occurs during the
winter months, the remainder is realized during the summer. The greatest portion of this
summer growth occurs at a time when producers have adequate available forage on
bahiagrass pastures. Realizing opportunities for further utilization of limpograss during
the late spring and summer may increase the overall value of this forage resource.
Current Limpograss Evaluations for Cow-Calf Production in South Florida
Using the same limpograss establishment utilized in the 3-year study described
above, we are now investigating the value of harvesting late spring hay followed by mid-
summer round-bale silage. In this system, we will continue to allow for fall accumulation
for winter stockpiled grazing.
In the first year (spring 2004), we fertilized 60 acres of limpograss on March 23
(20-5-10; 400 pounds per acre). Eight weeks later, the pastures were cut and hay
harvested. A total of 97 tons of hay dry matter was harvested (1.6 tons dry matter per
acre). The average total digestible nutrients (TDN) and crude protein of this hay was 51
and 9%, respectively, on a dry matter basis.
Limpograss contains long thick stems, requiring as many as 5 to 7 days of drying
to achieve > 85% dry matter for hay harvest. Once the rainy season begins, we have less
than a 20% probability of obtaining 3 consecutive drying days (mid-June through
August) for hay making. This is an unfortunate situation for our limpograss grazing
program, as substantial dry matter yield can be expected during these summer months.
This excess summer forage accumulation must be utilized prior to preparation for fall
stockpiling. Production of round-bale silage may be an interesting alternative to summer
grazing of this material. There are multiple systems available for harvesting and storing
forage silages. Dr. Bill Kunkle prepared a review of these systems. This paper is
available in the Proceedings of the 12th Annual Florida Ruminant Nutrition Symposium
In our system, we fertilized the limpograss pastures on May 25 for production of
summer round-bale silage (20-5-10; 400 pounds per acre). Coordination of custom
harvest and the summer hurricanes kept us from harvesting during this current summer;
however, adequate dry mater yield was achieved by eight weeks following fertilization.
Clipping estimates suggest that we would achieve six to seven tons of round-bale silage
per acre (65% moisture). This would equate to a total of about 2.4 tons of dry matter per
acre. Our estimate for custom harvesting this material was $135 per acre or $57 per ton
of dry matter harvested. Re-fertilization of this crop immediately after round-bale silage
harvest will allow plenty of time for fall forage stockpiling prior to winter grazing, which
should begin in late December or early January.
Table 2. Estimated annual harvest of limpograss forage"
Item Production, tons per acre Cost, $ per ton
Spring hayb 1.6 $92
Summer round-bale silageb 2.4 $72
Winter stockpiling and re-growthbc 3.0 $12
aFertilizer applied prior to hay harvest, round-bale silage harvest and winter stockpiling;
(400 pounds per acre of 20-5-10; $184 per ton; includes custom application).
bCustom hay harvest includes $15 per 900 pound bale (85% dry matter) and a single
application of fertilizer. Custom round-bale silage harvest includes $15 per 1500 pound
bale (35% dry matter) and a single application of fertilizer.
cEstimated for a 1000 pound cow provided 0.75 acres for 90 days of grazing (25 pounds
of dry matter intake per day).
This limpograss management system allows for the potential production of 7 tons
of dry matter per acre (Table 2). The majority of this is harvested during the summer
months, when continued accumulation of limpograss is often difficult to utilize. The most
efficient use of this forage base occurs over the 90 d of stockpiled winter forage harvest by
the cow. This estimated 3 tons of dry matter harvested per acre is realized with only the
input of fertilizer. Since the cow is harvesting the material through grazing, the cost of
custom harvest is saved. In comparison, the costs for producing spring hay and summer
silage depend predominantly on the dry matter yield of this material. Considering
approximately 51% TDN, these forage products provide us with a cost of $0.09 and $0.07
per pound of TDN. Using these figures, each are reasonable-cost feed sources for cows.
In the hierarchy of use, we would first utilize all the fall stock-piled forage,
followed by the round-bale silage and lastly the hay. The stockpiled forage has no sale
value. Similarly, the round-bale silage has little sale value due to the difficulty of
transporting this high-moisture material. Alternatively, the hay does provide an
opportunity for the producer to market excess material not needed to feed the cowherd.
This production system is currently being evaluated at the Range Cattle REC.
This evaluation will continue over the next three production cycles. The value of this
system may be realized by both large extensive ranches and smaller intensive production
operations. In the scenario described above, it may be possible to produce as much as 7
tons of usable forage dry matter per acre annually. Using a 1000 pound cow at 2.5%
annual forage dry matter intake (% body weight) as an example, this forage system may
support as much as 1.3 cows per acre. This is a clear advantage in terms of stocking rate;
however, intensive management is required. At a minimum, three management inputs
are needed, 1) three annual applications of a complete fertilizer, 2) hay and round-bale
silage storage, and 3) equipment for handling and feeding the stored forage. In addition,
producers that do not own their own hay and silage harvesting equipment are very
dependent upon scheduling of custom harvesters. Considerable planning and
coordination will be required for the successful implementation of this management
INFLUENCE OF MANAGEMENT ON YIELD AND PERSISTENCE OF
RHIZOMA PEANUT ON FLATWOOD SOILS
Paul Mislevy, A.R. Blount, K.H. Quesenberry, and M.J. Williams
There is a need in peninsular Florida for a long lived, persistent, warm season
perennial legume that will tolerate somewhat poorly drained soils. In central Florida
consistent establishment of warm season annual legumes has been difficult due to
inconsistent moisture at seeding. In addition, establishment and persistence of many
perennial legumes have not been satisfactory due to climatic extrems. Dr. Buddy Pitman
tested hundreds of legumes over a 12 yr period at Ona and found one legume [Vigna
parkeri (Shaw vigna)] that would persist under grazing in a bahiagrass sward. Growers
are reluctant to buy seed of Shaw Vigna because seed costs are about $13/lb and must be
imported from Australia. Legume research has been conducted at Ft. Pierce for over 30
years and more than 1000 entries were tested with only one long term persistent cultivar
(Florida carpon desmodium) in use today. These examples indicate the difficulty in
developing a legume that will persist in central Florida with or without a grass. Rhizoma
peanut (Arachis), currently being tested at Ona is a long-lived, warm season, persistent
perennial legume, adapted to well drained soils.
Studies were conducted over a 4-year period at Ona to determine the influence of
rhizoma peanut entries and stubble height (SH) on forage yield, nutritive value, and
persistence on a poorly drained soil. Peanut entries consisted of Arbrook, Arbrook Select,
Florigraze, Ecoturf, PI 262826, PI 262833, and PI 262839. Peanuts were clipped at 1 and
4 inch SH. Annual fertilization consisted of 300 lb/A 0-10-20 + 0.5% Zn, Cu, Mn, Fe
(sulfate form), 0.05% B and 1% S.
Higher dry matter yields were obtained when peanuts were harvested at a 1 inch
SH (5.1 ton/acre) compared with the 4 inch (SH 3.4 ton/acre). However differences
between SH disappeared after 3 years of clipping resulting in similar dry matter yields
between both SH. Yield decreased an average of 68% for Arbrook and Arbrook Select
between the initial and 3rd year of clipping and increased 36% for PI 262833 during the
same time period (Table 1).
Table 1. Influence of perennial peanut entry on total dry yield over years.
Peanut entry 1 2 3 Change
-------- Ton/acre -------- %
Arbrook Select 8.3 3.8 2.6 -69
Arbrook 8.3 3.5 2.8 -67
PI 262839 6.3 3.3 3.4 -45
PI 262826 6.2 3.3 4.5 -28
Florigraze 5.4 3.5 3.6 -34
Ecoturf 4.1 3.2 4.0 -1
PI 262833 3.2 2.8 4.4 +36
Forage Nutritive Value
Generally no difference was found in crude protein and in vitro organic matter
digestion between the 1 and 4 inch SH. Crude protein averaged 18% and digestibility
69% over two SH and a 3 year clipping period.
Perennial peanut is more persistent when plants are clipped back to a 4 inch SH
compared with a 1 inch stubble. Average peanut ground cover after 4 years of clipping
was 91% for the 4 inch stubble and 66% for the 1 inch SH. These data suggest taller
stubble have better persistence. Plants clipped at the tall stubble were always above the
water level regardless of the rain event. Some peanut entries were more water tolerant
regardless of SH. PI 262833 averaged 96 and 100% ground cover and Ecoturf averaged
76 and 100% ground cover for the 1 and 4 inch SH, respectively.
Root mass was measured at the end of the study to determine if the 4 inch SH had
a greater root/rhizome density than the 1 inch stubble. Data indicate harvesting perennial
peanut over a 4-year period, at a 1 inch SH decreased root mass by 44% when compared
with the 4-inch SH. This would indicate clipping peanut plants at a 4-inch SH allows
plants to continue top and root growth even under poorly drained soil conditions.
In summary harvesting rhizoma peanut at a 4-inch SH will generally produce
lower forage yields for about 2 years after establishment. However, after 2 years of
clipping above ground yields were similar for both the 1 and the 4 inch SH. Forage
quality is generally similar for both SH, however, persistence and root mass are always in
favor of the taller SH.