Our objective was to examine whether herd health data can be used as an indicator or early warning for Bovine Virus Diarrhea virus (BVDV) circulation. Our goal is to provide the veterinary practitioner with an easy tool to be able to advice the farmer to take timely measurements on BVD.
Materials and Methods
In the Netherlands continuous animal health monitoring (CAHM) data is part of the mandatory herd held management by the vet. The vet has access to this data. Retrospective evaluation of herd CAHM data on farms with a history of BVDV circulation was performed to analyze if calf mortality could be an indicator of BVDV infection in a herd. Three farms with a history of being BVD virus free (period 1), followed by a period of BVDV circulation in 2014 (period 2) and becoming BVDV free again (period 3) were analyzed. Retrospective data of the 3 periods per farm were evaluated and health parameters such as calf mortality were calculated. The calf mortality was also compared to the Dutch national average and the data from BVDV free farms (n=38) in the same practice. Calf mortality is defined as the number of dead calves less than one year of age divided by the total number of calves less than one year old. Data from the rendering organization and the national identification and registration system is used.
During the period of Bovine Virus Diarrhea virus circulation all three farms showed an increase in calf mortality (5,75) compared to the period before (0,54) and after (2,25). Also compared to the Dutch national average calf mortality of 3,23 calves in the same year (2014), the calf mortality on farms with Bovine Virus Diarrhea virus circulation was increased. The average calf mortality of 2,57 on the Bovine Virus Diarrhea virus free herds in the same practice was lower than the Dutch national average.
The results shows that calf mortality seems to be lower on BVDV free farms and higher on farms with BVDV circulation. Herd health data, such as calf mortality, can be used as indication for BVDV circulation. This data can be monitored by the vet even without being on the farm. The vet has an extra tool to advice the farmer to take timely measurements on BVD.