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
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:
Reduce the number of animals in your pastures (see overcrowding)
Change the browse in your pastures
Burn the pasture
Rest your pastures from grazing
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.
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
A clean or safe pasture is one in which sheep or goats have not grazed for 6 to 12
A tilled or burned pasture helps reduce the larvae count in it and certainly can
make it safer
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
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
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.
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.
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.