Review: Behavior and daily grazing patterns of cattle

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The Professional Animal Scientist 22 (2006):201–209
R
EVIEW
: Behavior and Daily Grazing
Patterns of Cattle
P. GREGORINI,*
†
PAS, S. TAMMINGA,
‡
and S. A. GUNTER,*
1
PAS
*Southwest Research and Extension Center, Division of Agriculture, University of Arkansas, Hope
71801;
†
Facultad de Ciencias Agrarias y Forestales, Universidad Nacional de La Plata, La Plata,
CP1900, Buenos Aires, Argentina;
‡
Wageningen Institute of Animal Science, Wageningen University
and Research Centre, 6700 AH Wageningen, The Netherlands
Abstract
Grazing ruminants consume their food
in discrete grazing events. The frequency
and distribution of these events depend
on the current physiological state of the
animal and its environment. Within a
small spatio-temporal scale, foraging deci-
sions such as when to begin, which fre-
quency, and how to distribute the graz-
ing events may determine how cattle allo-
cate time to meet their nutritional needs.
The longest and most intense grazing
events occur normally at dusk; this in-
take pattern serves to maximize daily en-
ergy intake, provide a steady release of
nutrients, and maintain satiety over the
night. Although ruminants may have a
high motivation to seek food at dawn,
this grazing event normally is of lesser in-
tensity and duration than the dusk graz-
ing event. Because of the timing of these
grazing events, ruminants seem to be cre-
puscular animals, and light provides an
environmental cue as to when to seek
food. Certainly, the preference for twi-
light grazing plays a role in shaping the
daily grazing pattern, yet it remains to
be explained if this preference also re-
flects temporal variation in the underly-
ing physiology. On the other hand, mod-
ern husbandry could not have eliminated
any evolved anti-predator strategy legated
1
To whom correspondence should be ad-
dressed: sgunter@uaex.edu
by their ancestors. Voluntary feed intake
ultimately abuts on animal psychology.
Clearly, there are major gaps in our
knowledge because there are virtually no
published data relating the last question
to domestic ruminants.
Key words: behavior, grazing, pat-
tern, cattle
Introduction
Herbage, the resource under exploi-
tation by grazing ruminants, is rarely
presented in discrete packages (Berg-
man et al., 2000). What we call rumi-
nant nutrition at pasture is therefore
an exciting area of research that links
the nutritional and behavioral sci-
ences. Regardless of the way forage is
offered, ruminants consume their
food in discrete meals that alternate
with periods of rumination and
idling (Forbes, 1995). The choice of
which behavioral activity is per-
formed depends on the current state
of the animal, its environment, and
possibly past and anticipated states
(Mangel and Clark, 1986). Under tem-
perate grazing conditions, cattle seem
to discriminate between temporal
states of pasture and graze selectively
when confronted with heterogeneous
swards. That is, foraging strategies are
dynamic in response to changing
sward conditions, and selection arises
as one of the main mechanisms en-
abling animals to control herbage in-
take and diet quality (WalliesDeVries
and Delabout, 1994). This selectivity
appears to be strongly affected by
landscape, and seems to differ greatly
among patch types (WalliesDeVries
and Delabout, 1994). In addition,
WalliesDeVries and Laca (1999) have
shown that size of patches affects se-
lection. An intriguing question thus
arises with regard to how to describe
grazing behavior and what happens
at the paddock level. Could daily graz-
ing pattern be changed? The objec-
tives of this review are to discuss an
outline about how to describe the
grazing patterns of cattle at the pad-
dock level, to identify gaps in our
knowledge of grazing behavior, and
to propose approaches to address
these gaps.
Review and Discussion
Spatio-Temporal Scales. Scale is an
essential concept in ecological and so-
cial sciences that refers primarily to
temporal and spatial dimensions at
which phenomena are observed (van
Gardingen et al., 1997; Paterson and
Parker, 1998). Integration of area and
time is referred to as spatio-temporal
extent (Rietkerk et al., 2002), and its
resolution as grain (Wu, 1999). Scale
gives us a fundamental framework in
which an ecological phenomena can
be studied and understood (Wu and

Gregorini et al.202
Figure 1. Attributes of different extents of scale in the foraging of a large herbivores [Adapted from Bailey et al. (1996) and drawing adapted
from Galli (1994)].
Qi, 2000; Pereira, 2002). Moreover,
patterns and processes observed in
plants and animals depend on scales,
as well as the functional responses. In
ecology, this response is defined as
the relationship between animal vol-
untary intake and the food offered
(Holling, 1959), or the relationship be-
tween predation rate and prey den-
sity [Solomon (1949), cited by
Jeschke et al. (2002)].
Giving attention to scales is im-
portant (Wiens, 1989), and that of nu-
tritional ecology of grazing ruminants
is not the exception (Fryxell et al.,
2001). If there is an imbalance of
scales, then scaling-up or down leads
to errors in interpretation (Brown and
Allen, 1989; Wiens, 1989; Marriot
and Carrere, 1998). Integrating func-
tional responses from small to larger
scales (Figure 1), as in the calculation
of daily herbage intake, is one such
example. Such scaling-up has been
made through daily grazing time:
herbage intake = (bites/unit time) ×
(intake/bite) ×(grazing time). This
type of scaling-up should be restricted
to homogeneous grazing environ-
ments where sward variables that de-
termine intake rate remain constant
(WalliesDeVries et al., 1998). How-
ever, cattle normally graze heteroge-
neous pastures (Schwinning and Par-
son, 2001). Heterogeneous environ-
ments are characterized by spatial
and temporal changes in their descrip-
tors. Hence, mean values of biomass,
height, or chemical composition
would be poor predictors of any func-
tional response (Laca et al., 1992;
Bergman et al., 2000, 2001). This fact
was clearly demonstrated by Cham-
pion et al. (1994), Orr et al. (1997),
and Gibb et al. (1998) (Figures 2 and
3) as well as Barret et al. (2001), who
found different parameter values of
the grazing process during the day.
The latter clearly demonstrated the
negative impact of the progressive
sward depletion on bite mass: 0.74
vs. 0.62 g DM at 0700 h and 1800 h,
respectively.
From a practical point of view, a
sum of feeding sites (Figure 1) could
be considered a paddock, which
could be seen as homogeneous; but
heterogeneity increases during graz-
ing, both spatially and temporally.
Moreover, heterogeneity may be mea-
sured, even before grazing starts,
since bulk density (Barthram et al.,
2000) and chemical composition (De-
lagarde et al., 2000; Taweel, 2004)
vary from the top to the bottom of
the canopy, and through the day.
Hence, when interpreting the re-
sponse of grazing ruminants, hetero-
geneity must be considered (Parsons
and Dumont, 2003). Given that heter-
ogeneity is scale-dependent (Kolasa
and Rollo, 1991), one could argue
that the study of plant-animal rela-
tionships is also dependent on scale
(Rietkerk et al., 2002) and scales
should be considered if the objective
is to gain better understanding of con-
cepts and mechanisms controlling cat-
tle-pasture relationships. Hence, func-
tional heterogeneity, defined as the re-
lationship between an organism and
its environment, (Kotliar and Wiens,
1990), is relevant in these types of
studies. For this reason, perceptions
of the cattle rather than the investiga-
tors must be considered [Wiens
(1976), cited by Arditi and Dacorogna

R
EVIEW
: Daily Grazing Pattern 203
Figure 2. Typical grazing pattern and organic matter intake rate of dairy cows under continuous stocking (M. J. Gibb, Inst. of Grassland and
Environ. Res., Okehampton, North Wyke, UK, personal communication).
(1988)]. It is thus a challenge to recog-
nize how our perceptual scales condi-
tion the way we describe the scales of
animals (Allen and Hoekstra, 1992;
Levin, 1992; Ritchie, 1998), how pat-
terns change across them, and how
phenomena at different scales influ-
ence each other.
Ecosystems, landscapes, communi-
ties, and populations are usefully de-
scribed as hierarchies of nested com-
ponents (Allen and Hoekstra, 1992).
Within these hierarchies the nested
components are distinguished by the
appropriate spatio-temporal scales.
Bailey et al. (1996) identified 6 scales
for large herbivores in the foraging hi-
erarchy: bite, feeding station, patch,
feeding site, camp, and home range.
If the extent of our work is an ar-
rangement (cluster) of feeding sites
(Figure 1), then it is useful to look at
the paddock to understand the con-
Figure 3. Effect of time of day on grazing behavior of lactating dairy cows, under continuous grazing (J. M. Gibb, Institute of Grassland and
Environ. Res., Okehampton, North Wyke, UK, personal communication). BM = bite mass; BR = bite rate; IR = intake rate; B/GJM = bite per
grazing jaw movement.
text and the next levels down to un-
derstand the mechanisms (Allen and
Hoekstra, 1992).
Grazing Events. Foraging decisions
made at broader scales (home range,
at dispersal, or during migration) an-
swer where to start grazing at the be-
ginning of a grazing event (Bailey et
al., 1996). However, that decision
probably is irrelevant for animals in
small paddocks because the entire
area is readily accessible (Bailey et al.,
1996). Metz (1975) suggested the con-
cept of a meal (grazing event in this
case) as a cluster of grazing bouts,
and Gibb (1998) pointed out that all
grazing events are cumulative and
therefore sum to daily grazing time.
Because grazing time encompasses a
cluster of discrete grazing events, for-
aging decisions such as when to be-
gin, at which frequency, and how to
spread the grazing events through
time might be more important
within a smaller scale (i.e., paddock).
Such decisions determine how cattle
invest their time in feeding to meet
metabolic requirements for nutrients.
Frequency and distribution. The
relevant period of time where meals
occur differs distinctly among animal
types (Collier and Johnson, 1990;
2004). In grazing ruminants, this pe-
riod lasts 24 h because their meal pat-
tern is circadian. In temperate cli-
mates, ruminants have 3 to 4 major
grazing events per day (Figure 2; Gibb
et al., 1998). However, this frequency
is not inflexible and is affected by ex-
ternal environment or behavioral ad-
aptations. During short days, grazing
events could merge as a consequence
of increased grazing bout length and
a decreased number. Preference to
graze during daylight hours may re-
flect greater difficulty of food selec-

Gregorini et al.204
tion in the dark (Linnane et al.,
2001). As a result of this change in
grazing pattern, daily grazing time
can be maximized. Cattle have be-
come adapted to modern husbandry
methods, which can be used to stimu-
late the motivation to graze (Toates,
2002). As such, the precise time of
the grazing events can be modified,
depending for instance upon events
such as removal for milking (M. J.
Gibb, Inst. Grassland Environ. Res.,
Okehampton, North Wyke, UK, per-
sonal communication) or time of
herbage allocations (Gregorini et al.;
2004, 2005a,b). Regardless of fre-
quency, the major grazing events oc-
cur near sunrise and sunset (Figures 2
and 3), with the latter having greater
intensity and longer duration (Gibb
et al., 1998; Taweel, 2004). Shorter
and less intense grazing events occur
at night. These events represent a
small percentage of daily grazing time
and contribute minimally to daily
herbage intake (O’Connell et al.,
1989; Krysl and Hess, 1993).
Discriminatory grazing activity.
Preference is the discrimination that
an animal displays in choosing be-
tween swards or sward components
when grazing (Hodgson, 1979). Hodg-
son (1979) suggested use of this term
until we are better able to assess the
relative importance of factors in-
volved in the grazing process.
Daily patterns in dietary preference
have been demonstrated by Newman
et al. (1994) and Parsons et al. (1994).
Recently, more detailed examination
of grazing behavior recordings has
shown the existence of both of the 2
major grazing events mentioned
above (Taweel, 2004), and differences
in the functional response among all
grazing events (Figure 3). These find-
ings provide definitive evidence that
the grazing patterns throughout the
day are discriminatory.
Several studies have shown diurnal
variation in herbage chemical compo-
sition (Fulkerson et al., 1994; Orr et
al., 2001b; Mayland et al., 2003;
Burns et al., 2005). Furthermore, diur-
nal variation has been noted in
grazed horizons (Barthram et al.,
2000; Taweel, 2004; Griggs et al.,
2005; P. Gregorini, unpublished
data). Dry matter and soluble carbo-
hydrate concentrations of the sward
increase through the day with the ac-
cumulation of photosynthates (Orr et
al., 2001b; Griggs et al., 2005), primar-
ily in the upper layers of the sward
(Delegarde et al., 2000). Increased
non-structural carbohydrate concen-
trations support greater digestibility
(Civarella et al. 2000; Linnane et al.,
2001) and palatability (Provenza et
al., 1998). Thus, diurnal changes in
herbage quality may play a role in
driving the preference for an intense,
extended grazing event at dusk. From
an evolutionary viewpoint, it seems
reasonable for cattle to graze at dusk
as this makes more efficient use of
plant phenology (Linnane et al.
2001). But the question remains,
why? Provenza et al. (1998) suggested
that grazing behavior may also be re-
lated to diurnal changes in food qual-
ity; animals may prefer foods that are
more digestible or greater in macronu-
trients (Provenza, 1996). Furthermore,
animals may use short-term intake
rate or post-ingestive outcomes to in-
tegrate information obtained through
diet selection (Provenza, 1995; Walli-
esDeVries et al., 1998). Thus, conse-
quences at lesser hierarchical levels
such as grazing bout or event might
be used to develop expectations at
greater levels of the feeding process
such as grazing event, daily intake, or
even grazing pattern (Figure 1; Bailey
et al., 1996; WalliesDeVries et al.,
1998). However, research evidence for
this is lacking. Most foraging behav-
ior studies have examined functional
responses that occur within one or
just a few grazing bouts and are not
able to fully capture the dynamics of
the grazing process (Newman et al.,
1994). Momentary maximization is a
mechanism that explains diet selec-
tion and animal movement along the
grazing pathway, which assumes that
animals select the best available alter-
native at any given time (Staddon,
1983). Thus, additional questions
arise regarding whether this phenome-
non takes place and if this concept
can be applied to a longer time inter-
val, such as a day. If it cannot be ap-
plied, it would appear that cattle ei-
ther apply an optimal foraging strat-
egy by trying to maximize the long-
term (daily) intake rate of energy (Ste-
phens and Krebs, 1986), or they just
look for the most comfortable situa-
tion. From a daily and longer perspec-
tive, the maximization of energy in-
take rates through a longer and more
intensive grazing event at dusk makes
sense for the animals, because fitness
(Newman et al., 1995) and perfor-
mance can be improved. This prem-
ise is supported by results of Orr et al.
(2001a), Eirin et al. (2005a,b), and
Gregorini et al. (2004; 2005a,b).
The longer, more intense grazing
event at dusk could also serve to
maintain a steady release of nutrients,
maintaining a comfortable state
through the night. Satiety is defined
as the effect of a food or a meal on
appetite after eating has ended (Kral
and Rolls, 2004). It is also the state
from the end of one meal to the oc-
currence of the next during which an
animal does not eat and is not moti-
vated to eat [Le Mangen, (1986), cited
by Lindstrm (2000)]. Satiety comes
from an integrated, complex set of sig-
nals from many parts of the body
(Forbes, 1999, 2000), even from oral
levels (Lindstrm, 2000; Toates, 2002).
A short-term supply of excess nutri-
ents or an imbalanced diet such as
found in herbage at morning (Rearte
and Santini, 1989; Poppi et al., 1999;
Elizalde and Santini, 1992) can result
in satiety that may also be described
as a state of metabolic discomfort. As
such, the ratio of nutrients being ab-
sorbed from the gastro-intestinal tract
would induce a metabolic imbalance
(Forbes, 2000). The importance of nu-
trient imbalance in the control of in-
take has been addressed (Poppi and
McLennan, 1995; Illius and Jessop,
1996; Simpson et al., 2004) and
might be relative to this question.
Conversely, under-eating (relative to
demands) generates hunger (Forbes
and Provenza, 2000). The degree of
hunger would be dependent on previ-
ous nutrition, both short- and long-

R
EVIEW
: Daily Grazing Pattern 205
term (Forbes and Provenza, 2000).
However, the process of satiation is
also directed within the context of
achieving the most comfortable situa-
tion. While comfort is a function of
appropriate nutrient supply, it is also
affected by other factors such as fear
of predators (Forbes, 2000). Animals
can perform only one behavior at a
time, even if the stimuli appropriate
for more than one behavior are pres-
ent (Lindstrm, 2000; Toates, 2002).
This means that there must be a deci-
sion-making process to determine
which activity the animal performs at
any given time. Natural evacuation of
digesta from the gastro-intestinal tract
leads to the smallest ruminal pool
size early in the morning. This would
generate hunger and could be one of
the reasons explaining the high moti-
vation to graze at sunrise when herb-
age has the most constraining fea-
tures for consumption, from a nutri-
tive and harvesting view point.
Therefore, the internal state (Mangel
and Clark, 1986; Newman et al.,
1995) and external incentives (sight,
delivery of fresh food, food presenta-
tion, and a cue that food will soon be
available) might stimulate the motiva-
tion of animals to graze at dawn.
Here, questions emerge: How big and
measurable is the stimulus of natural
digesta in the rumen, with ruminal
fill as one main determinant of the
internal state on the animal (New-
man et al., 1995)? How does this stim-
ulus affect not only short-term intake
rate, but also grazing dynamics? Can
grazing dynamics be managed
through manipulated ruminal fills?
Despite that strong motivation, the
first grazing event is both of lesser in-
tensity (intake rate) and shorter dura-
tion with longer intra-meal intervals
(Rook et al., 1994; Rook and Huckle,
1997). This grazing pattern may be a
function of an imbalanced diet or an
unbalanced ratio of post-ingestive
compounds such as volatile fatty
acids (Chilibroste, 1999). However,
plant physical characteristics and envi-
ronmental conditions may also con-
tribute to this grazing pattern. Short-
term intake rate is dependent upon
Figure 4. The components of ingestive behavior, which mediate between sward structure and
short-term intake rate.
bite mass in cattle and in other rumi-
nants (Hudson and Frank, 1986; Illius
and Gordon, 1987; Shipley and Spal-
inger, 1992), and bite mass is con-
trolled by the way that plant physical
characteristics (Burlison et al., 1991;
Laca et al., 1992; Ungar, 1996) inter-
act with the mouth morphology (Fig-
ure 4; Illius and Gordon, 1987;
Shipley et al., 1994; Rook et al.,
2004). Surface moisture also plays a
part in this interaction. Surface mois-
ture, prevalent on grasses in the
morning (Tallowin et al., 1991), may
also explain the lower bite mass at
this time of the day (Gibb et al.,
1998), as lubricity of the leaf laminae
may increase slippage between the in-
cisors and dental pad.
Photo-effect: A Stimulus. Photope-
riod has been hypothesized as one
factor controlling grazing activity (Ho-
gan et al., 1987; Linnane et al., 2001).
Due to the occurrence of dawn and
dusk grazing events, ruminants can
be described as crepuscular animals
(Phillips, 1993). Strong evidence for
this kind of pattern has been found
in the African buffalo (Sinclair, 1977),
bison (Hudson and Frank, 1986), and
grazing sheep (Champion et al.,
1994; Orr et al., 1997), as well as in
dairy cows (Gibb et al., 1998; Orr et
al., 2001b) and beef heifers (Gregorini
et al., 2004, Gregorini et al., 2005b).
This pattern follows a circadian
rhythm, and its association with sun-
rise and sunset implies that it is sensi-
tive to a photo-effect. This is sup-
ported by the timing of dusk GE,
which changes with day length dur-
ing the year. Moreover, duration of
the grazing event remains constant re-
gardless of the actual time of sunset
(Rutter et al., 2002). When the sun is
near to horizon (sunrise and sunset)
the ratio of shorter and longer wave-
lengths is different compared to that
at mid-day. The concurrence of these
different wavelengths with the most
intense GE led Linnane et al. (2001)
to suggest that these light characteris-
tics have a stimulatory effect on appe-
tite. In addition, Phillips and Scho-
field (1989) found cows had increased
numbers of feeding bouts when extra
light was provided during short days,
while Rutter et al. (2002) reported a
disruption of grazing patterns of dairy
cows during a total solar eclipse. Al-
though light should not be regarded
as the dominant environmental cue,
it influences cattle decisions about
when to seek food, and thus plays a
role in shaping daily grazing patterns.
Notwithstanding, it remains to be

Gregorini et al.206
seen if these temporal variations in
the grazing process reflect similar vari-
ation in the underlying physiology
and whether or not light acts synergis-
tically to initiate or intensify grazing
events. It should also be noted that
seasonal photoperiod variations affect
herbage intake (Rhind et al., 2002),
but such larger scale variation is be-
yond the scope of this discussion. On
the other hand, it is possible that
some other factors associated with
light intensity participate in the tem-
poral arrangement of grazing events.
Is It a Psychological Question? Re-
cently, studies have begun to investi-
gate the importance of greater levels
of trade-off other than energetic bene-
fits vs. time requirements. One such
trade-off is between foraging benefits
(net energy intake) and the cost of
predation risk (Houtman and Dill,
1998). Ruminants evolved primarily
as grazing animals, with a unique,
anti-predator digestion-enhancing for-
aging strategy (Phillips, 1993). This
strategy involves consuming herbage
as rapidly as possible, followed by
mastication later, when hidden in rel-
ative safety. Mastication occurs
mostly at night (Newman et al.;
1995; Prins, 1996; Houtman and Dill,
1998) because grazing diminishes
alertness and increases the risk of pre-
dation (Charnov et al., 1976). Em-
mans and Kiryazakis (1995) have de-
scribed the evolutionary advantages
of optimized food intake by farm ani-
mals. However, psychological effects
are rarely considered, and intake is of-
ten viewed in isolation from other
adaptive characteristics, such as syn-
chrony of certain behaviors.
It appears that cattle attempt to
maximize their intake rate at dusk
(Gibb et al., 1998). Even though in-
take rate increases with the level of
feeding motivation in both animals
and humans (Nielsen, 1999), it re-
mains unclear why they should be
motivated. An answer could be the
predation hazard, but it might possi-
bly be related to biochemical or physi-
ological processes or the retention of
an evolutionary anti-predator
strategy.
In reviewing over 50 studies of
mammals and birds, Elgar (1989) re-
ported a negative correlation between
group size and vigilant behavior, and
most of the studies concluded that
the relationship partly explained why
individuals foraged as groups. Al-
though wild ruminants presumably
are vigilant for predators (Jarman,
1974; Underwood, 1982; Fortin et al.,
2004a,b; Frair et al., 2005), there is
great debate about whether domestic
ruminants are under any serious
threat of predation (Newman et al.,
1995). However, sheep graze longer
when they are in groups [Penning et
al. (1993); Dumont and Boissy
(2001), cited by Parsons and Dumont
(2003)], and the same tendency has
been observed in dairy cows (Rind
and Phillips, 1999). Rook and Huckle
(1997) suggest that the preference to
graze and to be active in the light
may be a vestigial defense mecha-
nism that may reflect an increased
need for alertness.
Several studies (Samuelsson et al.,
1996; Johansson et al., 1999; Linds-
tro
¨m, 2000) make reference to corti-
sol and oxytocin as motivational hor-
mones for feeding behavior. Recently,
serotonin has been considered as a
key neuro-hormone agent in intake
regulation (W. Pittroff, University of
California, Davis, and P. Soca, Uni-
versidad de la Republica, Paysandu,
Uruguay; personal communication).
For our purposes, we consider seroto-
nin and melatonin. Serotonin is syn-
thesized from the amino acid trypto-
phan, and melatonin is derived from
serotonin in a 2-step enzymatic reac-
tion. Serotonin levels are high in the
pineal gland during the light hours,
but diminish during the darkness as
the hormone is converted to melato-
nin (Nelson, 1995). Serotonin deple-
tion as a deficiency syndrome may
lead to symptoms of lethargy, anxi-
ety, and carbohydrate craving (Wurt-
man and Wurtman, 1989), and as
such serotonin is necessary to main-
tain alertness and vigilance. Trypto-
phan circulates in the blood at low
levels and is converted to serotonin
in the brain (Cooper et al., 1986,
cited by Nelson, 1995). Diet affects
this conversion process because carbo-
hydrates stimulate pancreatic β-cells
to secrete insulin, which in turn facili-
tates the uptake of sugars and non-
tryptophan amino acids into periph-
eral cells (Nelson, 1995). This results
in a relatively high ratio of trypto-
phan to other amino acids in the
blood. Because tryptophan competes
with the other amino acids for access
to the central nervous system tissue,
carbohydrate ingestion results in
more tryptophan crossing the blood-
brain barrier and thus higher produc-
tion of serotonin. Solving carbohy-
drate cravings might stop the effect
of serotonin depletion in human be-
ings (Wurtman and Wurtman, 1989;
Hoebel et al., 1992). The question re-
mains whether this phenomenon
could be related to the behavioral ten-
dency of greater carbohydrate intake
found in the dusk grazing event.
Livestock were domesticated 10,000
to 11,000 yr ago in the Neolithic pe-
riod (Campbell and Lasley, 1969;
Pearse, 1971). However, this time pe-
riod is insignificant compared with
their longer period of evolution.
Moreover, modern husbandry could
not have eliminated any evolved
anti-predator strategy legated by their
ancestors. Clearly, there are major
gaps in our knowledge because virtu-
ally no data bear directly on the ques-
tions of whether cattle suffer anxiety,
have fear of darkness, or need to be
alert to predation hazard. Voluntary
feed intake ultimately abuts on ani-
mal psychology (Ungar, 1996; Illius
et al., 2000). Therefore, elucidation of
how signal integration is affected by
the cognitive, physiological, and men-
tal state of the animal remains an im-
portant challenge (Illius et al., 2000).
Implications
Because grazing is the product of
trade-offs, even at paddock level, its
behavior should be analyzed integ-
rating spatio-temporal scales. This is
essential for a better understanding of
grazing process because functional
heterogeneity implies that foraging

R
EVIEW
: Daily Grazing Pattern 207
strategies may not be constant but
vary through time. Daily grazing pat-
tern is the product of complex deci-
sions made by cattle responding to
multiple variables. Cattle seem to
maximize energy intake, preferring to
graze more intensively at dusk, when
the herbage has the greater quality.
Thus, linking plant and animal pro-
cesses to management strategies
emerges as an option to manipulate
temporal distribution, duration and
intensity of grazing events, and
thereby nutrient supply. Finally, graz-
ing behavior is beginning to reveal
how ruminants have evolved to ex-
ploit forage plants and survive in hos-
tile environments. Consequently, we
are able to go further in the knowl-
edge of the main causes of the feed-
ing patterns of domestic ruminants
on pasture.
Literature Cited
Allen, T. F. H., and T. W. Hoekstra. 1992. To-
ward a Unified Ecology. Columbia Univ.
Press, New York, NY.
Arditi R., and B. Docarogna. 1988. Optimal
foraging on arbitrary food distributions and
the definition of habitat patches. Am. Nat.
131:837.
Bailey, D. W., J. E. Gross, E. A .Laca, L. R. Rit-
tenhouse, M. B. Coughenour, D. M. Swift,
and P. L. Sims. 1996. Mechanism that result
in large herbivore grazing distribution pat-
terns. J. Range. Manage. 49:386.
Barret, P. D., A. S. Laidlaw, C. S. Mayne, and
H. Chistie. 2001. Pattern of herbage intake
rate and bite dimensions of rotationally
grazed cows as sward height declines. Grass
Forage Sci. 56:362.
Barthram, G. T., D. A. Elsto, and G. R. Bolton.
2000. A comparison of three methods for mea-
suring the vertical distribution of herbage
mass in grassland. Grass Forage Sci. 55:193.
Bergman, C. M., J. M. Fryxell, G. C. Cormack,
and D. Fortin. 2001. Ungulate foraging strate-
gies: energy maximizing or time minimizing?
J. Anim. Ecol. 70:289.
Bergman, C. M., J. M. Fryxell, and C. C.
Gates. 2000. The effect of tissue complexity
and sward height on the functional response
of Wood Bison. Funct. Ecol. 14:61.
Brown, B. J., and T. F. H. Allen. 1989. The im-
portance of scale in evaluating herbivore im-
pacts. Oikos 54:189.
Burlison, A., J. Hodgson, and A. W. Illius.
1991. Sward canopy structure and the bite di-
mensions and bite weight of grazing sheep.
Grass Forage Sci. 46:29.
Burns, J. C., H. F. Mayland, and D. S. Fisher.
2005. Dry matter intake and digestion of al-
falfa harvested at sunset and sunrise. J. Anim
Sci. 83:262.
Campbell, J. R., and J. F. Lasley, 1969. The Sci-
ence of Animal that Serve Mankind. McGraw-
Hill, Inc., New York, NY.
Champion, R. S., S. M. Rutter, P. D. Penning,
and A. J. Rook. 1994. Temporal variation in
grazing behavior of sheep and the reliability
of sampling periods. Appl. Anim. Behav. Sci.
42:99.
Charnov, E. L., H. O. Gordon, and K. Hyatt.
1976. Ecological implications of resource de-
pression. Am. Nat. 110:247.
Chilibroste, P., 1999. Grazing time: The miss-
ing link? A study on the plant-animal inter-
face by integration of experimental and model-
ing approaches. Ph.D. Diss., Wageningen Un-
iverity, Wageningen, The Netherlands.
Ciavarella, T. A., H. Dove, B. J. Leary, and R. J.
Simpson. 2000. Diet selection by sheep graz-
ing Phalaris aquatica L. pastures of differing wa-
ter-soluble carbohydrate content. Aust. J.
Agric. 51:757. [Au: this reference is not cited in
text. Either add to text or delete here]
Collier, G., and D. F. Johnson. 1990. The time
window of feeding. Physiol. Behav. 48:771.
Collier, G., and D. F. Johnson. 2004. The para-
dox of satiation. Physiol. Behav. 82:149.
Cooper, J. R., F. E. Bloom, and R. H. Roth.
1986. The Biochemical Basis of Neuropharma-
cology. 5th ed. Oxford Univ. Press, New York,
NY.
Delagarde, R., J. L. Peyraud, L. Delaby, and P.
Faverdin. 2000. Vertical distribution of bio-
mass, chemical composition and pepsin-cellu-
lase digestibility in a perennial ryegrass sward:
Interaction with month and year, re-growth
age and time of day. Anim. Feed Sci. Technol.
84:49.
Dumont, B., and A. Boissy. 2001. Grazing be-
havior of sheep in situation of conflict be-
tween feeding and social motivations. Behav.
Processes 49:131.
Eirin, M., Gregorini, P., M. L. Agnelli, R. Refi,
M. Ursino, and O. Ansin. 2005a. Respuesta
productiva de vaquillonas en recra ante dos
momentos de asignacin diaria de forraje
fresco. 29th Congr. Argentino de Produccin
Animal. Bahia Blanca, Buenos Aires. Rev. Ar-
gent. Prod. Anim. Argent. Prod. Anim. VIl.
Eirin, M., P. Gregorini, R. Refi, M. Ursino, and
O. Ansin. 2005b. Timing of herbage allocation
2. Effect on beef heifers weighs gain, body
condition score and daily herbage intake. J.
Anim. Sci. 83(Suppl. 2):202. (Abstr.)
Elgar, M. A. 1989. Predator vigilance and
group size in mammals and birds: A critical re-
view of the empirical evidence. Biol. Rev.
Camb. Philos. Soc. 64:13.
Elizalde, J. C., and F. J. Santini. 1992. Factores
nutricionales que limitan las ganancias de
peso en bovinos en el perı
´odo otono-invierno.
Bol. Te
´c. Estacion-Exp.-Agropecuaria,-Balcarce
104:54.
Emmans, G. C., and I. Kyriazakis. 1995. The
idea of optimization in animals: Uses and dan-
gers. Livest. Prod. Sci. 44:189.
Forbes, J. M. 1995. Voluntary Feed intake and
Diet Selection in Farm Animals. CAB Int.,
Wallingford, UK.
Forbes, J. M. 1999. Minimal and total discom-
fort as a concept for the control of food in-
take and selection. Appetite 33:371.
Forbes, J. M. 2000. Consequences of feeding
for future feeding. Comp. Biochem. Physiol. A
128:461.
Forbes, J. M., and F. D. Provenza, 2000. Inte-
gration of learning and metabolic signals into
a theory of dietary choice and food intake. In
Ruminant Physiology, Digestion, Metabolism,
Growth and Reproduction. P. Cronje, ed. CAB
Int., Wallingford, UK.
Fortin, D., M. S. Boyce, and E. H. Merrill.
2004a. Multi-tasking by mammalian herbi-
vores: Overlapping processes during foraging.
Ecology 85:2312.
Fortin, D., M. S. Boyce, E. H. Merrill, and J. M.
Fryxell. 2004b. Foraging costs of vigilance in
large mammalian herbivores. Oikos 107:172.
Frair, J. L., E. H. Merrill, D. R. Visscher, D. For-
tin, H. L. Beyer, and J. M. Morales. 2005.
Scales of movement by elk (Cervus elaphus)
in response to heterogeneity in forage re-
sources and predation risk. Landsc. Ecol.
20:273.
Fryxell, J. M., C. B. D. Fortin, and J. Wilmsh-
urst. 2001. On the scale dependence of forag-
ing in terrestrial herbivores. Proc.of the XIXth
Int. Grassland Congr. pp. 271-275. Sao Pablo,
Brazil.
Fulkerson, W. J., K. Slack, and K. F. Lowe.
1994. Variation in the response of Lolium gen-
otipes to defoliation. Aust. J. Agric. Res.
45:1309.
Galli, J. 1994. CONPAST. Thesis. Universidad
Nacional de Mar del Plata, Argentina.
Gibb, M. J. 1998. Animal grazing/intake termi-
nology and definitions. In Pasture Ecology
and Animal Intake. Proc. Workshop, Dublin.
Concerned Action. AIR3-CT93-0947. Occa-
sional Publ. No. 3.
Gibb, M. J., C. A. Huckle, and R. Nuthall.
1998. Effect of time of day on grazing behav-
ior by lactating dairy cows. Grass Forage Sci.
53:41.
Gregorini, P., M. Eirin, Agnelli, M. L., R. Refi,
M. Ursino, and O. Ansin. 2005a. Efecto del
momento de asignacin diaria de forraje fresco
en el patrn diario de pastoreo de vaquillonas
aberdeen angus. 29°Congreso Argentino de
Produccio
´n animal. Bahia Blanca, Buenos Ai-
res. Rev. Argent. Prod. Anim. Argent. Prod.
Anim. VIl.
Gregorini, P., M. Eirin, R. Refi, M. Ursino, and
O. Ansin. 2004. Efecto de dos momentos de

Gregorini et al.208
asignacio
´n del forraje fresco sobre el tiempo
de pastoreo y su distribucio
´n durante el dı
´a. II
Reunin Binacional de Ecologı
´a, XXI Reunio
´n
Argentina de Ecol., XI Reunin de la Sociedad
de Ecologı
´a de Chile.
Gregorini, P., M. Eirin, R. Refi, M. Ursino, and
O. Ansin. 2005b. Timing of herbage allocation
1. Effect on beef heifers daily grazing pattern.
J. Anim. Sci. 83(Suppl 2):202.
Griggs T. C., J. W. MacAdam, H. F. Mayland,
and J. C. Burns. 2005. Nonstructural carbohy-
drate and digestibility patterns in orchardgrass
swards during daily defoliation sequences initi-
ated in evening and morning. Crop Sci.
45:295.
Hodgson, J. 1979. Nomenclature and defini-
tions in grazing studies. Grass Forage Sci.
34:11.
Hoebel, B. G., S. F. Leibowitz, and L. Hernan-
dez. 1992. Neurochemistry of anorexia and bu-
limia. In The Biology of Feast and Famine. G.
H. Anderson and S. H. Kennedy, ed. p 21.
Acad. Press, San Diego, CA.
Hogan, J. P., P. A. Kenny, and R. H. Weston.
1987. Factor affecting the intake of feed by
grazing animals. In Temperate Pastures: Their
Production and Management. J. L. Wheeler,
C. J. Pearson, and G. E. Robards, ed. Austra-
lian Wool Corporation/CSIRO, Australia.
Holling, S. C. 1959. Some characteristics of
simple types of predation and parasitism.
Can. Entomol. 91:385.
Houtman, R., and. L. M. Dill. 1998. The influ-
ence of predation risk on diet selectivity: A
theoretical analysis. Evol. Ecol. 12: 251.
Hudson, R., and S. Frank, 1986. Foraging ecol-
ogy of bison in aspen boreal habits. J. Range
Manage. 40:71
Illius, A. W., and I. J. Gordon. 1987. The al-
lometry of food intake in grazing ruminants.
J. Anim. Ecol. 56:989.
Illius, A. W., and N. S. Jessop. 1996. Metabolic
constraints on voluntary Intake in ruminants.
J. Anim. Sci. 74:3052.
Illius, A. W., N. S. Jessop, and M. Gill. 2000.
Mathematical models of food Intake and me-
tabolism in ruminants. In Ruminant Physiol-
ogy: Digestion, Metabolism, Growth and Re-
production. P. B. Cronje, ed. CAB Int., Wall-
ingford, UK.
Jarman, P. J. 1974. The social organization of
antelope in relation to their ecology. Behav-
iour 48:215.
Jeschke, J. M., M. Kopp, and R. Tollrian. 2002.
Predator functional responses: discrimination
between handling and digesting prey. Ecol.
Monogr. 72:95.
Johansson, B., I. Redbo, and Svennersten-
Sjaunja, K. 1999. Effect of feeding before, dur-
ing and after milking on dairy cow behaviour
and the hormone cortisol. Anim. Sci. 68:
597.
Kolasa, J. and C. D. Rollo. 1991. The heteroge-
neity of heterogeneity: A glossary. In Ecologi-
cal Heterogeneity. J. Kolasa and S. T. A. Pick-
ett, ed. p 1. Springer-Verlag, New York, NY.
Kotliar, N. B., and J. A. Wiens. 1990. Multiple
sales of patchiness and patch structure: A hier-
archical framework for the study of heteroge-
neity. Oikos 59:253.
Kral, T. J. E., and B. Rolls. 2004. Energy den-
sity and portion size: Their independent and
combined effects on energy intake. Physiol.
Behav. 82:131.
Krysl, L. J., and B. W. Hess. 1993. Influence of
supplementation on behavior of grazing cat-
tle. J. Anim. Sci. 71:2546.
Laca, E. A., E. D. Ungar, N. Seligman, and M.
W. Demment. 1992. Effect of sward height
and sward density on bite dimensions of cat-
tle grazing homogeneous swards. Grass Forage
Sci. 47:102.
Le Magnen, J. 1986. Hunger. Cambridge Univ.
Press, Cambridge, New York, NY.
Levin, S. A. 1992. The problem of patterns
and scale in ecology. Ecology 73:1943.
Lindstro
¨m, T. 2000. Feeding behaviour in
dairy cows, motivational aspects. Ph.D. Diss.,
Swedish Univ. Agric. Sci., Uppsala, Sweden.
Linnane, M. I., A. J. Brereton, and P. S. Giller.
2001. Seasonal changes in circadian grazing
patterns of Kerry cows (Bos taurus) in semi-fe-
ral conditions in Killarney National Park, Co.
Kerry, Ireland. Appl. Anim. Behav. Sci.
71:277.
Mangel, M., and C. W. Clark.1986. Towards a
unifield foraging theory. Ecology 67:1127.
Marriott, C., and P. Carrere. 1998. Structure
and dynamics of grazed vegetation. Ann. Zoo-
tech. 47:359.
Mayland, H. F., J. W. MacAdam, G. E. Shew-
maker, and N. J. Chatterton. 2003. The diur-
nal cycling of sugars in grasses impact strip-
graze management plans. In Proc. 2nd Natl.
Conf. Grazing Lands, pp. 466-468. Nashville,
TN. CD-ROM.
Metz, J.H.M. 1975. Time Patterns of Feeding
and Rumination in Domestic Cattle. Medede-
lingen Landbouwhogeschool, Wageningen,
The Netherlands.
Nelson, R. J. 1995. Biological Rhythms and Be-
havior. In An Introduction to Behavioral En-
docrinology. R. J. Nelson, ed. Sinauer Associ-
ates, Inc. Sunderland, MA.
Newman, J. A., A. J. Parsons, and P. D. Pen-
ning. 1994. A note on the behavioural strate-
gies used by grazing animals to alter their in-
take rates. Grass Forage Sci. 49:502.
Newman, J. A., A. J. Parsons, J. H. M.
Thornley, P. D. Penning, and J. R. Krebs.1995.
Optimal diet selection by a generalist grazing
herbivore. Funct. Ecol. 9:255.
Nielsen, B. L. 1999. On the interpretation of
feeding behavior measures and the use of feed-
ing rates as an indicator of social constraint.
Appl. Anim. Behav. Sci. 79:79.
O’Connell, J., P. S. Giller, and W. Meaney.
1989. A comparison of dairy cattle behavioral
pattern at pasture and during confinement. Ir.
J. Agric. Res. 28:65.
Orr, R. J., P. D. Penning, A. Harvey, and R. A.
Champion. 1997. Diurnal patterns of intake
rate by sheep grazing monocultures of rye
grass or white clover. Appl. Anim. Behav. Sci.
53:65.
Orr, R. J., P. D. Penning, S. M. Rutter, R. A.
Champion, A. Harvey, and A. J. Rook. 2001a.
Intake rate during meals and duration for
sheep in different hunger states, grazing grass
or white clover swards. Appl. Anim. Behav.
Sci. 75:33.
Orr, R. J., S. M. Rutter, P. D. Penning, and A.
J. Rook. 2001b. Matching grass supply to graz-
ing patterns for dairy cows. Grass Forage Sci.
56:352.
Parsons, A. J., and B. Dumont. 2003. Spatial
heterogeneity and grazing process. Anim. Res.
52:161.
Parsons, A. J., J. A. Newman, P. D. Penning,
and A. Harvey. 1994. Diet preference of sheep:
Effect of recent diet, physiological state and
species abundance. J. Anim. Ecol. 63:465.
Paterson, D. L., and V. T. Parker. 1998. Ecolog-
ical Scale: Theory and Applications. p 615. Co-
lumbia Univ. Press, New York, NY.
Pearse, C. K. 1971. Grazing in the Middle
East: Past, present and future. J. Range Man-
age. 24:13.
Penning, P. D., A. J. Parsons, J. A. Newman, R.
J. Orr, and A. Harvey. 1993. The effect of
group size on grazing time in sheep. Appl.
Anim. Behav. Sci. 37:101.
Pereira, G. M. 2002. A typology of spatial and
temporal scale relations. Geogr. Anal. 34:21.
Phillips, C. J. C. 1993. Nutritional Behavior. In
Cattle Behavior. C. J. C. Phillips, ed. p 233.
Farming Press, Ipswich, UK.
Phillips, C. J. C., and S. A. Schofield. 1989.
The effect of supplementary light on the pro-
duction and behavior of dairy cows. Anim.
Prod. 48:293.
Poppi, D. P., J. France, and, S. R. McLennan.
1999. Intake, passage and digestibility. In Feed-
ing Systems and Feed Evaluation Models. M.
K. Theodorou and J. France, ed. p 481. CAB
Int., Wallingford, UK.
Poppi, D. P., and S. R. McLennan. 1995. Pro-
tein and energy utilization by ruminants at
pasture. J. Anim. Sci. 73:278.
Prins, H. T. 1996. Ecology and Behaviour of
African Buffalo: Social Inequality and Decision
Making. Chapman & Hall, London, UK.
Provenza, F. D. 1996. Acquired aversions as
the basis for varied diets of ruminants forag-
ing on rangelands. J. Anim. Sci. 74:2010.
Provenza, F. D. 1995. Postingestive feedback
as an elementary determinant of food selec-
tion and intake in ruminant. J. Range Man-
age. 48:2.
Provenza, F. D., J. J. Villalba, C. D. Cheney,
and S. J. Werner. 1998. Self-organization of
foraging behaviour: From simplicity to com-
plexity without goals. Nutr. Res. Rev. 11:199.

R
EVIEW
: Daily Grazing Pattern 209
Rearte, D. H., and F. J. Santini, 1989. Diges-
tion ruminal y produccin en animales en past-
oreo. Revista Argentina de Prod. Anim. 9:93.
Rhind, S. M., Z. A. Archer, and C. L. Adam.
2002. Seasonality of food intake in ruminants:
Recent developments in understanding. Nutr.
Res. Rev. 15:4.
Rietkerk, M., J. van de Koppel, L. Kumar, F.
van Langevelde, and H. H. T. Prins. 2002. The
ecology of the scale. Ecol. Model. 149:1.
Rind, M. I., and C. C. Phillips. 1999. The ef-
fects of group size on the ingestive and social
behavior of grazing dairy cows. Anim. Sci.
68:589.
Ritchie, M. E. 1998. Scale-dependent foraging
and patch choice in fractal environments.
Evol. Ecol. 12:309.
Rook, A. J., A. Harvey, A. J. Parsons, S. M. Orr,
and S. M. Rutter. 2004. Bite dimensions and
grazing movements by the ship and cattle
grazing homogeneous perennial ryegrass
swards. Appl. Anim. Behav. Sci. 88:227.
Rook, A. J., and C. A. Huckle. 1997. Activity
bout criteria for grazing dairy cows. Appl.
Anim. Behav. Sci. 54:89.
Rook, A. J., C. A. Huckle, and P. D. Penning.
1994. Effect of sward height and concentrate
supplementation on the ingestive behavior of
spring calving dairy cows grazing grass clover
swards. Appl. Anim. Behav. Sci. 40:101.
Rutter, S. M., V. Tainton, R. A. Chamion, and
P. le Grice. 2002. The effect of a total solar
eclipse on grazing behavior of dairy cattle.
Appl. Anim. Behav. Sci. 58:1.
Samuelsson, B., K. Uvnas-Moberg, R. C. Gore-
wit, and K.Svennersten-Sjaunja. 1996. Profiles
of the hormones somatostatin, gastrin, CCK,
prolactin, growth hormone and cortisol. I. In
dairy cows that are milked and fed separately
or milked and fed simultaneously. Livest.
Prod. Sci. 46:49.
Schwinning, S., and A. J. Parson. 2001. The
stability of grazing systems revisited: Spatial
models and the role of heterogeneity. Funct.
Ecol. 13: 737.
Shipley, L. A., J. E. Gross, D. E. Spalinger, N.
T. Hobbs, and B. A. Wunder. 1994. The scal-
ing of intake rate on mammalian herbivores.
Am. Nat.143:1055.
Shipley, L. A., and D. E. Spalinger. 1992. Me-
chanics of browsing in dense food patches: In-
fluence of plant an animal morphology on in-
take rate. Can. J. Zool. 70:1743.
Simpson, S. J., R. M. Sibly, P. M. Lee, S. T. Be-
hmer, and D. Raubenheimer, 2004. Optimal
foraging when regulating intake of multiple
nutrients. Anim. Behav. 68:1299.
Sinclair, A. E. 1977. The African buffalo: A
Study of Resource Limitation of Populations.
Univ. Chicago Press, Chicago, IL.
Solomon, M. E. 1949. The natural control of
animal populations. J. Anim. Ecol. 18:1-35.
Staddon, J. R. 1983. Adaptive Behavior and
Learning. Cambridge Univ. Press, Cambridge,
UK.
Stephens, D. W., and J. R. Krebs. 1986. Forag-
ing Theory. Princeton Univ. Press, Princeton,
NJ.
Tallowin, J. B., C. M. Tyson, and S. E. Brook-
man. 1991. Differences in lamina wetability
in some permanent pasture grass species and
two Lolium perenne cultivars. Grass Forage Sci.
46:265.
Taweel H. 2004. Perennial ryegrass for dairy
cows, grazing behavior, intake, rumen func-
tion and performance. Ph.D. Diss., Wagen-
ingen Univ., Wageningen, The Netherlands.
Toates, F. 2002. Physiology, motivation and
the organization of behavior. In The Ethology
of Domestic Animals: An Introductory Text. P.
Jensen, ed. CAB Int., Wallingford, UK.
Underwood, R. 1982. Vigilance behaviour in
grazing African antelopes. Behav. 79:81.
Ungar, E. D. 1996. Ingestive behavior. In The
Ecology and Management of Grassland Sys-
tems. J. Hodgson and A. W. Illius, ed. p 185.
CAB Int., Wallingford, UK.
van Gardingen, P. R., G. M. Foody, and P. J.
Curran 1997. Scaling-Up. From Cell to Land-
scape. Cambridge Univ. Press, Cambridge,
UK.
WalliesDeVries, M. F., and C. Delabout. 1994.
Foraging strategy of cattle in patchy grassland.
Oecologia 100:98.
WalliesDeVries, M. F., and E. Laca. 1999. The
importance of scale of patchiness for selectiv-
ity in grazing herbivores. Oecologia 121:355.
WalliesDeVries, M. F., E. Laca, and M. W.
Demment. 1998. From feeding station to
patch: Scaling up food intake measurements
in grazing cattle. Appl. Anim. Behav. Sci.
60:301.
Wiens, J. A. 1976. Population responses to
patchy environments. Annu. Rev. Ecol. Syst.
7:81.
Wiens, J. A. 1989. Spatial scaling in ecology.
Funct. Ecol. 3:385.
Wu, J. 1999. Hierarchy and scaling: Extrapolat-
ing information along a scaling ladder. Can. J.
Remote Sensing 25:367.
Wu, J., and Y. Qi. 2000. Dealing with land-
scape analysis: An overview. Geogr. Inform.
Sci. 6:1.
Wurtman, R. J., and J. J. Wurtman. 1989. Car-
bohydrates and depression. Sci. Am. 262:68.