After synchronization, heifers were submitted to a bull
breeding pasture for 45 days. At the end of the breeding period, heifers were assessed for
pregnancy using ultrasonography. Progesterone concentrations were evaluated at estrus and
10 days after unsynchronized and synchronized estrus, at initial pregnancy check, and at the
end of the study. All pregnant heifers in groups A and B and five pregnant heifers in group C
were euthanized between 44 and 62 days of gestation and ovarian and conceptus tissues
were assayed for BVDV and BoHV-1.