Select Committee on Environment, Food and Rural Affairs Minutes of Evidence


Examination of Witnesses (Questions 40 - 59)

MONDAY 18 JUNE 2007

PROFESSOR JOHN BOURNE CBE, PROFESSOR CHRISTL DONNELLY, PROFESSOR JOHN MCINERNEY OBE AND PROFESSOR ROSIE WOODROFFE

  Q40  Mr Drew: We have had at least a week of inspired leaks in the press which said that Ministers were going to bite the bullet and were going for large-scale culls. We have now had all the stuff this weekend where effectively Ministers are now saying they do not need to bite the bullet because there is no need for large-scale culls. We have obviously had various organisations, like the Badger Trust, making its own threepenny-worth. This has not been helpful in trying to get a scientific rationale of your report. You make a comment about that in terms of some of the critics that you have had to deal with over the years. They all seem to have got their retaliation in first. Have any of them helped you at all in trying to make your case?

  Professor Bourne: Not at all. Absolutely not. Absolutely and utterly not. I certainly made the case to Ministers, both to Mr Bradshaw and to Mr Miliband, and collectively, in the meetings we had in November last year and February this year that it would really be helpful if Defra embraced the science and stimulated discussions with the NFU in particular based on science to develop science-based policies. I have seen no sign of that. It may be happening in the background but I am not aware that it is happening and, if it is, it has certainly had no impact on the NFU response.

  Chairman: Come back on Wednesday and you can see the other side of the coin.

  Q41  Mr Gray: I am new to the Committee since you were here in 2006. I have just been reading the papers and forgive me if I have missed something. It seems to me there is a difference in tone between what you said particularly in your letter in 2006 and what you said in your report. If I could just quote a couple of bits that confused me rather, in your open letter of January 2006 you said, "Intensive culling over a large area and over an extended period of time could in principle reduce cattle breakdown rates", which I interpreted to mean that you thought that there could be a place for extensive culling over a long period.

  Professor Bourne: Read on.

  Q42  Mr Gray: In the second half you say there are logistical difficulties, yes, but let us leave aside—

  Professor Bourne: Read on, read on.

  Q43  Mr Gray: Perhaps you would like to answer the question in a moment and then you can tell me the bits that I have not actually—

  Professor Bourne: The bits that you have missed out said it can only be considered as a policy option with a cost benefit analysis.

  Q44  Mr Gray: Professor Bourne, perhaps you would let me ask the question before you seek to answer it.

  Professor Bourne: You were quoting a letter and you were not properly quoting that letter.

  Q45  Mr Gray: Perhaps I can ask the question. Perhaps that is a better way to do it, ask the question first and then let you answer it. My naïve interpretation of your letter then—and you can correct me in a moment—was that you said that under some circumstances, although there are logistical difficulties attached and there are costs attached, intensive culling, in your words, over a large area over an extended period of time could in principle reduce cattle breakdown rates. Am I wrong in thinking that means you think that under some circumstances extensive culling could break down cattle breakdown rates? Is that right or wrong?

  Professor Bourne: Mathematical modelling in extrapolation from trial data suggests that if you cull over a large area, you would ultimately get positive gains with respect to the area culled relative to the area that you were not culling, where we know one had this perturbation effect.

  Q46  Mr Gray: So the answer is yes.

  Professor Bourne: I also stated very clearly in that letter that there would be extreme logistical difficulties in achieving this with respect to culling over a large area repeated regularly over a large period of time, and it could only be considered as a policy option if there was an adequate cost benefit analysis.

  Q47  Mr Gray: What sort of logistical difficulties?

  Professor Bourne: The logistical difficulties are the ones that we had to face in doing full surveys of these areas, getting a trapping force into the field to do culling across the whole piece at the same time and continuing it for this very long period. There is a real logistical difficulty.

  Mr Gray: Hang on a minute. The logistical difficulties of doing it—

  Q48  Chairman: Let Professor Bourne answer.

  Professor Bourne: We also stated that if one required a cost benefit analysis and we have subsequently been able to do that because we have been able to identify the number of breakdowns that would be saved as a result of this sort of practice and the costs that would be incurred, but the fact the Government stated very clearly that they would not do this themselves, they would not be responsible for this, but farmers would in fact have to do this off their own bat, increases the logistical problems of doing this.

  Q49  Mr Gray: Let us leave the logistical difficulties to one side because there is no logistical difficulty in the world that it is not possible to overcome. What I want to focus on is what you said in your January letter, which was that in principle an extensive cull over an extensive period might well be beneficial in terms of reducing TB. That is what you said in your letter. Was that wrong or has the science developed since then?

  Professor Bourne: As an extrapolation, as a modelling exercise, that was correct but we are bound to write caveats to that, which I would have thought would have been a clear message to Ministers of the difficulty of doing that and the likelihood that the whole thing just would not be achievable. Subsequently, of course, we have been able to do a cost benefit analysis.

  Q50  Mr Gray: We will come back to the cost benefit analysis and cost, of course, is a separate matter but the important principle which has not really come over in the coverage today is that in that letter you accepted the principle, leaving aside the difficulties, leaving aside the logistics, leaving aside the costs, and those of course are big difficulties, according to my naïve reading of it, that an extensive cull over a wide area might have some benefits for reducing TB, leaving aside the logistics, leaving aside the costs. If that is the case, can I ask you a second question about area—you hinted at it a moment ago but we did not actually develop it quite as much as we perhaps could have done. Given that the tests were over ten square kilometres, and quite good effects were seen inside the ten kilometres squares, although there were bad effects around the border, what would happen if that were very much wider? For example, in the old days it used to be that the cull was across the whole of the county. Imagine that all the badgers in the county of Wiltshire were exterminated, what effect do you think that would have? Do you not think that possibly your tests being in small areas—ten kilometres is a very small area in terms of the land mass of Great Britain—given that you accept the principle that it does actually work, and leaving aside the logistics and leaving aside the costs—we will come back to that in a moment—do you think the small area over which the test was done might have constrained the outcome?

  Professor Bourne: If you look at page 105 of report, we express there the confidence limits that extrapolation suggests you might expect with trapping over a very large area. They are very wide confidence intervals. You ask if one culled out the whole of Wiltshire, what would the effect be on the whole of Wiltshire. The data from the trial would suggest that you would have a positive impact on cattle breakdown within the Wiltshire area, and it would be difficult to tell you what that was; one could extrapolate. One sees the very wide confidence intervals. But you would certainly have an unwanted effect in the neighbouring counties of Hampshire, Somerset, Dorset, what counties there are surrounding Wiltshire. Pragmatically, I think, attempting to cull badgers over such a large area would present extreme difficulties, difficulties which we have mentioned, with respect to how you would have to cull that area.

  Professor Woodroffe: If I could just continue on the theme that Professor Bourne has started, this issue about logistics is not just a question of you would have to do it and it is always achievable. The problem is what happens if you do not achieve it. If you attempt to cull badgers across the whole of Wiltshire, if you fail to achieve that, if there are chunks that you cannot access, if you do not do it all simultaneously, if you do not do it as we did it in this case, where we had large numbers of people coming in simultaneously over large areas to cull badgers, anything that you do which reduces a simultaneous, very widespread effect risks making the situation worse. So where culling is localised, you get the perturbation effects, you increase TB risk to cattle.

  Q51  Mr Cox: Subject to permeability of boundaries.

  Professor Woodroffe: Wiltshire being really quite permeable.

  Mr Cox: I understand that.

  Q52  Mr Gray: There is a lot of rain there.

  Professor Woodroffe: So, for example, we showed that, as I mentioned previously, every time you do a proactive cull across the whole area, the prevalence of infection in the badgers goes up on each cull. If you do not do that simultaneously but instead you do that cull as several sectors that you do successively, the increase is actually 1.7 times as much. So if you do not do a simultaneous cull, it makes the situation not just a bit worse but quite a lot worse in the badgers. So simultaneous culling is very important, good land access is very important, targeted culling around inaccessible areas is very important, and everything that you do which, because of logistical constraints, because of lack of land owner compliance, because you are just trying to do something on a massive scale, takes you away from an absolutely simultaneous cull, performed very extensively simultaneously, is going to take you more towards piecemeal culling, which is going to entail a high risk of making the situation worse rather than better. There is a big difference between saying in principle that you could reduce TB risk to cattle by culling badgers over very extensive areas, although within the range of areas we have projected the differences, the net effect is pretty small. The overall effects are very modest but there is also an increasing chance that you make it worse, especially if you are going to do that as one of the culling approaches that was formerly included in the consultation document was licensing farmers or farmers' representatives to do the culling. Without the resources of being a large government department, farmers trying to do it themselves or having contractors trying to do it themselves and so forth is going to take you more towards this piecemeal culling, which will have a massive risk of making things worse rather than better.

  Q53  Mr Gray: I see the logistical difficulties but you get my point that if there were to be in principle benefit from it and given that this is costing the nation millions of pounds, it might well be we could devote huge resources to it if indeed it was going to be the final solution. Is there not some argument in favour of doing that? Is that something which you considered?

  Professor Bourne: One could certainly do that, just as the Irish plan to remove badgers from 30% of their land mass.

  Professor Woodroffe: I am actually not sure that it is even achievable given the badger densities we have in TB infected areas of Britain, the lack of geographical boundaries. I think another difference between Britain and Ireland is that we have substantially higher baseline background badger density, so that immigration pressure is always going to be there. I am not convinced that you actually could eliminate badgers from Wiltshire, try as you might.

  Professor Bourne: The feasibility of it is extremely difficult but also, of course, it would not be the end of the cattle TB problem. It would make cattle TB controls very much easier but there would still be a very large cattle TB problem that would have to be addressed through improved diagnosis.

  Mr Gray: They have brought it to one strand.

  Mr Cox: You would have to bear down on both sides of the disease.

  Q54  David Taylor: My colleague Mr Gray has been trying to tease out whether there really were differences in time in the ISG's attitude between January 2006 and 18 months later, as we are now. I would like to see if there are differences within the ISG. I know it is not a seminar on semiology but nevertheless, can I point to Professor Bourne's letter to the Secretary of State where he refers to "badger culling can make no meaningful contribution to cattle TB control in Britain", which is drawn from paragraph 9 of the overview, where you mention a very similar point, "cannot meaningfully contribute towards future control", but yet, rather significantly, at paragraph 10.48 on page 172 we, the collective Committee, concluded that badger culling is unlikely to contribute positively. "Unlikely" and "cannot" are two distinctly different descriptions. I wonder what lies within the two different boundaries that they represent, Professor Bourne.

  Professor Woodroffe: As the author of several of these sentences, I am very happy to speak to them. I will just add while Professor Bourne is looking it up that saying badger culling is unlikely to contribute positively in a scientific forum is pretty damning. That is about as strongly as you ever say anything in a scientific paper.

  Q55  David Taylor: It is not the Chairman firming it up; it is just a scientifically alternative way of expressing the same set of circumstances?

  Professor Bourne: No, I think there are two issues here. What we are saying is that badger culling, in the way it can be conducted in the UK, we believe, cannot possibly contribute to cattle TB control, and in using the word "meaningfully", what we mean there is that if it is the only inducement that would encourage farmers to co-operate fully and introduce effective cattle control, it could have an effect.

  Q56  David Taylor: There is a difference to me between "cannot", which is a zero percentage probability and "unlikely", which is less than a 50% possibility. There is a big void there, is there not?

  Professor Woodroffe: There certainly is not any disagreement within the group about the conclusions.

  Professor McInerney: It is important to get a little perspective on this. In 2006 when the letter was written, a certain amount of data came through and the analysis was leading to some conclusions. By the time we get to our final report, there is a lot more data. The trends inside and outside the areas have become more firm. Whereas in 2006 the net effect on breakdowns was that the outside effects were neutralising the inside ones, as the trends have developed, we now find within 100 kilometres squared there is a net positive effect, but it is 1.4 breakdowns out of 50. This is where we do not think it is meaningful, if you believe it is worth throwing all this culling effort in order to prevent one and a bit breakdowns. We do not feel that is very meaningful in terms of policy. It is the raw numbers of what you achieve rather than technically whether it is zero or just a little bit above zero. In the end, our judgment is that this is not a very effective policy if all it achieves, after all this effort, is a minimal effect on breakdowns when there would seem to be opportunity to have a much bigger effect doing other things.

  Q57  David Taylor: To me, as a statistician, an equivalent phrase to "cannot meaningfully" would be "is highly unlikely to contribute positively".

  Professor Bourne: We are working within scientific confidence limits.

  Q58  David Taylor: 95%?

  Professor Bourne: Yes indeed. It is difficult to be utterly positive about everything.

  Q59  David Taylor: "Cannot" is utterly confident to me.

  Professor Bourne: We are confident that it will make no useful contribution.


 
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