2 November 2001

Farmers short of time to quarantine new ewes

By Richard Allison

MANY sheep producers routinely vaccinate replacement ewes against a range of diseases but only half of ewes are routinely quarantined before joining the main flock.

This is the alarming message from an Intervet commissioned survey of 432 sheep flocks, says the companys senior livestock product manager Graham Webster.

"It means many flocks are being placed at unnecessary risk of sheep scab, orf, foot-rot and enzootic abortion. But the survey was undertaken before foot-and-mouth when flock bio-security was less of an issue," he says.

One reason for replacement ewes not being quarantined before joining the main flock is timing. Ewes are normally purchased just before tupping, leaving insufficient time.

"Replacements should be purchased early enough to allow a 21-day quarantine period," he advises.

During the quarantine period, independent sheep vet consultant Chris Lewis says ewes should be treated for scab, worms, and foot-rot. Orf and maedi-visna should also be treated where necessary.

Treating ewes for disease before they join the main flock is one-fifth of the cost of eradicating it from the whole flock, says independent sheep vet consultant Chris Trower. "This is assuming a replacement rate of 20%."

Long-term costs can also be avoided with simple bio-security measures. An example is bringing resistant worms into a flock which will increase treatment costs for many years, warns Dr Webster.

As well as bringing new diseases into a flock, purchased ewes can also be more susceptible to diseases already present, says Dr Webster. "Toxoplasmosis can remain unnoticed in flocks until replacements are brought in and they show high levels of barrenness."

Homebred replacement ewes can be just as susceptible to diseases such as pasteurella and clostridial infections as purchased ewes. But, according to the survey, homebred ewes are less likely to be vaccinated. &#42

Ewes are often bought just before tupping, leaving insufficient quarantine time, says Graham Webster.