Getting to grips with technical issues... - Veterinary Practice
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InFocus

Getting to grips with technical issues…

Richard Gard concludes his reports from the 2013 congress of the British Cattle Veterinary Association

THE opening technical paper at
BCVA Congress 2013 addressed the
difficult topic of production and
fertility in dairy cows.

Stephen Le Blanc of the Ontario
Veterinary College supported the
proposal that high productivity and
good fertility are not antagonistic if
good management is applied.

The role for automated activity
systems is important and within the
USA/Canada programmes automated
heat detection can provide a herd
performance that is “as least as good
as with synchronised-based
management”. The use of
pedometers is expected to reduce
the frequency of hormone
synchronisation injections.

Research has highlighted a multi-
factorial relationship between
production and reproduction and these
vary between herds and between cows
within a herd.

Delivering high production, good
reproduction and cattle well-being is a
challenge with increasingly large and
productive herds, but providing for the
nutritional and behavioural needs of
cows is achievable.

Studies of standing time to be
mounted indicate that higher producing
cows stand for 22 seconds whereas
lower producers stand for 28 seconds.
Both situations represent a major
challenge for oestrus detection.

Various research groups worldwide
have shown an improvement in
pregnancy when yields increased. The
speaker indicates in the proceedings that
this association “should not be
surprising if good nutrition, cow
comfort and attentive management
provide the conditions for high
production and good productive
performance”.

He recognised, however, that
“questions about whether metabolic
demands for production and
reproduction are reaching a biological
limit and whether genetic selection
criteria are optimised are important and
warrant valid, large scale studies”. The
factors that influence automated activity
monitoring systems, the relative
performance between herds and
optimising performance within a herd,
remain to be clarified.

George Mann of the
University of Nottingham
discussed the role of
progesterone and embryo
survival in the dairy cow.
Although inadequate luteal
support of early
embryonic development
remains an important
cause of embryo mortality,
current scientific evidence
does not support milk yield as causal.

Direct progesterone supplementation and the enhancement
of endogenous progesterone
production, through gonadotrophic
stimulation, can improve pregnancy
rates but results are inconsistent. Careful
attention to the timing of therapy is
advised.

Low progesterone is an inherent
problem with individual animals and
studies indicated that 68% of cows within a herd have good progesterone,
21% lower and 10% poor with levels
too low for pregnancy. Progesterone
given 3-5 days following insemination
has shown a 10% improvement in
embryo survival, but not all studies have
reported a benefit.

Similarly, human chorionic
gonadotrophin treatment on day 5 has
been shown to increase pregnancy, but
not in all cases. Cows with other health
problems, such as BVD, have been
shown to benefit from progesterone
therapy. Metabolic issues are not
strongly correlated with low
progesterone.

Promoting the use of milk samples
to detect pregnancy, National Milk
Records launched the use of an ELISA
for Pregnancy Associated Glycoproteins
(PAG) in July 2013. From day 35 after
service, a PAG level of less than 0.1
indicates not pregnant, from 0.1 to 0.25
is inconclusive and above 0.25 indicates
pregnancy.

The same milk samples that are
collected at the monthly milk recording
are transported to the central laboratory.
The test is used to indicate early
pregnancy, followed by veterinary PD,
or at 90 days to confirm that the cow is
in calf. Inconclusive tests are re-tested at
no charge.

Some 650 herds are currently
utilising the test facility. Good on-farm
records and veterinary involvement are
indicated. Further information via
www.nmr.co.uk.

Schmallenberg
update

An update on
Schmallenberg disease,
which has propelled the
town in Germany to
international fame, was
detailed by Jules Minke
of Merial Animal
Health. Following the
malformations in calves
and lambs in 2011, with 50% milk drop in cows and 65% lamb
mortality, countries have now stopped
reporting cases as national reporting of
cases led to an export ban.

The virus is in semen and spread by
biting midges and is in the same virus
group as Rift Valley Fever. Vector
control, herd management and
vaccination are the recognised control
tools. An inactivated vaccine is now
available in France and a UK licence is
due. Two doses, three weeks apart, are
required for cattle and one dose for
sheep.

Spread of infection from herd to
herd and flock to flock is very variable
and there was discussion about the
justification of vaccination with immune
animals. The difficulty is that the
infection could arise again and threaten
a naive population of animals.
Monitoring any clinical incidence and
surveillance by veterinary surgeons
remains the first alert and this awareness
will direct a risk assessment for the
benefit of clients.

Lessons learned

Learning the lessons from other
experiences of BVDv was strongly
highlighted by Klaus Doll of the
University of Gleissen. The sequence
of an outbreak in Germany is that two
heifers were bought into the herd and a
month later the herd suffered milk
drop, respiratory distress, diarrhoea and
abortions. Mortality was 12%.

Calves and two cows were sold to
other farms with 23 herds becoming
infected, 20% mortality in dairy herds
and 80% on veal units. There was
continuous virus shedding for weeks.
Transfer of the virus was due to cattle
movements but also from cow to cow
and farm to farm by vets.

Vaccination with BVDv-1 live
vaccine commenced under emergency
procedures but not all herds improved.
The incidence of BVDv-2 has been
low in Germany but the relevance of
genotypes will be important in the
future.

Control initiatives

Joe Brownlie reviewed relevant BVD
control initiatives taking place
throughout Europe and the BVD-free
initiative promotion to farmers in England. Cattle
Health England is seen as
the way forward, food
industry led, a legal
framework, an executive
function and
concentrating on endemic
diseases.

A realistic budget of
some £10 million per year
would enable the first role
to be BVD eradication and then build in other disease control.
A long-term government commitment
is sought; the returns are substantial
(£46 million losses) and it is important
that the UK at least matches the effort
of other countries. Persistently infected
animals would be paid for.

A breakthrough has occurred with
veterinary surgeons. Some time ago it
was recognised that vets do not like the
complexity of BVD, but training and
application has shown that once the
disease is understood it is a pleasure to
work with. “No farmer has ever
regretted getting rid of BVD,” Prof.
Brownlie said.

Richard Booth of the RVC has
investigated BVD controls and
outbreaks in the UK and advises that
vaccination is not enough: there has to
be removal of PIs and biosecurity.

Determining the herd status
requires assessment of herd screen and
individual tests. Blood tests, bulk tank
milk samples for Elisa or PCR and ear
notch samples all have a role to play
within a managed programme to search
out the PIs. Antibody levels change
with vaccination. The tools are in place,
with farmers and vets able to have
confidence that BVD can be
eliminated.

Progress in Ireland

Finola McCoy spoke about the work of
Animal Health Ireland. Recognising the
obstacles to change on the farm,
emotional distress, personal pride,
installing confidence, no quick fix, small
things being done right, a team
approach and a science base are all
aspects that are included.

Working to control BVD, mastitis,
Johne’s, IBR, infertility, lameness and
calf health involves farmer workshops,
monthly articles, consistent
information, technical working groups
and up to date research.

The initiative is a not-for-profit
public/private partnership with time
given for free by industry. Over 1,000
farmers were involved in 2013. There is
much to be learned from this model of
activity and enthusiasm for success.

Equally enthusiastic was the
presentation from Bryony Kendall and
Andrew Henderson of Tynedale Farm Vets about dairying in
the dust in Mozambique.
This project involving
XL Vets’ members aims
to provide financial and
nutritional security for
families by managing a
jersey heifer to pro-
duction. Local obstacles
are great but veterinary
input is helping to
achieve significant
results.

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