THE REAL cost of an outbreak of orf is often underestimated, claims a partner in a Welsh vet practice following a recent field trial.

Ian Jones of the Hafren Practice, Newtown, Powys, whose clients run more than 1m ewes, assisted in field trials of an improved live vaccine and delivery system developed by Schering-Plough Animal Health.

The product, Scabivax Forte, provides protection against more strains of the orf virus than the company’s previous vaccine. It has a shelf life of 18 months, or one year longer than was available before, and gives 12 months’ immunity from the disease, says Schering Plough.

John Griffiths of Tymawr Farm, Caersws – one of two units Mr Jones used to trial the vaccine – says it proved very effective, with no cases of orf recorded over two years.

While overseeing the trial on the 1200-ewe flock at Tymawr, Mr Jones also monitored a serious outbreak of orf on another client’s farm nearby. Excluding labour, he estimated orf cost the farm £700.

Mr Griffiths spent more than £200 on treatments, with delayed lamb marketing and lower prices realised by 120 poorer-looking affected lambs costing the enterprise £490.

“Lambs can die from the disease and growth rates can be severely reduced,” says Mr Jones. “Unseen costs include a lower lambing percentage the following season because slow lamb finishing reduces availability of grass for flushing ewes.

“Udder damage can also force premature culling of ewes. Orf can affect up to 25% of a flock and direct costs can be 3.5 times what vaccination would cost the flock.”

Mr Jones tells his clients vaccination is not necessary when there is no indication of orf in sheep, but where it is, he warns that a producer or his staff can catch the disease and develop unpleasant symptoms.

The new vaccine is available only from vets in bottles containing 50 doses, which will cost about 25 depending on the practice.

It is administered on the inside of a sheep’s front leg, where the resulting scab cannot be licked off, using new pump-action scratch applicators. These are expected to sell for about 15 each and are guaranteed for use on 20,000 sheep.