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Turnout must now be just around the corner so your
planned pre turnout treatments such as Huskvac should
be well under way. Deciding which worming strategy and
product to use a confusing. Many of you have used the
same regime successfully for many years but new products
appear and old ones become less useful. Circumstances
may change e.g. less staff or you may now be aiming
for higher growth targets. A change in stocking density
may affect worm burdens. Therefore it’s always
worth reviewing worming policy in your youngstock.
The ideal should be to treat as little as possible
to maximise weight gains and avoid disease but at the
same time allowing the calf’s immunity to worms
to develop in the first season so that worming is unnecessary
in the subsequent grazing seasons.
First, choosing a wormer to use should be based on
what chemical works. Worm resistance is widespread in
sheep worm species but will become more significant
in cattle if care is not taken in choosing when and
how often to treat. SAC have developed a new advisory
policy called SCOPS to help farmers reduce the risk
of worm resistance and we can advise you on how to reduce
the chances of wormer resistance in your herd.
So what choices have you got? The table on
the pdf version of this newsletter gives you a quick
reference regarding the types of wormers and recommended
worming regimes but let’s look at the options.
- Do nothing and treat only if disease occurs. This
is cheap in terms of drug bills but can lead to poor
growth rates and risks of death. Sods law says you’ll
be busy silaging when they start to scour.
- Move onto clean pasture i.e. aftermath mid grazing
season. This in itself can reduce worm burdens enough
to stop disease. Dosing and worming is now discouraged
under SCOPS but dosing a week before or after moving
can reduce worm burdens enough to increase growth
rates.
- Set grazing and strategic worming. Dosing calves
early in the season e.g. ivermectin at 3 and 8 weeks
after turnout (or Dectomax 0 and 8 weeks) is very
cost effective and is a personal favourite of mine
but it does require handling stock twice at grass
and gives no protection against husk if vaccine isn’t
used. In addition, care must be taken not to put stock
onto contaminated pasture later in the season.
- Set grazing and pulse release boluses. Autoworm
is the only pulse release bolus giving about 5 months
treatment but releasing drug every 3 weeks so that
the calves can be exposed to worms and so develop
immunity and give good growth rates. Therefore it’s
perhaps the gold standard for replacement stock. The
drawbacks are administering the bolus in the first
place (avoid very young calves) and cost.
- Extra long acting injection. Cydectin 10% LA lasts
up to 5 months it is a bit fiddly to administer (in
the ear) but is slightly cheaper than a bolus. The
drawback is that we suspect the calves develop little
immunity to worms so we wouldn’t recommend its
use in replacement cattle or any cattle you’re
going to graze next season. In common with boluses,
it has a long meat withdrawal (over 100 days) so don’t
use it in stock close to finishing.
Please remember that lungworm (husk) is so unpredictable
that none of the above regimes prevent it. Huskvac is
the gold standard for control but please don’t
worm your calves within 2 weeks of giving the second
dose of vaccine. Without vaccination, you need to keep
a close eye on your calves in the second half of the
grazing season and treat groups of coughing calves promptly.
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