Determining bovine viral diarrhea and infectious bovine rhinotracheitis infections in dairy cattle using precolostral blood.

The objective of this study was to determine if precolostral blood samples are useful to detect apparent fetal infections with bovine viral diarrhea (BVD) and infectious bovine rhinotracheitis (IBR) viruses. A convenience sample of 317 sera from 50 Canadian herds was used in the study. Antibody level was measured using 2 commercial IBR and BVD ELISA kits. Precolostral status of sera was confirmed on 304 samples using serum gamma-glutamyl transferase activity. Postcolostral serum samples yielded a higher proportion of positive results to IBR (OR = 86; 95% CI: 17.8 to 415.7) and BVD (OR = 199.3; 95% CI: 41.7 to 952.3) than did precolostral samples. All positive precolostral serum samples (n = 7 of 304) originated from calves born to vaccinated cows. Postcolostral positive serum samples (n = 11 of 13) originated mostly (60%) from calves born to non-vaccinated cows. Precolostral serum sampling can detect apparent fetal infections in a herd.