The prevalence of serum neutralizing antibodies to infectious bovine rhinotracheitis virus in Scotland.

The prevalence of serum neutralizing antibodies to infectious bovine rhinotracheitis virus in 1152 serum samples from adult cattle in 114 dairy and beef herds in different regions of Scotland was 12%. In the Grampian region, the number of seropositive cattle in the self-contained herds was significantly less (P less than 0.01) than in the "other" herds. Holstein cattle had been introduced into five of these "other" herds, and significantly more (P less than 0.01) of the samples from these five herds were seropositive compared with the samples from the rest of the "other" herds in the same region into which recently purchased cattle had been introduced. The introduction of Holstein cattle was also a major factor in the association between the prevalence of antibodies and herd size in the Grampian region. The prevalence of serum neutralizing antibodies to infectious bovine rhinotracheitis virus was significantly greater (P less than 0.001) in this survey than in those previously undertaken in the United Kingdom.