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WORKING
TOGETHER
FOR A HEALTHIER FUTURE...
15
LIVESTOCK MATTERS
F A R M S K I L L S
Watergate Farm, near Harrogate is a good
example of a farm working to eradicate BVD
from their herd. The Baul family are milking
a closed herd just short of 200 pedigree
Holsteins averaging 9,000 litres milk
sold/cow/year. The farm's calving interval is
currently at a respectable 415 days, with a
100-day in calf rate of 33%, with all cows
served by AI to black and white sexed semen.
At Watergate they sell many of their high
value freshly calved pedigree heifers, so loss
of heifer calves or poor fertility will hit them
hard financially.
The Bauls recognise the threat posed to their
herd by BVD so have been vaccinating for
almost 20 years. Besides vaccinating, the
Bauls work closely with their vets,
Bishopton Veterinary Group, to monitor
infectious disease by carrying out yearly heifer
cohort bleeds and regular bulk tank testing.
BVD wasn't apparently an issue until four
years ago when problems started occurring.
The herd vet found a poor doing heifer with
respiratory disease along with multiple oral
lesions, this immediately sounded alarm bells
and a PI (persistently infected) animal was
suspected. This heifer was confirmed to be a
PI. As this animal was only 18 months of age
its cohort had escaped the previous year's
testing as they were too young to be eligible.
This all tied in with previous misalliance issues
in groups of heifers all in calf to a beef bull
that didn't belong to the farm. When the
BVD case study
- Watergate farm
It is estimated that 90% of UK cattle herds have been exposed to BVD.
With active BVD virus costing from £50-£100 per breeding animal it pays
to monitor and eradicate BVD from your herd.
outbreak was investigated it became clear that
these heifers were not covered against BVD by
the vaccine, due to a combination of primary
course and booster timing failures.
A thorough investigation was required as it is
likely that there are other PI's in the herd. A PI
hunt was started, with initially just all milking
cows, dry cows, in-calf and bulling heifers
blood sampled and pooled BVD antigen test
carried out. This revealed another PI in the
milking herd, which again was removed.
Moving forward a strict vaccination protocol
was re-implemented along with regular bulk
milk BVD antigen testing and heifer cohort
bleeds. Surveillance showed no signs of
circulating BVD and everything seemed fine.
A year on, bulk tank BVD antigen showed
positive and a heifer cohort bleed of 10 non
vaccinated heifers 9-18 months old, was
carried out. This revealed BVD was once
again circulating as nine out of the 10 heifers
were positive for BVD antibody. Although this
could have been due to a transient infection,
it was hypothesised that there may be a
number of PI's within the herd. The Bauls’
imminent worry was adding a PI heifer to the
milking herd, and thus exposing pregnant
cows to BVD. As a precautionary measure all
bulling and in calf heifers were blood sampled
and BVD antigen was tested for in pooled
bloods. Three heifers were positive for BVD
antigen, these were isolated and confirmed as
PI's three weeks later, so removed from the
herd. Finding more PI's in the younger animals
wasn't a huge surprise as a young stock bleed
wasn't carried out at the time of the last PI
hunt, but also cows sampled may have been
acting as a Trojan horse and carrying
undetectable PI calves.
It was assumed that no PI's were present in the
milking herd as they had been screened as
negative only a year back. All youngstock
over a month old were then bled, again
looking for BVD antigen. This revealed two
more PIs, which were both removed. Once
all the younger calves were over a month old
they were also sampled. Watergate Farm is