Different approach needed to reduce somatic cell counts in herds - Veterinary Practice
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Different approach needed to reduce somatic cell counts in herds

reports on an international symposium on dealing with SCCs

FARM vets must persuade their
dairy clients to adopt a different
approach to reducing somatic cell
counts in their herds, Andrew
Biggs, a past president of the
BCVA, told an international
symposium on mastitis in Brussels
in September.

Instead of
concentrating their
efforts on cows with
the highest individual
cell counts, farmers
and their vets should
be focusing on those
animals with only
moderately raised
counts.

Those individuals
with counts of between
200,000 and 500,000 cells/ml for the
first time in monthly tests will be ones
that produce worse results in
subsequent tests.

Treating cows which have tested
over one million cells/ml on two or
more occasions is a waste of time and
effort as these must be considered to
be chronic cases which are unlikely to
respond to antibiotic therapy.

“It is essential to pick the right
cases to pluck off the escalator: we
should not be treating broken cows,
but today’s cows with mediocre cell
counts may well be tomorrow’s chronic
cases and we ignore them at our peril,”
he said.

Cell counts are a fairly blunt
instrument for dealing with cases of
subclinical mastitis in dairy herds but
with advanced data collection and
analysis techniques they can be used to
good effect as part of dynamic
management policy, Mr Biggs
suggested.

The goal is to use these data to set herd performance targets and prepare
action lists of those cows requiring
treatment – normally those cows with
new infections acquired in the dry
period or during the current lactation,
although some cows in the very early
stages of chronic infections may also
be suitable.

Decisions on how
many cows should
receive treatment will
depend on a number
of factors, such as the
rate of new infections
within the herd and
perceptions of the
chances of achieving
clinical cure in that
particular animal.

But farmers should
recognise that there are other ways of addressing poor performance rather
than relying on medical solutions.
Changes in management will often
address some of the underlying
problems by improving hygiene
standards in the housing or milking
parlour: “Treatment is only part of the
story,” he said.

Inappropriate treatment

Antibiotic dry cow therapy is often
used inappropriately in dairy herds
because of the stockman’s concern
about the cost of the product rather
than choosing the right product in the
right cow, said Marion Tischer, a
Berlin-based veterinary consultant.

She advised applying a strategy
based on testing to identify the causal
pathogen and only using treatment
against newly-established infections.
She agreed that attention to
management issues is vital in the dry
cow period as the rate of new
infections is determined by the cow’s
physical and physiological environment.

She also recommended reducing
the risk of bacteria gaining access to
the udder with the routine use of teat
sealant, such as Orbeseal, produced by
Pfizer Animal Health, which sponsored
the meeting.

Farmers producing milk with high
cell counts will not only face financial
penalties imposed on the whole milk
but can also lose money on the
processed product, said Marco Nocetti,
head of the laboratory for the
consortium of 405 dairies making
Parmigiano-Reggiano cheeses.

Their product, known outside Italy
as parmesan, is a “protected
designation of origin” under EU law
and the consortium imposes strict
controls during manufacture to maintain quality and protect the
product’s reputation.

Poorer quality milk contains less
casein as a percentage of total protein
and consequently produces less cheese
– a standard 1,100kg vat of raw milk
with a 250,000 cells/ml count would
yield 1.58kg more cheese than the same
quantity with a cell count of 500,000.

Moreover, milk from herds with
high cell counts will often contain
detectable antibiotic levels which can
affect the composition of the bacteria
population used in the coagulation
process and result in cheeses
containing unsightly bubbles of gas.

Attacking the industry

Misleading information on cell counts
is being used by animal rights groups
as a means of attacking the dairy
industry, warned Ynte Schukken from Cornell
University, New York.

The campaigning
group PETA has issued
posters parodying the
industry’s own advertising
slogan “Got milk” with
the provocative “Got pus”.

But somatic cells, mainly
macrophages, are a normal component
of healthy milk and indeed the cow
would not survive unless her milk
contained these cells.

Short-term increases in the
numbers of neutrophil cells are also a
sign of a healthy immune system and
should be of concern only if there are
persistent high cell counts.

But farmers and their veterinary surgeons should maintain a focus on
controlling cell counts as a quality
assurance measure in an increasingly global market for milk and
dairy products, Professor
Schukken said.

The EU has taken the
lead in pressing for
improved standards and
given the impact of the
export trade in maintaining domestic milk prices, other exporters will have to follow. But
he warned European producers that
they must be seen to be playing by the
rules.

If their actions are shown to be
inconsistent, they may face expensive
and damaging disputes with the US,
conducted through the World Trade
Organisation, like those that have
occurred over growth hormones and
genetically modified crops.

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