12 July 2012

3 minute read

Europe

In cattle over three months of age, step one is a single intramuscular dose of Rispoval® IBR Marker Live vaccine. Six months later, step two requires either another dose of the same for six months further protection, or a single dose of Rispoval IBR Marker Inactivated vaccine for a 12 month protection period.

Thereafter, the programme is maintained with a single dose annual booster of inactivated vaccine, or a six-monthly booster with the live one. The programme is made possible by a recently approved update to the live vaccine’s product licence.

According to Pfizer National Veterinary Manager Carolyn Hogan, the new protocol can apply equally to an entire herd where IBR vaccination is being introduced for the first time, or to replacement heifers before they join the milking herd for the first time.

“Compared with previously available programmes involving live and inactivated marker vaccines, the new one simplifies IBR vaccination for beef and dairy farmers at the same time as extending protection for up to 12 months,” she says.

Over the past nine months in South Wales, vet Rob Davies at Allen & Partners in Whitland has found 75–80 per cent of herds positive for IBR, based on bulk milk antibody surveillance in client herds. Over England and Wales as a whole, a 1998 paper in The Veterinary Record reported that 69 per cent of dairy herds were seropositive, since when Mr Davies suggests the figure is much more likely to have risen than subsided. And a study reported in 2009 identified that 96 per cent of dairy herds in south west England contained at least one sero-positive animal.

Prompted by his practice’s surveillance, Mr Davies has introduced an IBR control initiative to clients involving live IBR vaccine initially for the entire herd, including breeding bulls, followed by inactivated vaccine at the manufacturer’s recommended intervals, with dramatic results.

At one large scale dairy unit, Mr Davies reports a two litres/cow/day yield increase which he believes is attributed directly to the programme. Before its introduction, he says a dedicated sick-cow stockman was spending three to four hours a day attending to 35–40 per cent of freshly calved cows at any one time. Following adoption of the IBR protocol, Mr Davies reports that this reduced quickly to about one hour a day. He says the incidence of displaced abomasums fell from one a week to one a month, and a marked increase in conception rates from 27 to 38 per cent has been recorded. Independently, evidence has been reported that BHV-1 – the virus responsible for IBR – can cause immuno-suppression.

The vaccines employed by Rob Davies are ‘Rispoval® IBR-Marker Live’ and ‘Rispoval® IBR- Marker Inactivated’ and he has developed a layman’s explanation for clients of how they work in combination: “I believe each vaccine does a different job,” he explains. “In cows that have never been infected – what scientists and vets call ‘naïve’ animals – the live vaccine fools them into thinking they have been infected and stimulates the immune system to create protection against a subsequent real infection.

“In cattle already carrying the virus, the inactivated vaccine is more effective than a live one at stimulating protection in the face of the virus’s re-emergence from dormancy. Stress factors known to trigger this can include calving, changing groups, change of diet, heat stress and other infectious or metabolic diseases.”

In effect, Mr Davies tells farmers that live vaccine mainly protects against animal-to-animal transmission, while inactivated vaccine offers protection in the face of re-activation within the same animal. He adds that inactivated vaccine has also been shown to be more effective than live at reducing viral shedding by IBR carrier animals, thereby reducing infection pressure on naïve herd mates.

Pfizer Animal Health says the new IBR vaccine programme is available now from veterinary practices.

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