Bluetongue-vaccinated ewes pass on protection to lambs

Ewes receiving a booster shot of bluetongue vaccine in the second year of a vaccination programme have been shown to pass on extended protection against the disease to their lambs.

Lambs born to ewes that had received a booster shot of inactivated BTV8 vaccine were protected against the disease for at least 14 weeks, the age at which many lambs go for slaughter, says Chris Oura, the Institute for Animal Health.

Dr Oura and colleagues, along with the University of Cambridge and the VLA have shown protection is a result of high amounts of colostral antibody passed from ewe to offspring.

Most significantly, ewes that had only been vaccinated once passed on lower amounts of colostral antibody to their lambs.

Although these lambs were not challenged with BTV in the experiment, lambs from a single vaccinated sheep were likely to be protected for a shorter time than lambs born to ewes in the second year of a vaccination programme.

In a related study, Dr Oura showed sheep vaccinated once with inactivated BTV8 vaccine had protection for at least 10 months – more than sufficient for the UK midge season.