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estimated diet composition of dairy
criollo bucks and
does and also recorded the integrity of their incisors. In
general, goats with worn teeth avoided grasses and also
had a higher preference for saltbush and for succulents. It
is worth noting in passing that despite the marked effect
of worn teeth on diet selection, gender differences in diet
composition were greater than the effects of worn teeth.
The state of incisor dentition can be scored in a manner
similar to the well-accepted body condition scoring
systems. Given the magnitude of the effect of dentition on
diet composition, more effort should be made in future
studies to obtain dentition scores and to use these as
explanatory variables when assessing differences in diet
composition.
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sheep, is relatively constant or rises when goats are grazing
a ryegrass/white clover sward. This has practical conse-
quences within mixed farming systems, because it raises
the possibility of using a leader-follower grazing system
in which goats are used to increase the clover content of a
sward, which is then grazed by sheep.
In an attempt to understand the mechanisms underpin-
ning such effects, De Rosa et al. (2002) extracted the “odor
principles” from perennial ryegrass and white clover. They
then sprayed distilled water or aqueous solutions of the
odor extracts onto straw pellets. Goats had an almost two-
fold preference for straw pellets sprayed with perennial
ryegrass odor over those sprayed with distilled water.
Pellets sprayed with white clover odor were less preferred
than those sprayed with ryegrass extract, but were still
preferred to those sprayed with distilled water. Once again,
these data provide no support for the idea that goats have
a low preference for perennial ryegrass or will “not eat”
white clover.
Hence, taken together, these data provide little support
for the notion that goats will reject or select strongly
against white clover. Rather, they support the suggestion
that goats will eat white clover but prefer it less than sheep,
or that no selection against clover exists when it is part of
the grazing horizon of the goat. Goats can and do consume
perennial ryegrass as a major portion of their diet, when
grazing sown swards of ryegrass/clover.
C LOVER C ONTENT AND C LOVER P OSITION W ITHIN
THE S WARD
One of the most common assertions in popular writings
about goat husbandry is that goats have a strong preference
against clover and would rather not eat it. To take an
extreme example, Hetherington (1977) suggested that “…
(goats) will only eat ryegrass under sufferance and entirely
ignore white clover.” The evidence does not support either
of these assertions.
In addition, one should also bear in mind that in such
discussions, what is actually meant by “clover” is “white
clover ” ( Trifolium repens ). The preference of goats for
other Trifolium species has not been reported, though goats
are known to eat other legumes (e.g., Papachristou, 1994).
In a study with esophageal-fi stulated Cashmere
P RESENTATION OF THE B IOMASS : S WARD H EIGHT ,
B IOMASS , AND S TOCKING R AT E
In studies of ingestive behavior and diet selection, goats
have been presented with different plant species in many
ways: as individual plant species indoors; as mixtures of
plants outdoors; or as the same material both indoors and
outdoors. The method of presentation can itself alter the
observed diet composition, because compared with housed
goats, grazing goats are better able to select as they forage
in a sward.
The published data for white clover selection by goats
indicate that they are “top-down” grazers with a shallow
biting depth, whereas sheep are more inclined to graze
deep into the sward. In turn, this should render goats more
susceptible to the effects of sward height, which does seem
to be the case. Merchant and Riach (1994), for example,
reported that goats found it more diffi cult to maintain
intake and live weight gain as sward height decreased.
Based on this and on studies with sheep, a reduction in
the amount of biomass on offer, or of sward height, due to
increased stocking rate will infl uence both diet selection
and intake. In general, stocking rate effects in goats have
feral
goats grazing a perennial ryegrass/white clover pasture,
Fraser and Gordon (1997) found that perennial ryegrass
leaf laminae made up 66% of the diet of goats. Their diet
also contained 9-18% white clover. The goats appeared to
select positively for green clover leaf, relative to its avail-
ability in the total sward, but the clover proportion in the
diet was similar to that at the sward surface, where the
goats appeared to concentrate their grazing.
Penning et al. (1997) also examined the dietary prefer-
ences for perennial ryegrass and white clover in sheep or
goats. Sheep grazed for longer than goats, and their extra
grazing time was spent grazing clover. Dietary preference
for clover, defi ned as the percentage of the total grazing
time spent grazing clover, was 70% for sheep. The equiva-
lent preference for goats was 52%, which certainly does
not imply rejection of clover, but merely that goats have a
lower preference for white clover than do sheep.
As a result of the somewhat lower preference for white
clover demonstrated by goats, it has often been observed
that whereas sward clover content falls under grazing by
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