Results from a national bulk milk and blood sampling service show that 72% of herds tested positive for exposure to infectious bovine rhinotracheitis (IBR). For dairy herds this can mean to a reduction in milk yield of up to 173 litres a cow or more than £4500 for a 100-cow herd.
An increasing number of cattle are now routinely vaccinated for IBR, and Intervet/Schering-Plough Animal Health has just announced the replacement of the UK’s leading IBR vaccine – Bovilis IBR – with Bovilis IBR Marker Live, Europe’s number one IBR vaccine.
The live marker vaccine offers the same level of effective IBR protection as the non-marker vaccine, but delivers some additional benefits, explains vet Rosemary Booth from the company.
“As with the non-marker vaccine, it can be administered intra-nasally (IN) or intra-muscularly (IM). The IN route can be use in animals from only two weeks of age. Stock then need re-vaccinating every six months.”
Marker vaccines mean that animals can be traded more freely with Europe, where many countries have IBR eradication programmes. “Marker technology makes it possible to identify an animal that has antibodies as a result of vaccination, as opposed to one with antibodies picked up through natural infection or disease exposure at some point,” Ms Booth adds. “If a UK producer wants to work towards eradicating IBR in a herd, marker technology is a must.”
IBR is highly contagious and can spread quickly through a group of animals. It can be spread by direct contact, infected semen, through the air and other indirect methods. The secretions, in the form of mucous, from affected calves are extremely infectious and assist with disease transmission.
Once an animal has become infected with IBR, it remains infected for life, despite the development of an immune response. Worryingly, these animals can shed virus (through coughing and sneezing) at any time, particularly when stressed. This means that infection can suddenly occur again, or be spread at events such as sales or shows.
“Because bulls cannot be vaccinated they should be kept naïve, which also means they are highly susceptible to infection. Units should use an IBR marker vaccine on the rest of the herd, as it will ensure there are no infected animals and no virus circulating on the unit. Operating high standards of bio-security will ensure bulls remain naïve.”
IBR is easiliy spread in groups, especially when animals are under stress.