An attempt to establish a herd serologically negative for infectious bovine rhinotracheitis

To improve his position as an exporter of pedigree animals, an owner wished to establish his herd as serologically negative for infectious bovine rhinotracheitis (IBR). After a test on all animals older than six months the herd was split into seronegative and seropositive groups. The seronegative group was tested four times during the first year, twice during the second year and given a final test 12 months later; any positive animals were removed. The results indicated that in the right circumstances the establishment of an IBR seronegative hard is practicable.