How a sheep farmer cut OPA disease cases by two-thirds


A mixture of culling, ultrasound scanning and tighter biosecurity has cut cases of ovine pulmonary adenocarcinoma (OPA) by two-thirds on a Monmouthshire sheep farm.

From a excessive of 11.6%, prevalence within the flock of 550 Texel cross Lleyns and Aberfields at Court Farm, Llanthony, close to Abergavenny, is now at 4%.

OPA was identified within the flock in 2021 after a number of ewes confirmed scientific indicators of the disease. They have been skinny, respiratory closely and had extreme nasal discharge.

See additionally: How a Welsh farm lowered ewe mortality by tackling OPA

There had additionally been a 30% discount within the flock’s being pregnant scanning fee, from 170% earlier than the disease was detected, to 140%.

A autopsy on one of many animals recognized in depth OPA lesions – the primary time the disease had been identified within the flock.

Bryony Gittins, who farms in partnership along with her father, Colin Passmore, launched into a Farming Connect focus website mission to deal with the disease.

Thoracic ultrasound scanning was used to ascertain the true incidence of OPA throughout the flock and to restrict the danger of it being reintroduced after culling affected ewes.

Vet Vicky Fisher lung scanning ewes for Bryony Gittins

© Debbie James

Scan and cull coverage

In February 2021, ultrasound scanning of all ewes greater than two years outdated detected a 3.7% incidence amongst 545 animals. Six months later, 457 have been scanned and the incidence degree had elevated to 11.6%.

Mrs Gittins has since adopted a scan and cull coverage. Any animals that take a look at constructive are culled, or, if they’re pregnant, they’re marked and lamb individually from the primary flock.

They are then bought with the progeny as quickly because the lambs have hit slaughter weights of 41-45kg.

An extra scan in February 2022 confirmed the an infection fee had fallen to 4%. Twenty-three animals have been recognized with OPA; of these, 4 had scientific indicators and 19 lesions on their lungs.

Biosecurity

Action has additionally been taken to enhance flock biosecurity. Measures embody investing in enhancements to boundary fences to forestall nose-to-nose contact between the sheep at Court Farm and people grazing neighbouring land.

Pregnant ewes are being saved at grass a month later than standard, till the top of January. This is as a result of there may be better chance of OPA spreading when animals are housed.

Housing additionally will increase the danger of ewes with underlying OPA succumbing to secondary diseases resembling pneumonia.

This threat arises from the stress of switching from a grass-based weight-reduction plan in an open-air atmosphere to being inside and consuming silage.

“When the sheep are outdoors, they have a lot more space and they are not sharing a water tank because they have access to a stream,” Mrs Gittins explains.

She had been giving hint component boluses to the flock as soon as a 12 months, in addition to providing powdered minerals. Now, she offers them boluses twice a 12 months to take away any threat of OPA being unfold by means of the feeding of minerals.

Body situation scoring

Body situation scoring can be being carried out extra ceaselessly. Thin sheep are culled: even with out an OPA analysis, a skinny sheep will probably be much less productive, Mrs Gittins factors out.

Her subsequent step is to spend money on software program to file lambs born from ewes with OPA. These ewes will cross the disease to their lambs as they’re in such shut proximity.

The lambs will probably be bought fats or as shops, quite than being saved as flock replacements.

“Lambs don’t show clinical signs of OPA until they are two years or older and they don’t pass it on, so there is no issue with selling them as stores,” says Mrs Gittins.

Options for ongoing management

She is working in direction of a place the place the an infection fee is secure, and she will be able to rebuild numbers.

Another possibility can be to cull the whole flock and to restock with “clean” animals. But there is no such thing as a assure these wouldn’t be contaminated with OPA or different illnesses.

Many flocks could also be harbouring OPA with out their homeowners understanding it. This means the size of OPA within the UK sheep flock may very well be a lot increased than is being reported.

“It is likely there are greater numbers of flocks with iceberg diseases that farmers are just not aware of,” says Mrs Gittins. “Without on the lookout for these and with out cautious monitoring you simply don’t know they’re there.

“Building a good relationship with the farm vet can help with diagnosis.”

Culling the entire flock can be pricey: at a cull worth of £90 a ewe, the sale of 550 animals would increase £49,500, in contrast with the £93,500 value of shopping for in replacements at £170 a head.

Bryony Gittins in shed with sheep

Bryony Gittins © Debbie James

However, a few of the £44,000 deficit can be recouped: Mrs Gittins calculates that growing the scanning fee from 145% to 170% would produce 138 extra lambs. These may generate an earnings of about £9,660/12 months.

By retaining the flock, there may be additionally an ongoing annual lung-scanning value of about £2 a ewe, and a increased culling fee.

But Mrs Gittins says she isn’t prepared to take the danger of shopping for in except she will be able to make sure that she received’t discover herself in a comparable place with a new flock.

Restocking stays an possibility for the longer term. “I will always keep it at the back of my mind. If there is a flock dispersal where I could get a similar breed from a single farm I might think ‘let’s go with this’.”

Working with Farming Connect on this mission has been a beneficial expertise, she provides.

“It has enabled me to gather knowledge and the information to make my decisions going forward on the future of this flock at Court Farm.”

What is OPA?

Ovine pulmonary adenocarcinoma (OPA) is a viral an infection that ends in tumours throughout the lungs.

Infection is unfold by means of nasal secretions, in keeping with Vicky Fisher of Abergavenny-based Farm First Vets, who labored with Bryony Gittins on the Farming Connect mission.

Clinical indicators are typically weight reduction and respiratory difficulties resembling coughing and elevated labouring of breath. “You may see them ‘tummy-breathing’,” says Ms Fisher.

“Because this virus causes tumours in the cells that produce the fluid within the lungs, in about half of cases you will see copious amounts of fluid coming out of the nose or out of the mouth,” she provides.

The nasal excretions include the virus and infect the remainder of the flock.

The disease manifests in older animals however it’s contracted when they’re much youthful. The signs simply take a whereas to be evident.

OPA is terminal and there’s no therapy for it. Infected animals will die from the tumours or as a result of lung harm ends in a bacterial an infection, inflicting septicaemia.

Ms Fisher says controlling the disease could be troublesome. Tests are at the moment restricted to scanning a portion of the lungs on each side, the place tumours are mostly discovered.

New checks are in improvement within the UK, however these will not be but commercially obtainable.


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