Effect of bovine viral diarrhea virus infection on fertility of dairy heifers
Received 26 February 2003; accepted 2 June 2003.
Abstract
A prospective field study in heifers from birth to first breeding was undertaken on two commercial dairies to assess the effect of bovine viral diarrhea virus (BVDV) congenital and post-natal infection (PNI) on fertility. A high BVDV Type 2 antibody titer (1:4096) at 10 months of age was associated with 32 more days to conceive, compared with a low titer (1:128). Conversely, infection with BVDV by 5–6 months of age and high BVDV Type 2 titers 1 month before conception or breeding was associated with improved fertility. Heifers with evidence of congenital BVDV infection had lower fertility than non-infected heifers (15–42 days longer time-to-first AI), which depended on BVDV Type 2 titers at 10 months of age. Neospora caninum infection was associated with additional services per conception (SPC) and Leptospira interrogans infection was associated with a delay in the time-to-first breeding. It appears that under field conditions, the effect of subclinical BVDV infection on subsequent heifer fertility may be due to a complex of interrelationships among multiple BVDV infections that depend on the type and timing of infection relative to reproductive development and events.
aDepartment of Medicine and Epidemiology, School of Veterinary Medicine, University of California, Davis, CA 95616, USA
bCalifornia Animal Health and Food Safety Laboratory, University of California, Davis, CA 95616, USA
Corresponding author. Present address: Department of Clinical and Population Sciences, College of Veterinary Medicine, University of Minnesota, 1365 Gortner Ave. St. Paul, MN 55108, USA. Tel.: +1-612-625-7755; fax: +1-612-625-6241.
ABSTRACT