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During the warm
months of the year enormous numbers of larvae can build up on your
pasture. Your pastures are the primary source of the round worm
larvae for your goats. Parasite larvae can live for long periods of
time on your pastures. You can’t eliminate completely parasites in
the pasture.
The magnitude of pasture contamination is
affected mainly by
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Stocking
rate (number of animals per grazing area). The higher/lower
the stocking rate, the more/less feces are deposited on the
grazing area, thus more/fewer eggs.
-
Genetics of your herd - Some goats have more problems
with worms than others and will produce more eggs in the
pasture.
-
Age
of the animals – More eggs are also passed from young vs
older animals.
-
Season
of the year and if parasites in the stomach are in arrested
development or not.
Most worms have a definite seasonality, so during their
season, more eggs are produced and passed.
Pasture management is done by the following:
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Reduce
the number of animals in your pastures
(see overcrowding)
-
Change
the browse in your pastures
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Burn the pasture
-
Rest your pastures from grazing
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Rotate
the animals in the pastures
-
Wait to turn your herd into a pasture until after the morning
dew is gone which forces the larvae to the ground.
-
Dry lot your animals at critical times and feed hay instead of
going to a pasture.
Change the
Browse
Goats are browsers. Goats love to browse and
prefer shrubs and forages to grass. That means goats can be found
sampling plants at all levels. Round worm and similar parasites will
be found on grass. The larvae normally only travel 2-4 inches up
a blade of grass. The higher your
animals are grazing above the ground, the less likely they will
ingest the larvae. Allowing goats to browse on other
vegetation at higher levels will reduce the goat’s exposure to these
worms. Incorporate browse plant species when possible..
There is growing evidence in work from New
Zealand and Europe that grazing or feeding
of plants containing condensed tannins (CT) can reduce the fecal egg
count, larvae development in feces, and adult worm numbers in the
stomach and small intestine.
Researchers are exploring the use of plants to control round
worms with medicinal plants having anthelmintic properties. Forages,
such as clover, vetches, chicory, and Sericea lespedeza, contain
condensed tannins. Condensed tannins can
reduce the number of stomach worms and egg production.
Some of the forages that may have anti-parasitic effects include
Birdsfoot Trefoil, Chicory, Sericea Lezpedeza.
-
Sericea
Lespedeza - Preliminary test with sericea lespedeza, a
CT-containing perennial warm-season legume, have shown positive
effects of reduced fecal egg counts in grazing goats and goats
in confinement when the forage was fed as hay. Some studies
have indicated feeding sericea lespedeza hay to goats can reduce
fecal eggs counts by 80 percent and create a higher packed cell
volume. We have planted some Sericea Lespedeza this year to see
how it will do. It seems to be a very slow starting legume. We
are hoping the growth dramatically improves next year so we will
feel more comfortable allowing our herd to graze it.. Sericea
Lespedeza, when fully developed, is a tall legume and that keeps
the goats away from the ground while browsing.
-
Chicory –
In a study in Scotland, lambs
reared on chicory without strategically used dewormers had lower
faecal egg counts than their grass/clover grazing counterparts,
and grew at similar rates as lambs reared on grass/clover in the
presence of strategically used dewormers. The study indicated
short and long term grazing on chicory has the potential to
reduce worm burdens.
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Hay Grazer - Planting a Hay Grazer forage (sorghum x
sudan hybred forage). This is a forage that grows tall. It can
have a tall stem with big wide leaves higher up the stem. The
goats only like the leaves therefore they will eat the leaves
that are not near the ground and avoid the living site of the
larvae. We planted some of this as a trial in one pasture this
year. The goats ate the leaves and left the stem at least 4-5
inches tall. After they had eaten most of the leaves from the
forage, we moved them to another pasture. In no time at all, the
hay grazer shot up several feet tall again thus allowing our
goats to come back and graze the higher forage again. The major
focus on planting this is it keeps the
goats away from the ground level where the parasite larvae are
living.
Rotate the pastures
Rotating your animals to different pastures
may help reduce the number of larvae available to them. The longer
you can wait before grazing your herd in a pasture again, the better
the chance that some of the larvae have died thus reducing the
number of larvae that your goats may ingest to start their life
cycle again.
As long as your goats are on the pasture, they
are continuing to drop their pellets with millions of parasite eggs
just waiting to hatch. The longer a pasture is resting from goats on
it, the more larvae die and no new eggs are being dropped for future
hatching. However, the main reason many breeders use pasture
rotation is not for parasite control but to provide the most
nutritious forage for growth and development. If grazed correctly,
most forages reach the next most nutritious stage in about 30 days,
so many rotation schemes have the animals returning to pastures at
around 30 day intervals. Unfortunately, this 30 day interval is also
about the same time necessary to ensure that the previous worm
parasite contamination has now been converted into the highest level
of contamination for the next grazing group.
Thus, 30 day rotation schemes may actually
lead to increased worm parasite problems. In fact, heavy exposure
over a short period of time can lead to disastrous clinical disease
and losses. Rotation schemes of 2-3 months have been shown to have
some effect on reducing pasture contamination in tropical and
subtropical environments but in more temperate environments,
contamination can extend out to 8-12 months depending on the
conditions. For the most part, it is impractical to leave pastures
ungrazed for such extended period of time.
Rotational grazing generally does not help to
control internal parasites unless pasture rest periods are long
enough (> 70 days). In fact, management intensive grazing (short
duration, high intensity grazing) may exacerbate parasite problems
in goats because the goats are grazing low to the ground right where
the larvae are living..
A
Clean or Safe Pasture
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A clean or safe pasture is one in which sheep or goats have not
grazed for 6 to 12 months
-
A
tilled or burned pasture helps reduce the larvae count in it and
certainly can make it safer
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If
other animals like cattle or horse have grazed a pasture, they
have consumed some of the larvae. The larvae are not harmful to
them
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If
a pasture has had hay removed from it, that will also reduce the
height of the grass and allow more heat and sunlight to impact
the larvae
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When possible, use the pasture for hay cutting after grazing.
This will help to break the worm life cycle and prevent
re-infestation. Direct sunlight during the summer months or
during freezes in the winter will also help decrease the
population of larvae that remain in the soil.
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When possible, alternate the pasture with a short cycle crop,
such as culture alfalfa. This management practice will help to
break the worm's life cycle, and decrease larvae population in
the pasture and prevent re-infestation.
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The effect of mowing, if any, is not large. The proven effect of
mowing early in the grazing season on pastures has resulted that
farmers and extension workers think that a mown pasture is safe.
Unfortunately, the preliminary data presented in studies
demonstrate that this is not necessarily true for goat pastures
that have been contaminated earlier in the grazing season.. Most
goat farmers in the study indicated that they had mown in
between grazing periods. Nevertheless, problems occurred on some
farms applying mowing in 2002 Thus, the study concluded that
they have to convince farmers that they should not only rely on
mowing as a measure to get clean pastures
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