Examination of Witnesses (Questions 20
MONDAY 18 JUNE 2007
BOURNE CBE, PROFESSOR
OBE AND PROFESSOR
Q20 Mr Williams: Just to take the
reasoning of the Chairman a little bit further, as I understand
it, the average over the five years or four years was 23% improvement
and 25%, but then the actual figures in the fourth or fifth year
were 33% less breakdowns and 11% more. It seems to me you are
going in the right direction. What we are trying to get to is,
is it that the process has not been carried on over a long enough
period of time to achieve the most beneficial results?
Professor Bourne: You are not
only considering the time you do it, but that then takes you into
the area over which you cull, because you are continually going
to get the drain of badgers into the culled area, as Rosie indicated.
Q21 Mr Williams: The ecology of the
badger has been explained but the actual numbers of herds breaking
down, which is what we are about, in a way, seems to be improving
and going in the right direction.
Professor Bourne: If you consider
the number of cases actually saved, it is still very, very low.
Q22 Mr Williams: Even per year towards
the end of the experiment?
Professor Bourne: Yes.
Q23 Mr Williams: Are those figures
in your report?
Professor Woodroffe: After the
first cull, if you do the benefit versus the detriment, the detrimental
effect in the first year is so huge that in fact if you did proactive
culling once, or even twice, your overall outcome is that you
just make things worse.
Q24 Mr Williams: What we are saying
is that yes, we understand at the beginning, when you remove a
huge part of the population and you get lots of movement of badgers,
you do not get very good results in terms of herd breakdown but
as you are going on, it improves.
Professor McInerney: One of the
difficulties that you are groping for is: can we extend on from
the five-year experience to another five years and another five
years? One can, if one is speculative, but it would be a very
dangerous thing to do to extend five years' experience into 20
years. The simple answer to your question, Chairman, is, if you
can get 25% of TB removed with five years' culling, can you get
another 25% so that in 20 years you have got rid of it? My understanding
of the ecology is that no, it is not that simple, which is a pity
because if it was that clear, one could at least sit down and
say, "OK, can we contemplate a 20-year culling programme?
Where might we be and might that be worthwhile?" I would
tend to shudder at the cost of a 20-year culling programme given
the cost of a five-year culling programme but I can see why one
would like to feel that the ability to control the disease could
be just rolled on from the five years' experience of this cull.
Q25 Chairman: I ask these questions
because among those who will listen and reflect on what is being
said, there are those who are entirely with you and those who
remain deeply sceptical, and we just have to try and tease out
whether in fact the idea of a cumulative policy has any merit.
Professor Bourne: There are other
important caveats to this culling programme and those are that
the culling is done sequentially on an annual basis by professional
teams over a very, very long period. You may wish us to comment
further on the professionalism required, particularly in relation
to land access and also the level of trapping efficiency that
you might expect to get.
Professor Woodroffe: The level
of effort that this took was in the region of 40 trap nights per
square kilometre per year for five years, but the way that the
trapping was done was not just that you sling out some traps and
wait. Bear in mind that not every land holder provided consent
to cull. In order to achieve the most effective culling success
that we could, traps were deployed around areas of inaccessible
land to try to achieve the best removal that we could, including
areas that were inaccessible for trapping. That was successful
and we were able to show that by culling around those, in patches
of accessible land we were able to suck the badgers out, but that
sort of process requires a great deal of experience in badger
natural history and behaviour, recognising field signs and so
on. It is something that professional staff are needed to do.
The level of success that we achieved is shown in various different
measures: the density of badger field signs, various different
measures of badger activity in proactive areas was about 70% lower
in the proactive areas towards the end of the trial relative to
the areas that were not culled, and bearing in mind this substantial
evidence of immigration of badgers into the area, that suggests
we are catching more than 70% of them each time, it is just that
more keep immigrating. So our trapping efficiency is probably
upwards of 80%, I would estimate, on that basis. We have been
criticised for having not removed enough of the badgers but a
lot of those badgers that are there are ones that came in from
outside and we have genetic evidence in support of that.
Professor McInerney: Even if you
did go on for five years and five years and five years, at the
end of it you would only have managed to eliminate the badger
element of TB, and since we do not know exactly how much that
would be or how that might change over time, it is very difficult
to predict therefore what the TB occurrence would be at the end
of a long and extended culling programme.
Q26 Dan Rogerson: We are saying that
it is possible potentially to have an impact through quite a large-scale
cull in an area but the problem is that it is re-populated. In
an area such as, for example, a peninsular, might it be possible
to look at what happens if you were looking at tougher measures
of controlling it in the herd and also some form of cull in an
area that is quite well geographically defined?
Professor Woodroffe: Yes, we can
speak directly to that because one of our trial areas was West
Cornwall, the Penwith Peninsula, but we had a variety of different
trial areas with different permeability of the boundaries to badgers.
The extent to which badgers can immigrate into an area certainly
influences the course of infection in the badger population over
successive culls, so each time you cull the badgers across all
the different trial areas, you see on average that the prevalence
of infection in badgers goes up. So each time you cull, the prevalence
is higher and higher and higher, to the extent that by the fourth
cull the prevalence in the badgers has roughly doubled and that
is to do with mixing of the badgers, breakdown of the social organisation,
which causes disease to spread. What we see is that that effect
is influenced by this boundary permeability, so in the badgers
we see that places like West Penwith, the prevalence in the badgers
actually did not rise; it remained roughly constant. So you are
really successfully there forcing down the density of infected
badgers. Unfortunately, when we looked for a similar effect on
the impact of culling on the incidence of TB in cattle, we were
not able to detect any effect.
Professor Donnelly: The difficulty,
of course, is it was not set up to be able to distinguish within
these groups of ten comparisons, so certainly we would expect
on the basis of the mechanism that we believe is taking place
that it is extrapolation on that basis rather than what we have
been able to estimate from the data.
Q27 Dan Rogerson: So it is possible,
and farmers in a place like Cornwall who would want to perhaps
co-operate in some form of action of this nature, that if measures
were taken to deal with it within the herd as well, the testing
programme and so on, that some form of a generalised control
Professor Woodroffe: I would make
two comments on that. One is that if we stick with that specific
example, which is an area I know well, being from there, that
actually of all the areas where we worked in the course of the
trial, Triplet F, the West Penwith proactive area, had the lowest
land owner consent, far and away; half the area was accessible
to us, so if that was the place that we considered the best, that
would probably offset the benefits for an area like that. One
point to which this is highly relevant is comparison with results
from the Republic of Ireland, where there has been a great deal
of discussion and speculation over the application of the Irish
findings to ours. Of course, one of the key differences between
our trial and the trial that was conducted in the Republic of
Ireland was that, whereas we chose representative areas of high
TB risk to cattle, in setting up the Irish study they chose the
areas where they thought that culling was going to work best,
and they deliberately chose the four places in Ireland where they
could find places with these sort of geographical barriers to
badger immigration, and where they could not find barriers like
that, they had very substantial areas which they culled but from
which they never reported the incidence of cattle TB. What I think
that means is, I suspect it is probably the case that those sorts
of geographical boundaries might well be expected to influence
the impact of badger culling on cattle TB incidence and perhaps
a comparison with Ireland might lend support to that. There are
very few places in Britain that have those sorts of geographical
barriers, so whilst it might be something that is locally potentially
of some value, in terms of national TB control it is probably
not that useful.
Professor Bourne: You mentioned
Ireland. I think there are other issues there which are important
in comparing the Irish situation with the one in this country.
They certainly have a much lower badger population than we do.
In tackling their badger culling they, of course, used snaring
and have less welfare considerations than we were forced to give
to the trapping that we carried out in the trial. Very importantly,
they had 100% farmer co-operation and we did not get that. Defra
could not find out who owned 13% of the land area in our trial
area, in spite of the resource they have to try and resolve that
issue. 13% of the land over here just was untrappable in that
sense. The other thing is that there is no badger group in Ireland.
The social attitude to the badger over there is totally different
to social attitudes here.
Q28 Chairman: We are going to come
on to Ireland in a little while. Just on a point of methodology,
you have made it very clear to us that peer reviewin other
words, you are not coming under flak from scientists that in some
way your analysis and its conclusions were flawed, but you have
just made the point that you had at least half a hand tied behind
your back because you could not get 100% land owner co-operation,
and you made that point of contrast in relation to the Irish trials.
I suppose it is an impossible question to answer but nonetheless,
I might ask it: if you had had, were there examples within all
of the trials that you did where you got 100% land owner co-operation
and, if so, were there any significant differences between the
lower order where you did not get that co-operation and those
areas where you got a higher percentage of co-operation?
Professor Donnelly: There certainly
were no areas with 100% coverage but what we did find was we divided
up in further analysesand this is part of the IJID paper
that was just published. We actually looked at farms that were
on accessible land versus farms that were on inaccessible land
and we did not find a significant difference between them. In
fact, the non-significant difference was in the opposite direction
to what you would expect, so what we found was that those farms
on accessible land actually did slightly worse than on inaccessible.
There was nothing in the statistics to show that the benefits
were different. The explanation for that is that actually, the
vast majority of areas of inaccessible land were very small. So
while we had direct access to about 70% of the land area, traps
were deliberately placed on the boundaries and about 70% of the
remaining land was within 200 metres of accessible land.
Professor Woodroffe: Which is
well within the ordinary daily ranging behaviour of badgers. On
successive culls we were clearly sucking more and more badgers
out from those areas of inaccessible land, so we were pretty convinced
that we were removing substantial numbers of badgers from those
little pockets of inaccessible land, even though we could not
place traps on that land.
Professor Donnelly: We showed
that per square kilometre in the little strips just around the
inaccessible land on subsequent culls we actually took out more
badgers per square kilometre than on the remainder of the accessible
Professor Bourne: It did require
trapping expertise to achieve that, of course.
Q29 Mr Cox: I am in danger here of
getting into territory that we may explore later but, as I understand
your reporthelp me if I am wrong, Professor Bourne -you
have consistently said in this report that though as an instrument
of general national policy you take the view that culling is not
a cost-effective or sustainable policy, it may beand I
am looking here at number 8 of your general conclusionsthat
areas with boundaries impermeable to badgers could contribute
to TB control on a local scale, although you make the point that,
of course, such areas in England are relatively few.
Professor Bourne: There we were
referring actually to the odd farm that does build badger-proof
boundaries. I am aware that some of these farms do exist in the
South West. We recognise that they are expensive and we recognise
that although they might make a contribution to that farm, they
make no contribution to the national impact.
Q30 Mr Cox: Can we also look at paragraph
5.16 at page 90 of your report, where you deal specifically with
the impact of permeability of trial area boundaries. What you
seem to conclude there is that your trial, scientifically speaking,
can really shed very little lightindeed, you say "currently
available data shed no direct light on whether a proactive culling
policy would be more beneficial if conducted in more geographically
isolated areas". It follows from that report, if one can
take the black and white letters, that in areas which may be geographically
isolated or may be otherwise able to be impermeable to the immigration
effect, that it is conceivableand Ireland would seem to
support thatthat culling might be beneficial.
Professor Woodroffe: Yes. You
are absolutely right to pick up the difference between page 90
and page 20 whatever it is, and that is an extrapolation. Within
the areas that we actually studied we found no impact of boundary
permeability on the effect on cattle, bearing in mind that most
of the trial areas had areas that were considered to be 100% permeable
to badger immigration.
Q31 Mr Cox: But you had no evidence
either way. That is the point.
Professor Woodroffe: We could
not detect any effect, but we were able to detect an effect on
the badgers themselves and we were able to show that you did not
get this rise in the prevalence among the badgers in badger TB
prevalence in these areas the badgers could not easily re-colonise,
and it was on the basis of that that we extrapolated to suggest
that perhaps therefore, if you were to expect culling to work
anywhere, that would be where you would expect it, but we have
not detected ourselves in the trial an effect of barrier permeability
on TB incidence in cattle.
Q32 Mr Cox: Professor Woodroffe,
forgive me, but the report says it sheds no light on whether a
proactive culling policy would be more beneficial if conducted
in more geographically isolated areas. The conclusion that that
states is either way: it might be, it might not be.
Professor Woodroffe: It might
be or it might not be. Exactly.
Q33 Mr Drew: Can we move on to policy?
Professor Bourne, it would be interesting to know if you have
had a discussion with Ministers since the report has been made
Professor Bourne: No.
Q34 Mr Drew: So you have not met
Professor Bourne: No. I last met
Ministers on 1 February.
Q35 Mr Drew: Can we move on then
to looking at how the Government may come to its policy evolution.
When you were interviewed this morning on Farming Today,
you were somewhat querulous about how Defra were going to handle
the scientific data and then subsequently translate it into policy,
given that you felt they did not have a good track record with
their attempts to draw up their consultation document. Is there
any discussion on how you might help them with that, given that
you have not talked to Ministers, but presumably you have talk
to officials about how they might be wanting to take policy forward?
Professor Bourne: We have not
directly had these discussions, no. I certainly have had more
discussions with the scientific expertise within Defra based at
VLA and CSL and recognise the quality of that expertise, and I
think the frustration they experience in not having adequate opportunity
at extending science into practice. You mentioned the consultation
exercise. That was just one indicator.
Q36 Mr Drew: It was a fairly important
Professor Bourne: Yes. There was
an even more important one, and that relates to the discussions
we had with Defra in 2001 on work to develop the gamma interferon
test. It was apparent at that time that future policy would demand
improved diagnostic tests. We discussed with Defra ways in which
field data could be gathered to provide information to inform
on a range of policy options, and they rejected our proposals
and went ahead with a pilot trial on the grounds that they could
not afford to do anything else, and you know the outcome of the
pilot trial. It did provide some very informative data but it
did not inform scientifically in the way one would have hoped.
We have advised that there has to be a closer working relationship
with scientists, particularly in Defra, to ensure that appropriate
data is collected to inform on future policy options. Also, that
data available from the testing of animals is regularly interrogated
with a clear strategic view as to what that data might tell them
and how that in turn can be implemented into policy in a way that
we have called adaptive management, which really means extending
scientific findings into the policy of disease control. We have
not seen signs that that has happened and we believe it is critically
important that it should. Equally, we have stressedand
I think this is a very important recommendation of the reportthat
Defra should develop a very clear strategy. At the moment it would
claim it does have a strategy, the strategy of reducing the incidence
of disease in high-risk areas and preventing its geographical
spread, but what are the details of that strategy? It has not
really been thought out. I believe there should be a clear strategy
of what they want to achieve, what is achievable, what resources
are necessary to do that, and this should be driven by a focus
group involving scientifically informed individuals driving that,
certainly with farmer input because they are important stakeholders,
and in that way develop a strategy, sell that strategy to stakeholders
and drive it forward in a way that one sets targets and knows
where one is going. That would in turn require that the whole
thing is costed. I am not aware that Defra have ever costed any
policy and determined how the policy can be matched to cost. They
have certainly borne the increasing cost of compensation payments
but that is not the same as what we are proposing. These are the
elements of our proposals which relate to data collection, rigorous
and ongoing data analysis and interrogation, and how one uses
that to feed into a strategy that has already been focused and
you have a group driving it. I do not see the mechanisms within
Defra at the moment to do that.
Q37 Mr Drew: What has been your response
to ministerial statements, written and oral, that have come out
since your report has been published?
Professor Bourne: I was aware
of Mr Miliband's statement this morning. I am not aware of any
Q38 Mr Drew: What is your response
to that? It is fairly anodyne.
Professor Bourne: It does not
say anything. If I were a badger welfarist, I would see something
there for me and if I were a farmer I would see something there
for me but really it did not say anything.
Q39 Mr Drew: In the weeks leading
up to the publication we have had everybody spinning against everybody
Professor Bourne: That has happened
for the last ten years.