Genetic parameters for the occurrence of bovine viral diarrhea virus in Holstein cattle in Brazil

Bovine viral diarrhea virus (BVDV) is a significant infectious disease that affects livestock worldwide and is primarily associated with reproductive problems. Due to the absence of studies that have determined genetic parameters for the disease, the aim of this study was to estimate the heritability coefficient for the occurrence of BVDV and the correlation between estimated breeding values (EBVs) for BVDV and EBVs for productive, reproductive, and health traits in Holstein dairy cattle in Brazil. 18,464 BVDV phenotypes from animals tested between September 2015 and June 2021 across 8 commercial dairy farms were provided by the Holstein Cattle Breeders Association of Parana State, Brazil. Animals with an ELISA antigen test equal to or greater than 0.3 were classified as BVDV positive, and the prevalence of the disease was determined. For the genetic analyses, 6,202 phenotypes were used. Heritability coefficient and EBVs were estimated using a threshold animal model with GIBBSF90+ software, considering as fixed the effect of the class of animal's age (calves, from 1 to 183 days old; young animals, from 184 to 365 days old; heifers, from 366 to 599 days old; primiparous cows, from 600 to 1,000 days old; and multiparous cows, from 1,001 to 3,650 days old), as random the effect of the contemporary group (herd-year-season of the test), direct additive genetic, and residual. Pearson correlations were performed among the EBVs of bulls estimated for BVDV and the EBVs for productive, reproductive and health traits obtained from the Council on Dairy Cattle Breeding database. The overall prevalence of BVDV infection was 2.56 %. The estimated heritability was 0.18 +/- 0.09, suggesting some genetic variability. Most of the correlation estimates among EBVs were negative, non-significant, and close to zero. However, the estimates among BVDV and some traits were low-magnitude, negative, and significant (P<0.05) as Productive Life (-0.13), Daughter Pregnancy Rate (-0.07), Cow Conception Rate (-0.11), Cow Livability (-0.15), Displaced Abomasum (-0.11), Ketosis (-0.06), Mastitis (-0.09), and Feed Saved (-0.07). Therefore, genetic selection has limited potential in addressing the occurrence of BVDV. Nevertheless, it is recognized that the combination of disease eradication protocols with better-organized recording of phenotypes in herds could enable farms to improve herd health and animal welfare.