Farming

‘False positives’ must be eliminated

Published

10 years ago

March 12, 2015

New bovine TB tests needed?: Cambridge University has recommended

A NEW study performed by researchers from Cambridge University has recommended that new tests are needed to make vaccination against bovine tuberculosis (bovine TB). The report points out that in order for vaccination to be viable, the number of false positives from these tests must be significantly reduced. The scientists have said the reduction in false positives in cattle is feasible, but that a vaccination programme would be challenging. Despite an intensive, and costly, control program in the United Kingdom, bovine TB persists. Although vaccinating cattle with the human BCG vaccine offers some protection in cattle, doing so is currently illegal within the EU, due to the vaccine’s interference with the skin test used for surveillance.

The Cambridge team worked alongside researchers at the government’s Animal & Plant Health Agency (APHA), to show the importance of specificity – the proportion of uninfected animals that test negative – to making disease control strategies work. The skin test currently in use has a very high estimated specificity of over 99.97%, which means that less than three animals in 10,000 will test falsely positive. However, the test as carried out in Great Britain is thought to have at best an 80% sensitivity – a measure of how many infected animals will correctly test positive – missing around 1 in 5 bovine TB-infected cattle. It is used to determine if animals, herds and countries are officially free of bovine TB.

Vaccinated animals that test positive have to be treated as infected animals. Under European law, if an animal tests positive, it must be slaughtered. The remaining herd is put under movement restrictions and tested repeatedly using both the skin test and post-mortem examinations until it can be shown to be officially clear of infection. Researchers said the duration of movement restrictions is important due to the considerable economic burden they place on farms. Also, the cost to the UK government alone is estimated to amount to half a billion pounds over the last decade; this cost includes visits to farms by veterinarians, tests carried out and compensation for the slaughter of infected animals.

For vaccination to be economically viable and acceptable within the EU, the benefits of vaccination must be great enough to outweigh any increase in testing. A new generation of diagnostic tests, known as ‘Differentiate Vaccinated from Infected Animals’ (DIVA) tests, has opened up the opportunity for the use of BCG within current control programmes. The EU has recently outlined the requirements for changes in legislation to allow cattle vaccination and a recent report from its European Food Safety Authority (EFSA) emphasized the importance of demonstrating that BCG vaccine works, and that DIVA tests can be shown to perform in large-scale field trials.

However, a key factor overlooked in the EU report was that the currently viable DIVA tests have a lower specificity than tuberculin testing; this could lead to vaccinated herds being unable to escape restrictions once a single test-positive animal has been detected, as the more times the herd is tested, the more likely the test is to record a false positive. In their study, the researchers from Cambridge and APHA used herd level models to show that the level of infection can be reduced in vaccinated herds even when DIVA sensitivity is lower than tuberculin skin testing.

However, in order to see this benefit of vaccination over 99.85% of uninfected animals will need to test negative in the DIVA test. This improved accuracy will be necessary to avoid increasing the duration of breakdowns and the number of animals condemned. Using data from previous tests on cattle, the researchers said this level of ‘specificity’ is achievable, though they said there will be challenges associated with improving accuracy. The researchers said, “Currently, there is no gold standard test to diagnose TB in cattle. Cattle that test positive are slaughtered immediately and therefore have rarely developed any physical signs – in fact, only around a half of animals examined post-mortem show physical signs of infection even if they are, indeed, infected.”

Dr Andrew Conlan from the Department of Veterinary Medicine at the University of Cambridge explained “In order for vaccination to be viable, we will need a DIVA test that has extremely high specificity. If the specificity is not good enough, the test will find false positives, leading to restrictions being put in place and a significant financial burden for the farmer. “But validating a test that has a very high specificity will in itself be an enormous challenge. We would potentially need to vaccinate, test and kill a large number of animals in order to be confident the test is accurate. This would be very expensive.”

Business

Huge slurry lagoon to be built in Pembrokeshire countryside

Published

3 days ago

April 25, 2025

Bruce Sinclair - Local Democracy Reporter

PLANS to build a new slurry lagoon at a 650-dairy herd Pembrokeshire farm have been given the go-ahead.

In an application to Pembrokeshire County Council, Richard Morris of Bowett Ltd sought permission for the construction of the lagoon, and associated works, at Quoits Hill Farm, Bentlass Road, Hundleton, near Pembroke.

A supporting statement through agent Cynllunio RW Planning Ltd stressed the applicant does not intend to increase livestock numbers on farm as a result of this 60 by 35 metre development.

“The Morris Family farm at Quoits Hill Farm and specialise in dairy farming. The farm is home to approximately 650 dairy cows plus followers. The herd is autumn calving with milk sold to Laprino. The home farm is grass based and extends to over 300 acres, with more off lying land utilised for growing winter forage.

“The family have invested significantly in recent years in on farm infrastructure to include a rotary milking parlour, silage clamps and covered feed yards.”

It added: “The proposed development seeks to increase the farms slurry storage capacity to above the five-month storage required by NVZ regulations. The existing slurry store and slurry handling facilities are not adequate to comply with the new regulations.”

It went on to say: “The proposed store will provide the farm with 6452 cubic meters of storage capacity (minus freeboard) which will equate to over 171 days storage. It is proposed to use the existing field slurry store as a lightly fouled water store to collect the parlour washings and reduce the size of the store required. Slurry will continue to be scrapped into the existing yard store and then pumped to the new store when required. This work will be monitored closely to reduce the risk of any leakage.”

It concluded: “The proposed development will enable slurry to be spread during the growing season rather than during more difficult weather conditions in the winter. This will be of benefit to farm efficiency and the wider environment.”

The application was conditionally approved.

Farming

Samuel Kurtz MS warns Chancellor: ‘Don’t sell out British farming in US trade talks’

Published

3 days ago

April 25, 2025

Tom Sinclair

SHADOW Rural Affairs Minister Samuel Kurtz MS has urged the UK Chancellor not to sacrifice British farming standards as trade negotiations with the United States continue this week.

The intervention comes as Shadow Chancellor Rachel Reeves visits Washington for her first in-person meeting with US Treasury Secretary Scott Bessent. The meeting is part of early-stage discussions aimed at forging a UK-US trade agreement.

The Herald understands that the UK government is hoping to secure tariff relief on a number of goods still affected by duties imposed during the Trump administration. However, recent signals from US negotiators suggest that any such deal could require the UK to allow imports such as chlorine-washed chicken—currently banned in Britain.

Chlorine-washing is a process used in parts of the US poultry industry to disinfect meat that may have been exposed to poor hygiene conditions. Critics say it masks low welfare and sanitation standards that would be illegal under UK regulations.

Speaking this week, Mr Kurtz said: “British consumers and farmers expect better. Chlorine-washed chicken isn’t just a food safety issue—it’s a red flag for low animal welfare. Allowing such products into our market would fly in the face of everything we ask our own farmers to uphold.

“Our food producers work tirelessly to meet some of the highest standards in the world. Undermining them with a trade deal that rewards countries cutting corners is short-sighted and shameful. It’s not free trade—it’s a free pass for poor practice.”

He added: “If the UK is serious about food security and sustainability, then we must stand by the people who grow our food. That means defending British farming in the negotiating room—not bargaining it away behind closed doors.”

Farming

Pembrokeshire’s top progressive farmers are encouraged to apply for award

Published

5 days ago

April 23, 2025

Tom Sinclair

IF YOU farm in Pembrokeshire and can demonstrate your farm’s use of the latest technological methods to promote progressive, sustainable agriculture then the Pembrokeshire Agricultural Society encourage you to enter the prestigious Baron de Rutzen Award.

Tim Johns, Pembrokeshire Agricultural Society’s President, said, “We are looking for local Pembrokeshire farmers, under the age of 45, who can demonstrate their farm’s use of the latest technological methods to promote progressive, sustainable agriculture. They also need to show consideration for the environment and habitat sensitivity on their farm as well as present an aesthetically pleasing example of farming in the county. The competition welcomes all those in the livestock and arable sectors to enter.”

Last year’s winners of the Award were Andrew and Jane Phillips of Windsor Farm, Lamphey. They farm 1,100 acres, with 3,000 breeding sheep and lambs. A herd of British Blue cross Limousin suckler cows sired by a Limousin bull and all calves are sold as weaned. The arable side of the business includes 80 acres of winter and spring barley which is mostly used for stock consumption. The surplus is sold. They grow 150 acres of maize which is used in a Totally Mixed Ration (TMR) for their sheep. Again, the surplus is sold to dairy farms. Some land is rented out for growing potatoes and leeks. The autumn season sees the general public invited in to buy some of the six acres of Pumpkins they grow for the Halloween market. Besides this, they are also involved with the holiday business by renting out two shepherd’s huts for visitors.

Baron John Fredrick De Rutzen was President of Pembrokeshire Agricultural Society in 1936 and the Baron de Rutzen Trophy was produced in his memory. The third Baron served in the Welsh Guards and tragically died, aged 36, in 1944.

This year’s entrants must be fully practising farmers within the county of Pembrokeshire and were under the age of 45 years on 1 January 2025. Entries can either be by nomination or direct application online on the Pembrokeshire Agricultural Society website. Click here to apply: Pembrokeshire Agricultural Society Baron de Rutzen Award 2025

The closing date for nominations and applications is at noon on Monday, 30 June 2025.