ERADICATION OF ENZOOTIC BOVINE LEUKOSIS IN DAIRY CATTLE FROM THE LOWER SILESIA REGION

摘要

The aim of the study was to present and review the measures applied in the programme of the eradication of enzootic bovine leukosis (EBL) in dairy cattle from the Lower Silesia region of Poland. At the beginning of the programme, there was no BLV freeherd and the seroprevalence was high and ranged from several to 70% in a herd. The programme was based on serological examinations of all animals in a herd followed by the separation of seroreactors. During execution of the programme in 1983-1989, only10%-16% of dairy herds were examined and none of them achieved BLV free status. Failure to eradicate EBL from dairy cattle at that time was caused by the lack of an official sanitary programme defining clear and uniform rules, which should be taken towards seropositive animals. The EBL control programme in 1991-2004, comprised of all dairy herds and resulted in the eradication of BLV infection from most of them. The success of the programme could be attributed to the correct application of sanitary rules. It was suggested that the long-lasting process of EBL eradication during 1983-2004, was based on the test and separation approach, applied in cattle population with high EBL prevalence, and could result in natural selection towards EBL resistant cattle.