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D A I R Y F E A T U R E
‘Having a parasite control plan is part of
the jigsaw - if cows' growth is good and
there's no scouring, then we don't need
to interfere at all.’
CHAR L E S S AMP SON
Drench-free
parasite
control
One very successful health initiative on the
farm has been to ensure youngstock are
protected against worms during the grazing
months, without worming them.
Stuart explains: ‘Fortunately, there has never
been any fluke on the farm, in part due to
the sloping fields which make it less wet.
‘However we can't predict the lungworm
challenge, so we have to assume that in a
heavily stocked area we are going to have a
problem with this in the late grazing season.
The crux of Charles' parasite control plan is to
vaccinate against lungworm with Huskvac at
the start of the grazing season. And then to
monitor the parasite burden in the sward
through the summer.
‘It's all about optimal use of drugs not
maximal use,’ says Charles. ‘If I didn't
vaccinate then routine worming every five
weeks would be needed.’
Stuart points out: ‘Admittedly, it is easy to
carry out a worming programme. Options
include a pulse release bolus administered
once at the start of the season. Alternatively,
cattle can be drenched every five weeks and
again before being brought inside for winter.
This is more time-consuming, and both have
a cost.
‘But for the past two grazing seasons, Charles
has not needed to worm his youngstock and
the single lungworm vaccination has been all
that is needed, in conjunction with a grazing
management plan and carrying out faecal
worm egg counts.
The first egg count is made one month after
turnout: samples from ten cow pats are taken
and sent for analysis at the SAC, at a cost of
approximately £15. In youngstock, it takes
between three and six weeks from the ingestion
of infected larvae to the excretion of eggs,
depending on the warmth and moisture content
of the sward. So the frequency with which
subsequent counts are made depends on the
previous results, and is altered accordingly.
Stuart explains: ‘It's a careful balance - we
want the first season grazers to develop
immunity but not develop production-limiting
levels of parasites. Last year, the egg count
started to rise around mid-July, but then
dropped, demonstrating that, as healthy
heifers, they had coped with the
challenge themselves.’
‘The biggest issue in the early part of the
grazing season is over-wintered infection.
However, if the pasture is not grazed until
after mid-July, then the last year's worm
infestations will have died off. So Charles
keeps a record of when fields were last
grazed, and selects which ones are 'safe'
for heifers.’
All cows and heifers are wormed at
housing in October using a wormer product
specifically to tackle the Type II ostertagia
encysted larvae. This is required because
the stress can cause them to break out and
animals will scour. It also helps reduce pasture
infestations as cows are coming out of the
sheds 'clean' in the spring.
Stuart explains: ‘Worm infections in pasture
take a while to build up. Without using the
initial lungworm vaccination then we would
have to assume that in the second season of
grazing there would be a rapid acceleration
in worm populations in the late season.
‘Over-worming is more of a sin than
under-worming as the animal never gets a
chance to develop immunity. This then makes
them very susceptible in the second season.
‘Having a parasite control plan is part of the
jigsaw - if cows' growth is good and there's
no scouring, then we don't need to interfere
at all.’ Charles adds: ‘Taking this approach,
not only have we saved time and money, but
it's a more responsible use of medicines and
I can justify my actions to people outside
of farming.’
SUMMER 2010 ISSUE
LIVESTOCK MATTERS
6