The vaccine, Improvac, which was developed initially in Australia and has been on the Australian and South East Asian markets for a number of years removes the need to castrate pigs to prevent boar taint.

The vaccine is being produced for the European market in the Pfizer laboratories in Belgium.

The vaccine, which has to be delivered twice to male pigs prevents temporarily interrupts the testicular function reducing the level the compounds that produce boar taint - androstenone and skatole.

Pfizer says the vaccine is welfare friendly as it avoids the need for castration and it also has benefits for better growth performance and feed conversion. By suppressing the hormone activity, the pigs are also calmer and less likely to bite one another.

The vaccine has yet to be approved by the US authorities.