24 Dec 2011, 6:43 PM
We have been sent correspondence by a farmer, who, despite being in the middle of a so called bTB hot spots has never suffered a herd breakdown. We have been given permission to publish the exchange of correspondence that gives a lot of interesting information about the number of officially TB free herds. The farmers conclude that the 'never restricted' figures add significant weight to the criticism that the reporting style chosen by the government and the NFU in their efforts to justify a badger cull is proportionately negative and sensationalised.
The farmer concluded, from the correspondence he received (which is extracted further on below) that:
“If we take as an example the Farmers Weekly 'TB Key Facts' http://www.fwi.co.uk/landing-page/livestock/badger-cull/key-facts/ based on a Defra press release. They report that '10.8% of herds were restricted in 2010' but they could equally report that '89.2% of herds were not restricted in 2010. They report that ‘22.7% of cattle farms in the south-west were under cattle movement restrictions in 2010’, instead of saying 77.3% of cattle farms in the south-west were free of TB movement restrictions.
And they fail to report that the 25000 cattle slaughtered in 2010 for TB control is less than 0.5% of the 7.5 million cattle tested and is a figure easily beaten by the number of fallen stock on beef and dairy farms in the normal course of events. (Defra DETAILED TB STATISTICS: 1 Jan to 31 Dec 2010 (GB) http://archive.defra.gov.uk/foodfarm/farmanimal/diseases/atoz/tb/stats/documents/10/2010gb.pdf)”
The farmer goes on to say say: “These 'never restricted' figures also counter the argument that the disease is 'cycling' around all of the herds but instead show that the bulk of the problem is most likely made up of the same herds 'cycling' in and out of breakdowns. A map on the NFU's 'TB Free England' site adds weight to this in its efforts to paint a gloomy picture - see http://www.tbfreeengland.co.uk/TB-Graphs-and-Maps/Map
The 'never restricted' figures also demonstrate that far more research could and should have been undertaken along the lines of the report from the Royal Society - 'Bovine tuberculosis - reduced risk on wildlife friendly farms' http://rsbl.royalsocietypublishing.org/content/suppl/2008/12/08/2.2.271.DC1/rsbl20060461supp.pdf comparing farms which remain clear to those that do not”.
The farmer points out that “The high number of 'never restricted' herds also explains the ease with which the Royal Society found their control farms which had remained OTF since 1994, ie. at least ten continuous years clear at the time they were collecting data.n
And it is interesting to note that, despite the time which has elapsed since the Royal Society study was undertaken, the figures show that researchers would still have no trouble finding their 'control' herds in the area studied as there are 3367 herds which have never been restricted in the Devon/Hereford/Worcester area”.
If you calculate overall totals from the spreadsheet, the result is as follows:
As of 4th Sept 2011
out of a total of 78006 Officially Tuberculosis Free (OTF) herds in GB,
60811 herds have never been under TB restrictions.
If this is broken down into regions then
out of a total of 48363 OTF herds in the East/North/Scot region,
43340 herds have never been restricted
out of a total of 29643 OTF herds in the West/Wales 'hot-spot' region,
17471 have never been restricted
The spreadsheet only gives the total number of OTF herds but the total number of herds overall can be obtained from Defra stats
Taking the figures from Defra DETAILED TB STATISTICS: 1 Jan to 31 Dec 2010 (GB) http://archive.defra.gov.uk/foodfarm/farmanimal/diseases/atoz/tb/stats/documents/10/2010gb.pdf , the total number of herds overall is given as:
83636 for GB
50683 for East/North/Scot region
32953 for West/Wales 'hot-spot' region
This confirms that, based on the figures provided by the AHVLA, the percentage of herds which have never been restricted - ie. consistently OTFthroughout - is the majority of herds overall and also by region.
CORRESPONDENCE BETWEEN FARMER AND ANIMAL HEALTH/VLA
Farmer’s email dated 4/9/11:
‘Dear VetNet, we have a cattle herd in a bTB hot-spot which has remained Officially Tuberculosis Free (OTF - formerly 'unrestricted') since the 80's. According to Defra's DETAILED TB STATISTICS: 1 Jan to 31 Dec 2010 (GB), the GB total number of cattle herds registered on VetNet, Jan - Dec 10, was 83636 & the GB total of herds under movement restriction on 31 December 2010 was 6090.We calculate from this that there were 77546 Officially Tuberculosis Free (OTF) GB herds on 31 Dec 2010. We would like to ascertain how many years, or proportion thereof, these 77546 herds have remained OTF/unrestricted by region and county.’
Response email from Animal Health and Veterinary Laboratories Agency dated 8/09/11:
‘Your request for bovine TB information has been passed on to me, but I need to clarify exactly what you are asking for. Firstly we will be producing the output from our own ‘version’ of the cattle TB data at our disposal, and although this originates from the same source as that on the DEFRA website, there maybe slight differences in the numbers for several reasons. For ease we plan to work with currently OTF herds rather than compute which were OTF at the end of 2010, if that is agreeable with yourselves.
It is for the ‘how many years, or proportion thereof’ part that I need some clarification. Do you wish for the time in years to be totaled that has elapsed since each was last under restrictions or until they came into existence if never under restrictions? Some kind of indication of the maximum this could be for each county may be beneficial, indicating total time in existence. Our knowledge of when a herd came into being is limited, so we would propose to use a known date if exists, but for older herds we would have to consult their TB testing histories and take the earliest test date. Note also that we can only look at restrictions due to suspect disease and not due to non-compliance, though I expect that is what you would want to confine it to anyway.’
Farmer’s email dated 8/9/11:
‘Thank you very much for your detailed reply. Your plan to work with currently OTF herds makes absolute sense. If you are able to produce figures based on the conditions you describe in your second paragraph then this would be ideal and we would be very grateful.’
Response email from Animal Health and Veterinary Laboratories Agency dated 16/09/11:
‘Apologies for submitting this later than anticipated, due to my workload and passing it to another member of staff in order for them to gain experience in dealing with this type of data processing. Attached is a spreadsheet (at www.bovinetb.co.uk/docs/OFT_2011.xls) hopefully containing the information you request.
For each county it totals the number of live herds currently (as of 4th September) not under restrictions due to bTB, both OTF-S and OTF-W. This does not include restrictions for overdue tests.
For each herd the time since the herd last ended a period under restrictions has been calculated, and if never under restrictions this will be the period since the herd was created on the VetNet system (all data originates from VetNet). This is the column Years Clear. So it thus represents time to last incident ends, and should not be confused with total time inexistence not under restrictions, which is not presented in this output. The total time in existence has also been calculated, column Years In Existence. The two values will be equal for a herd never under restrictions. These have been summed to give county and regional values.
We have set a cut off date of 1990, and so herds existing prior to then have a start date of 1/1/1990, for both Years Clear and Years In Existence. Those herds without a created date will take the date of their earliest TB testing record. Those herds with neither a created date nor a tb test record have been omitted (501).
A proportion of the years clear to the years in existence is also presented.
Data has been calculated at the herd, CPHH level, not at CPH.
I hope this meets your requirements, but please get back to us if you require additional refinements.’
Farmer’s email dated 16/9/11:
‘Many thanks for the info. Assuming we're unable to get this from the spreadsheet supplied (please advise), are you able to provide the number of herds in each county which have remained OTF since your records began?’
Response email from Animal Health and Veterinary Laboratories Agency dated 16/09/11:
‘I have added 3 additional columns (www.bovinetb.co.uk/docs/OFT_2011.xls):
* Herds Never Restricted - as it says, but all herds, regardless when they came into existence.
* 1990 Herds Never Restricted - herds existing at start of 1990 never under TB restrictions.
* 1990 Herds - the total number of herds in existence since 1990.
It should be noted that data from the early 1990s predates VetNet, and although our dataset contains data from a preceding data set there may be one or two gaps that could lead to some herds that were in existence prior to 1990 appearing to have commenced after that year from the data at our disposal. Also CPHs that change their final H, herd number, for whatever reason, may exist as a CPH for the whole period, but the change in herd number will result in them only counting from the date each new CPHH commences.
One other thing, a herd restricted only prior to 1990 will for the purposes of this extra information count as restricted, and thus ‘never under restrictions’ means just that.’
Farmer’s email dated 18/9/11:
‘I've worked through the figures on the spreadsheet and would like to present the information in the following form:
59% of herds in Wales and the West Region have never been restricted.
90% of herds in the East, North and Scotland have never been restricted.
I would be very grateful if you could you confirm that I have interpreted your figures correctly?’
Response email from Animal Health and Veterinary Laboratories Agency dated 19 September 2011:
‘That is the percentage I would get from the data provided, so yes. However, the herds contributing do not include those currently under restriction, as requested, so in effect the percentages will be a little lower for all herds. Also those herds without a creation date or any testing records have been omitted (501, as stated earlier). It should also be noted that we are relying on the VetNet status as to whether a herd is still live or not and there will inevitably be a small proportion that will have fallen under the radar and perhaps not be still active. But we can only work with the data at our disposal! These minor unknowns are not going to alter the overall trend though.’
Please note that figures are as of 4th Sept 2011 and the column headed 'Herds' is total of OTF herds and not total of herds overall.
Column headed 'Herds Never Restricted' speaks for itself.