How one dairy farmer is getting a grip on bovine TB

A Pembrokeshire dairy farmer who decided a fresh approach was needed to manage bovine TB in his herd has seen promising results by working more closely with his vet and using new technology to score risky cows.

See also: 5 ways to improve biosecurity on dairy farms

Michael Williams, who farms at Fagwrfran East, Puncheston, has been in and out of TB restrictions for many years.

Driven by a desire to eradicate TB from his herd, he joined the Pembrokeshire Project – a five-year Welsh government-funded initiative that brings together farmers and vets in the county to explore new measures to tackle the disease.

Risk factors

Through the project, he discovered the biggest risks to his herd were bought-in cattle and cattle falsely passing the Single Intradermal Comparative Cervical Tuberculin (SICCT) test.

“In 2018, we had a neospora outbreak that impacted fertility quite badly, and we were struggling to keep up with breeding and rearing replacements.

“We bought more cattle – and that was when we realised we were possibly bringing disease on to the farm,” he explains.

Not having a treatment plan in place was another issue identified by the farmer-vet team.

“Whether it’s Johne’s, neospora or mastitis, you have a plan in place to eradicate it. TB is no different and you must be pro-active in managing it,” he says.

“Then came the understanding that just because a cow has passed the test, doesn’t mean she’s clear.

“She just hasn’t failed the government interpretation of the test. For example, the last test we had was under a standard interpretation.

“We passed the test, but under severe interpretation I would have had 10 IRs [inconclusive reactors],” he explains, adding that with only 50-80% sensitivity, the SICCT test can miss one in four animals at every testing.

© MAG/Anne Dunn

Risk register

Michael is now using an algorithm developed by MV Diagnostics, which collates data from the SICCT test to create a risk score for each cow.

Based on the risk the cow represents, he can then make an informed decision about whether, and when, to voluntarily cull.

The first risk score, or RiskRate (RR), was produced following skin tests in January 2024. “We passed this test technically, but the RR pulled up many high-risk animals.

“When we looked closely at these, we found that many were on our ‘do not breed’ or ‘culling’ list already due to other disease, such as lameness or mastitis,” he explains.

Michael began voluntarily culling RR animals over the course of the next few months. The test in March 2025 was an eye-opener: almost 70% of the animals measured were already on the risk register.

“This gave us faith in the system and reassured us that these were indeed risky animals,” he says.

Michael Williams © MAG/Anne Dunn

Michael and his vet then developed a breeding/culling standard operating procedure for the herd, which has been important in developing a sustainable policy to remove risky animals.

This uses a colour-coded system to help determine breeding decisions. “Red” and “amber” animals (if otherwise eligible for breeding) are culled, while “yellow” animals (if otherwise eligible to be bred) are bred to terminal sires.

“This avoids breeding replacements from potentially infected animals. We have seen clear links between risk-rated mothers and gamma positive animals,” he explains.

In 2024, he voluntarily culled 34 animals based on RR (not all milking cows) and says he plans to continue using this method to reduce TB risk.

© MAG/Anne Dunn

Calf management

As well as keeping a closed herd, calves are separated at birth and fed a colostrum replacement.

All cows are calved on rubber mats in the winter, which are cleaned and disinfected immediately after each calving to avoid any faecal contamination.

Over the summer, cows calve outside, but Michael still aims for maximum hygiene.

“If we think of managing TB the same way we do Johne’s and prevent transmission from mother to calf through faecal transmission, then we can mitigate for both diseases,” he says.

Biosecurity and slurry management

To further minimise risk, he has a dedicated collection point for deadstock close to the farm entrance. He avoids holding farm visits and discourages anyone coming onto the farm without prior appointment.

Foot-bathing points at each section of the farm have been set up and youngstock are visited first before moving around to the older livestock to prevent any contamination.

Contractors are no longer used for applying slurry to grassland, and slurry is not put on the youngstock grazing ground.

Instead, application is targeted on the arable and silage fields to reduce the risk of contamination from TB-infected slurry.

An electric fence keeps badgers out of the clamp © MAG/Anne Dunn

Wildlife measures

Other changes include raising water troughs, putting polywire electric fencing in front of the maize clamp, and storing other feeds in bins out of reach of badgers.

Trail cameras to monitor badger movements have been set up and electric fencing stops them going on to pasture, as well as preventing cows from getting near badger latrines.

Looking at “Badger Found Dead” survey results for his area, Michael knows that the badgers within 3 miles of his farm have all tested negative for TB.

He wants to protect not just his herd, but also badgers in the area. “We’re hopefully going to avoid infecting badgers and stop that cycle from coming back onto the farm,” he says.

Long game

However, he is clear that these measures are ongoing. “It could take two to three years for all those things to have an effect. Hopefully, those calves in two years’ time will be passing the test,” he says.

The herd passed its most recent test, making it TB free for more than seven months, the longest clear period in six years.