Effect of Bovine Herpesvirus 1 infection on pregnancy rate of beef cows in Uruguay

Abstract

Bovine herpesvirus type 1.1 (BoHV-1.1) can cause infertility and abortions. The objective of the present work was to  evaluate the viral transmission with the use of BoHV-1 infected bulls and its influence in the pregnancy rate. Eighty three cows were divided in 3 groups: negative control group (GC) was mated with a seronegative bull, seropositive group (GS) with a seropositive latently infected bull (infected 60 days prior to the experiment) and a third group with a bull with BoHV-1.1 acute infection (GIA). BoHV-1 seroneutralizing antibody detection was used as indication of viral infection. Conception was diagnosed by ultrasonography and rectal palpation every 30 days until 180 days after the end of the breeding period. BoHV-1.1 was rapidly transmitted in the GIA group as specific antibodies were detected in 70% of the cows in the first 30 days of the experiment. At 52 days, the GIA group had a lower pregnancy rate (33%) than the GC group (86%; P<0.001). There were no significant differences on the pregnancy rates between the GS and GC groups. Reproductive losses were observed during the first two cycles only with the BoHV-1 acute infected bull.