Tracking IB as the Crow Flies08 March 2012
AUSTRIA - Serology and polymerase chain reaction testing might be effective ways to track the prevalence and scope of infectious bronchitis (IB) variants, but sometimes circumstantial evidence and even old-fashioned farmer intuition can pick up patterns as well.
“Farmers always told me that they associated QX problems with the arrival of crows from eastern countries,” says Franz Sommer, DVM, DACPV, a consulting veterinarian based in Vienna, Austria.
Whether crows have anything to do with the level or type of IB pressure is wide open for discussion at egg producers’ nearest café. Meanwhile, Mr Sommer says, he isn’t taking any chances.
To provide the broadest protection against IB, he builds vaccination programmes around a concept called Protectotype, which involves using specific IB vaccines in the same programme, at specific times, for added cross-protection against different variants, including QX.
“Infectious bronchitis is rather tricky,” he says. “If you use the Ma5 vaccine, it covers the Massachusetts-serotype virus. If you use the 4/91 vaccine, it covers the 4/91 type of virus. But if you use the two of them together in the same programme, they cover a couple of different serotypes. Vaccine A plus vaccine B protects not only against A and B, but also against serotype strains C and D.”
As a consulting veterinarian for Schropper, a leading layer multiplier that supplies readyto- lay pullets to more than 40 per cent of Austria’s layer market and covers more than 80 per cent of that country’s day-old pullet market, Mr Sommer and his veterinary colleague manage the health programme for 80,000 breeders plus a hatchery that produces 7 million birds a year. In addition, they consult with about 60 independent egg producers in Austria and work with clients in Hungary, Slovenia, Croatia, Montenegro, Albania and Bulgaria that buy day-old chicks from Schropper.
For all of these birds, Mr Sommer says, IB looms as a “two-fold problem” that affects the reproductive and respiratory systems. “It’s more a respiratory disease in young birds and a reproductive disease in older birds,” he says. Losses of 50 per cent When QX came on the scene in 2006, many producers in the area suffered production losses up to 50 per cent. The QX outbreaks returned in 2008, but the variant has been relatively quiet since then — partly because producers are taking more strategic measures to ensure broad protection against all IB viruses.
“The main difference now is that we use the Ma5 vaccine at day 1 in the hatchery and 4/91 at day 14,” he says. “With these two vaccines, we’ve been really successful in preventing any major IB problems.”
In addition, Mr Sommer recommends vaccinating with H-52, another live IB vaccine, at 10 weeks and then coming in again with 4/91 at 14 weeks.
At 17 weeks, when birds are being transferred, he vaccinates with an inactivated vaccine that provides additional protection against IB variants, plus Newcastle disease, egg drop syndrome and avian pneumovirus.
“I look at the killed vaccine as an insurance policy,” Mr Sommer explains. “In my opinion, with this vaccine, you get more stable birds that are able to withstand challenges a lot easier because they have antibodies against the major diseases of concern in our area.”
After week 26, Mr Sommer urges producers to revaccinate with the live Ma5 and 4/91 vaccines, usually alternating them every 6 to 7 weeks.
“With the live vaccines, you get local immunity at the oral mucosa, nasal mucosa and ocular mucosa,” he says.
“Those areas — the ocular one, in particular — are main entrance ports for IB. So, on top of vaccinating them with a killed vaccine at transfer, we run a really successful revaccination programme.”
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