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Cattle and bovine TB



 Added by  Patty (Guest)
 29 Sep 2009, 7:38 PM


This forum strand looks at the general issues involved in the bovine TB debate.

Sally
Email from P dated 9/9/11.
 
This is why Defra's advice to dispose of milk from reactor dairy cows by pouring it into the slurry tank is so dangerous. Unlike the old-fashioned dry muck heap which generates very high temperatures as it decomposes, the watery hosings down from the milk parlour can remain in the slurry tank at a low temperature leaving pathogens untouched. Then this toxic mix is sprayed back onto the grass which is either grazed or silaged and fed back to the dairy cows. Don't suppose we're the first to think that this could be a major contributing factor to the highest incidence of bTB being in the dairy herds.
 
A report from the Farming Regulation Task Force produced in May 2011 to look at ways of reducing burden and better regulation, suggested changes although not with reference to slurry but to the practice of destroying milk from TB reactors:
 
Para 10.23 'Concerns were raised around....the ban on milk from cows that react to the tuberculosis test (“TB reactors”) entering the food chain. Respondents suggested that the regulatory decision is not justified by scientific evidence, since pasteurisation means that such milk does not pose a risk to food safety. They highlighted the costs of this policy for producers, and asked for pasteurised milk to be allowed to enter the food chain. We also heard that the necessary mechanisms are not in place to enforce the ban;'
.
.
Chapter 10 'We believe that burdens on business can be reduced without compromising food safety, and recommend:....renegotiating the requirement to destroy milk from TB reactors;'
 
http://www.defra.gov.uk/publications/2011/05/17/pb13527farming-reg-report/ to download reports
 
Sally
See http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1082502/pdf/0366-04.pdf for an interesting report from 2004 - PCR primers specific for the Mycobacterium tuberculosis complex were used to detect the presence of
Mycobacterium bovis BCG (Pasteur) in soil microcosms and Mycobacterium bovis in environmental samples taken from a farm in Ireland with a history of bovine tuberculosis. M. bovis genes were detected in soil at 4 and 21 months after possible contamination. Areas around badger setts apparently had the highest levels of detectable
genes and were shown to have the highest levels of gene persistence. e of viable cells in Irish soils. Studies of DNA turnover in soil microcosms proved that dead cells of M. bovis BCG did not persist beyond 10 days.
 
Further microcosm experiments revealed that M. bovis BCG survival was optimal at 37°C with moist soil.
 
This study provides clear evidence that M. bovis can persist in the farm environment outside of its hosts and that climatic factors influence survival rates.
 
From the evidence presented in the report, it can be concluded
that M. bovis BCG remains viable in soil for more than 15
months and that significant levels of M. bovis DNA and RNA persist in the field, indicating the presence of viable cells as an environmental reservoir for infection, which may pose a risk to cattle.
 
becky
Interesting post at www.fwi.co.uk/community/forums/p/60717/188238.aspx#188238 from a farmer in Glos - a so called TB hot spot area.
 
'Own farm in Glos, in process of retiring from rearing dairy x beef calves indoors, grazing beef stores to finish outdoors, suckler herd, lambing flock and followers on 48ha organically managed pastures. Intensive indoors, extensive outdoors. Market strengths - high health and welfare standards for all stock traded direct farm to farm and respect for the ecosystem with regard to land use and wildlife. Prefer to leave Mother Nature to balance out wild predator and prey over time on own land having seen that interference causes a see-saw effect in numbers leading to increase in problems which leads to more interference, a vicious circle.
 
Despite turnaround of cattle on the farm, including calves brought in on a regular basis from other farms across the country, we have been TB free on this annually tested holding since 1994 and TB free for more than a decade before that elsewhere.
 
The hype around the badger is a red herring, distracting attention away from the EU regs which are at the root of this trouble. All farmers stand to lose what little respect they have from the general public if they keep hanging onto the coat tails of the badger cull proponents instead of demanding a new approach by rejecting the futile drive for eradication and pushing ministers for cattle vaccine and changes to EU export rules instead.'
 
On this thread too are some interesting comments relating to compensation payments for cattle slaughtered under bTB policy.

 
becky
Email received from P 3/9/11 re posting 1910 paper athttp://www.ncbi.nlm.nih.gov/pmc/articles/PMC2543804/pdf/amjphygiene00004-0113.pdf
 
It seems forgivable in 1910 to read the sentence "None of the various methods for the immunization of animals against tuberculosis has passed beyond the experimental stage" but to see the same words being repeated in 2011 beggars belief.
 
Our opinion from reading the IAH research papers is that the vaccine could be made available now - the pharmaceutical companies invariably deliver given the right incentive - and they state quite clearly that the Diva test has already been developed.
 
It benefits the minsters to give the impression that there is no vaccine because they are clearly desperate to avoid challenging the EU directives. Something is holding them back. Maybe there's some influential beef baron who doesn't want to risk his lucrative export trade being disrupted by the wrangling that is bound to accompany a challenge to the EU? There is some undercurrent for sure.
 
But for us all to still be reacting to bTB in the same way as we did 110 years is disgraceful. Although there seem to be plenty of people out there prepared to believe the earth is still flat if a politician says so! Ho hum.
 
Sally
Interesting article, lots of interesting points including, the following:
 
"..Meanwhile, the statistics about the number of cattle slaughtered every year because of bTB, and the amount this costs, have been very visible in the media, but no one mentions the other causes of premature slaughter.
 
In 2009, 120,000 cattle were slaughtered because they were infertile. In 2008, 75,000 were slaughtered because they were "not in calf"; 50,000 because of mastitis; 25,000 because of lameness; and 7,000 because they were "low yield". Not to mention the male dairy calves that are killed at birth because they are unprofitable. Compare these figures with the 30,000 with bTB that are slaughtered..."
 
http://www.guardian.co.uk/environment/blog/2011/aug/11/badger-cull-dont-stop-bovine-tb
 
becky
We have been sent this link . It is a paper from 1910 and worth reading. Little has changed.
 
 
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2543804/pdf/amjphygiene00004-0113.pdf
 
becky
Compassion in Farming has recently reported that cows with MRSA are linked to antibiotic misuse. It refers to a new report published in June which found a new strain of the MRSA superbug in British cows. This is suspected to be linked to the overuse of antibiotics in dairy cows. There is a potential risk that bacteria could be spread to farmers and others working with dairy cattle.
 
So, here we have yet another example that something is seriously wrong with today's farming systems if animals have to be treated with antibiotics on a regular basis. One wonders if such treatment has any effect re bovine TB situation?
 
It is well known that over-use of antibiotics can lead to dangerous antibiotic-resistent bacterial infections.
 
Perhaps if cattle's immune systems were not so undermined by the stress of intensive milk production routine use of drugs would not be necessary.
 
Last year the Director General of the World Health Organisation warned we are heading for a post-antibiotic era.
 
Sally
There are some very vocal farmers who seem to want to protect the status quo. There are some that fear change, believing it may lead to worsening situations. I mentioned this to an expert recently and the response was; 'I think the vocal farmers who want to protect the status quo do not understand the differences between the adverse effects of the disease (somewhere close to nil) and the adverse effects of the control programme (£100 million plus per year and untold misery to farmers. There are two ways to prevent the latter - the first is to successfully eliminate bovine TB so that the UK obtains official bovine TB free status (with the disease gone, there is no longer any need to have a control programme), or secondly, quite simply just stop the control programme. This is what farmers need to understand'.
 
Sally
Email from MR dated 5/511
 
The links below are worth reading – another great hole in the “kill first ask questions later” principle used by Defra and WAG in disease control. Bovine TB next for enlightenment?
 
http://www.guardian.co.uk/uk/2011/may/05/foot-and-mouth-disease-detectable
 
http://www.sciencemag.org/content/332/6030/726
 
 
 
 
becky
From a chat with farmer from Wiltshire who had suffered from TB and restrictions intermittently for past fifteen years. a few interesting points emerged. He is clear at moment and has been for several months. Even during the periods of TB breakdowns he and his family continued to drink the raw milk from his herd, with no negative effects. He blames the badger but could not explain why he was clear at moment as nothing had been done with badgers.
 
Sally
I have kept coming across this disease in my research. It is another disease caused by Mycobacteria and is rife throughout world, including UK. In March/April is was the subject of a story line in Archers.
 
The similarities to bTB are uncanny and yet there is no compulsory test/cull etc. The symptoms are as bad as bTB. The disease progresses over many years. It is rife in many areas of the UK. There is a vaccination that can be used to prevent it. However, this can cause a positive reaction in the skin test and for this reason some vets do not suggest using the vaccination at certain times. It can have human health implications - associated with Crohn's disease (albeit minor as pasteurisation kills off bacteria).
 
Sally
LG (email 23/2/11) sent us following link http://ec.europa.eu/food/animal/diseases/eradication/programme2010/Bovine_tuberculosis_uk.pdf
 
This sets out how the UK's eradication programme is doing under the EU reporting requirements. The information is up to 2010 (approved for 2010 by Commission decision 2009/883/EC).
 
In an email dated 25/2/11 from MG he advises he has been sent the 2011 papers (96 pages) (which will be available online but in the meantime can be obtained from us on request). Acceptance of the report, which is produced annually, releases millions of Euros in funding to the UK government to fight Bovine TB. It was approved
 
 
 

 
Sally
Is the spread of tuberculosis due to the presence of nematodes? This is the subject of an article in The Scientist at http://www.the-scientist.com/article/display/57935/
 
And comment from RW (emails both 31/01/11) regarding the article.
 
I think it would have been true to say that all humans were infected with worms until potable water. lous. washing hands and so on.  In primitive conditions they are still. In India all the poor are anaemic from hookworms.  I would have thought all wild animals were also infected with intestinal parasites too.  How many of the wild buffalo studied had none?  In cattle as in sheep there is said to be some immunity when the animal reaches one year old or so, though there is no immunity at least in sheep to liver fluke.  The difference between individuals is that some have heavier burdens of these parasites.  I don't know why.  Healthy children sometimes died of nematode obstruction in the small bowel or choked to death on worms in the respiratory tract. Perhaps if one looks at it the other way round, do active TB infected individuals have heavy worm burdens and if so is it that an active progressing TB infection supprressing T-helper cell activity also fails to suppress worms so the worm burden becomes heavier?
 
It is quite true there are inter-relationships between different pathogenic or non-pathogenic organisms, but also between nutritional status, diet (some plant chemicals have anti-worm properties) and genetics.  All very complicated.
 
Genetically people are said to inherit a propensity towrds the TH-1 or TH-2 response (TH-1 is associated with T-helper cell immunity to produce gamma interferons for example) and TH-2 with the production of high levels of antibodies (useful in response to the Hepatitis B surface antigen vaccine for example because good levels of protective antibody protects from infection after exposure). Each person has both responses but not in equal measure..
 
I notice in the abstract that he writes about invasion with M bovis in buffalo. I think by this he does not mean infection in the first place but whether the infection spreads outside the primary focus, ie from the lungs to the blood stream and to the kidneys, udder and so on, rather than remaining either latent or localised. If worms suppress TH-1 so does a heavy and widespread infection with M bovis.
 

 
Sally
Email from RW dated 30/1/11 makes following comment on the paper at
http://rspb.royalsocietypublishing.org/content/early/2010/05/28/rspb.2010.0830.full.pdf
 
I am reading the paper on genetics that you so kindly sent me that I have printed out but I think the basic premise is wrong- we cannot eliminate the infection by breeding a relative resistance in cattle. In an organism like TB, M bovis or M tuberculosis, the evolution in response will always be the greater. Bacteria evolve more rapidly than eukaryotic cells. We have these 2 with us as we have for many thousandsof years though the infections may eventually evolve to be less pathogenic at least in some species.

 
Sally
Email from MG dated 27/1/11 refers us to the following paper which is of interest as it discusses an area rarely mentioned in any of the debates on bTB.
 
http://rspb.royalsocietypublishing.org/content/early/2010/05/28/rspb.2010.0830.full.pdf
 
It is a paper (Proceedings of the Royal Society of Biological Sciences) Bovine tuberculosis: the genetic basis of host susceptibility published in June 2010.
 
The contribution that host genotype makes to disease outcome has, until recently, been overlooked; yet, it is biologically untenable that genetic variation does not play a role. In this review, the authors highlight the evidence, past and present, for a role of host genetics in determining susceptibility to BTB in livestock. They then address some of the major issues surrounding the design of future studies tasked with finding the exact causative genetic variation underpinning the TB susceptibility phenotype. Finally, they discuss some of the potential future benefits, and problems, that a knowledge of the genetic component to BTB resistance/susceptibility may bring to
the agricultural industries and the wider scientific community.
 
 
Sally
I was listening to Farming Today one morning last week and it was reported that the price of heifers had, according to Defra, doubled due to bTB.
 
Also on the same programme more doom and gloom. Apparently eight farms a week are ceasing to farm, mainly the smaller holdings. Supermarkets have put up the price of milk by around 25% with only a small percentage of this going to the farmer. Increased fuel costs are causing problems, particularly for the rural areas re deliveries. Feed prices continue to rise. It does not bode well for the future of small scale farmer, food security or our desire for local produce. Are we going to see more intensive and larger scale farming, similar to what is happening in the States? What about animal welfare issues, effects on the countryside? Hard times ahead for the consumer and the farmer? Then there is the ongoing problem of TB.
 
becky
I see that the bovine tb blog (http://bovinetb.blogspot.com) is ceasing. It was built on the 500 Parliamentary Questions on bTB, badgers, badger welfare, bTB transmission and general epidemiology which were lobbed by its co-editor at the then Minister, Ben Bradshaw, in 2003/4. The aim was to collect as much information on experiences with herd restrictions, on TB transmission opportunities and on other country's efforts to clear the disease.
 
The penultimate post on the site sums why the decision call it a day was made. It is reproduced below.
 
'For some time now, we have been considering the time and effort which all of us put into this site. But over these six years, things have moved on and now alpaca owners are wringing their hands as 'environmental' TB rips through their herds. Similarly pig owners face TB restrictions which have no legal exit route except the skin test, which is not an option for many. Cats, dogs, bison, sheep, goats and deer have all made headlines which we have conveyed to you. While Defra have been noticeable by their absence in support for the true level of other species 'overspill'.
 
Did we say bTB was a beneficial crisis? You bet we did.
 
In mid February, while a couple of us were busy preparing cattle for sale,(having dutifully pre movement tested them) a site comment late on Friday night had us reeling. No, not a scumbag dealer switching eartags, but one of the most high profile pedigree breeders in the country, drives a coach and horses through everything we have been trying to achieve over the last decade. No matter that none of this site's contributors have shifted restricted cattle, bounced them between holdings or presented unidentified cattle of unknown parentage for veterinary inspection. We're all tarred with the same brush, the damage is huge and the reaction, brutal.
 
Needless to say, the Badger Trust lumps us all together though.
 
And tonight another comment has found its way to our inbox. This describes how a Shropshire veterinary surgeon has been found guilty of not discharging his duty in respect of a TB test on a restricted farm.
 
No matter that we have yet to find our own vets wanting in this respect, and no matter that it is not the norm. Reports like this are seriously bad for our industry - and music to the ears of all those who do not want to face the fact that TB is endemic in badgers, and that over population has now exploded that disease into other mammals.
 
So, on balance, we have achieved nothing. And we have decided that enough is enough.'
 
Sally
Email MS 8/11/10 'It looks to me to be a licence to sell potentially infected cattle and move them about the countryside in a poorly policed fashion. It looks almost as if the agricultural sector have given up on containing TB!!'
 
Sally
Email from Ruth 8/11/10
 
I believe all these cattle are from farms on standstill because of positive tuberculin skin tests and the farms have to keep on going through 60 day cycles of repeat testing until they have 2 negative tests on the whole herd. What to do with all the young stock on such farms destined for beef but that have tested negative on the skin tests? It is these TST negative stock that are being sold (at low prices) to designated farms where they are fattened up for beef. They go nowhere else except finally to slaughter. I do not know what the conditions are on these designated units but they would hold no other cattle and I am not sure if the cattle are allowed outside or not, and what the conditions are to keep badgers out of their sheds. One presumes that some of these cattle may be infected. I guess also that the inspection by meat inspectors at slaughter would remove cattle with lesions from the food chain otherwise they all go into the food chain but not the offal. M bovis is not supposed to be found in meat and should anyway be killed by the cooking.
 
As some farms have difficuly ever coming off TB restriction or soon fall back into restriction it is vital they can move the young stock to be finished for beef off the farm otherwise they can have a huge build up of cattle to feed. It is probably better to sell the stock to these designated farms than to keep it on farm until there is a chink in the application of TB restrictions when anyone may then buy the stock when it is taken to market unaware that the farm of origin has been on TB restriction.
 
Some of the young stock that is TST negative may have early infection or have an infection during which they never make a skin test response, but remain well without overwhelming TB infection (some anergic young cattle do have overwhelming TB infection and fall sick and die). I do not know what the numbers of such are likely to be on a farm that has a confirmed TB breakdown.
 
Thanks for sending me this report. On the whole I think it is a good thing and is to be encouraged.
 
 
Sally
According to the Meat Trade News Daily (http://www.meattradenewsdaily.co.uk/news/081110/uk___breakthrough_over_sale_of_cattle_from_tb_infected_farms.aspx) or the first time ever, cattle from farms infected with bovine tuberculosis will be sold at an open livestock market at Holsworthy Market on Monday, November 22 2010.
 
Up until now all cattle from farms where any animals have registered positive to TB tests have been subject to a 60-day movement restriction, causing considerable problems for farmers and their businesses. Farmers have been unable to trade until the whole herd tested negative for TB – putting on crippling financial burdens, and running down fodder stocks during winter months. Their only means of trading has been to take animals to dedicated "red" markets, where all animals have to be slaughtered, irrespective of whether they have been sold.
 
Now, though, following lengthy discussions with various Government departments, Kivells auctioneers are able to offer the opportunity to sell stock in the usual manner and allow farmers whose holdings are under TB restriction to return to the livestock auction. The concession has been made with the proviso that all purchasers of cattle must have a registered TB holding certificate (we have been unable to find out exactly what this means), with approved isolation units on their farm. At present there are more than 400 holdings with approved isolation units in the South West.
 
Keith
The attached chart shows data for the premature culling of dairy cattle over two years of age in Great Britain 2008.

 
Sally
In an email dated 17th June 2010 Rowena said,
'It has been suggested by some that badgers should be collected and fenced into woodlands with cattle grazing areas being kept completely separated. This sounds like a good idea, but apparently badger fencing is prohibitively expensive. Elin Jones has stated that WAG policy is to extend the area of woodland in Wales by thousands of hectares over the coming years, and farmers will be given incentives to create areas of woodland on their farms. This is part of the One Wales policy framework intended to deliver multiple beneficial outcomes, because woodlands are viewed as vital to efforts to mitigate climate change, providing a stable, clean, renewable energy source and building material whilst absorbing carbon dioxide. Why not use movable cattle fencing to create ungrazed buffers around existing woodlands, for natural regeneration or planting for coppice production, which would also reduce badger / cattle interactions and the potential for TB transmission, while simultaneously providing additional protection from slurry pollution? There have been a couple of serious slurry incidents over the last few months, which damage tourism, give Wales a dirty image and create a health risk by polluting natural watercourses that many genuine country dwellers in this area rely upon for their supply.'
 
Sally
More pressure on farmers with the recent legislation coming into force - the Tuberculosis (Wales) Order 2010. This makes changes re pre-movement testing and links compensation payments from TB losses to good practice and compliance with the stringent testing regimes. Compensation continues to be paid for the market value only of the animal and does not include consequential losses such as loss of income or increased costs due to bovine TB restrictions. The Order also introduces Veterinary Improvement Notices which will be issued by Animal Health if farmers do not comply with the Order or bio-security measures suggested. The order also allows for cattle that are difficult to handle to be treated as if they have TB and slaughtered (won't this distort the figures even more?).
 
With regards to protecting payments and complying with regulations, Cross Compliance requirements etc, it should also be noted that where Animal Health (on behalf of the Welsh Assembly Government) has issued letters indicating that a herd TB test is overdue and the test has not been carried out, farmers will face penalties and a reduction in their payments.

 
Sally
With regards to the risks associated with manure spreading, there is an article in Gwlad, Issue 96, June 2010 which considers the risks associated with manure and slurry spreading. It confirms that the bacteria that causes bovine TB can survive for many months in slurry and manure. It suggests to reduce risk:
1. Slurry should be stored for as long as possible (preferably six months or more).
2,=. Manure should be stored in a good manure heap as the effects of heating and composting usually means less storage time is required before disease causing micro-organisms (pathogens) are killed or diminish.
3. Ideally slurry and manure should be spread on the premises of origin. It states there is a high probability of disease spread if it is spread on other premises where it ay become a source of disease to other livestock !
4. If contractors are used you should ensure their equipment is not contaminated with material from other farms.
5. When spreading manure or slurry from your mown farm, or anyone else's, it should preferably be on arable land or failing this on land used for grass conservation. Where it has been spread on pasture grazing should be delayed for as long as possible (minimum 2 months suggested). It says that even if disease is already present in your herd, there is a risk of making the situation worse if animals graze land where pathogens are still active. It specifically says TB contaminated dung will be more likely to infect other cattle if it is spread over grassland where it cannot be avoided by animals grazing it.
6. It warns of possible spreading on the wind as aerosol droplets when using equipment other than soil injections, as TB can be spread in this way to neighbouring farms.
 
Sally
Richard Black who is the Environment correspondent for the BBC News website has reported (http://news.bbc.co.uk/1/hi/sci/tech/4783368.stm) on some interesting research. The recent study suggests that farm practice is an important factor and simple changes in farming practice could stem the spread of tuberculosis in cattle. Writing in the UK scientific journal 'Biology Letters', researchers say herds on farms with hedges and ungrazed land are less likely to become infected. They suspect hedges keep cattle away from badgers, which carry TB.
A government consultation on TB plans ended in June 2010, and the researchers say it is 'extraordinary' that ministers should be considering a badger cull.
"It is extraordinary based not only on my work but on the evidence they collected," said Dr Fiona Mathews, from the Wildlife Conservation Research Unit at Oxford University. "Their own advisers have put out a report saying a cull could be counter-productive or have limited effects," she told the BBC News website, "and still it's being put forward as an option."
 
The new study compares 30 randomly selected British farms that experienced TB outbreaks between 1994 and 1999 against 30 more which were disease-free. Scientists used statistical methods to identify issues which differed between the two groups. Not surprisingly, outbreaks were more likely where cattle on nearby farms had already contracted the disease. But the analysis also threw up several issues of farm management, with hedges being particularly prominent. TB was markedly less likely in farms with abundant hedgerows and ungrazed strips of land along fences; but markedly more likely where hedges had lots of gaps. Dr Mathews calculates that 'hedge-poor' farms are 60% more likely than 'hedge-rich' ones to experience an outbreak. Why hedges and ungrazed strips of land should lower TB incidence is not clear.
It may be that they keep badgers and cattle apart, preventing transmission of bacteria; alternatively it could be that either badgers or cattle living on ecologically managed farms are healthier, raising their immunity.
 
However, Professor Christl Donnelly, a member of the government's Independent Scientific Group on Cattle TB (ISG), cautioned against reading too much into the results. She said the Oxford team had not proven a causal link, just a correlation. "The results are interesting, but the key thing is to realise there aren't any messages about potential disease control options coming out of this study," the Imperial College London researcher told the BBC News website. "Habitat could influence disease transmission; but you wouldn't want to go out now and tell people to grow longer hedgerows."
 
Fiona Mathews agrees that more research is needed - and says the government should pay for it. "We can't demonstrate that if farmers changed farming practices they would bring TB down," she said, "but we can demonstrate there are relationships between farming practice and TB rates, and these deserve further investigation."
 
This current study, which was partially funded by Defra, cost a mere £12,000."They spent millions each year on the Krebs trial," said Dr Mathews. "And we sat in meeting after meeting with them and asked 'what is the Plan B if culling doesn't work?'"
She also said Defra blocked access to data gathered since the Krebs trial began - data which could have led to a firmer conclusion.
 
A Defra spokesman told the BBC News website: "We will use this [new research] as part of the science base when making a decision on whether to introduce a policy which allows the culling of badgers to control bovine TB in cattle in high incidence areas. "No decisions have yet been made," he added.
 

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