Pasture Design and Grazing Management

Prévia do material em texto

�
� �
�
CHAPTER
44
Pasture Design and Grazing Management
Lynn E. Sollenberger, Distinguished Professor, Agronomy, University of Florida,
Gainesville, FL, USA
Yoana C. Newman, Associate Professor, Plant and Earth Science, University of
Wisconsin River Falls, Madison, WI, USA
Bisoondat Macoon, Research Professor, Mississippi State University, Raymond, MS,
USA
Importance of Grazing Management and Pasture
Design
Grazing management is defined as the manipulation
of grazing in pursuit of a specific objective or set
of objectives (Allen et al. 2011). There are often multiple
objectives in addition to forage production including
forage-use efficiency, plant persistence, production per
animal and per unit of land area, economic return,
and delivery of ecosystem services (Sollenberger et al.
2012). Pasture design relates to pasture and/or paddock
size and shape, slope and aspect of grazing units, and loca-
tion of feeding, watering, shade, and handling facilities.
The goal of pasture design is to achieve a livestock dis-
tribution that positively affects pasture utilization, plant
diversity, watershed function, and control of animal
wastes and nutrient flows. This chapter will (i) describe
plant responses to defoliation and the mechanisms under-
pinning them, (ii) define the key grazing management
choices and their potential impact on a grazing system,
and (iii) review the elements of effective pasture design.
Defoliation and Plant Response
Grazing Vs Cutting
Grazing and mechanical harvesting affect forage swards
differently. Grazing livestock exert a pulling force, possibly
Forages: The Science of Grassland Agriculture, Volume II, Seventh Edition.
Edited by Kenneth J. Moore, Michael Collins, C. Jerry Nelson and Daren D. Redfearn.
© 2020 John Wiley & Sons Ltd. Published 2020 by John Wiley & Sons Ltd.
disturbing the root system or even uprooting the plant.
They also selectively consume plant species, tillers within
a plant, and plant parts within a tiller. In contrast, defoli-
ation by clipping is instantaneous for all plants and tillers
to the selected stubble height. Defoliation by grazing is
also accompanied by treading and excreta deposition that
present impacts unlike those associated with mechanical
harvesting (Mikola et al. 2009). Thus, clipping and graz-
ing are very different and plant responses to clipping may
not be indicative of the response to grazing (Gastal and
Lemaire 2015).
Immediate Responses to Defoliation
Gastal and Lemaire (2015) state two guiding principles
for understanding plant responses to defoliation. First,
defoliation disturbs the carbohydrate supply for plant
growth by removing photosynthetic tissues, and second,
plant growth processes operate to maintain plants in a
dynamic equilibrium with their environment such that
resource use is optimal for growth and reproduction.
When defoliation removes leaf tissue, reduced photosyn-
thesis limits carbohydrate available to support growth,
and a series of physiologic responses ensues to restore
homeostatic growth (Richards 1993). These responses are
short lived, and if defoliation is infrequent or lenient,
803
�
� �
�
804 Part IX Pasture Management
leaving a significant portion of the leaf area, then restora-
tion of carbohydrate supply and growth patterns will
occur before another defoliation event (Chapman and
Lemaire 1993).
Photosynthesis
When plants are grazed, instantaneous reduction of pho-
tosynthesis occurs and translocation of previously fixed C
is temporarily stopped (Richards 1993). The proportional
reduction in photosynthesis exceeds the proportion of leaf
area removed because residual leaf is often older than the
average of the pre-grazing canopy and had previously been
shaded (Gold and Caldwell 1989).
Root Processes
Root elongation ceases within 24 hours after removal of
40–50% or more of the forage shoot mass, and some fine
roots may also die and begin to decompose soon after
defoliation (Jarvis and Macduff 1989). Biologic N fixa-
tion by legumes and nutrient absorption by most plants
decline rapidly after defoliation (Richards 1993). The rate
of nitrate absorption by perennial ryegrass roots declined
within 30 minutes after removal of 70% of forage mass
and reached levels less than 40% of pre-defoliation rates
within 2 hours (Clement et al. 1978).
Resource Allocation
Carbon supply is diminished due to the reduction in
photosynthesis, but plants compensate for the reduced
supply. The amount of photosynthate allocated to roots
is reduced, and the proportion that is exported from
photosynthetically active leaves to actively growing shoot
meristematic regions increases (Richards 1993). These
compensatory processes begin within hours after defo-
liation and contribute to more rapid replacement of
photosynthetic leaf area. Nitrogen allocation patterns
are similar to those described for C. After defoliation
of perennial ryegrass, previously absorbed N was pref-
erentially allocated to regrowing leaves, and 80% of
the N originated from remaining stubble (Ourry et al.
1988). The remainder came from the root system. These
processes appear to be sink driven and provide for rapid
recovery from grazing by defoliation-tolerant plants
(Richards 1993).
Short-Term Responses to Defoliation
After the immediate responses to defoliation, subsequent
processes are set in place that lead to restoration of a
positive whole-plant C balance. This phase of recovery
requires up to several weeks. Richards (1993) suggested
that two main processes contribute to increased “car-
bon gain capacity” after defoliation. These processes
include reestablishment of the photosynthetic canopy
and increases in the photosynthetic capacity of remaining
foliage.
Reestablishment of Positive Whole-Plant Carbon
Balance
The most important factor affecting rapid restoration of
the leaf canopy is the presence of active shoot meristems.
It is not until the plant has enough leaf area to provide the
plant with adequate photosynthetic capacity for mainte-
nance and growth that the plant begins reserve replenish-
ment and initiation of root growth. In the case of ryegrass,
this occurs when about 75% of a new leaf has regrown
(Fulkerson and Donaghy 2001). Leaf expansion results
from expansion of already formed cells, and their pres-
ence serves as a strong sink for remobilized C and N soon
after defoliation (Briske 1986). During this intermediate
period, remobilized and current photosynthate continue
to be preferentially allocated to the regrowing shoots until
their demand is met. Dependence of regrowth on stored
reserves is thought by some to persist longer for N than C
because of the delay in resumption of N uptake until the
plant achieves a positive C balance (Culvenor et al. 1989).
Compensatory Photosynthesis
Another factor affecting canopy recovery, though less
important than rapid reestablishment of photosynthetic
canopy area, is the potential for increased photosynthetic
rates of leaves remaining after defoliation. Compensatory
photosynthesis may reflect the ability of mature leaves
to rejuvenate their photosynthetic capacity to the higher
levels of younger leaves or of younger leaves to slow the
normal decline in photosynthetic capacity with aging
(Richards 1993).
Long-Term Responses to Defoliation
Plants exhibit physiologic and morphologic responses to
defoliation. Physiologic responses generally occur over
short-time scales, whereas morphologic responses are
generally longer term and are associated with sustained,
more severe defoliation (Chapman and Lemaire 1993).
Like morphologic responses, plant reserves become more
important with extended periods of relatively severe
defoliation.
Morphologic Responses
Plants and swards have the capacity to adapt their struc-
ture to defoliation, i.e. they exhibit plasticity of sward
structure (Gastal and Lemaire 2015) or phenotypic
plasticity (Nelson 2000). Plasticity of sward structure
is reversible and includes changes in size, structure, and
spatial positioning of organs (Huber et al. 1999).For
example, optimization of canopy leaf area at lower defoli-
ation height may be achieved through a decrease in mean
tiller mass and an increase in tiller population density
(Matthew et al. 2000). There are limits to phenotypic
sward plasticity, however, and if grazing becomes too
severe, leaf area, substrate supply, and tiller production
�
� �
�
Chapter 44 Pasture Design and Grazing Management 805
are decreased and tiller survival diminished (Matthew
et al. 2000), weakening the stand.
Morphologic responses to defoliation are an important
part of an “avoidance” mechanism (Briske 1986) that
reduces the probability of defoliation for individual
plants. There is considerable variation among species or
even among cultivars within a species in the extent of
phenotypic plasticity for particular traits (Gibson et al.
1992; Shepard et al. 2018), and this can be related to
grazing tolerance. Less erect tiller angle, shorter stems,
and greater herbage bulk density have been associated
with phenotypic plasticity. These changes can result in
greater post-grazing residual leaf mass and leaf area index,
increasing rate of refoliation and decreasing dependence
on stored reserves during regrowth (Hodgkinson et al.
1989; Mullenix et al. 2016; Shepard et al. 2018).
Plant Reserve Status
The mobilization of C and N reserves and their supply to
growing leaves is a direct effect of defoliation (Alderman
et al. 2011a; Gastal and Lemaire 2015). The importance
of reserves in the regrowth and persistence of peren-
nial grasses under defoliation has long been recognized
(Richards 1993) but is not without controversy. Some
consider plant reserves to play a limited role in regrowth
(Humphreys 2001). Others suggest that reserves are used
for regrowth only for a few days after defoliation (Richards
1993), yet reduction in storage tissues has occurred from
one to several weeks (Skinner et al. 1999; Alderman et al.
2011b). Fulkerson and Slack (1994) observed a positive
correlation between water-soluble carbohydrate content
(g per plant or g m−2) in perennial ryegrass stubble
and leaf growth in the six days following defoliation;
regrowth was more closely correlated with stubble carbo-
hydrate content than concentration (g kg−1). For several
cool-season grasses, including perennial ryegrass, it was
only during the first 2–6 days after defoliation that remo-
bilization of reserves was the primary source of C and
N for regrowth (Thornton et al. 2000). Thereafter, the
plant became progressively more dependent on current
assimilate for growth and replenishment of reserves. If
current assimilation rates recover quickly to support plant
needs, as described earlier for plants demonstrating phe-
notypic plasticity, the role of reserves is relatively small.
However, in some environments and, with particular
combinations of forage species and management, reserves
are very important.
A general rule is the more stressful the conditions
(e.g. heavier grazing, colder winter temperatures, pro-
longed drought, lower light environments), the more
likely reserves will play a significant role in response to
defoliation. Under stressful conditions, reserve content
in storage organs, a function of both storage organ
mass and reserve concentration, is more responsive to
defoliation than is reserve concentration (Ortega-S et al.
1992; Chaparro et al. 1996). These results support the
conclusion that some forage species depend significantly
on stored reserves to sustain growth during extended
periods of severe defoliation.
Grazing Management Choices
A goal of grazing management is to achieve canopy condi-
tions and forage productivity that result in optimal levels
of animal performance (Hodgson 1990). Manipulation of
grazing intensity, stocking method, and timing of graz-
ing are the primary means of achieving the desired canopy
characteristics.
Grazing Intensity
Grazing intensity relates to the severity of grazing. Mea-
sures of grazing intensity are animal or pasture based
or both. Stocking rate (animal units ha−1) is the most
common animal-based measure of grazing intensity.
Pasture- or sward-based measures include forage mass,
canopy height, and canopy light interception. Forage
allowance and grazing pressure incorporate both pasture
and animal measures (Allen et al. 2011).
Importance
The selection of grazing intensity is more important than
any other grazing management decision (Sollenberger
et al. 2012) due to its prominent role in determining
forage plant productivity and persistence (Newman et al.
2003b; Hernández Garay et al. 2004), animal perfor-
mance (Sollenberger and Vanzant 2011), and profitability
of the grazing operation (Table 44.1). Understanding the
relationship of grazing intensity to pasture and animal
performance is crucial for the long-term success of the
forage–livestock enterprise.
Effects on Pasture Attributes and Animal Performance
Increasing grazing intensity consistently (>90% of exper-
iments reporting these responses) decreases forage mass
and forage allowance, but the effect on forage accumu-
lation rate depends on forage species, grazing frequency,
and the environment (Figure 44.1; Sollenberger et al.
2012). In 66% of studies reporting forage nutritive value
responses to grazing intensity, nutritive value increased
with greater stocking rates and when swards were grazed
to shorter rather than taller stubble heights (Table 44.1;
Hernández Garay et al. 2004; Jones and LeFeuvre 2006;
Sollenberger et al. 2012). In more intensively grazed
swards, leaf proportion of the forage mass is greater and
average age of regrowth is younger because of shorter
intervals between grazing bouts or slower regrowth fol-
lowing heavy defoliation (Roth et al. 1990; Pedreira et al.
1999; Dubeux et al. 2006).
Continuously stocked limpograss pastures grazed
to a 20-cm stubble had greater leaf, stem, and total
bulk density, and crude protein concentration than
�
� �
�
806 Part IX Pasture Management
Table 44.1 Stocking rate effects on pre-grazing forage mass and nutritive value, forage allowance,
and animal performance of weanling bulls rotationally stocked on stargrass (Cynodon
nlemfuensis Vanderyst) pastures
Stocking rate
(head ha−1)
Forage mass
(Mg ha−1)
Forage
allowance
(kg kg−1)
Crude protein
(g kg−1)
In vitro
digestion
(g kg−1)
Neutral
detergent
fiber (g kg−1)
Average daily
gain (kg)
Gain
ha−1 (kg)
2.5 6.6 7.6 134 586 774 0.68 500
5.0 4.5 2.7 140 593 762 0.54 760
7.5 2.7 1.2 151 599 749 0.31 550
Polynomial
contrast
Linear Linear,
quadratic
Linear Linear Linear Linear,
quadratic
Quadratic
Source: Adapted from Hernandez-Garay et al. (2004).
P
e
rc
e
n
t 
o
f 
S
tu
d
ie
s
0
20
40
60
80
100
 Mass
(n = 31)
Allowance
 (n = 9)
Accumulation
(n = 17)
 Nutritive
Value
(n = 41)
Lower < Higher
Lower > Higher
No difference
90
70
50
30
10
FIG. 44.1. Percentage of studies showing
responses to higher and lower grazing intensity
for experiments reviewed that reported data
based on measures of forage mass, forage
allowance, forage accumulation, and forage
nutritive value. Number of experiments for each
data set is indicated in parentheses. “Higher” and
“lower” refer to grazing intensity (i.e. higher or
lower stocking rate). Source: Adapted from
Sollenberger et al. (2012).
pastures grazed to 40 or 60 cm (Newman et al. 2003a).
Though greater leaf proportion and bulk density are
often positively associated with animal daily gain (Burns
and Sollenberger 2002), accessibility of leaf to grazing
herbivores may be more important than abundance of
leaf (Sollenberger and Burns 2001). Limpograss canopies
grazed to a 40-cm height had lower bulk density and
greater livestock daily gain than those grazed to 20 cm,
attributable to greater opportunity for leaf selection in
the less-dense 40-cm sward (Newman et al. 2002).
The main objective of numerous grazing-intensity
studies during the past five decades has been to describe
the individual animal performance response as a function
of stockingrate or grazing pressure (Sollenberger and
Vanzant 2011). All authors agree that performance per
animal declines as stocking rate increases across a wide
range of stocking rates, but there are different perspectives
among authors on the shape of the curve (Jones and Jones
1997).
The differential effects of grazing intensity on forage
nutritive value and forage mass underlie this relationship.
Above some forage mass threshold, perhaps 2 Mg ha−1 for
temperate and 4 Mg ha−1 for tropical swards, animals are
able to select a diet of their choice in a sustainable daily
grazing time (6–9 hours) (Burns et al. 1989; Hernández
Garay et al. 2004), and forage mass has little causative
influence on animal response. With extreme understock-
ing, however, daily animal production may be reduced
due to accumulation of mature and senescent forage.
Newman et al. (2002) showed that lightly grazed canopies
had more trampled and lodged forage, and gains were
lower than with moderately grazed swards. In contrast,
as stocking rate is increased, at some point forage intake
decreases sufficiently to cause a shift in use of consumed
energy away from maximum daily animal growth and
toward meeting the animals’ maintenance requirement
(Burns et al. 2004). The consequence is reduced gain
per animal (Figure 44.2). Thus, the influence of forage
quantity on animal performance is greater at low levels
than at high levels of forage mass or allowance. When
forage mass or allowance were not limiting, forage nutri-
tive value explained 56–77% of variation in performance
per animal (Duble et al. 1971; McCartor and Rouquette
1977). Based on a meta-analysis, forage nutritive value
(i) sets the upper limit for average daily gain, (ii) deter-
mines the slope of the regression of daily gain on stocking
rate, and (iii) establishes the forage mass at which daily
gain plateaus (Sollenberger and Vanzant 2011). In
contrast, forage quantity determines the proportion of
potential daily gain that is achieved and is the primary
determinant of the pattern of the daily gain response
(negative) to increasing stocking rate.
�
� �
�
Chapter 44 Pasture Design and Grazing Management 807
Stocking rate or grazing pressure
A
n
im
a
l 
g
a
in
Gain per
unit area
Gain per
animal
FIG. 44.2. The relationship of gain per
animal and gain per hectare with stocking rate or
grazing pressure. Source: Adapted from Mott and
Moore (1985).
In contrast to its effect on individual animal gain,
increasing stocking rate on a previously underutilized
pasture causes animal gain per hectare to increase up to
some maximum (Figure 44.2; Hernandez Garay et al.
2004). Increasing stocking rates above this level causes
production per hectare to decline because animals can
consume only enough forage to support lower levels of
daily gain (Figure 44.3).
Stocking Method
Stocking method is the manner that animals are stocked
or have access to a number of pastures (grazing man-
agement units) and paddocks (pasture subdivisions, if
present) during the grazing season. Choice of stocking
method is distinctly separate from that of grazing inten-
sity; thus, a particular stocking method may be used
across a wide range of stocking rates or grazing pressures.
Many stocking methods have been described (Allen
et al. 2011), but they conform to or derive from one of
two types: continuous or some form of rotational (also
called intermittent) stocking. Under continuous stock-
ing, animals have unlimited and uninterrupted access
to the grazing area throughout the period when grazing
occurs. If the number of animals used is fixed, it is referred
to as set stocking. Rotational stocking uses alternating
periods of stocking and rest among two or more paddocks
in a pasture (Figure 44.4). The objective is to balance rest
and stocking periods to achieve an efficient and uniform
defoliation of the pasture. Stocking period length is set to
leave a target stubble height or residual leaf area, and the
optimum height is dictated by the grazing tolerance of the
forage species and the nutrient requirements of the graz-
ing animal. The rest period is, likewise, species dependent
and is set to allow the maximum forage accumulation
rate without compromising persistence or unduly
compromising nutritive value (Pedreira et al. 1999).
A literature synthesis found that 71% of studies com-
paring rotational and continuous stocking reported no
difference in forage nutritive value, but 81% reported
an advantage in pasture carrying capacity for rotational
stocking (Sollenberger et al. 2012). This advantage
averaged approximately 30% and was due, in part, to
greater forage accumulation rate for rotational stocking,
attributable to greater average leaf area index and younger
average leaf age than on continuously stocked pastures
(Parsons et al. 1988). Rotational stocking also resulted in
greater homogeneity of forage utilization than continuous
stocking which reduced spot overgrazing and increased
the proportion of pasture area experiencing a longer
linear growth phase (Figure 44.5; Saul and Chapman
2002; Hunt et al. 2007; Barnes et al. 2008). Sixty-six
percent of studies comparing animal performance on
rotationally and continuously stocked pastures showed
no difference in daily animal performance, and 69%
showed no difference in production per unit land area
(Sollenberger et al. 2012). The latter response was depen-
dent on research methodology, because when stocking
methods were compared using a variable stocking rate
technique, rotationally stocked pastures achieved greater
animal production per unit land area in more than 40%
of experiments (Sollenberger et al. 2012).
Though greater uniformity of excreta deposition is
often attributed to rotational stocking, this response is
environment specific. Continuous stocking was compared
with rotational stocking with 1-, 3-, 7-, and 21-days graz-
ing periods and a 21-days rest period (Dubeux et al. 2014).
Soil nutrients accumulated for all stocking methods in
the surface 8 cm of soil in zones near shade and water.
Air temperature, wind speed, and temperature–humidity
index explained 49% of the variation in time cattle
spent under shade, confirming the importance of the
environment in animal behavior. Results of this, and
other studies (Mathews et al. 1994), support a conclusion
that the greatest benefit of rotational stocking in terms
of uniformity of nutrient return in excreta is likely to
occur in temperate environments or during cool seasons
(Dubeux et al. 2007).
Rotational stocking can occur in several forms. The
least-complex is alternate stocking where two paddocks
are used for the rotation. At the other extreme is strip
stocking, more commonly used in pasture-based dairies
with forages such as alfalfa or hybrid bermudagrass.
Paddocks in strip stocking are smaller than for other
rotational systems, and the grazing period is usually a
fraction of a day to 2 days. Strip stocking minimizes
daily variability in diet nutritive value because the res-
idence period in the paddock is short and selectivity is
reduced. The first–last grazer approach to rotational
stocking is used when animals with different nutritional
requirements are grazed sequentially on a given paddock.
Animals with higher nutritional requirements are allowed
�
� �
�
808 Part IX Pasture Management
FIG. 44.3. The weanling bulls in the foreground were stocked at 7.5 head ha−1 on stargrass pas-
tures for a 300-days grazing season while the bull in the background was on a pasture stocked at 2.5 head
ha−1. Average daily gain was 0.31 and 0.68 kg for animals from high- and low- stocking rate treatments,
respectively (Hernández Garay et al. 2004). Source: Photo by Lynn Sollenberger, University of Florida.
FIG. 44.4. Rotational stocking applied to a ‘Florakirk’ bermudagrass pasture. Source: Photo by
Lynn Sollenberger, University of Florida.
�
� �
�
Chapter 44 Pasture Design and Grazing Management 809
H
e
rb
a
g
e
 M
a
s
s
Time of Regrowth
Phase I Phase II Phase III
FIG. 44.5. Accumulationof forage mass
during a regrowth period follows a sigmoid curve
as the canopy develops from low mass (Phase 1:
low accumulation rate) to intermediate mass
(Phase 2: high accumulation rate) to high mass
(Phase 3: little or no net accumulation due to
balance between new growth and senescence).
Source: Adapted from Saul and Chapman (2002).
first access, making it possible to achieve targeted rates
of daily gain for two classes of livestock grazing the same
pasture. Other methods in use, but less widely adopted,
are frontal stocking and creep stocking. Frontal stock-
ing is a type of strip stocking in which a sliding fence
is pushed by cattle and gradually exposes new forage.
A back fence prevents the animals from accessing the
previously grazed areas. This approach has resulted in
uniform grazing and defoliation of close to 100% of tillers
(Volesky 1994). Creep stocking uses lactating–nursing
animal pairs. A higher-quality forage is available adjacent
to the base rotation module, and this forage is available
to the nursing animals through the use of creep gates.
The use of continuous stocking is widespread through-
out the US. Reasons include fewer management decisions
(Bertelsen et al. 1993), rotational stocking is not required
for persistence of some species (e.g. tall fescue and
bahiagrass), and no consistent advantage in animal per-
formance has been documented for rotational stocking
(Sollenberger et al. 2012). Continuous stocking is a
common practice in extensive grazing systems, includ-
ing shortgrass rangeland (Hart and Ashby 1998) and
mixed-grass prairies (Guillen et al. 2000). In these loca-
tions, dividing pastures and moving cattle may not be
practical or economic. If stocking rates are moderate, ani-
mals have opportunities for selection when continuously
stocked (Vallentine 2001).
In some cases, stocking method may be used strate-
gically to control weeds in planted pastures. Vaseygrass,
a bunchgrass weed, becomes stemmy and unpalatable
during the rest period in rotationally stocked limpograss
pastures, resulting in avoidance by cattle, seed set, and
an increase in weed density and cover. Under continuous
stocking, as new vaseygrass leaves emerged they were
readily consumed by cattle, and vaseygrass plant density
and cover decreased (Newman et al. 2003b). Yet, in
other cases, control of a weed was achieved by rotational
stocking. In tall fescue (Hoveland et al. 1997) and ‘Callie’
bermudagrass (Mathews et al. 1994) pastures, rotational
stocking allowed the preferred species to shade com-
mon bermudagrass during the rest period and favored
persistence of tall fescue and Callie.
Still for other species, such as alfalfa, production
and persistence may not be sustained under continu-
ous stocking (Schlegel et al. 2000), though there are
large differences among cultivars (Brummer and Moore
2000). In considering persistence, it should be noted
that continuous stocking does not imply a high stocking
rate. In some cases, where continuous stocking has been
implicated in stand loss, overstocking may have been
more directly responsible.
Timing of Grazing
Use of a particular management practice may be effective
at some times or under certain conditions but not others.
The choice of timing for defoliation may be influenced by
stage of plant regrowth following defoliation. An example
is the degree to which reserves have been restored prior
to onset of winter or a dry season. In other situations,
timing of defoliation is influenced by reproductive tiller
formation or elevation of apical meristems (Matches and
Burns 1995). Stand losses of smooth bromegrass and
timothy growing with alfalfa have been associated with
defoliation during the critical period between stem elon-
gation and heading growth stages (Casler and Carlson
1995). Early-maturing timothy cultivars persisted better
with alfalfa than did late-maturing cultivars (Casler and
Walgenbach 1990). Similarly, defoliation that removes
shoot apices of switchgrass often reduces tiller density
and, if not followed by a long regrowth period, may
compromise stand persistence (Anderson et al. 1989).
Closure date of late-season grazing can be critical
for annual or short-lived perennial species that rely on
natural reseeding for stand regeneration. In northeastern
Texas, most cultivars of annual ryegrass grazed until late
April produced satisfactory volunteer stands the following
autumn (Evers and Nelson 2000). Later grazing greatly
reduced inflorescence density and seed weight per spike
and decreased volunteer seedling density. Similarly, seed
yield of the summer-annual legume aeschynomene was
greatly reduced if autumn grazing continued after first
flower (Chaparro et al. 1991).
There is diurnal variation in forage nutritive value
that may influence recommended timing of defolia-
tion. These changes are associated with accumulation of
photosynthate during the day (Fisher et al. 2002). They
�
� �
�
810 Part IX Pasture Management
showed that nutritive value and animal preference were
greater for hays cut in the afternoon compared with those
harvested in the morning. In strip-stocking systems where
animals are moved daily (e.g. lactating dairy cows), it may
be advantageous to move animals to new paddocks in the
afternoon/early evening so that the larger meal that usu-
ally follows transition to a new grazing area is composed
of forage of the greatest possible nutritive value.
Pasture Design in Grazing Systems
Design of pastures depends on a number of fac-
tors, including landscape characteristics and inten-
sity/complexity of grazing management. Pasture design
is particularly important when considering responses
that are affected by distribution of livestock across the
landscape. These include efficient utilization of forage,
sustaining plant diversity, maintaining riparian control
and watershed function, avoiding animal waste and excess
nutrient flow into water bodies, supporting stream bank
stability, and provision of ecosystem services.
Fencing to define the boundaries of pastures and pad-
docks can be permanent or temporary. Permanent fences
often require less management once installed but initial
costs are greater than for temporary fences, and manage-
ment flexibility is reduced.
Paddock Number, Size, and Shape
Choice of stocking method is a major determinant of pas-
ture design. In rotational stocking, the optimum number
of paddocks depends on grazing management objectives
and type of animal production system. The required
number of paddocks in a rotational stocking scheme
can be calculated as: rest period ÷ grazing period+ 1.
The literature is not clear on the benefits of greater
vs fewer number of paddocks in rotational stocking.
Greater number of paddocks had a positive effect on
forage accumulation rate or pasture carrying capacity in
approximately 50% of research comparisons but had no
effect on forage nutritive value in 75% of comparisons of
more vs fewer paddocks (Sollenberger et al. 2012). In a
study with grazing periods of 1, 3, 7, or 21 days (all with
a 21-days rest period), there was no effect of number of
paddocks on forage accumulation rate, crude protein, or
in vitro digestibility of bahiagrass (Stewart et al. 2005).
More vs fewer paddocks in rotationally stocked swards
definitely reduces day-to-day variation in diet nutritive
value, and in some cases, it increases uniformity of excreta
deposition (most likely in cooler environments) and
homogeneity of forage utilization across the pasture. The
latter contributes to greater pasture carrying capacity.
Increasing popularity of rotational stocking methods
with many paddocks in the rotation is facilitated by the
easy availability, improved technology, and economic
benefits of temporary fencing. A form of high-density
rotational stocking with long rest intervals (60 days or
more) between grazing events is called mob grazing in
the popular press. While the International Forage and
Grazing Terminology Committee does not include mob
grazing as official terminology,they define mob stocking
as “a method of stocking at a high grazing pressure for
a short time to remove forage rapidly as a management
strategy” (Allen et al. 2011). It is useful to note that the
definition of mob stocking does not reference length of
rest interval between grazing events, thus it should not
be confused with the informal term mob grazing. While
mob grazing is practiced in various forms by growers, this
method of grazing is poorly defined and its source unclear.
Practitioners of mob grazing claim numerous pasture and
animal benefits (Gompert 2010). Some recommend that
achieving 60% trampling of the standing forage mass is
the optimum level for increasing soil organic matter and
nutrient concentration (Peterson and Gerrish 1995), but
data are currently lacking to substantiate these claims.
The optimum size of paddocks depends on many
factors, including management objectives and number of
paddocks desired, land availability and terrain, and herd
size relative to stocking density desired. Distribution of
animals in the landscape is affected by stocking density
and this can be manipulated to make more effective use
of pasture resources (Hunt et al. 2007) as well as reduce
potential for grassland degradation that may result from
patch grazing (Barnes et al. 2008). Nutrient distribution
in pastures benefits from smaller paddock sizes in some
environments (Dubeux et al. 2009). Temporary fencing
can be used to allow flexibility of subdivisions within per-
manent boundaries of paddocks or pastures in cases where
management based on forage allowance is desired. It may
be desirable to have larger pastures with low-productivity
forage systems while highly productive pastures may be
better managed by division into smaller paddocks.
Shape of pastures is determined by management
objectives, land availability, and landscape features. It
has been suggested that, within practical limits, square
pastures allow more grazing efficiency than other shapes
by allowing greater forage intake in less grazing time, less
energy expenditure incurred during grazing, and reduced
loss of forage due to trampling. It is recommended that
long, narrow pastures be avoided, mostly because they
tend to increase the potential for patch grazing. Irreg-
ularly shaped pastures are sometimes the only option
when dictated by terrain and landscape constraints and
are often practical for commercial pasture-based livestock
production. In research settings, however, consistency
in shape and size of paddocks is important, especially
to minimize variation in implementing non-treatment
management practices like applying fertilizer.
Slope and Aspect
Topography and aspect can affect type of vegetation and
timing of forage readiness, for example, in the northern
�
� �
�
Chapter 44 Pasture Design and Grazing Management 811
hemisphere north-facing slopes are likely to start growing
later in spring than south-facing slopes. Steepness of slope
can affect herbage accumulation rate with lower slopes
having greater herbage accumulation; this can affect
grazing behavior of animals and should be considered in
pasture design (López et al. 2003). Topography affects
distribution of livestock on pasture and plays a key role
in deposition of dung and urine (Rowarth et al. 1992),
which is closely associated with time spent in a portion of
the landscape (Dubeux et al. 2009). Most livestock species
prefer easy access to forage and to minimize expenditure
of energy during grazing. As a result, they spend more
time on flat areas than on slopes, and time spent on slopes
decreases with increasing slope (Rowarth et al. 1992). A
key consideration regarding slope and aspect in designing
and laying out pastures is erosion control and nutrient
runoff. Fences should be erected across slopes rather than
up and down. Animals, especially cattle and horses, patrol
fence lines and the resulting paths developed by their hoof
action become natural channels for water flow. Addi-
tionally, management practices like spraying herbicide in
fence lines increase likelihood of channels forming.
Shade and Water Placement
In addition to topography, shade sources, water sources,
and feed and mineral salt sources placement affect distri-
bution of livestock across pastures because they tend to
congregate at these locations (Sollenberger et al. 2012).
Shade, both natural and artificial, is useful to livestock
management because it allows animals to escape from
heat. Dubeux et al. (2009) reported that cattle spend a
disproportionate amount of time in shade during warm
weather. Management concerns center around unequal
distribution of nutrients, bacteria, and other contami-
nants of pasture due to the concentration of urine and
feces in areas frequented by cattle. Shade, water, and
feed sources can be used as a management tool to, for
example, lure animals away from natural water sources
such as streams where congregation by livestock may
damage banks and cause other undesirable environmental
effects (Belsky et al. 1999; Agouridis et al. 2005).
When locating water sources, how far animals have to
travel should also be considered. Many practitioners sug-
gest a rule of thumb that livestock not walk more than
400 m to water. Where the distance is greater, animals may
spend more time near the water source leading to overgraz-
ing and excessive nutrient build up.
Factors Affecting Choice of Grazing Management
In practice, choice of a grazing management is much more
complex than identifying the combination of intensity,
method, and timing that maximizes forage accumulation,
daily animal performance, or production per unit of land
area. Other key considerations are risk and economic
return to the producer, long-term pasture persistence,
environmental impact, and whether or not the level of
decision making associated with a given management
practice suits the interests of the practitioner.
Looking forward, production potential may play a
lesser role in management decisions, and environmental
impact and delivery of ecosystem services may assume a
greater importance. Thus, the effects of grazing manage-
ment on soil nutrient redistribution and accumulation
(Dubeux et al. 2007), nutrient runoff and leaching, soil
compaction and erosion (da Silva et al. 2003), surface
water and groundwater quality, and C sequestration may
well be critical factors that affect future recommenda-
tions of grazing management in forage–livestock systems
(Sollenberger et al. 2012).
References
Agouridis, C.T., Workman, S.R., Warner, R.C., and
Jennings, G.D. (2005). Livestock grazing management
impacts on stream water quality: a review. J. Am. Water
Resour. Assoc. 41: 591–606.
Alderman, P.D., Boote, K.J., and Sollenberger, L.E.
(2011a). Regrowth dynamics of ‘Tifton 85’ bermuda-
grass as affected by nitrogen fertilization. Crop Sci. 51:
1716–1726.
Alderman, P.D., Boote, K.J., Sollenberger, L.E., and
Coleman, S.W. (2011b). Carbohydrate and nitrogen
reserves relative to regrowth dynamics of ‘Tifton 85’
bermudagrass as affected by nitrogen fertilization. Crop
Sci. 51: 1727–1738.
Allen, V.G., Batello, C., Berretta, E.J. et al. (2011). An
international terminology for grazing lands and grazing
animals. Grass Forage Sci. 66: 2–28.
Anderson, B., Matches, A.G., and Nelson, C.J. (1989).
Carbohydrate reserves and tillering of switchgrass fol-
lowing clipping. Agron. J. 81: 13–16.
Barnes, M.K., Norton, B.E., Maeno, M., and Malechek,
J.C. (2008). Paddock size and stocking density affect
spatial heterogeneity of grazing. Rangeland Ecol. Man-
age. 61: 380–388.
Belsky, A.J., Matzke, A., and Uselman, S. (1999). Survey
of livestock influences on stream and riparian ecosys-
tems in the western United States. J. Soil Water Conserv.
54: 419–431.
Bertelsen, B.S., Faulkner, D.B., Buskirk, D.D., and
Castree, J.W. (1993). Beef cattle performance and
forage characteristics of continuous, 6-paddock,
and 11-paddock grazing systems. J. Anim. Sci. 71:
1381–1389.
Briske, D.D. (1986). Plant responses to defoliation: mor-phological considerations and allocation priorities. In:
Rangelands: A Resource Under Siege (eds. J.W. Joss et al.),
425–427. UK: Cambridge University Press.
Brummer, E.C. and Moore, K.J. (2000). Persistence
of perennial cool-season grass and legume cultivars
�
� �
�
812 Part IX Pasture Management
under continuous grazing by beef cattle. Agron. J. 92:
466–471.
Burns, J.C., Lippke, H., and Fisher, D.S. (1989). The rela-
tionship of herbage mass and characteristics to animal
responses in grazing experiments. In: Grazing Research:
Design, Methodology, and Analysis (ed. G.C. Marten),
7–19. Madison, WI: CSSA, Special Publication No.
16.
Burns, J.C., McIvor, J.G., Villalobos, L. et al. (2004).
Grazing systems for C4 grasslands: a global perspective.
In: Warm-Season (C4) Grasses (eds. L.E. Moser et al.).
Madison, WI: ASA, CSSA.
Casler, M.D. and Carlson, I.T. (1995). Smooth
bromegrass. In: Forages: An Introduction to Grassland
Agriculture (eds. R.F Barnes et al.), 313–324. Ames:
Iowa State University Press.
Casler, M.D. and Walgenbach, R.P. (1990). Ground cover
potential of forage grass cultivars mixed with alfalfa at
divergent locations. Crop Sci. 30: 825–831.
Chaparro, C.J., Sollenberger, L.E., and Linda, S.B.
(1991). Grazing management effects on aeschynomene
seed production. Crop Sci. 31: 197–201.
Chaparro, C.J., Sollenberger, L.E., and Quesenberry,
K.H. (1996). Light interception, reserve status, and
persistence of clipped Mott elephantgrass swards. Crop
Sci. 39: 649–655.
Chapman, D.F. and Lemaire, G. (1993). Morphogenetic
and structural determinants of plant growth after defo-
liation. In: Grasslands for Our World (ed. M.J. Baker),
55–64. Wellington, New Zealand: SIR Publishing.
Clement, C.R., Hopper, M.J., Jones, L.H.P., and Leafe,
E.L. (1978). The uptake of nitrate by Lolium perenne
from flowing nutrient solution. II. Effect of light, defo-
liation, and relationship to CO2 flux. J. Exp. Bot. 29:
1173–1183.
Culvenor, R.A., Davidson, I.A., and Simpson, R.J.
(1989). Regrowth by swards of subterranean clover
after defoliation. 1. Growth, non-structural carbohy-
drate and nitrogen content. Ann. Bot. 64: 545–556.
Dubeux, J.C.B. Jr., Stewart, R.L. Jr., Sollenberger, L.E.
et al. (2006). Spatial heterogeneity of herbage response
to management intensity in continuously stocked Pen-
sacola bahiagrass pastures. Agron. J. 98: 1453–1459.
Dubeux, J.C.B. Jr., Sollenberger, L.E., Mathews, B.W.
et al. (2007). Nutrient cycling in warm-climate grass-
lands. Crop Sci. 47: 915–928.
Dubeux, J.C.B. Jr., Sollenberger, L.E., Gaston, L.A. et al.
(2009). Animal behavior and soil nutrient distribu-
tion in continuously stocked Pensacola bahiagrass pas-
tures managed at different intensities. Crop Sci. 49:
1453–1459.
Dubeux, J.C.B. Jr., Sollenberger, L.E., Vendramini,
J.M.B. et al. (2014). Stocking method, animal behav-
ior, and soil nutrient redistribution: how are they
linked? Crop Sci. 54: 2341–2350.
Duble, R.L., Lancaster, J.A., and Holt, E.C. (1971).
Forage characteristics limiting animal performance on
warm-season perennial grasses. Agron. J. 63: 795–798.
Evers, G.W. and Nelson, L.R. (2000). Grazing termina-
tion date influence on annual ryegrass seed production
and reseeding in the southeastern USA. Crop Sci. 40:
1724–1728.
Fisher, D.S., Mayland, H.F., and Burns, J.C. (2002). Vari-
ation in ruminant preference for alfalfa hays cut at
sunup and sundown. Crop Sci. 42: 231–237.
Fulkerson, W.J. and Donaghy, D.J. (2001). Plant-soluble
carbohydrate reserves and senescence – key criteria for
developing an effective grazing management system for
ryegrass-based pastures: a review. Aust. J. Exp. Agric. 41
(2): 261–275.
Fulkerson, W.J. and Slack, K. (1994). Leaf number as a
criterion for determining defoliation time for Lolium
perenne. 1. Effect of water-soluble carbohydrates and
senescence. Grass Forage Sci. 49: 373–377.
Gastal, F. and Lemaire, G. (2015). Defoliation, shoot plas-
ticity, sward structure and herbage utilization in pas-
ture: review of underlying ecophysiological processes.
Agriculture 5: 1146–1171.
Gibson, D., Casal, J.J., and Deregibus, V.A. (1992). The
effect of plant density on shoot and leaf lamina angles
in Lolium multiflorum and Paspalum dilatatum. Ann.
Bot. 70: 69–73.
Gold, W.G. and Caldwell, M.M. (1989). The effects of the
spatial pattern of defoliation on regrowth of a tussock
grass. II. Canopy gas exchange. Oecologia 81: 437–442.
Gompert, T. (2010). The power of stock density. Pro-
ceedings of the Nebraska Grazing Conference, Kearney,
NE, USA (20 July 2010).
Guillen, R.L., Eckroat, J.A., and McCollum, F.T. III
(2000). Vegetation response to stocking rate in south-
ern mixed-grass prairie. J. Range Manage. 53: 471–478.
Hart, R.H. and Ashby, M.M. (1998). Grazing intensities,
vegetation, and heifer gains: 55 years on shortgrass. J.
Range Manage. 51: 392–398.
Hernández Garay, A., Sollenberger, L.E., McDonald,
D.C. et al. (2004). Nitrogen fertilization and stock-
ing rate affect stargrass pasture and cattle performance.
Crop Sci. 44: 1348–1354.
Hodgkinson, K.C., Ludlow, M.M., Mott, J.J., and
Baruch, Z. (1989). Comparative responses of the
savanna grasses Cenchrus ciliaris and Themeda triandra
to defoliation. Oecologia 79: 45–52.
Hodgson, J. (1990). Grazing Management: Science into
Practice. New York: Wiley.
Hoveland, C.S., McCann, M.A., and Hill, N.S.
(1997). Rotational vs. continuous stocking of
beef cows and calves on mixed endophyte-free tall
fescue-bermudagrass pasture. J. Prod. Agric. 10:
245–250.
�
� �
�
Chapter 44 Pasture Design and Grazing Management 813
Huber, H., Lukács, S., and Watson, M.S. (1999). Spatial
structure of stoloniferous herbs: an interplay between
structural blueprint, ontogeny and phenotypic plastic-
ity. Plant Ecol. 141: 107–115.
Humphreys, L.R. (2001). International grassland
congress outlook: an historical review and future
expectations. In: Proceedings of the International Grass-
lands Congress, 19th, São Pedro, Brazil, 10–21 February
2001 (eds. J.A. Gomide et al.), 1085–1087. Piracicaba,
Brazil: Brazilian Society of Animal Husbandry.
Hunt, L.P., Petty, S., Cowley, R. et al. (2007). Factors
affecting the management of cattle grazing distribution
in northern Australia: preliminary observations on the
effect of paddock size and water points. Rangeland J.
29: 169–179.
Jarvis, S.C. and Macduff, J.H. (1989). Nitrate nutrition
of grasses from steady-state supplies in flowing solu-
tion culture following nitrate deprivation and/or defo-
liation. I. Recovery of uptake and growth and their
interactions. J. Exp. Bot. 40: 965–975.
Jones, R.J. and Jones, R.M. (1997). Grazing management
in the tropics. In: Proceeding of the International Grass-
lands Congress, 18th, Winnipeg and Saskatoon, Canada.
8–17 June 1997. Grasslands 2000, Toronto, 535–542.
Jones, R.J. and LeFeuvre, R.P. (2006). Pasture produc-
tion, pasture quality and their relationships with steer
gains on irrigated, N-fertilised pangola grass at a range
of stocking rates in the Ord Valley, Western Australia.
Trop. Grasslands 40: 1–13.
López, I.F., Hodgson, J., Hedderly, D.I. et al. (2003).
Selective defoliation by sheep according to slope and
plant species in the hill country of New Zealand. Grass
Forage Sci. 58: 339–349.
Matches, A.G. and Burns, J.C. (1995). Systems of grazing
management. In: Forages: The Science of Grassland Agri-
culture (eds. R.F Barnes et al.), 179–192. Ames: Iowa
State University Press.
Mathews, B.W., Sollenberger, L.E., Kunkle, W.E. et al.
(1994). Dairy heifer and bermudagrass pasture
responses to rotational and continuous stocking. J.
Dairy Sci. 77: 244–252.
Matthew, C., Assuero, S.G., Black, C.K., and Sackville
Hamilton, N.R. (2000). Tiller dynamics of grazed
swards. In: Grassland Ecophysiology and Grazing Ecol-
ogy (eds. G. Lemaire et al.), 127–150. New York: CABI
Publisher.
McCartor, M.M. and Rouquette, F.M. Jr. (1977). Grazing
pressures and animal performance from pearl millet.
Agron. J. 69: 983–987.
Mikola, J., Setälä, H., Virkajärvi, P. et al. (2009).Defolia-
tion and patchy nutrient return drive grazing effects on
plant and soil properties in a dairy cow pasture. Ecol.
Monogr. 79: 221–244.
Mott, G.O. and Moore, J.E. (1985). Evaluating forage
production. In: Forages: The Science of Grassland Agri-
culture (eds. R.F Barnes et al.), 97–110. Ames, IA: Iowa
State University Press.
Mullenix, M.K., Sollenberger, L.E., Wallau, M.O. et al.
(2016). Sward structure, light interception, and
rhizome-root responses of rhizoma peanut cultivars
and germplasm to grazing management. Crop Sci. 56:
899–906.
Nelson, C.J. (2000). Shoot morphological plasticity of
grasses: leaf growth vs. tillering. In: Grassland Ecophys-
iology and Grazing Ecology (eds. G. Lemaire et al.),
101–126. New York: CABI Publisher.
Newman, Y.C., Sollenberger, L.E., Kunkle, W.E., and
Chambliss, C.G. (2002). Canopy height and nitrogen
supplementation effects on performance of heifers graz-
ing limpograss. Agron. J. 94: 1375–1380.
Newman, Y.C., Sollenberger, L.E., and Chambliss,
C.G. (2003a). Canopy characteristics of continuously
stocked limpograss swards grazed to different heights.
Agron. J. 95: 1246–1252.
Newman, Y.C., Sollenberger, L.E., Fox, A.M., and
Chambliss, C.G. (2003b). Canopy height effects on
vaseygrass and bermudagrass spread in limpograss pas-
tures. Agron. J. 95: 390–394.
Ortega-S., J.A., Sollenberger, L.E., Bennett, J.M., and
Cornell, J.A. (1992). Rhizome characteristics and
canopy light interception of grazed rhizoma peanut
pastures. Agron. J. 84: 804–809.
Ourry, A., Boucaud, J., and Salette, J. (1988). Nitrogen
mobilization from stubble and roots during re-growth
of defoliated perennial ryegrass. J. Exp. Bot. 39:
803–809.
Parsons, A.J., Johnson, I.R., and Harvey, A. (1988). Use of
a model to optimize the interaction between frequency
and severity of intermittent defoliation and to provide a
fundamental comparison of the continuous and inter-
mittent defoliation of grass. Grass Forage Sci. 43: 49–59.
Pedreira, C.G.S., Sollenberger, L.E., and Mislevy, P.
(1999). Productivity and nutritive value of ‘Florakirk’
bermudagrass as affected by grazing management.
Agron. J. 91: 796–801.
Peterson, P.R. and Gerrish, J.R. (1995). Grazing Man-
agement Affects Manure Distribution by Beef Cattle,
170–174. Lexington: Proceedings of American Forage
Grassland Council.
Richards, J.H. (1993). Physiology of plants recovering
from defoliation. In: Grasslands for Our World (ed.
M.J. Baker), 46–54. Wellington, New Zealand: SIR
Publishing.
Roth, L.D., Rouquette, F.M. Jr., and Ellis, W.C. (1990).
Effects of herbage allowance on herbage and dietary
attributes of Coastal bermudagrass. J. Anim. Sci. 68:
193–205.
�
� �
�
814 Part IX Pasture Management
Rowarth, J.S., Tillman, R.W., Gillingham, A.G., and
Gregg, P.E.H. (1992). Phosphorus balances in grazed
hill-country pastures: the effect of slope and fertilizer
input. N.Z. J. Agric. Res. 35: 337–342.
Saul, G.R. and Chapman, D.F. (2002). Grazing methods,
productivity and sustainability for sheep and beef pas-
tures in temperate Australia. Wool Technol. Sheep Breed.
50: 449–464.
Schlegel, M.L., Wachenheim, C.J., Benson, M.E. et al.
(2000). Grazing methods and stocking rates for
direct-seeded alfalfa pastures: I. Plant productivity and
animal performance. J. Anim. Sci. 78: 2192–2201.
Shepard, E.M., Sollenberger, L.E., Kohmann, M.M. et al.
(2018). Grazing management affects Ecoturf rhizoma
peanut forage performance and canopy structure. Crop
Sci. https://doi.org/10.2135/cropsci2015.02.0090.
da Silva, A.P., Imhoff, S., and Corsi, M. (2003). Evalua-
tion of soil compaction in an irrigated short-duration
grazing system. Soil Tillage Res. 70: 83–90.
Skinner, R.H., Morgan, J.A., and Hanson, J.D. (1999).
Carbon and nitrogen reserve remobilization following
defoliation: nitrogen and elevated CO2 effects. Crop
Sci. 39: 1749–1756.
Sollenberger, L.E. and Burns, J.C. (2001). Canopy char-
acteristics, ingestive behaviour and herbage intake
in cultivated tropical grasslands. In: Proceedings of
the International Grassland Congress, 19th, São Pedro,
Brazil. 10–21 February 2001 (eds. J.A. Gomide et al.),
321–327. Piracicaba, Brazil: Brazilian Society of Ani-
mal Husbandry.
Sollenberger, L.E. and Vanzant, E.S. (2011). Interre-
lationships among forage nutritive value and quan-
tity and individual animal performance. Crop Sci. 51:
420–432.
Sollenberger, L.E., Agouridis, C.T., Vanzant, E.S. et al.
(2012). Prescribed grazing on pasturelands. In: Con-
servation Outcomes from Pastureland and Hayland Prac-
tices: Assessment, Recommendations, and Knowledge Gaps
(ed. C.J. Nelson), 111–204. Lawrence, KS: Allen Press.
Stewart, R.L. Jr., Dubeux, J.C.B. Jr., Sollenberger, L.E.
et al. (2005). Stocking method affects plant responses
of Pensacola bahiagrass pastures.Online. Forage Graz-
inglands https://doi.org/10.1094/FG-2005-1028-01-
RS.
Thornton, B., Millard, P., and Bausenwein, U. (2000).
Reserve formation and recycling of carbon and nitro-
gen during regrowth of defoliated plants. In: Grassland
Ecophysiology and Grazing Ecology (eds. G. Lemaire, J.
Hodgson and A. de Moraes), 85–99. New York: CABI
Publisher.
Vallentine, J.F. (2001). Grazing Management, 2e. San
Diego, California: Academic Press.
Volesky, J.D. (1994). Tiller defoliation patterns under
frontal, continuous, and rotation grazing. J. Range
Manage. 47: 215–219.
https://doi.org/10.2135/cropsci2015.02.0090
https://doi.org/10.1094/FG-2005-1028-01-RS
https://doi.org/10.1094/FG-2005-1028-01-RS