FOLLOWING letters on the subject of badger culling by Melanie Squires of the NFU (We want to get rid of TB, not badgers, July 7) and Justin Kerswell of Viva! (Territorial badgers not spreading TB, July 13), I would like to try to inject some balance into the discussion.

Contrary to what Justin Kerswell says, badgers do spread TB to cattle, as the Randomised Badger Culling Trial (RBCT) showed. Monitoring of the trial areas showed a 27.4 per cent overall reduction in TB cases in cattle attributable to culling, close to the 28 per cent figure quoted by Melanie Squires.

However, the big hike in TB cases in areas restocked after the 2001 foot-and-mouth outbreak demonstrated the importance of cattle movement in spreading the disease, which Defra hope they have at least partially addressed by the introduction in 2006-7 of pre-movement testing of cattle.

In fact, TB cases have dropped since 2008 although three years is too short to identify a trend.

The RBCT results I quoted above were achieved by culling for twice as long as the currently proposed four years, carried out by systematic trapping and killing of badgers over, on average, 70 per cent of the land within each culling area. Where culling has been carried out in practice in Ireland this appears to have reduced TB cases by 15-20 per cent.

The current proposals for England apparently assume that culling will also be carried out over 70 per cent of the land within designated areas and that a similar proportion of the badgers will be killed at each phase within the specific areas where culling takes place. So Justin Kerswell is wrong to imply that badgers will be eliminated altogether within these areas, although he is right that only a small proportion of those killed will carry the disease.

A highly relevant research finding is that individual badgers within culled areas roam about 70 per cent further than those in undisturbed areas, which increases the TB-spreading potential per surviving badger correspondingly.

Estimates of between 12 per cent and 28 per cent potential reductions in TB by badger culling are being quoted. Professor Krebs, who initiated the RBCT, expects a figure of about 15 per cent in culled areas and believes the exercise will not be worthwhile. The question is who is right, and what level of success will be worth the effort and expense?

Francis Kirkham

Nymet Rowland, Crediton