Dairy farmer Ian Bulman has taken a proactive approach to disease
control since an outbreak of BVD in his herd 10 years ago, carrying
out an animal health testing and vaccination programme at Bank
House, Armathwaite, near Carlisle in consultation with his vet.
Vet Graham Brooks takes a sample to test for
Johne's Disease in Ian Bulman's Bankhouse Holstein herd.
The Bankhouse Holstein herd, which was closed from the mid 1960s
until the foot and mouth epidemic in 2001, is one of the first
to be tested for Johnes disease through a simple bulk milk sample
by Carlisle vet Graham Brooks’ Coomara
practice – thankfully
the test proved negative.
“After losing our cattle to foot and mouth we re-stocked
in 2002 with a herd from Scotland which was closed and we have
continued that policy since, using AI through Genus to breed our
own replacements,” said Ian Bulman.
“The outbreak of BVD took us completely by surprise as we
thought with having a closed herd we would have a lower disease
risk. Now we test for anything that’s possible to test for
- BVD, IBR, Leptospirosis, and now Johnes disease - on a regular
basis or when Graham advises it is appropriate,” said Ian
Bulman, a former NFU county milk committee chairman
“I believe that if we have healthy stock we have profitable
stock. It also has important implications for us when we sell dairy
disease is caused by a slow-growing organism, Mycobacterium
avium subspecies paratuberculosis, often known as MAP, that
may not be detected for many years making it important for farmers
to be vigilant for signs of the disease. These include reduced
milk output or reduced fertility in older animals, profuse diarrhoea
and significant weight loss in advanced stages of the disease.
Guidance to the dairy industry on the control of Johne's Disease
in dairy herds was published by Defra 18 months ago (Sept 04),
in partnership with the British Cattle Veterinary Association (BCVA).
The guidance suggested that farmers should prepare a herd health
and welfare plan with their vet which should include measures to
control the disease such as early removal of diseased cattle, not
breeding from offspring, and making sure that calves only receive
colostrum from their own mother where possible.
Last September (2005)
at the Dairy Event the Johne's Initiative was launched with backing
which included the National Beef Association, National Farmers
Union, Livestock Auctioneers Association, Royal Association of
British Dairy Farmers, Holstein UK, Cattle Health Certification
Standards, British Cattle Veterinary Association, Scottish Agricultural
College and Defra.
The aim of the Johne's
Initiative is to raise awareness of the disease and encourage farmers
to test and cull and identify other measures which can be taken
on farm to reduce risk of infection. Improved bio-security and
hygiene, particularly in calf rearing units, is seen as a major
objective. Rabbits and other wildlife have been shown to contract
the disease and control of rabbits on pasture will help break the
Accreditation for freedom from Johne's Disease is available
to qualifying herds through cattle health schemes approved by Cattle
Health Certification Standards (CHeCS).
In addition to the economic
benefits to individual farmers, the eradication of the disease
is vitally important in pedigree herds, to prevent transmission
into commercial herds, and will be an important factor in developing
exports of British pedigree stock when export markets re-open.
Johne's Disease can halve the productive life of a bull.
cost to the dairy industry of Johne's Disease is difficult to estimate
as the disease can seriously impair the performance of cattle long
before clinical signs appear. The long incubation period means
clinical signs of the disease may not appear until the animal is
three to six years of age, although it will harbour the disease
sub-clinically before then.
Mr Brooks said: “Most
dairy farmers will have heard of Johne’s
disease and are probably aware that the main symptom is a cow losing
weight with profuse diarrhoea, and a majority will probably remember
having a cow with these symptoms at some point in their farming
“What most farmers will not realise is that
the cows that scour are only the tip of the iceberg. A lot of cows
are slaughtered out of the national dairy herd each year for weight
loss, poor milk production and poor fertility. A significant proportion
of these cows are infected with Johne’s disease and the symptoms
are due to this infection.
“Johne’s disease is an insidious disease, with calves
being infected soon after birth either from infected colostrums
or faecal contamination on the cow’s teats or in the environment.
It does not pass from cow to cow.
“This infection then takes a long time usually two to three
years before it begins to have an effect upon the animal’s
health. These cows will be shedding bacteria in their faecaes before
they show any symptoms; this means that the next generation of
animals is infected without the farmer knowing it.”
The results are reduced productivity, fertility problems, weight
loss and large economic problems if it becomes advanced within
the herd. With possible links to the human Crohn’s disease,
as yet to be established, there are also implications for sales
of milk and stock.
Johne’s disease was more prevalent in re-stocked herds and
certain breeds were more susceptible (eg Channel Island). In Cumbria
60 herds had Johne’s however bulk tank tests carried out
by Coomara had so far proved negative.
Mr Brooks said that main difficulty in the past with the diagnosis
of Johne’s disease was that each individual animal had to
be looked at in turn to make a diagnosis. Tests are both expensive
and also very insensitive. The gold standard test is faecal culturing
but this can take up to six weeks for a positive diagnosis.
He said that examining a faeces sample from scoured cows under
the microscope will usually give a positive diagnosis but the animals
in sub-clinical disease may appear negative.
Animals can also develop antibodies to the bacteria, but this
is usually late in the infection. Therefore in the past blood screening
tests have had to be carried out on a large number of animals to
determine if any animals in the herd are infected.
This needs to be repeated at regular intervals to detect those
animals that are incubating the disease; this has made the process
expensive and in general has only been taken up in herds which
are selling high genetic animals or where there is known to be
“The recent development of a bulk milk antibody test for
Johne’s disease means that we now have a cheap and easily
performed test that can be repeated on a regular basis to assess
the Johne’s disease status of the dairy herd,” said
“Most farmers will be familiar with monitoring of disease
by using bulk milk antibody tests which tests for Leptospirosis,
Bovine Viral Diarrhoea (BVD) and Infectious Bovine Rhinotracheitis
(IBR) being available for a number of years now. The Johne’s
disease test is the same only requires the collection of a well-agitated
bulk milk sample.”
The bulk tank test costs £7 although pharmaceutical company
Virbac, which is importing the vaccine for Johne’s, is currently
offering the test free, with back-up vaccination should a test
“Due to the possibility that young cows in the herd may
be infected but not yet producing antibodies it is not possible
to say that a herd is free from the disease, but as more tests
are carried out, with negative results, then the probability increases.
“The test also gives a result of positive suggesting that
there are a number of cows in the herd infected and producing antibodies.
Depending on the herd, there are a number of ways to determine
which cows are infected.
“Bulk milk samples can be taken from various subsets of
cows i.e. first lactation heifers, second calvers, older cows etc.
This will allow the extent of the infection in the herd to be determined.
Individual cows can be blood tested to determine their status.
“The main advantage of the bulk milk test is it allows the
disease status of the herd to be known and this allows specific
herd health planning to be instigated to control the disease in
the herd or to prevent it’s introduction into a free herd.”
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