Vaccinations cost caution
By Allan Wright
BE cautious before rushing into an expensive vaccination programme against abortion in sheep, despite the problem costing the UK industry an estimated £35m a year.
Dumfriesshire vet Peter Wray says: "Invest time and money in determining the exact cause of abortion on farm, then decide on the best control or eradication programme.
"The main causes of loss are enzootic abortion and toxoplasmosis and both can be controlled by vaccination. But there are other causes such as Campylobacter, listeria, and salmonella, and a producer could invest heavily in vaccines and still have an abortion problem. Vaccinating against enzootic abortion would also make it difficult for a flock to become accredited as free of the disease," says Mr Wray.
The £35m loss figure was given at a news conference last week by Ian Mawhinney, of Intervet, which has completed a four-year study of 27 flocks and 19,000 ewes. He claimed that 80% of losses could be attributed to enzootic abortion and toxoplasmosis.
"In a 500-ewe flock with an annual abortion rate of 5%, the problem would costs more than £2000 a year with lost production, veterinary charges, extra labour, and increased replacement costs adding up to £85 a ewe. A 5% level is far higher than need be tolerated. Our trials have shown that vaccinated flocks are bringing the base abortion rate down to 1% over three to four years," he said.
His firms Enzovax, claimed to give cover for up to four years, costs about £4 and is now being challenged in the marketplace by Mydiavac from C-Vet which costs £3. Intervet also markets Toxovac to prevent toxoplasmosis. *