6 CUMBRIA FARMER June 2009VetsTalk
Stop that dripping tap
before it causes a flood
Martin Squires, of the Green Veterinary Surgery, discusses Johne's
disease, particularly in relation to current health planning initiatives
E
veryone working in
agriculture needs to
be aware of Defra's
consultation on
`Responsibility and Cost
Sharing' in animal health.
Ultimately, the Government
wants the industry to take on
more of the costs of maintain-
ing and improving livestock
health.
Many of you will be aware
that Defra has released money
to the North West Develop-
ment Agency (NWDA) for a
four-year programme for agri-
culture in the north west. Part
of this is directed at the live-
stock sector, particularly
health planning, through the
Northwest Livestock Pro-
gramme (NWLP).
There is a significant list of
health problems that cause a
constant drain on farm eco-
nomics. Many of these can be
assessed in terms of impact
on the individual farm, cost to
remedy the problem and eco-
nomic and financial benefit of
improvement or elimination
of the problem. The NWLP
aims to encourage farmers to
engage in this process.
All livestock farmers should
talk to their vets about what
`inefficiencies' may be present
on their farm. Other advisers
could be part of this process,
including a nutritionist,
breeding adviser and environ-
mental impact adviser.
You may be wondering
where this is heading � anoth-
er rant, an apologist for
DEFRA/NWDA? Neither of
these. I would like you to con-
sider looking for what may
seem a low-level or even non-
existent problem on your farm
in consultation with your vet.
It will cost money, but it will
cost more if you have the prob-
lem and ignore it, or if you
introduce it inadvertently.
Most of you will have heard
of Johne's disease. It is a bac-
terial infection caused by
mycobacterium avium sub-
species paratuberculosis
(MAP). The bacterium
invades the intestine wall of
affected animals, leading to
inflammatory changes and
thickening of the intestine.
This stops nutrients being
absorbed, so affected animals
fail to thrive, or dramatically
lose condition. They also
develop profuse diarrhoea.
These animals are an eco-
nomic loss to the farm, requir-
ing culling.
Two further considerations
make Johne's worth avoiding
or combating. Firstly, if left,
the disease will persist, often
in increasing numbers over
time. Secondly, MAP may be
linked to Crohn's disease in
humans. The Government has
taken a `precautionary prin-
ciple' approach to this unre-
solved question, urging farm-
ers to take steps to reduce the
level of MAP-infected animals.
MAP is probably most sig-
nificant in cattle, although
sheep can be affected.
MAP is a hardy organism,
generally spread through fae-
ces after being shed from the
intestine lining. It can survive
in the environment for several
weeks or months, with impli-
cations for slurry and manure
use. Most infection is by oral
ingestion, with most cattle
being affected as calves under
three months old, and devel-
oping the disease as adults.
Colostrum and milk can be
a source of MAP to calves.
Some calves can be infected in
the womb via the bloodstream.
It is also possible for older ani-
mals to become infected by
ingestion of the organism, and
develop clinical signs. Some
animals may contract the
infection and recover, not
showing signs of infection. It
is also possible for infection to
be present on a farm without
any animals showing signs.
Research shows that for
every clinical case of Johne's
in a herd, another seven to 10
animals will be shedding
MAP, and another seven to 10
will be in the `silent infection'
stage. In a heavily infected
herd, up to 25 per cent of the
herd may be infected. The
tests we have will detect only
around 15 to 30 per cent of
infected animals on a single
herd test. If tests are repeated
on a regular basis, 90 per cent
of infected animals can even-
tually be identified before
becoming clinical cases.
While repeat tests may
seem an expensive process,
UK disease models have pre-
viously put the annual cost of
Johne's at �2,600 per 100 cows
in dairy cattle and �1,600 per
100 cows in the beef herd.
Beef and dairy cows both
have significantly reduced
productive lives if affected.
They may also have increased
levels of mastitis, infertility,
lameness and other digestive
disturbances.
Control measures are often
best applied to individual
farms after a risk assessment
by you and your vet. Biosecu-
rity is central to disease con-
trol. Buying from accredited or
monitored sources can reduce
the risk. Disinfection of staff
protective clothing, and sepa-
ration of adults and young-
stock on a dairy farm can help
reduce transmission. `Snatch-
ing' calves at birth may reduce
the risk of ingestion of bac-
teria from the mother or envi-
ronment on a dairy unit.
Some of these measures are
difficult or impossible in the
beef herd.
Testing, identifying, sepa-
rating and/or culling infected
animals will reduce infection
levels over time. Again, your
vet will advise you on the best
approach.
Some transmission is
shown to occur directly from
dam to calf in colostrum. Not
feeding pooled colostrum is an
important step to take. Pas-
teurisation at the correct tem-
perature and time will kill
MAP, and treating colostrum
and whole milk before feeding
it to calves may help reduce
infection in calves. Identifying
family lines and not breeding
from them can assist in cut-
ting the risk.
Other measures that can be
taken include regular clean-
ing of calving boxes and, if
you are in a control pro-
gramme, having separate
calving boxes for identified
`infected' and `uninfected' ani-
mals. Careful slurry manage-
ment is needed to avoid con-
tamination of grazing land.
It may also be important to
identify other animals, such
as sheep and wildlife, that
may be an infection source.
As far as vaccination goes,
it would appear that while the
vaccine may reduce clinical
signs, it does not reduce bac-
terial shedding. It is unclear
whether the vaccine actually
prevents infection.
At risk? Beef and dairy cows both have significantly reduced productive lives if affected by Johne's disease
PRACTICE NOTES
THE Green Veterinary Surgery has
been based at Skelton for nearly 50
years and now has three vets and
five support staff dedicated to
providing a high-quality, personal
service to the farms in the local area.
Over the last few years, a growing
demand for small animal services has
contributed to the growth of the practice
and the premises were extended to create
dedicated facilities for the veterinary care of
pets.
The farm practice continues to evolve,
responding to changes in agriculture. It has
developed a new role with respect to herd
and flock healthcare while still providing
high-quality care for the individual animal.

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