IT is always refreshing to be able to
read about studies that have
identified a negative.
Clearly it is exciting for the authors
to report that a gem of an idea, hatched
over coffee, has been developed into a
trial or examination with outstanding
results.
Further requests for additional work
will follow with reference made to the
study by future researchers. But the
negative finding, that
proves that a particular idea
or concept is not valid, may
have saved other workers
much effort.
There should be a
textbook of negatives that recognises
good practice and glorious failure. It
should be an honour to have one’s
name mentioned within such a
publication.
Step up to the plate therefore
Harland, Whay and Barrett from the
School of Veterinary Science at the
University of Bristol. The coffee
moment was that local inflammation
resulting from digital dermatitis may be
able to be identified using a thermal
imaging camera.
Many feet were examined and the
maximum foot temperature recorded.
Thermal contrast in the region of the
caudal interdigital space was analysed
but although 59% of the feet with
digital dermatis showed contrast so did
60% without infection.
The conclusion is that thermal
imaging for the detection of digital
dermatitis is as effective as a visual
inspection. However, much has been
learned about the wide variation in foot
temperature. It will be interesting to see
whether the team are able to apply the
knowledge gained with other
investigations.
Another group from Bristol,
Pengelly, Barrett, Baillie and Fuller,
highlighted that veterinary students
demonstrate poor ability to apply
scientific knowledge, particularly in the area of bovine reproduction.
In the words of the authors,
“Students demonstrated a poor ability
to integrate pre-clinical bovine
reproductive teaching despite exposure
to veterinary practice.” The challenge is
to integrate knowledge from the various
disciplines such as anatomy, physiology
and pharmacology and this was tested
by developing a computer-based
tutorial.
Before participating in the tutorial,
91% of the students scored less than
50% in an assessment. The tutorial
combined pre-clinical teaching material
successfully, with 93% of the students
better able to integrate knowledge. Work
is ongoing to develop a quantitative
objective valuation of the new resource.
Additional practical sessions
involving post-mortem tracts, two
physical models, the Haptic Cow (a
virtual reality simulator) and a farm visit
were held, over two days, for fourth-
year students. This structured approach
to skills development is now to be
incorporated into the third year
programme so that students will be
better prepared when undertaking
extramural studies. A new integrated
online teaching aid is now installed and
available for the current year.
Sources of BVD re-infection
There is much activity concerning
bovine virus diarrhoea and in Scotland
there is work to identify sources of re-
infection. A group from Moredun and
Biobest Laboratories – Bachofen,
Willoughby, Zadoks and Russell – have
identified the value of a BVDV
sequence database collated by
knowledge of the genetic diversity of
circulating strains of the virus.
To date the prominent virus is BVDV-1a, but only viruses originating
from the same holding were identical.
More extensive sequencing of isolates,
combined with epidemiological/animal
movement data, will maximise the use
of the database. The detection and
removal of persistently-infected animals
is ongoing in many countries and more
information about the transfer of
infection sounds important.
Workers in France at LSI
Laboratories Service International –
Magnee, Charrot, Daly, Moine and Sellal
– have established that ear notch sample
detection of BVDV is equivalent to
detection from blood samples. Pooled
samples from 10 animals are equally
effective to detect persistently-infected
animals as part of a large-scale control
initiative.
Using bovine nasal secretions
The possibility of using bovine nasal
secretions to detect pathophysiological
responses to respiratory disease is being
investigated by Ghazali, Jonsson,
Burchmore and Eckersall from the
University of Glasgow.
The value of nasal secretion as an
indicator of immune function and
status has been advanced by identifying
that alkaline phosphatase is higher in all
nasal secretion samples than in serum.
Believed to be the first study to show
that alkaline phosphatase is synthesised
and secreted from the nasal epithelium,
the authors indicate that its function in
this tissue is unclear. A high abundance
of proteins is also found in the fluid.
Following the successful analysis, the
identification of bio-markers for
immune function of the bovine nasal
mucosa is ongoing. Alkaline
phosphatases are known to have an
effect on the liposaccharides of Gram-
negative bacteria. It is interesting that
the role of nasal secretions is only now
being fully investigated and no doubt
there will be genetic variations and age
responses to be further talked about.
The indication that some cows are considered “unlucky” by farmers when
emergency culling takes place has been
investigated, and challenged by Orpin,
Sibley and Fox. Cows culled due to
traumatic recumbency (splits), stuck in
cubicles and other trauma have been
recorded by 234 farmers. Freshly-calved
cows, oestrus behaviour and calving
problems were the top reasons given for
recumbency and the risk areas identified
as un-grooved concrete, congestion
points and sloping areas.
A range from two to eight cows
falling over per 100 cows per month
was recorded. It was indicated that the
death of a cow did not necessarily lead
to on-farm improvements with the view
of unlucky cows often expressed.
The study also revealed that the
economics of emergency culling was
not considered and the authors
conclude that traumatic recumbency
constitutes a significant unrecognised,
avoidable, economic loss on UK dairy
farms.
A challenge study of young calves
with Mannheimia haemolytica at Moredun
by Reddick has shown that feeding
colostrum from vaccinated cows offers
partial protection from disease. The
survival rate of calves given the
colostrum from vaccinated cows was
50% with only 16.7% in the control
group.
Active vaccination of young calves
is impractical due to the time needed for
an immune response and animals
transported at an early age are at high
risk from transport fever.
Passive immunity offers a degree of
protection against acute, experimental
Mannheimia infection. It is hoped that
further field work will demonstrate
direct benefits in reducing the impact of
respiratory bacterial infections.
Many of these initial studies may be
discussed in greater depth as more
information is added and the authors
should be credited with making their
early observations available for scrutiny
and comment.
