The serology survey, commissioned by Datapoul as part of the South West Health Initiative and supported by a Pfizer Poultry Health educational grant, covered 169 farms representing more than 90 per cent of the broiler farms in the region.

The survey found that 20 per cent of farms tested positive for IB 793B infection – higher than expected and not associated with any clear clinical signs on the farms in question

The newer IB QX variant strain of the disease, which has spread to the UK over the past four years, was found on seven per cent of farms. These farms were in areas where QX virus had already been diagnosed on layer units.

The positive farms were given advice on adopting a more robust vaccination programme using the vaccine on day 1 and day 10, and on biosecurity measures.

The survey report stated: "The most important thing that farmers can do to protect their flocks against IB is to have good biosecurity and hygiene measures in place."

Regarding IBD, also known as Gumboro disease, 24 per cent of farms had positive titres suggesting infection on top of vaccine and pointing to a large number of farms where the disease is sub clinical with raised blood titres.

An audit of the administration and type of vaccine was carried out by the farmers' vets and, says the report, all farms on intermediate vaccine with evidence of sub clinical infection were moved to a hotter strain of vaccine.

The survey covered 81 farms with standard or lower stocking density indoor production and 88 free range or organic farms. A higher percentage of free range and organic farms tested positive for each type of infection.

"Field based studies such as this one by Datapoul are a vital part of our global research," says James Porritt, UK poultry manager for Pfizer.

"It is vital for producers to know which virus strains are potentially causing problems on their units. Equally, as a manufacturer we need to make sure vaccines are used correctly to obtain the best uptake and response from the birds."

Richard Turner, director of Datapoul and St David's Poultry Team, commented: "The survey was the first if its kind in the South West and has given us a very useful spot check on viral challenges in the region. The result highlights a disease challenge which was sub clinical, and it is a great service that Pfizer has provided by sponsoring this survey.

"I have been quite surprised at the findings – the level of IB is a lot higher than expected and, worryingly, none of the farms with either positive or inconclusive results for Gumboro showed any clinical signs. We aim to build on the results of this survey by conducting some further investigation with the use of PCR (polymerase chain reaction) testing. The results should be announced this autumn."

The serology survey, carried out from October 2010 to February 2011, involved more than 8000 blood tests offered free of charge with most of the samples taken at processing plants. It represents the first serological monitoring of broiler flocks across the South West, with the aim of providing the basis for improved disease control and welfare for the poultry sector.

Datapoul, part funded by the Rural Development Programme for England, is an innovative programme combining farmers' practical knowledge with veterinary expertise to improve farm performance and economic productivity across Cornwall, Devon, Somerset, Dorset, Wiltshire and Gloucestershire.

Further Reading

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Find out more information on the diseases mentioned in this article by clicking here.