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(from 72-38% of the day), rather than an actual increase
in the time spent browsing. By contrast, goats browsed for
more than 60% of their feeding time during the rainy
season, and as the season progressed and the herbaceous
component declined, the time spent browsing rose to more
than 90% of the feeding time. The marked increase in
browsing time by sheep in the dry season was not due to
a reduction in their time spent feeding but was a real
increase in the actual time spent browsing.
Although goats often consume most of their diet from
the browse component, during some seasons or circum-
stances the grass/herbaceous component can be a major
contributor to the diet. Published data indicate that when
this occurs, herbaceous species can comprise more than
half of the diet of goats. For example, Papachristou (1994)
found that the herbaceous component could make up > 50%
of the diet of goats in a Mediterranean shrubland when
herbage availability was high. This serves as a reminder
that although goats have a much stronger preference for
browse than sheep or cattle, goats are intermediate feeders,
and the herbaceous component of the plant biomass can
still contribute an important fraction of their diet.
Figure 9.3
Browsing goat showing typical
bipedal stance (photo courtesy Dr. S.G.
Solaiman).
F
ORAGING
H
EIGHT
— B
IPEDAL
V
ERSUS
Q
UADRIPEDAL
F
ORAGING
It is frequently suggested that a major contributor to goats'
achieving their higher intake of browse is their adoption
of a bipedal stance, as shown in Figure 9.3. Indeed, some
reports almost suggest that the adoption of a bipedal stance
is what confers on goats their browsing success. Given the
assumed importance of this, it is remarkable that there is
so little quantitative evidence to support the notion. One
must also remember that in a ruminant, the adoption of a
bipedal stance comes at an energy cost, which might be
expected to infl uence the time spent in bipedal browsing.
How do goats browse, relative to other ruminants?
Sanon et al. (2007) recently reported foraging heights
for co-grazing goats, sheep, and cattle in the Sahel. The
mean and the maximum foraging heights recorded for the
species follow:
goats — 1.65 m and 2.10 m
cattle — 1.47 m and 1.90 m
sheep — 0.87 m and 1.17 m
However, these heights are obviously infl uenced by the
size of the species themselves. Differences in foraging
heights become even more marked if they are recalculated
in terms of the shoulder heights of the three animal species.
In these terms, sheep and cattle foraged to similar mean
heights (sheep 1.18, and cattle 1.21 times their respective
shoulder heights) and maximum heights (sheep 1.58 and
cattle 1.57 times shoulder height). By contrast, goats
foraged to a mean of 2.42 times their shoulder height and
a maximum of 3.08 times their shoulder height. Clearly,
this could not have been attained without the goats adopt-
ing a bipedal stance for some of their foraging.
There are few estimates of the proportion of their
feeding time that goats actually do spend in bipedal
foraging. Pfi ster et al. (1988) measured the percentage
of their foraging time that sheep and goats spent foraging
within a series of strata defi ned as “ ground level ” (0 - 5 cm),
“ animal height ” (6 - 75 cm), “ overhead quadripedal forag-
ing ” (76 - 115 cm), or bipedal foraging (116 - 160 cm) in
the wet, dry, and late-dry seasons in the Brazilian caatinga.
Their recalculated data (Figure 9.4) confi rm that goats
spent much more time than sheep browsing above animal
height, though it should be noted that in all seasons,
both animal species spent a large proportion of their
grazing time foraging at animal height or at ground level.
This study also showed that most of the browsing
above animal height occurred using quadripedal browsing;
goats spent much longer than sheep browsing in this
stratum. Bipedal browsing essentially only occurred with
the goats, but even in this species, it accounted for only
