Farming Monthly National November 2017 | Page 32

| Sheep & Lambing
Review worm control for optimal lamb growth
Merial Animal Health is encouraging farmers to put effective parasite control plans in place using an individual
approach based on farm-specific risks , to protect against losses in production and clinical disease associated with
gastrointestinal nematodes or gutworms in weaned lambs.
very farm has its own specific
parasite profile - working
closely with a vet or qualified
animal health advisor to assess
this, and getting to grips with
the risk periods for different
worm species, and the impact of season,
climate and management practices on the
parasite challenge will improve control.
Reviewing lamb performance and anthelmintic
treatments administered so far this year will
also provide an indication of the threat worms
pose in the coming months.
Minimising the pasture challenge faced by
growing and finishing lambs is the first step in
effective worm control. Prioritising low risk
pasture for lambs after weaning will help to
maximise their performance and reduce
reliance on wormer treatments. Low risk
pasture includes reseeding, aftermath and
pastures only grazed by cattle or other species
this year.
Resistance management
In addition to management strategies, a
major factor affecting the effectiveness of
control is the increasing emergence of
anthelmintic resistance. Assessing the
effectiveness of the different wormer groups at
farm level will allow informed treatment
decisions to be made.
Five anthelmintic groups are available for
use in sheep, although multiple active
ingredients sit within some of these groups. In
the UK, resistance has been identified to
Groups 1-3 (benzimidazoles, levamisole and
macrocyclic lactones), but its presence varies
and farm status should be investigated to allow
effective products to be selected. Groups 4 & 5
contain more recently registered products that
can be integrated into a treatment programme
E
to manage the risk of resistance.
A sheep drench containing ivermectin, such
as ORAMEC© Drench, can provide an effective
tool for the treatment and control of
gastrointestinal nematodes as resistance to
ivermectin is much less widespread than
resistance to commonly used benzimidazole-
base d products.1 Investigation of farm status
will determine whether using ORAMEC©
Drench could improve worm control on-farm.
What’s more its short six day meat withhold can
prove valuable when worming fattening lambs.
Understanding the principle of refugia is also
vital for resistance management and
sustainable worm control. Sioned Timothy
Ruminant Technical Manager at Merial Animal
Health, advises that: “To minimise selection for
resistance a proportion of the worm population
on the farm should remain unexposed to the
wormer used at each treatment. This includes
worms present in untreated animals and worms
present on pasture. This mixed population of
worms will act to dilute any resistant strains that
may survive wormer treatments.”
Treating all animals in a group, removing all
susceptible worms, and moving them to clean
pasture (dose and move) removes the diluting
effect of refugia. This strategy can quickly lead
to a serious resistance problem; any resistant
strains of worms quickly become dominant in
the population leading to worm treatments
becoming ineffective. This approach should be
avoided.
Diagnose and monitor for effective worming
Increasingly the benefits of a move away
from routine worming of lambs are being
recognised both in terms of the economic
savings and the long-term sustainability of
taking an informed approach to treatment
decisions. Where more targeted approaches
are taken, a reduction in the number of
treatments administered and a corresponding
drop in medicine costs is typically seen without
any associated reduction in lamb performance.
Using faecal egg count (FEC) results from
pooled faecal samples collected from at least
10 lambs in each management group is a
proven approach to determining whether
treatment of lambs is indicated. Counts of
above 750 eggs per gram are typically
considered high, but the significance of results
should be assessed in the context of other farm
level risk factors.
A follow up faecal egg count on samples
collected after treatment is a useful and simple
means of assessing treatment efficacy. The
sampling interval will vary depending on the
active ingredient used, for lambs treated with
levamisole a second FEC should be conducted
7 days after treatment, and for benzimidazoles
and macrocyclic lactones samples should be
collected 14 days after treatment.
Regular monitoring of growth rates is an
alternative and effective method of assessing
the need for anthelmintic treatment. A failure to
meet growth targets is strongly associated with
parasite challenge, and routine weighing allows
targeted treatment of the individual lambs
within a group that are most likely to be
carrying heavy worm burdens.
As with all medicine treatments, correct
dosage and administration is critical. When
treating for worms, the weight of lambs should
be determined as accurately as possible, to
reduce the risk of under or over-dosing. Using
appropriate dosing equipment that is well
maintained and correctly calibrated is also an
important factor in treatment efficacy.
Machine feeders consider rearing more surplus lambs
More than 50% of sheep producers using an automatic machine to feed ewe milk replacer to surplus lambs find the
practice so straightforward that they plan to rear more animals artificially during the 2018 lambing season.
he feedback comes from a
recent survey of 35 farmers
purchasing a Volac Eco Feeder
within the last 24 months and
highlights how successful
artificial rearing is becoming.
“Enquiries about automatic milk feeding are
at an all-time high in the sheep sector,” reports
Jackie Bradley from Volac. “Sheep farmers are
undoubtedly attracted by the labour-saving
benefits and the fact that machine-rearing frees
up time to focus on other important jobs. But
they also report faster growth rates because
there is no limit to how much or when the
lambs can drink. Producers also say they see
fewer digestive upsets. Most significantly,
though, users are reporting a decent margin
over lifetime feed of anywhere between £15 and
£25 per lamb.”
But it’s not just orphan and third lambs that
producers are now putting on machines. The
survey shows that farmers are increasingly also
taking pressure of young ewes rearing
T
32 | Farming Monthly | November 2017
multiples to boost lamb survival rates and
performance. “This is particularly important for
young mothers and will help them keep
growing and producing enough milk for the
lambs they have left,” Ms Bradley says.
When deciding which lamb to remove from a
triplet-bearing ewe, Volac nutritionists advise
removing either the smallest or the largest one
to leave a balanced pair. “Whichever lamb is
chosen it must be sucking well, been with its
mother for 24 hours after birth and have
received a good supply of colostrum,
particularly in the first six hours of life.”
Machines are available to buy directly from
Volac, but Ms Bradley stresses that they are not
a substitute for good husbandry. “Sound
hygiene is crucial and lamb pens must be
draught-free, and well drained and bedded to
keep lambs as warm and dry as possible.
Clean, fresh water also needs to available along
with creep feed (18% crude protein) offered ad
lib to encourage early intake. Lambs should be
weaned abruptly at no less than five weeks of
age when they are eating an average of 0.25kg
of creep a day over three days,” she says.
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