Bovine respiratory disease (BRD) is the most common cause of morbidity and mortality in young cattle, with estimates suggesting it costs the UK cattle industry £50 million a year (Agriculture and Horticulture Development Board, 2024). This makes it essential that vets and farmers work together to improve welfare, as well as productivity.
Healthy animals are more productive and will achieve higher outputs such as daily live weight gain, lower age at first calving, higher milk yields, and feed conversion rates.
BRD is caused by a complex interaction between viruses, bacteria and mycoplasma pathogens, many of which live harmlessly in the respiratory tract of healthy cattle as commensal organisms (Campbell, 2022). The disease is often triggered during or after a stressful period by a viral infection and a subsequent infection of the airways with opportunistic bacteria. This combination of stress factors and infectious agents makes young cattle especially vulnerable.
Bovine respiratory disease improvement project
CVS' Dyfed Farm Vets is undertaking a project to improve the use of diagnostic testing of respiratory disease in calves to better manage herds, guide appropriate treatments and reduce the unnecessary use of antibiotics – a key aim of the OneHealth initiative.
Within just one year it has increased the use of nasopharyngeal swabbing by vets on farms by 55%. Similar increases in serology testing for respiratory pathogens were also seen.
Dyfed Farm Vets hopes to reduce the level of BRD through increased use of nasopharyngeal swabbing, serology testing and resulting tailored farm management protocols.
Since September 2022, 10 vets in the practice have submitted either nasal swabs or serology samples from 15 farms for respiratory pathogen investigations. The sample collection method has been determined on a case-by-case basis depending on the type of enterprise, age of animals and sourcing policy.
A resulting mixture of agents have been identified from the samples collected at CVS Labs. These have included; Mycoplasma (47%), IBR (13%), P13 (47%), Histophilus (20%), RSV (47%), Mannheimia (33%), BVD (33%) and Pasteurella (47%) being identified across the two sampling methods. Interestingly, the majority of the nasopharyngeal (PCR) results showed mixed infections involving bacterial, viral and mycoplasma pathogens, whereas the serology testing showed only viral and mycoplasma pathogens to be present. This could be due to the presence of commensal (usually bacterial) pathogens in the nasopharyngeal region or due to case selection. All of these agents have the potential to cause BRD, whether acting in isolation or in conjunction with other agents as demonstrated by these results.
The results of each farm's respiratory pathogen tests have been presented to each farmer and discussions held on taking a more preventative approach. These have included conversations on biosecurity, immunity, housing, environmental management, vaccination and treatment protocols. Through this process, Dyfed Farm Vets have gained a greater understanding of problems specific to each client enabling the production of bespoke action plans.
Targeted vaccination
The respiratory pathogen results have also enabled Dyfed Farm Vets to target the right vaccine to the right farm to cover the key risk periods for those animals. There has been a 60% uptake in vaccination following respiratory testing on farms. All vaccinations have been timed in relation to peaks in clinical cases and pre-stress periods - such as weaning, group movements or transport – to ensure covering animals against the correct pathogen effectively. Taking this preventative herd health measure has resulted in significantly fewer antibiotics being required to treat respiratory infections and disease in the past year.
Harriet Spittle, a vet at Dyfed Farm Vets, said: ‘Many of our clients have calves on farm, whether homebred or bought in. So to safeguard their herds and income we wanted to do more to effectively prevent bovine respiratory disease. The new nasopharyngeal swabbing and serology testing programme we've introduced over the last year has given us significant data. We're now using this to help farmers to successfully implement a range of ‘on farm’ measures to help prevent and vaccinate against BRD – and to reduce antibiotic use.’