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43
AUGUST 2019
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Research Innovation Focus
Research Innovation
AUGUST 2019
Research Innovation Focus
www.irishfarmersmonthly.com
It is important to understand that parasite larvae that
survived the winter will become active at around the
time when grasses turn green in the spring. Cattle can
potentially become infected with parasites from every
bite of forage they take throughout the grazing season.
When developing a parasite control program for the
grazing season consider the type and age of cattle, farm
topography and facilities, and the farm's objectives and
capabilities. Climatic conditions will inevitably impact on
plant growth, parasite epidemiology, cattle husbandry,
farm management and housing, and thus parasite
control approaches may need to be adapted to take this
into account. Parasite populations typically increase
from spring into summer resulting in an increasing risk
of parasitic gastroenteritis (PGE), whilst clinical lungworm
disease usually occurs from July onwards.
Planned ahead, grazing management can be used to
reduce the risk of PGE, particularly in young cattle at
highest risk of disease. Map the farm at the start of
the grazing season to determine the use of pastures,
particularly in terms of parasite risk, when aftermaths will
become available and which classes of stock will be moved
there.
Timing is everything
Treating the right animals at the right time is critical to the
success of gutworm control.
Each spring, decide whether the parasite control plan for
youngstock will be a preventive strategy, using anthelmintic
and grazing management, or whether a targeted approach,
based on on-going risk assessment, is more appropriate for
the farm. To be e ective, strategic anthelmintic treatments
need to begin early in the grazing season, at or shortly after
turnout. Thereafter, this approach will help to minimise
pasture contamination up to mid-July, by which time
the over-wintered population should have declined to
insignificant levels. If a targeted approach is implemented,
then ensure that e ective, regular cattle growth monitoring
is carried out to assess the risk of parasite exposure.
Diagnostic testing may also be useful. Faecal egg counts
can provide some indication of worm burdens early in the
grazing season and can be a useful tool for monitoring
trends and infection dynamics as the season progresses.
Grazing management
Grazing management will also have a bearing on parasite
control. Being proactive, and adapting to seasonal
variations in grass growth will allow the most e cient use
of pasture. However, remember that the majority of larvae
on the pasture are very close to the ground, so grazing
hard may increase the likelihood of parasite consumption.
Parasite control should be a key consideration when
management decisions are being made, since failure
to e ectively control the risk in growing cattle will
compromise their health and growth. Monitoring is
also vital. Regular weighing of cattle will allow the
performance of individual animals to be tracked and
ensure that they don't fall behind targets. It also allows
an indirect assessment of gutworm control to take place,
since impaired growth in the face of good nutrition is
often associated with a high parasite burden. Targeting
anthelmintic treatments at individuals that are failing to
thrive can control gutworms e ectively.
When anthelmintic treatments are administered, it is critical
that best practice is observed. Accurate dosing can only be
achieved if you have assessed the weights of the animals to
be treated. To ensure that any anthelmintic products you
use to treat cattle are as e ective as possible, you should:
f
f
Maintain all equipment and cattle handling facilities
f
f
Choose the most appropriate product for the parasites
present.
f
f
Administer products at the right dose.
f
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Store and handle products safely and correctly.
f
f
Consult the label and/or datasheet before using a
product.
It's also critical to make an assessment of the risk periods
for di erent parasites on your farm. Targeting the right
parasites at the right time will give predictable results and
may mean re-treatment is less likely to be needed.
The e cacy of a gutworm treatment can be accurately
assessed using a faecal egg count reduction test (FECRT).
To do this, faecal samples are collected from cattle before
treatment and follow up samples are taken from the same
animals 10-14 days later, depending on the product used.
The faecal egg counts are compared and when a treatment
has been fully e ective a reduction of 95% or more is
expected. A lesser reduction could be a sign of resistance,
but could also reflect poor treatment technique or under-
dosing and this should be investigated further. Knowing
the resistance status of your farm will allow the most
appropriate treatment choices to be made.
Understanding the parasite dynamic on your farm and
using this information to develop a season-long parasite
control programme will ensure that the productivity
and health of your cattle are maximised, whilst allowing
sustainable, e ective treatment decisions to be made and
helping to safeguard future performance.
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