08/02/08
Now is the time to make sure high value dairy heifers are
fully protected against bovine leptospirosis, well in advance of
the peak disease transmission period at turnout.
“Turnout often heralds the mixing of cattle for the first
time and the disease spreads easily between infected and uninfected
animals at this time of year,” said Paul Williams MRCVS,
livestock veterinary adviser, Schering-Plough UK. “Heifer
replacements can be particularly vulnerable if they have not had
their full primary vaccination course, which is two doses of Leptavoid-H
four to six weeks apart. Ideally, the vaccine course should be
completed by the end of the winter and at least two weeks before
turnout,” he said.
Two strains of leptospirosis affect UK cattle and at grass uninfected
stock are suddenly exposed to the urine of infected animals that
may be shedding leptospires. Cows become infected through urine
splashing into their eyes, mouth or a cut in their skin and from
the bull by infected semen. Moist grass is also a relatively favourable
environment for leptospires and these organisms generally survive
for longer outside the host in mild spring conditions. That’s
why the spring is such a peak time for disease transmission.
“Advance planning to make sure heifers are properly protected
from leptospirosis is crucial and only Leptavoid-H protects them
against both UK strains,” Williams said. “In addition
to any bought in stock, it is important that youngstock coming
onto the system are fully protected from the disease. Too often
heifers only get their first dose at the same time as the annual
herd boosters, but this is often too late from a practical point
of view. These young animals then get turned out to grass at the
same time as the lactating cows, but the youngsters often go to
quite remote parts of the farm so it’s easy to forget to
give them their second vaccination. It’s important for the
efficacy of the vaccine and the health of the animals that this
doesn’t happen.”
Sub optimal fertility can cost over £400 per cow. To avoid
the potential financial losses associated with leptospirosis, Schering-Plough
recommends that all unvaccinated dairy herds should screen for
infection using a simple bulk milk test, which avoids the need
for blood sampling individual animals.
“The test results will indicate the level of infection in the herd and
provide a starting point for developing a strategy to vaccinate against both
strains of the disease with your vet,” he said. For beef herds, blood
sampling is the only practical diagnostic option.
Dairy farmers can ask their vet to screen a bulk milk sample for
leptospirosis through the BLiSS scheme. Alternatively, producers
who send milk samples to NMR for fat, protein and cell count analysis
can ask for a leptospirosis screen on these samples as well, using
the NMR Healthcheck Service.
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