Pfizer Animal Health has launched Poulvac, the first modified live vaccine against E.coli in chickens.

The company claims that the vaccine, which can be used from one day of age, is set to bring major benefits in safeguarding the health of broilers, pullets for egg laying and breeding stock.

According to Pfizer, E.coli is one of the most significant bacterial pathogens found in chicks during the first week, leading to problems throughout the life of a flock including inferior performance, lack of uniformity and increased mortality. It is a costly, widespread problem for the UK poultry industry.

The vaccine was developed from research beginning in the 1990s at the Government's veterinary laboratories at Weybridge (now AHVLA) in the UK, employing genome technology to produce an avirulent strain of E.coli that induces protective immunity to the pathogenic strains of the bacteria.

The vaccine is completely non-pathogenic, and does not persist in the bird or the environment for any significant period of time. A gene deletion in its development restricts in vivo replication and leaves behind activated macrophages ready to respond to pathogenic E.coli strains.

Dr Stuart Andrews, poultry technical manager of Pfizer in the UK and Ireland said: "Poulvac E. coli provides broad cross protection against the key serotypes of E. coli infecting chickens. It is the only modified live, nonreactive vaccine proven to meet the European regulatory requirements for efficacy and safety.

"Trials have confirmed that Poulvac E.coli does not persist in the bird and proves to be self-limiting. The vaccine can survive in the environment for only a short time, and spread to in-contact birds is also limited."

The vaccine is administered as a coarse spray with onset of immunity 14 days afterwards and duration of immunity for up to 12 weeks. It can be used from day-old up to six weeks before the onset of lay, and has a nil day withdrawal period.

In the USA where Poulvac E coli has been available for six years field experience has shown the considerable benefits. In the Midwest where average layer mortality at 50 weeks of age was 2.31 per cent, this was reduced to 1.51 per cent with three doses of the vaccine*. In Eastern USA flock mortality compared with five previous flocks was reduced from over three per cent to one per cent.

A field trial in the USA with more than 300,000 broiler breeders vaccination before lay reduced mortality from 2.8 to 1.9 per cent - with only two out of 28 flocks needing antibiotic treatment compared with 13 of the 28 unvaccinated flocks.

On a broiler field trial in Georgia over four million birds were vaccinated with Poulvac E. coli at hatch. The vaccinated birds had a better feed conversion (1.79 against 1.84 for the controls) and with condemnations at the processing plant down from 1.22 to 0.73 per cent the result was a lower production cost of 0.51¢ per lb. 

In another broiler trial covering more than two million birds in Arkansas livability was improved from 95.20 to 95.77 per cent and feed conversion improved from 1.95 to 1.90, gaining 0.45¢ per lb.

* Pfizer says it is important to note that in these studies carried out in the USA more than one dose of the vaccine was often administered. A single vaccination is licensed in the Summary of Product Characteristics however, where clinical disease requires and at the discretion of a veterinary surgeon, the vaccination schedule may be re-started as there is no contra-indication on the SPC.

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