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Barren ewe tests reveal hidden disease


An underlying disease problem was a significant cause of barrenness in ewes this year according to the latest diagnostic results released by MSD Animal Health.

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Blood samples from more than 140 UK sheep farms were tested between December 2013 and March 2014, when the Expertis Barren EweCheck diagnostic service was made available to vets.


The analysed data showed 85 per cent of flocks tested had been exposed to the parasite toxoplasma gondii, which causes toxoplasmosis.


Toxoplasmosis is a key cause of barrenness and infectious abortion in UK sheep flocks.


The disease is a real drain on profits, says John Atkinson, livestock veterinary adviser with MSD Animal Health.


But he says now is the time to review last year’s flock performance and put plans in place to prevent potential problems from this financially damaging disease next year.


This is a strategy sheep farms across the south west of England have implemented to deliver improved lamb rearing percentages, output and profit by placing greater emphasis on minimising losses.


The South West Healthy Livestock Initiative (SWHLI) – part of the Government’s Animal Health and Welfare programme of delivery under the Rural Development Programme for England (RDPE) - recently set up a number of focus farms to help demonstrate the benefits of health planning on physical and financial flock performance.

Focus farms

Mair Morgan, research consultant with the sustainable food and farming group within ADAS UK, one of the project delivery co-ordinators says: “A total of 18 sheep farms across the South West were selected at the start of 2011 to act as SWHLI focus farms.


“ADAS was responsible for monitoring 13 of these units, which were located in Devon, Somerset, Gloucestershire, Wiltshire and Dorset.


“Over the last three years we have held seven meetings on each farm to discuss flock changes and improvements, and share best practice with local sheep producers.


“The project has provided a tremendous amount of valuable data, useful management insights and - through the various knowledge transfer events - helped a lot of South West farmers improve the health of their flocks.”


At the start of the project, ADAS consultants analysed 2010 flock performance on all the focus farms before discussing with the local vet and farmer realistic and achievable targets for each unit.


Ms Morgan says: “Typical targets included: reduce lamb losses, reduce ewe losses to 3 per cent, reduce ewe barren rate to 2 per cent, improve prolificacy, improve carcase weight and conformation, reduce prolapse incidence and cut the incidence of lameness.


“One of the greatest achievements was reducing the barren rate on nine of 13 focus farms. The primary cause of a high barren rate was toxoplasmosis, but other factors included poor ram performance, inadequate nutrition and fluke infestations.”


Mr Atkinson says toxoplasmosis is a particularly significant disease because it is widespread and causes problems throughout pregnancy.


“Toxoplasmosis can cause abortions, barrenness, reabsorptions, mummified foetuses, stillbirths and weakly lambs,” he says.


“Importantly, sheep pick up the infection from the environment, so normal biosecurity measures are not enough to control the disease.


“Infected cats shed toxoplasma eggs in their faeces and sheep become infected when they ingest these eggs from contaminated pasture, feed and water.”


He adds another underlying disease problem which often manifests itself as significant early lamb losses is enzootic abortion of ewes (EAE).


“EAE is caused by chlamydophila abortus bacteria,” says Mr Atkinson. “The disease can cause devastating abortion storms affecting about 25 per cent of ewes.


“Once a flock has the disease, it is likely it will never disappear, due to its persistence in carrier sheep.


“The disease usually arrives on-farm through replacements and is passed on from ewe to ewe at lambing time.


“If an unvaccinated ewe is infected, she will more than likely abort in the next pregnancy.


“Vaccination of already infected ewes reduces the risk of abortion and bacterial shedding, lowering the chance of transmission to their lambs and the rest of the flock.


“If either toxoplasmosis or EAE has been diagnosed in a flock, vaccination is the most effective way to help protect against these diseases for future years.


“Now is the time to think about protecting your breeding ewes because the vaccines for both diseases can be administered up to about a month pre-tupping.”


Flock barren rate advice

  • If records show a flock barren rate greater than 2 per cent last season talk to your farm vet, even if diagnostic blood samples have not been taken.
  • Ask for help too if any ewes aborted lambs during lambing.
  • Discuss vaccination for both EAE and toxoplasmosis.
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