Student Case Presentation
On arrival upper respiratory tract microbiome analysis and Histophilus somni incidence with serology in midwestern backgrounded steers
| Date/Time: |
9/12/2024 09
|
| Presenter: |
Alexander Bebb |
| Veterinary School: |
IA |
Abstract:
Bovine respiratory disease (BRD) is the number one cause of morbidity and mortality in confined cattle feeding enterprises. It is reported that the industry loses > $800 million in mortality, treatment cost, and lost production.
Objectives included investigating changes in prevalence of BRD bacteria in the nasal passage, determining the seroprevalence of Histophilus somni among calves with no history of H. somni vaccination at arrival and after vaccination, and investigating a relationship between nasal microbiome and H. somni titer on morbidity and mortality.
The population included (n=79), 700 lbs. Angus steers without prior vaccination to H. somni randomized into two groups. TX1 received Bovilis Vision 7 and TX2 received Bovilis Vision 7 HS. Both received Bovilis Vista Once SQ. The prevalence of Mannheimia haemolytica, Pasteurella multocida, Mycoplasma bovis, and Histophilus somni were analyzed via deep nasal swab PCR on arrival and 28 days post vaccination. Histophilus somni titers were measured by serum collection upon arrival and 28 days post vaccination.
Pasteurella multocida prevalence on Day 0 was higher (p<0.01) than on Day 28. Mycoplasma bovis, M. haemolytica and H. somni prevalence did not differ over time or treatment group. Mean H. somni titers on arrival did not differ (p = 0.58) between the vaccinated group vs. non-vaccinated group. We failed to reject the null hypothesis TX1=TX2. However, H. somni titers differed (p < 0.01) over time in both groups with an overall mean at Day 0 (8.32 SEM:0.16) lower than on Day 28 (8.91 SEM:0.16). There were no morbidity or mortality reported.
This study provides evidence that backgrounded calves seroconvert to H. somni through natural exposure. It appears the H. somni killed bacterin did not produce an anamnestic humoral response. Finally, we found that deep nasal swabs were not predictive of BRD within the timeframe of this study.
