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WINTER 2012 ISSUE
LIVESTOCK MATTERS
6
F LOCK HEALTH
Routine flock health matters
When first establishing the Lleyn flock in
1996, Duncan made the decision to protect
health and performance of the sheep by
ensuring it remained free of the virus
Maedi Visna.
Andrew explains: ‘Maedi Visna is a wasting
disease which has a long incubation period.
There's no vaccine or cure for it. So to protect
flock performance, the best approach is to
keep it out of the flock altogether. So Duncan
keeps a closed flock and will only buy in
rams from breeders that are members of an
MV-certification health scheme, like his
own flock.
Lameness is another issue on which Andrew
and Duncan have worked together. It is well
under control now with less than a 2%
prevalence. Duncan adds: ‘It's not going to be
possible to totally eradicate footrot due to the
high stocking density. But thanks to Andrew's
input we've got it well under control using a
combination of zinc sulphate footbathing and
if required, antibiotic.’
Duncan adds: ‘We did start using EID to
de-select lame sheep. But then stopped as we
became concerned that there wasn't sufficient
genetic connection to justify it and we might
wrongly be penalising some animals.’
‘In Northumberland, selenium levels in the soil
are low, and this shortfall carries through into
grass and forages. Selenium deficiency will
limit animal performance and farmers should
check whether stock require mineral
supplementation,’ advises Andrew.
Since Thistleyhaugh Farm is organic, blanket
selenium supplementation is not permitted.
Instead, a number of ewes are blood-sampled
pre-tupping to assess levels of selenium (and
also copper). If required, a derogation is
obtained and a long-acting selenium injection
can then be administered to protect health.
The system works
Andrew says: ‘Duncan has been prepared
to experiment and do things differently. He
started off with Mule and Charollais flocks but
then made the decision to switch to the Lleyn
as it fitted the system he wanted to run.
He adds: ‘Duncan and his brother go shearing
in the summer, so their own flocks are
winter-shorn at the end of February. They are
kept housed for two weeks before being
turned out onto grass again, where they lamb
down in April. This not only fits in with the
labour requirements, but also improves lamb
vigour - because the ewes eat more, and are
more inclined to seek shelter when about to
lamb. So this different approach has benefits
all round.’
Duncan adds: ‘My brother Angus manages
a suckler herd, and so Andrew normally
visits about once a month, to see at least one
of us. It's a planned visit, he's rarely here on
a 'blue light'.’
‘We are using EID to record worm resilience,
lambing assistance, lamb vigour, udder
conformation, and maternal drive. We can
then use this information and select the
best animals to go forward into our
breeding programme.’
EID also proved very useful when a surprise
case of copper poisoning led to the death
of around 20 ewes, which were grazing
some rented land.
Andrew explains: ‘Sheep are very sensitive to
copper - it builds up in the liver more readily
than in other animals. They become lethargic
and anaemic, and will grind their teeth and
become very thirsty. Jaundice sets in, and
death follows a few days after these clinical
signs are first seen.
‘The ewes had been grazing on red clover,
and this plant can take up a lot of copper.
Postmortem biopsies showed that their livers
had become overloaded with the mineral.
Hence jaundice developed and in a few
cases, fatalities.’
Using EID information from the affected
animals, Duncan was able to identify the
families and sirelines that were more sensitive
to copper levels. He now limits the time certain
animals are grazed on this particular area
of ground.
To help prevent any further problems, Andrew
has also prescribed mineral licks containing
molybdenum. This locks up, or binds, the
copper in the liver, and reduces its toxicity
to the animal.
Handheld ID
Weighing sheep