Concepts in the prevention of Bovine Respiratory Disease

Rome, Italy, 9-10 June 2008

Vaccination protocols, boosting cow immunity in late gestation and metaphylaxis on Spanish beef lots were some of the new angles on a well-known subject, discussed by scientists and vets who attended a recent Intervet/Schering-Plough Animal Health-sponsored Bovine Respiratory Disease (BRD) symposium in Rome.

Despite considerable research that has identified the risk factors and key pathogens, and a number of effective vaccines available to farmers, BRD remains one of the most significant causes of mortality in calves and costliest diseases in beef and dairy herds. Experts from many European countries discussed new research, heard practical experience from countries such as Spain, France and Belgium, and considered new solutions.

The advantages and disadvantages of a number of diagnostic techniques for practitioners faced with clinical signs were discussed. These included a comparison on the use of nasal swabs with alternatives such as broncho-alveolar lavage and transtracheal aspiration.

When it came to discussions on the effect of BRD on farm performance, one French study revealed that a typical bull rearing farm, fattening 150 bulls a year, would see a drop in net profit of 11% whenever there was a moderate incidence of BRD. At a high occurrence rate, profits fell by 26%. Results of sero-positivity on arrival and seroconversion six weeks later revealed that M haemolytica was responsible for 80% of young bulls being seropositive on arrival and 61% that sero-converted. In addition, Bovine Respiratory Syncytial Virus (BRSV) caused 32% and 80% respectively with PI3 at 57% and 79% respectively.

One option is to use metaphylaxis (mass medication), particularly on beef units which buy in stock from several sources – often several countries. However, a Spanish study showed that selective metaphylaxis, using rectal temperature to identify candidates, can reduce antibiotic use, yet is just as effective at controlling BRD and is cheaper than treating the whole herd.

Prevention is always best, but how can practitioners persuade farmers to keep vaccinating their stock? The answer to this age-old problem came from Belgium, where the advice was to educate farmers. They need to understand that vaccination is not a cure-all – learning about the effects of housing and management in this multi-factorial disease is critical for vaccines to work effectively. Boosting immunity in high value beef herds by an intensive vaccinating programme (up to five times) when there is huge infection pressure was also more cost-effective than a mild outbreak.

Another new option reported at the meeting was a study into vaccinating dry cows on a dairy farm, four weeks before calving. As well as complementing a calf vaccination programme, this practice boosts cow immunity at calving when she is typically immune suppressed.

Click on image for full sized picture

Click on above image for a full sized picture of the symposium participants.