Reduction in Mortality of Calves with Bovine Respiratory Disease in Detection with Influenza C and D Virus

SIMPLE SUMMARY: Respiratory diseases in cattle are multifactorial diseases caused by many pathogenic viruses and bacteria that cause economic losses both directly and indirectly. The objectives of this study were to assess the dead or culling and reproductive performances in heifer calves with different isolated viruses of bovine respiratory disease. We collected nasal swabs from calves that had respiratory signs in Chiang Mai Province, Thailand, and data with respect to age, farm type, and respiratory signs were recorded on the date of sample collection; thereafter, the data on the dead or culling, mortality, and reproductive performance of the BRD calves were collected. This study shows that the virus that causes the respiratory disease mixes with bovine viral diarrhoea virus (BVDV), influenza C (ICV), and influenza D virus (IDV). The calves with mucous secretion and at a younger age had higher risks of culling or death. On the other hand, the calves with IDV had a lower risk of culling. For the reproductive efficiency of BRD calves, we did not find any relationship between individual virus exposure and reproductive performance. ABSTRACT: Both influenza C (ICV) and influenza D (IDV) viruses were recently included as bovine respiratory disease (BRD) causes, but their role in BRD has not been evaluated. Therefore, the mortality and reproductive performances of BRD calves with different isolated viruses were determined in this study. Data on 152 BRD calves with bovine viral diarrhoea virus (BVDV), bovine respiratory syncytial virus (BRSV), bovine coronavirus (BCoV), bovine parainfluenza virus 3 (BPIV-3), ICV, or IDV from nasal swab samples using real-time rt-PCR were used. The general data and respiratory signs were recorded immediately, and thereafter, the data on dead or culling calves due to BRD and reproductive performance were collected. The percentages of the BRD calves were 71.7%, 52.6%, 40.8%, 10.5%, 68.4%, and 65.8% for BVDV, BRSV, BCoV, BPIV-3, ICV, and IDV, respectively. Mucous secretion (OR = 4.27) and age ≤ 6 months (OR =14.97) had higher risks of mortality than those with serous secretion and older age. The calves with IDV had lower risks of culling than those without IDV (OR = 0.19). This study shows that most viral infections in BRD calves are a combination of viruses with BVDV, ICV, and IDV. In addition, IDV might have a role in reducing the severity of BRD calves.