"20% of farms tested positive for IB 793B - this was a lot higher than expected and generally not associated with any clear clinical signs on farms."
Richard Turner, Datapoul
Between October 2010 and February 2011 Datapoul conducted the first ever serology monitoring across the South West region with some surprising results. The aim of the survey was to form the basis of better disease and welfare control for the poultry sector. The Pfizer sponsored survey involved three main veterinary practices; St David’s Poultry Team, Slate Hall and Minster Veterinary Practices.
Over 90% of the region’s farms were tested with blood samples analysed for Infectious Bronchitis (strains 793B and QX) and Gumboro (IBD – Infectious Bursal Disease). These diseases were chosen because they affect crop production and often remain undetected in flocks.
The first of its kind in the South West, the survey gave a very useful spot check on viral challenges in the region, highlighting a disease challenge which was sub clinical. Results showed that 20% of farms tested positive for IB 793B, which was a lot higher than expected. Gumboro was present on 23% of farms and Richard Turner commented “Worringly, none of these farms had any clinical signs of Gumboro. Quite a lot of farms which vaccinated against Gumboro had surprisingly negative titres, which suggest the vaccines had not worked”.
View the Full Serology Report (March 2011) with conclusions and veterinary recommendations.
Serology Survey sparks further investigation into broiler disease control
Following this survey further investigation for both diseases via PCR analysis is being carried out on some farms. Early indications for Gumboro indicate that there was only one positive result for vvIBD (Thailand) all the others were classic Gumboro strains. This confirms that there is no change in the field in the UK and there is no need for variant Gumboro vaccine at the moment. Once the final results have been published these will be disseminated to the industry. Keep and eye out on our training and conferences page.
Further investigative work is also being carried to ascertain the Optimal Predicted Vaccination Date for Gumboro (IBD).
Gumboro vaccines are in use throughout the world but all have a common problem i.e. when is the best time (age) to vaccinate? It is not possible to know accurately without testing how much MDA a chicken receives from the hen. The principle behind estimating the optimal age of vaccinating is simple, i.e. measure the level of MDA at a very young age and, as there is a regular decline of the MDA in the chick, it can be predicted when the level of MDA will be low enough to allow vaccination.
The formula used in this instance is the ‘the Deventer formula’ used in The Netherlands since 1990. The Optimal Vaccination Age Calculator is available on the Gumboro website.